The James Webb Space Telescope isn’t even fully operational yet, but researchers are getting more and more excited about what it can do. In a recent study, researchers claim we may be on the cusp of being able to discover other civilizations based on specific types of pollution in their planets’ atmosphere.
The alien ozone hole
Human society has changed a lot over the centuries, but the shifts in the past 200 years have been truly mind-bending. The Industrial Revolution changed how many things work, fueling, well, a revolution in our society. If you were a patient alien scouting the Earth from close by (or from farther away, but with a good enough telescope) you may have seen the signs of this industrial revolution happening through the emissions we produced by burning fossil fuels.
But they could see other forms of pollution even better.
Chlorofluorocarbons (CFCs) are a type of chemical notorious for causing the ozone hole in the 1980s (until regulations entered into force to address the problem). They’re produced industrially as refrigerants and cleaning agents — and if an alien civilization would resemble ours, it would likely also start producing them at some point. CFCs are also very unlikely to appear naturally so if you see them in a planet’s atmosphere, someone is producing them artificially. Furthermore, even if a civilization stops producing them or reduces their production (like we did), they still have a long life in the atmosphere, meaning they could be detected long after they’ve been produced.
This brings us to an interesting point: our most clear sign of civilization may also be one of our worst impacts on the planet — pollution. We don’t really know whether this would also be the case for an alien civilization but there’s a decent chance it is. Now, we could also have a way to detect this, thanks to the James Webb Space Telescope (JWST).
Looking for pollution on alien planets isn’t the main objective of the JWST, and its capability in this regard is limited. For instance, if a planet is too bright, it could drown out the CFC signal. So the new study focused on M-class stars — a type of dim, long-lived red dwarf. Researchers believe M-class stars make out the majority of stars in the universe.
A team of researchers led by Jacob Haqq-Misra, an astrobiologist at the Blue Marble Space Institute of Science, analyzed the JWST’s ability to detect CFC around a TRAPPIST-1, a typical red dwarf relatively close to Earth (40 light-years away). TRAPPIST-1 also has several Earth-sized planets within the habitable zone, so it would be a good place to start looking for alien civilizations (although M-stars, in general, aren’t considered to be conducive to life).
According to the study, there’s a good chance that the JWST could be able to detect CFC in this type of scenario.
“With the launch of JWST, humanity may be very close to an important milestone in SETI [the Search for Extra-Terrestrial Intelligence]: one where we are capable of detecting from nearby stars not just powerful, deliberate, transient, and highly directional transmissions like our own (such as the Arecibo Message), but consistent, passive technosignatures of the same strength as our own,” the researchers write in the study.
Funny enough, this detection isn’t necessarily reciprocal: just because we can detect potential CFCs around a planet doesn’t necessarily mean aliens could do the same for us. Remember when we said in order for the method to work, the planet needs to not be too bright? Well, the Sun is pretty bright, and it sends out enough light that it would obstruct much of the useful signal. So if an alien civilization were to exist closeby, there’s a chance we could be able to spot them without them being able to do the same thing to us. Of course, this is all speculation at this point, but it’s something that astronomers are looking into as JWST will soon become operational.
The telescope is currently in its calibration stage. James Webb is expected to offer researchers an unprecedented view of the universe, focusing on four main objectives:
light coming from the very first stars and galaxies that formed after the Big Bang;
The James Webb telescope has completed another milestone of its journey. The so-called “Segment Image Identification” rendered one star 18 times, arranging the unfocused images into a hexagonal shape. Eventually, these 18 images will perfectly align into a single, sharp image — but for now, researchers are excited about this interim result.
The James Webb Space Telescope’s (JWST) primary mirror, the Optical Telescope Element, consists of 18 hexagonal mirror segments made of gold-plated beryllium. Together, these mirrors combine to create a 6.5-meter (21 ft) diameter mirror — almost three times larger than Hubble’s 2.4 m (7.9 ft) mirror. But aligning them perfectly is a delicate process.
As part of this process, engineers are now using each mirror individually to create 18 unfocused copies. We’ve previously seen this happen but now, they’re organized in a shape that resembles JWST’s hexagonal mirrors.
“We steer the segment dots into this array so that they have the same relative locations as the physical mirrors,” said Matthew Lallo, systems scientist and Telescopes Branch manager at the Space Telescope Science Institute. “During global alignment and Image Stacking, this familiar arrangement gives the wavefront team an intuitive and natural way of visualizing changes in the segment spots in the context of the entire primary mirror. We can now actually watch the primary mirror slowly form into its precise, intended shape!”
As Lallo mentioned, the current orientation will make it easier to further arrange and focus the mirrors. This alignment stage began on February 2 and is expected to be completed by the end of the month. After this stage, the “image stacking” stage will begin, with researchers working to bring the 18 images on top of each other into one clear, focused view. It’s expected that the telescope will become fully operational in June 2022.
It’s one of the most ambitious space missions in recent history, an “Apollo moment” that will fundamentally alter our understanding of the universe, NASA says.
James Webb is expected to offer researchers an unprecedented view of the universe, focusing on four main objectives:
light coming from the very first stars and galaxies that formed after the big bang;
galaxy formation and evolution;
star formation and planet formation;
planetary systems and the origins of life.
We expect the first images and studies to come in from JWST later this year.
It’s done: NASA’s team behind the James Webb Space Telescope successfully deployed its massive primary mirror, marking a big milestone in one of the most complicated missions in space. Now, the team will focus on directing the telescope to its final destination to explore every phase of cosmic history, but so far, so good.
The two winds of the mirror had been folded inside the nose cone of the rocket before the launch. After weeks of other important spacecraft deployments, the team started to unfold the hexagonal segments of the mirror, the largest ever launched into space. This was done at the end of last week and was then followed by the secondary mirror.
The honeycomb-shaped mirror measures 21 feet (6.5 meters) across, three times the size of Hubble’s mirror. It will be sensitive enough in order to see celestial objects undetectable by previous observatories, enabling us to peer into the depths of the universe with unprecedented accuracy. Its deployment also marks the end of a very important first phase after the Webb was launched on Christmas Day.
“NASA achieved another engineering milestone decades in the making. While the journey is not complete, I join the Webb team in breathing a little easier and imagining the future breakthroughs bound to inspire the world,” NASA Administrator Bill Nelson said in a statement. “The James Webb Space Telescope is an unprecedented mission,” he added.
The telescope is expected to arrive at its destination by January 23. Then it will use its engines to reach a spot about 1.5 million kilometers (930,000 miles) away from Earth, known as L2 — a so-called Lagrangian Point where gravity will keep the telescope stable. But there’s a lot more coming up. Team members will spend the next two weeks aligning all mirror segments to perform as one, NASA said in a press conference.
NASA chose L2 specifically due to its ideal conditions for Webb to work. Its great distance from the sun, combined with its recently deployed sunshield, will allow the telescope to do its infrared observations without any disturbance. If all goes well, and we hope it does, Webb will give us an inside look into the universe and its evolution.
Webb has a set of science instruments that will allow observations in mid-infrared, near-infrared and visible wavelengths – including a combination of fine guidance sensor and spectrograph, a near-infrared camera and spectrograph, and a mid-infrared instrument. It’s the world’s largest and most complex space science telescope.
This week, NASA will start with the basic aligning of the mirrors, a task that will take about three months in order to get them ready for the telescope’s first testing image. These will likely be blurry, NASA said, anticipating any questions, as Webb won’t be fully ready yet. More imaging and testing will be needed to get the configuration right
“The successful completion of all of the Webb Space Telescope’s deployments is historic,” Gregory L. Robinson, Webb program director at NASA, said in a statement. “This is the first time a NASA-led mission has ever attempted to complete a complex sequence to unfold an observatory in space – a remarkable feat for our team, NASA, and the world.”
It took a few more days than expected but the enormous 21-meter (70-foot) sunshield of the James Webb Space Telescope has now been deployed, an important milestone that brings the telescope closer and closer to becoming operational. NASA team members clapped and cheered as they followed the process, but there’s still a bit left to go before the telescope can commence operations.
The telescope, which cost $10 billion and was launched on Christmas Day, is the most powerful ever sent to space, with a mirror six times bigger than the one included in the Hubble. It has been carefully unfolding in zero gravity for days. While all the required setup steps are tricky, setting up the sunshield was considered the most difficult part.
It was a big moment for the engineering teams at NASA and the American aerospace manufacturer Northrop Grumman, the main contractor for the telescope. Years of testing on sub-scale and full-scale models paid off as controllers separated the five layers of the sunshield and tensioned them – all controlled remotely from Earth.
“This is the first time anyone has ever attempted to put a telescope this large into space,” Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate, said in a statement. The success of its most challenging deployment – the sunshield – is an incredible testament to the human ingenuity and engineering skill.”
The very important sunshield
The sunshield will safeguard the telescope from the heat and the light of the Earth, Sun, and Moon. The five plastic layers are as thin as a human hair and are coated with reflective metal. Together, they reduce exposure from the Sun from 200 kilowatts to a fraction of a watt – crucial to keep the scientific instruments cold enough to work.
The team at NASA had delayed the sunshield deployment and tensioning to make sure Webb’s power systems were good to go. The task meant using 139 of the 178 release mechanisms included in the telescope, as well as eight deployment motors, 400 pulleys, and 90 cables. Any mistakes at this part could have doomed the telescope.
“Unfolding Webb’s sunshield in space is an incredible milestone, crucial to the success of the mission,” Gregory L. Robinson, Webb’s program director at NASA, said in a statement. “Thousands of parts had to work with precision for this marvel of engineering to fully unfurl. The team has accomplished an audacious feat with the complexity of this deployment.”
While it all went smoothly, several steps still remain for the telescope to become operational – including the deployment of the telescope’s main and secondary mirrors. This would start this weekend and last for 10 days. It’s the biggest mirror NASA has ever built, so big that engineers had to design the Webb as moving parts that can fold in the rocket.
The telescope is now on its way to its job site, a million miles from Earth, where it will sit in a solar orbit and be held stable by the gravitational pull of the Sun and the Earth. Once fully operational, the telescopes will look at all aspects of cosmic history. Thanks to its infrared observations, it can look deeper into the universe and even look back in time, enabling us an unprecedented view into the very depths of the universe.
NASA’s new James Webb Space Telescope is one step closer to a launch in October after passing two critical test steps.
Known as comprehensive systems tests, these procedures are meant to ensure that vital systems aboard a craft are fully functional ahead of a launch. The two steps that the telescope successfully passed are tests pertaining to its internal electronic suite, as well as the confirmation that its four scientific instruments can send and receive data properly through the network it will be using in space. The tests took place at Northrop Grumman in collaboration with the Space Telescope Science Institute in Baltimore.
Closer to space
“It’s been amazing to witness the level of expertise, commitment, and collaboration across the team during this important milestone,” said Jennifer Love-Pruitt, Northrop Grumman’s electrical vehicle engineering lead on the Webb observatory. “It’s definitely a proud moment because we demonstrated Webb’s electrical readiness.”
“The successful completion of this test also means we are ready to move forward toward launch and on-orbit operations.”
The tests took 17 consecutive days, during which the team powered on all of the telescope’s electrical components, and ran them through their operation procedures to ensure that they’re all running smoothly and can share data among themselves. All the electrical boxes on the craft have two sides to allow for redundancy, and they were all tested successfully.
After this step came the ground segment test, which simulates a mission plan for the craft’s four instruments to follow. This included commands to sequentially turn on, move, and operate each of its instruments, and meant to establish whether these devices would work as intended. The commands were relayed from Webb’s Mission Operations Center (MOC) at the Space Telescope Science Institute (STScI) in Baltimore, to test whether the network that’s meant to shuttle data to and from the satellite once in orbit works. As such, the commands were relayed through the Deep Space Network, an international array of radio antennas that NASA uses to communicate with spacecraft in orbit. Special equipment was used to simulate the satellite being in space, not on the surface.
At least from an internal systems standpoint, then, the James Webb telescope is good to go.
“Working in a pandemic environment, of course, is a challenge, and our team has been doing an excellent job working through its nuances. That’s a real positive to highlight, and it’s not just for this test but all of the tests we’ve safely completed leading up to this one,” said Bonnie Seaton, deputy ground segment and operations manager at Goddard.
“This recent success is attributable to many months of preparation, the maturity of our systems, procedures, and products, and the proficiency of our team.”
The ground team is now preparing for the next set of technical tests, which will include folding of its sunshield and deployment of the mirror. If these go well, the James Webb Space Telescope will be shipped to its launch site.
An international team of astronomers has discovered a nearby exoplanet orbiting a red dwarf star that is perfect for deeper investigation. In particular, this exoplanet could be a prime target for precise atmospheric measurements, something that, for planets outside the solar system, has so-far eluded astronomers.
The team’s findings documenting the discovery of this relatively close super-Earth–so-called because they have a mass greater than our planet but still lower than planets like Uranus and Neptune which are classified as ‘ice giants’–are published in the latest edition of the journal Science.
The team discovered Gliese 486 b whilst surveying 350 small red dwarf stars for signs of low-mass planets using the CARMENES spectrograph mounted on the 3.5m telescope at the Calar Alto Observatory telescope, Spain. The exoplanet was found due to the ‘wobble’ it caused in the orbit of its parent star.
“Our team is searching primarily for Earth-like and super-Earth planets orbiting nearby stars. In this case, we have found a nearby super-Earth, just 26 light-years away orbiting a small star every 1.5 or so Earth days,” Karen Collins, an astronomer at the Center for Astrophysics, Harvard & Smithsonian, and a co-author on the paper tells ZME Science. “We were certainly excited to have found a transit signal in the light curve of a star that is so close to the Sun in astronomical terms.
“We quickly realized that Gliese 486 b, with radial velocity mass measurements in hand, would likely become a prime target for additional detailed follow-up studies, particularly atmospheric investigations.”
Karen Collins, Center for Astrophysics, Harvard & Smithsonian
These investigations could include searching for the conditions necessary for life, or even for biomarkers left behind by simple lifeforms.
Colins continues by explaining that it is Gliese 486 b’s proximity–it is the third closest transiting exoplanet yet to be uncovered– that, amongst other things like its temperature, makes it a good candidate for more in-depth study. “Because Gliese 486 b is so close to the solar system, relative to most known transiting exoplanets, we may be able to probe the atmosphere of the planet using the upcoming James Webb Space Telescope and possibly other telescopes,” she explains.
That is, of course, if it actually has an atmosphere.
What We Know About Gliese 486 b So Far…
Whilst the team of astronomers may not yet be certain that Gliese 486 b has an atmosphere, there are some things that they do know about the exoplanet and its red dwarf home star.
“It is only about 30% larger than Earth but has a mass of about 2.8 times that of our planet,” study author Trifon Trifonov, Max Planck Institute for Astronomy, explains to ZME Science. The researcher adds that models suggest that the exoplanet’s composition is similar to Venus and Earth, including a metallic core. “Anyone standing on Gliese 486 b would feel a gravitational pull that is about 70% stronger than what we experience on Earth.”
In addition to being denser than the earth, Gliese 486 b is also much hotter according to Trifon. This is because the exoplanet revolves around its host star on a circular orbit every 1.47 days, with one side permanently pointing towards its parent star.
“The proximity to the red dwarf Gliese 486 heats the planet significantly, making its landscape hot and dry, interspersed with volcanos and glowing lava rivers,” Trifon says. “There are quite a few super-Earth type exoplanets already discovered. All of these exoplanets are exceptional on their own. In this context, the physical characteristics of Gliese 486 b are not uncommon. However, the proximity of Gliese 486 b, allowed us to measure its mass with unprecedented precision, thanks to observations done with the CARMENES and the MAROON-X instruments.”
From the information the astronomers do possess regarding Gliese 486 b, especially its mass, Collins adds that the clues it also has an appreciable atmosphere are in place.
“Because we do know that the planet surface gravity is relatively high–about 70% stronger than Earth–we believe that there is a chance the planet may have retained an appreciable atmosphere.”
Karen Collins, Center for Astrophysics, Harvard & Smithsonian
Using NASA’s Transiting Exoplanet Survey Satellite (TESS) spacecraft the astronomers were able to deduce that Gliese 486 b periodically crosses the stellar disk of its parent red dwarf star, a rare and fortuitous event.
“For transiting planets like Gliese 486 b, we have two primary methods to probe the atmospheres, if they exist,” Collins continues. “Transit spectroscopy allows us to study the planet’s atmosphere as the planet passes in front of the star from the telescope’s perspective.”
Collins says that should the exoplanet possess an atmosphere part of the light from its parent star that reaches our telescopes will have been filtered through this. This means that the light profile filtered by the atmosphere can be compared to an unfiltered version when the planet is not in front of the star.”By comparing the in-transit spectrum of the star with a spectrum of the star when the planet is not transiting, we can isolate atmospheric signals from the planet and possibly detect some of the components of the atmosphere.”
The second method detailed by Collins involves the detection of radiation directly from an exoplanet’s hot surface as it occupies different orbital phases across the star’s face. The emission spectrum that gives this technique its name–emission spectroscopy–reveals characteristic traits that indicate the presence of certain elements emitting and absorbing light in the exoplanet’s atmosphere.
“Its temperature of around 700 Kelvin makes it suitable for emission spectroscopy and phase curve studies in search of an atmosphere,” adds Trifonov.
The Golden Age of Exoplanet Science
Concluding our interview I ask Collins and Trionov if we are entering a ‘Golden Age’ for exoplanet science. They are both quick to correct me. “I would say we are living in it!” Trinov exclaims. “During the past three decades, astronomers have discovered thousands of exoplanets, and the number is increasing daily.
“Every day, we enhance our knowledge about the physical properties of exoplanets, their formation, and evolution.”
Trifon Trifonov, Max Planck Institute for Astronomy
Collins is equally assured that exoplanet science is in its prime, but adds that there is no decline in sight. “Frankly, I believe we have been in the golden age of exoplanet science for over a decade now,” the astronomer says. “Even so, with the advent of TESS to discover and measure the size of nearby small transiting planets, precise radial velocity machines like that of the CARMENES consortium and the MAROON-X instrument to measure their masses, and soon the James Webb Space Telescope to investigate their atmospheres, it’s fair to say that we are entering the golden age of well-characterized small planet exoplanet science.”
And Collins is clear how lucky she regards herself for just being involved with astronomy at this crucial juncture in its history. “I am excited to be involved in the search for and characterization of Earth-sized and Super-Earth planets such as Gliese 486 b,” says explains enthusiastically. “Precise atmospheric measurements are likely around the corner! What will this relatively new scientist from a small but progressive astrophysics program at a school in Kentucky be involved with next? Will we soon discover an Earth twin with an Earth-like atmosphere or even signs of life in an atmosphere?
“It is almost as if I’m living in a series of Star Trek. I can’t wait to see what we discover next!”
Karen Collins, Center for Astrophysics, Harvard & Smithsonian
Unfortunately, science journalists don’t generally carry crystal balls as part of their arsenal, and if 2020 taught us anything, it’s not always safe to predict what the forthcoming year will bring. With that said, there are some space and physics developments that we can be fairly certain that will come to pass in 2021.
These are ZME Science’s tips for the top space science and physics events scheduled to occur in 2021.
Back to the Beginning with the James Webb Launch
It’s almost impossible to talk about the future of astronomy without mentioning NASA’s forthcoming James Webb Space Telescope (JWST). To call the launch of Webb ‘much-anticipated’ is a vast understanding.
The reason astronomers are getting so excited about the JWST is its ability to see further into the Universe, and thus further back in its history than any telescope ever yet devised. This will allow astronomers to observe the violent and tumultuous conditions in the infant Universe. Thus, it stands poised to vastly improve our knowledge of the cosmos and its evolution.
Part of the reason for JWST’s impressive observational power lies in its incredible sensitivity to infrared light–with longer wavelengths than light visible with the human eye.
The ability to observe the early Universe could help settle confusion about what point in its history galaxies began to form. Whilst the current consensus is that galaxies began to form in later epochs, a wealth of recent research has suggested that galaxies could have formed much earlier than previously believed.
“Galaxies, we think, begin building up in the first billion years after the big bang, and sort of reach adolescence at 1 to 2 billion years. We’re trying to investigate those early periods,” explains Daniel Eisenstein, a professor of astronomy at Harvard University and part of the JWST Advanced Deep Extragalactic Survey (JADES). “We must do this with an infrared-optimized telescope because the expansion of the universe causes light to increase in wavelength as it traverses the vast distance to reach us.”
The reason infrared is so important to observe the early Universe is that even though the stars are emitting light primarily in optical and ultraviolet wavelengths, travelling these incredible distances means light is shifted into the infrared.
After years of setbacks and delays and an estimated cost of $8.8 billion the JWST is set to launch from French Guiana, South America, on 31st October 2021.
JET Will Have Star Power
The race is on to achieve fusion power as a practical energy source here on Earth. Nuclear fusion is already the process that powers the stars, but scientists are looking to make it an energy source much closer to home.
When it comes to bringing star power down to Earth the Joint European Torus (JET)–the world’s largest tokamak–leads the way, housing plasmas hotter than are found anywhere else in the solar system, barring the Sun.
A tokamak is a device that uses a powerful magnetic field to trap plasma, confining it in a doughnut-like shape. Containing and controlling these plasmas is the key to generating energy through the fusion process. Within the plasma, particles collide with enough energy to fuse together forming new elements and releasing energy.
The process is cleaner and more efficient than fission power, which rips the atoms of elements apart, liberating energy whilst leaving behind radioactive waste.
JET itself isn’t a power station, rather it was designed to conduct experiments with plasma containment and study fusion in conditions that approach that which will be found in working fusion power plants. So, whilst the International Thermonuclear Experimental Reactor (ITER)–set to be the world’s largest tokamak–is still under construction and won’t be operational until at least 2025, this year is set to be an important year for the experiment that inspired it.
Following upgrades conducted during 2020, JET is scheduled to begin experiments with a potent mix of the hydrogen isotopes deuterium and tritium (D-T). This fuel hasn’t been used since 1997 due to the difficulties presented by the handling of tritium– a rare and radioactive isotope of hydrogen with a nucleus of one proton and two neutrons.
The JET team will be looking to attain an output similar to the 16 megawatts of power that was achieved in ’97, but for a more sustained period and with less energy input. The initial test at the end of the 20th century consumed more power than it produced.
Back to the Moon in 2021
2021 will mark the 52nd anniversary of NASA’s historic moon landing and will see the launch of several missions back to Earth’s natural satellite as well as continuing efforts to send humans following in the footsteps of Armstrong and the crew of Apollo 11.
As part of NASA’s deep space exploration system, Artemis I is the first in a series of increasingly complex missions designed to enable human exploration of the Moon and beyond.
Artemis I will begin its journey aboard the Orion spacecraft, which at the time of its launch in November will be the most powerful spacecraft ever launched by humanity producing a staggering 8.8 million pounds of thrust during liftoff. After leaving Earth’s orbit with the aid of solar arrays and the Interim Cryogenic Propulsion Stage (ICPS) Orion will head out to the moon deploying a number of small satellites, known as CubeSats.
After a three week journey to and from the moon and six weeks in orbit around the satellite, Orion will return home in 2022, thus completing a total journey of approximately 1.3 million miles.
NASA isn’t the only space agency with its sights set on the moon in 2021. The Indian Space Research Organisation (ISRO) will launch the Chandrayaan-3 lunar lander at some point in 2021. It will mark the third lunar exploration mission by ISRO following the Chandrayaan-2’s failure to make a soft landing on the lunar surface due to a communications snafu.
Chandrayaan-3 will be a repeat of this mission including a lander and rover module, but lacking an orbiter. Instead, it will rely on its predecessor’s orbiter which is still in good working despite its parent module’s unfortunate crash lander. Should Chandrayaan-3 succeed it will make India’s ISRO only the fourth space agency in history to pull off a soft-landing on the lunar surface.
Back with a Blast: The LHC Fires Up Again
The world’s largest, most powerful particle accelerator, the Large Hadron Collider (LHC) ceased operations in 2018 and this year, after high-luminosity upgrades, it will begin to collide particles again.
During its first run of collisions from 2008 to 2013 physicists successfully uncovered the Higgs Boson, thus completing the standard model of particle physics. With the number of collisions increased significantly, in turn, increasing the chance of spotting new phenomenon, researchers will be looking for clues of physics beyond the standard model.
The function of the LHC is to accelerate particles and guide them with powerful magnets placed throughout a circular chamber that runs for 17 miles beneath the French-Swiss border. When these particles collide they produce showers of ‘daughter’ particles, some that can only exist at high energy levels.
These daughter particles decay extremely quickly–within fractions of a second– and thus spotting them presents a massive challenge for researchers.
Luminosity when used in terms of particle accelerators refers to the number of particles that the machine can accelerate and thus collide. More collisions mean more daughter particles created, and a better chance of spotting exotic and rare never before seen particles and phenomena. Thus, high luminosity means more particles and more collisions.
To put these upgrades in context, during 2017 the LHC produced around 3 million Higgs Boson particles. When the High-Luminosity LHC (HL-LHC) begins operations, researchers at cern estimate it will be producing around 15 million Higgs Bosons per year.
Unfortunately, despite firing up for a third run after these high luminosity upgrades, there is still work to be done before the LHC becomes the HL-LHC.
The shutdown that is drawing to completion–referred to by the CERN team as Long Shutdown 2 (LS2)–was just part of the long operations that are required to boost the LHC’s luminosity. The project began in 2011 and isn’t expected to reach fruition until at least 2027.
That doesn’t mean that the third run of humankind’s most audacious science experiment won’t collect data that reveals stunning facts about the physics that governs that cosmos. And that collection process will begin in 2021.
Many mysteries surround conditions in the early Universe, chief amongst these is the question of how and when galaxies began to form. At some point in the Universe’s history, gravitational instability brought together increasingly larger clumps of matter, beginning with atoms, dust, and gas, then stars and planets, clusters and then massive galaxies.
Whilst early protogalaxies may have formed as early as a few hundred million years after the Big Bang, the first well-formed galaxies with features such as spiral arms, rings and bars are thought to have only formed around 6 billion years into the Universe’s 13.8 billion year lifetime.
Astronomy has, in general, confirmed this. With closer and thus later galaxies displaying characteristics such as rings, bars and spiral arms, like our own home, the Milky Way. Features lacking in more distant, earlier galaxies.
New discoveries, however, are challenging this accepted view, with three recent pieces of research, in particular, suggesting that well-ordered and massive galaxies existed much earlier in the Universe than previously believed. This either means that the formation of galaxies began much earlier than expected or progressed much faster than many models suggest.
As a consequence scientists may have to refine models of galaxy formation to account for much earlier or much more rapid evolution.
The key to solving the mystery of how soon after the Big Bang galaxies with definitive shapes and features such as thin discs and spiral arms formed begins with examining theories that describe this formation. One family of theories which implies these processes occur over a prolonged period of time, and another, that suggests formation can proceed much more quickly.
Bottom’s Up! Did Formation Start Earlier or Proceed Quicker?
The simplest model of galaxy formation suggests that at a time when the Universe was mostly hydrogen and helium, such structures emerged from dense clouds of gas that collapsed under their own gravity. This so-called ‘monolithic model’ was the first suggested formation process for galaxies and the stars that comprise them and is referred to as a ‘bottom-up’ or hierarchical formation model.
There are also ‘top-down’ formation models that suggest galaxies may have emerged from larger conglomerates of matter that collapsed in a similar fashion but then went on to break apart, but these currently aren’t favoured by most cosmologists.
Under the influence of gravity, gas and dust collapse into stars which are drawn together as clusters, then superclusters, and finally galaxies. The question is, how do galaxies grow and develop their characteristics?
One idea suggests that the seed of a galaxy continues to accumulate gas and dust, slowly growing to massive size. When it reaches gigantic proportions, this galaxy is able to gobble up clusters of stars and even smaller galaxies. This process should be fairly slow, however, glacially so at first, in fact, accelerating once smaller galaxies begin to be absorbed.
If this is the predominant formation mechanism for galaxies, then what we shouldn’t see in the early universe, before about 6 billion years after the Big Bang, are disc-like massive galaxies or spiral armed galaxies like the Milky Way. Further out in space and thus further back in time, irregulars galaxies and amorphous blobs should be favoured heavily. Unless that is, galactic formation got a serious head-start.
But, there is another theory of galactic evolution. What if galaxy growth progresses predominantly through merger processes?
Rather than a galaxy waiting until it grows massive in size to start accumulating its smaller counterparts, mergers between similar-sized galaxies could be the driving factor in creating larger galaxies. This would mean that the process of galaxy formation could proceed much more quickly than previously believed.
In either case, what we should see is massive galaxies well-formed with characteristics like disks, bars, and spiral arms way further out into space, and thus further back in time.
It just so happens that is exactly what astronomers are starting to find.
Should’ve Put a Ring on it!
One such line of evidence for a more rapid form of galactic formation or a much earlier start, comes in the distinctive doughnut-like shape of a collisional ring galaxy discovered 11 billion-light-years away. This means this “cosmic ring of fire” — similar in mass to the Milky Way and notable for the massive ‘hole’ in its centre which is three million times the distance between the Earth and the Sun — existed when the Universe was just 2.7 billion years old. Far earlier than predicted.
Dr Tiantian Yuan, of Australia’s ARC Centre of Excellence for All-Sky Astrophysics in 3 Dimensions (ASTRO 3D) was part of a group that successfully gave the ring galaxy — designated R5519 — an age.
“It is very a curious object, one that we have never seen before, definitely not in the early Universe,” explains Yuan, a specialist in studying galactic features like spiral arms. “R5519 looks like a corona galaxy, but it isn’t.”
So, even if R5519 is striking, how does this imply that models of galaxy evolution could be inaccurate? The answer lies in how collisional ring galaxies such as this are created.
Yuan explains that the ‘hole’ at the centre of R5519 was created when a thin disk-like galaxy was ‘shot’ by another galaxy hitting head-on, just like a bullet hitting a thin paper target at a shooting range.
“When a galaxy hits the target galaxy — a thin stellar disk — like a bullet, head-on, it causes a pulse in the disk of the victim galaxy,” Yuan says. “The pulse then induces a radially propagating density waves through the target galaxy that form the ring.”
Yuan explains that at one time astronomers had expected to find more collisional ring galaxies in the young universe, simply because there were more galactic collisions progressing at that time. “We find that is not the case,” she continues. “The young universe might have more collisions and bullets, but it lacks thin stellar disks to act as targets… or so we thought.”
Here’s where the problem lies, thin stellar disks that serve as targets in this cosmic firing range aren’t supposed to exist so early in the Universe’s history according to currently favoured cosmological models.
“Our discovery implies that thin stellar disks similar to our Milky Way’s are already developed for some galaxies at a quarter of the age of the universe.”
Yuan and her team’s findings show galactic structures like thin disks and rings could form 3 billion years after the Big Bang. The researcher points to another piece of research that supports the idea of structured galaxies in the early Universe.
“The first step in disk formation is to form a disk at all — an object that is dominated by rotation,” Yuan says. “This is why the recent discovery of the ‘Wolfe disk’ is truly amazing — it pushes the earliest formation time of a large gas disk to much earlier than we previously thought.”
Who’s Afraid of the Big Bad Wolfe?
The discovery Dr Tiantian Yuan refers to is the identification of a massive rotating disk galaxy when the Universe was just 1.5 billion years old. The galaxy — officially named DLA0817g — is nicknamed the ‘Wolfe Disk’ in tribute to the late astronomer Arthur M. Wolfe, who first speculated about such objects in the 1990s.
The fact that the Wolfe Disk —which is spinning at tremendous speeds of around 170 miles per second — exists when the Universe was just 10% of its current age, strongly implies rapid galactic growth or the early formation of massive galaxies.
“The ‘take-home’ message from the discovery of a massive, rapidly rotating disk galaxy that resembles our Milky Way but formed only 1.5 billion years after the Big Bang, is that galaxy formation can proceed rapidly enough to generate massive, gas-rich galaxies at early times,” says J. Xavier Prochaska, professor of astronomy and astrophysics at the University of California Sant Cruz, and part of a team that discovered the Wolfe Disk.
The team behind the Wolfe Disk discovery posit the idea that its existence and the fact that it is both massive and well-formed indicate that the slow accretion of gas and dust may not be the dominant formation mechanism for galaxies. Something much more rapid could be at play.
“Most galaxies that we find early in the universe look like train wrecks because they underwent consistent and often ‘violent’ merging,” says Marcel Neeleman of the Max Planck Institute for Astronomy in Heidelberg, Germany, who led the astronomers. “These hot mergers make it difficult to form well-ordered, cold rotating disks as we observe in our present universe.”
If the Wolfe Disk grew as the result of the accumulation of cold gas and dust, Prochaska explains that this leaves questions unanswered about its stability: “The key challenge, is to rapidly assemble such a large gas mass while maintaining a relatively quiescent, thin and rotating disk.”
Of course, sometimes it can be the absence of something that provides evidence that a theory, or family of theories is inaccurate, as the following research exemplifies.
Further away and further back in time: Some of our Stars are Missing
The Hubble Space Telescope (HST) allows astronomers to stare back in time to when the Universe was just 500 million years old, allowing researchers to finally investigate the nature of the first galaxies and could deliver more contradictions to current cosmological models just as the Wolfe Disk and R5519 have.
Results recently delivered by the HST and examined by a team of European astronomers confirm the absence of the primitive stars when the Universe was just 500 million years old.
These early stars — named Population III stars — are thought to be composed of just hydrogen and helium, with tiny amounts of lithium and beryllium, reflecting the abundances of these elements in the young Universe.
A team of astronomers led by Rachana Bhatawdekar of the European Space Agency confirmed the absence of this first generation of stars by searching the Universe as it existed between 500 million years to 1 billion years into its history. Their observations were published in a 2019 paper with further research due to publish in Monthly Notices of the Royal Astronomical Society as well as being discussed at a press conference during the 236th meeting of American Astronomical Society.
“Population III stars are extremely hot and massive and so they are much bluer in colour than normal stars,” Bhatawdekar says. “We, therefore, looked at the ultraviolet colours of our galaxies to see exactly how blue they looked.”
The team found even though the galaxies they observed were blue, they weren’t blue enough to have stars with very low metals–by which, astronomers mean any element heavier than hydrogen and helium, such as oxygen, nitrogen, carbon, iron etc…
“What this tells us is that even though we are looking at a Universe that is just 500 million years old, galaxies have already been enriched by metals of significant amount,” Bhatawdekar. “This essentially means that stars and galaxies must have formed even earlier than this very early cosmic time.”
Thus the team’s observations imply that stars had already begun to fade and die by this point in time, shedding heavier elements back into the Universe. These elements would go on to form the building blocks of later generations of stars.
This piece of the puzzle would seem to suggest that the presence of massive galaxies is not a factor that arises as the result of rapid growth, but that the growth processes began earlier.
“We found no evidence of these first-generation Population III stars in this cosmic time interval,” explains Bhatawdekar. “These results have profound astrophysical consequences as they show that galaxies must have formed much earlier than we thought.”
Finding More Evidence of Early Galaxy Formation
For Bhatawdekar the further investigation on conditions in the early Universe will only really open up with the launch of the James Webb Space Telescope.
“Whilst we found is that there is no evidence of existence of Population III stars in this comic time but there are many low mass/faint galaxies in the early Universe,” she says. “This suggests that the first stars and first galaxies must have formed even earlier than this incredible instrument Hubble can probe.
“The James Webb Space Telescope, which is scheduled to be launched next year in 2021, will look even further back in time as far as when the Universe was just 200 million years old.”
Even before the launch of the James Webb Space Telescope, and as if to dismiss the idea that these results could be a fluke and thus not indicative of a wider shift towards earlier massive galaxies, Tiantian Yuan describes further findings yet to be published.
“I have actually found more collisional ring galaxies in the early universe!” exclaims Yuan. “There is a cool one that is gravitationally lensed, giving us a sharper view of the ring.
“I can tell you that this new ring is 1 billion years older than R5519, and it looks a lot different from R5519 and more like rings in our nearby Universe.”
As we refine our ideas of galaxy evolution we are likely to find that when presented with two conflicting theories, the truth is that which lies somewhere in-between. Thus, as we observe the formation of galaxies currently progressing, the mergers between galaxies, and complex structures in the Universe’s history we may find that galactic evolution may progress both slowly and quickly.
Hopefully, this mix of models will also deliver an accurate recipe for how spiral arms, rings, and bars arise from thin disks. Something currently lacking.
“What these discoveries mean is that we are entering a new era that we can ask the question of how different structures of galaxies first formed,” Yuan explains. “Galaxies do not form in one go; some parts were assembled first and others evolved later.
“It is time for the models to evolve to the next level of precision and accuracy. Like a jigsaw puzzle, the more pieces we reveal in observations, the more challenging it is to get the theoretical models correct, and the closer we are to grasp the mastery of nature.”
Sources and further reading
Yuan. T, Elagi. A, Labbe. I, Kacprzak. G. G, et al, ‘A giant galaxy in the young Universe with a massive ring,’ Nature Astronomy, .
Bhatawdekar. R, Conselice. C. J, Margalef-Bentabol. B, Duncan. K, ‘Evolution of the galaxy stellar mass functions and UV luminosity functions at z = 6−9 in the Hubble Frontier Fields,’ Monthly Notices of the Royal Astronomical Society, Volume 486, Issue 3, July 2019, Pages 3805–3830, , https://doi.org/10.1093/mnras/stz866
“Liftoff of the space shuttle Discovery, with the Hubble Space Telescope, our window on the universe,” were the words uttered by George Diller as STS-31 lifted off into a partly-cloudy Florida sky. That day — April 24, 1990 – was one, indeed, that would shape how we saw the unending expanse of space. The cargo aboard Discovery, 30 years ago, would end up becoming the most prolific space telescope in history and would change not only how we thought about the universe, but the creation of it itself.
The United States space program was still reeling from the Challenger explosion four years prior, and the launch of Hubble was not only a chance to learn more than ever about the universe, but a chance for NASA to remake its image with the public as well.
However, the story of Hubble started much earlier than that.
The road to Hubble
From the dawn of humankind to a mere 400 years ago, all that we knew about our universe came through observations with the naked eye. When Galileo turned his telescope toward the heavens in 1610, the world was in for an awakening.
Saturn, we learned, had rings. Jupiter had moons. That nebulous patch across the center of the sky called the Milky Way was not a cloud, but a collection of countless stars. Within but a few years, our notion of the natural world would be forever changed. A scientific and societal revolution quickly ensued.
In the centuries that followed, telescopes grew in size and complexity and, of course, power. They were placed on mountains far from city lights and as far above the haze of the atmosphere as possible. Edwin Hubble, for whom the Hubble Telescope is named, used the largest telescope of his day in the 1920s at the Mt. Wilson Observatory near Pasadena, California, to discover galaxies much further than our own.
the 1970s, NASA and the European Space Agency (ESA) began planning
for a space telescope that could transcend the blurring effects of
the atmosphere and take clearer images of the Universe than ever
The Hubble telescope was the first major optical telescope to be
placed in space, the ultimate mountaintop. Without the atmosphere to
hinder its observations, and far removed from rain clouds and light
pollution, Hubble has an unobstructed view of the universe.
“Hubble is really a time machine,” said Larry Dunham, Hubble’s chief systems engineer at NASA’s Goddard Space Flight Center, in an interview. “We’re looking at data from light years in the past. Hubble is giving us the opportunity to look back in time to see how things were formed.”
Like every good love story, this one has its ups and downs with Hubble being the knot that ties the marriage of human curiosity and the science with satisfies it. Also, like a good marriage – and unlike most satellites – it gets better and stronger with age. Fifteen years after its expected lifespan, she has still not given up the ghost and has some of her most important discoveries just ahead.
The most marvelous part of the telescope, of course, is the 94.5-inch (2.4-meter-wide) mirror. As Eric Chaisson, an American astrophysicist and author wrote in his book The Hubble Wars, “While not the largest ever built, Hubble’s mirror is assuredly the cleanest and most finely polished mirror of its size. If Hubble’s mirror were scaled up to equal the width of the North American continent, the highest hill or lowest valley would be a mere few inches from the average surface.”
Up to a slow start
The mirror was also the headline when Hubble’s debut picture was snapped. Four weeks after leaving Discovery’s payload bay, the telescope’s initial offering to the public was that of a somewhat blurry photo of binary star HD96755, about 1,300 light-years away. A spherical aberration caused by a manufacturing error was causing the telescope to bring in only 10 to 15 percent of a star’s light into focus, as opposed to the 70 percent it should be gathering. Picture after picture revealed in no clearer images. Engineers eventually found that the shape of the concave mirror, moving from the center to the outer edge, was too shallow by up to two microns — 1/50 the width of a human hair.
slight, the error turned what was the most heralded telescope in
NASA’s history into the laughingstock of the world. In fact, it
wouldn’t be until December of 1993, three and a half years later,
that the crew of Columbia would come to the rescue with a set of
corrective optics to restore Hubble’s vision.
“The mirror flaw was a disappointment,” said Dunham. “It was really a disappointment that it showed up in the news. Even with the spherical aberration, the images we were getting were still better than anything we had ever had in the past.”
Replacing the mirror was not practical, so the best solution was to build replacement instruments that fixed the flaw much the same way a pair of glasses correct the vision of someone who is near-sighted. The corrective optics and new instruments were built and installed on Hubble by spacewalking astronauts during the STS-61 mission in 1993. The Corrective Optics Space Telescope Axial Replacement (COSTAR) instrument, which was about the size of a telephone booth, placed into Hubble five pairs of corrective mirrors that countered the effects of the flaw.
Once the mirror had a new set of spectacles, she now had the ability to look farther into universe than anything humans had ever produced. When astronomers pointed her to before had been an empty patch of sky in Ursa Major in 1995, they captured an image of over 3,000 galaxies too distant to be detected by other telescopes. (This was later called the Hubble Deep Field). Some of the galaxies Hubble found were so young, they had not yet begun serious star formation. Other deep field findings in the same area were performed, peering deeper into space each time. These were called the Hubble Ultra-Deep Field (released in 2004) and the Hubble eXtreme Deep Field (released in 2012).
Besides the extraordinary finds, Hubble was famous for another reason. Unlike other satellites, Hubble was made into a better machine as time wore on. Each service mission would renew and improve her capabilities.
“With the servicing missions have allowed us to upgrade both the science instruments as well as the spacecraft hardware,” said Dunham. “Actually, it took us so long to get it up there initially (due to the delay after the Challenger explosion), that by the time we finally got Hubble up, a lot of its hardware was already obsolete. The recorders we launched with were tape, and now we have upgraded those to digital. The original computer we had was six-point binary assembly coding with a huge 32k of memory. Now we’ve got a 46 computer up there that has megabytes.”
In February 1997 the second servicing mission took place, resulting in the replacement of degrading spacecraft components, and the installation of new instruments such as the Space Telescope Imaging Spectrograph (STIS) and the Near Infrared Camera and Multi-Object Spectrometer (NICMOS). STIS separated the light the telescope took in, and “dissected” it so that the composition, temperature, motion and other properties could be analyzed. With NICMOS, astronomers could see the first clear views of the universe at near-infrared wavelengths.
On November 13, 1999, the fourth of six gyroscopes failed, and the telescope temporarily closed its eyes on the universe. Traveling at speeds of five miles per second, the gyros measure the spacecraft’s rate of motion and help point Hubble toward its observation target. Unable to conduct science without three working gyros, Hubble entered a state of safe mode dormancy. Essentially, Hubble took a nap while it waited for help.
The third servicing mission was originally conceived as one of maintenance, but when the fourth gyro failed, NASA divided the work into two missions — and in the process, upheld the time-honored tradition of governments just making things more confusing by instead of calling them a third and fourth service mission, called them Servicing Mission 3A (SM3A) and Servicing Mission 3B (SM3B).
SM3A flew in December 1999 and the second in March 2002. During SM3A astronauts replaced all six gyroscopes with new ones, and installed a faster, more powerful main computer, a next-generation solid-state data recorder, a new transmitter, new insulation and other equipment. During SM3B, astronauts installed a new science instrument called the Advanced Camera for Surveys (ACS). ACS sees in wavelengths ranging from visible to far-ultraviolet, and can produce 10 times the science results in the same amount of time than the camera it replaced, the Faint Object Camera (FOC).
Servicing Mission 4 (SM4), the fifth – and last — visit to Hubble, occurred in May 2009. Astronauts installed two new scientific instruments: the Cosmic Origins Spectrograph (COS) and Wide Field Camera 3 (WFC3). Two failed instruments, the Space Telescope Imaging Spectrograph (STIS) and the Advanced Camera for Surveys (ACS), were brought back to life by the first-ever on-orbit instrument repairs. In order to prolong Hubble’s life, other components were replaced including new batteries, new gyroscopes and a new science computer. In addition, a device was attached to the base of the telescope to facilitate de-orbiting when the telescope is eventually decommissioned.
As things are now, that decommissioning date looks like it will be long in the future. Originally given a shelf life of 15 years, Dunham says that reentry of the satellite probably won’t occur until 2046, a 56-year span since it lifted off aboard Discovery. To put that in perspective, that is only five years less than when the telescope’s namesake reached his expiration date.
With the launch of the highly touted James Webb Telescope approaching nearer, the Hubble’s capabilities should only increase.“There are a lot of observations that people want to do in parallel with the Webb,” said Dunham. “The two spacecraft look at different light spectrums, so you can look at something with the Webb and get once sense of the object you’re looking at and then look at it with the Hubble and get another sense. Together you can produce some amazing science.”
Maybe it was appropriate that Discovery was the ship that took Hubble into orbit. The opportunities and discoveries we have made are more than the number of coins it took to produce it.
Famed poet Walt Whitman might have pegged it when he wrote:
“O to realize space! The plenteous of all, that there are no bounds, To emerge and be of the sky, of the sun and moon and flying clouds, as one with them.”
We have all, at some point, stared at the stars and dreamed lazily of other worlds, but, fortunately, for many of us, dreaming alone was not enough. These people set about building a toolkit stocked with instruments and techniques to find planets outside our solar system — exoplanets. In turn, these tools help us better understand our place in the Universe.
In October the Nobel Committee awarded the 2019 Nobel Prize in Physics to Michel Mayor, Professor at the Observatory of the Faculty of Science of the University of Geneva (UNIGE), Switzerland, and his doctoral student Didier Queloz for their discovery of 51 Pegasi b in 1995 — which marked the first discovery of an exoplanet orbiting a Sun-like star. The award marked the first time that exoplanet research has scooped what is, arguably, the most prestigious prize in science. Quite fitting as even though 51 Pegasi b was not the first exoplanet to be discovered — that honour goes to Astronomers Aleksander Wolszczan and Dale Frail who discovered an exoplanet around a neutron star in 1992 — it was Mayor and Queloz’s breakthrough that really spurred on the science of exoplanet investigation.
As extraordinary as it sounds, before the 1990s, it wasn’t entirely certain that other stars actually possessed planets of their own. Whilst there was technically no reason to suspect that the solar system was unique, the 1980s had proved a frustrating time for exoplanet hunters. By the turn of that decade, many potential candidates had come and gone evading positive confirmation.
Despite early setbacks, since 1995, the catalogue of exoplanets has soared, with over 4,000 examples now in NASA’s catalogue. And with technology only improving, that collection is set to soar. This animation and sonification from SystemSounds is a stunning representation of how the field has exploded since the 1990s. Created by SYSTEM Sounds (Matt Russo, Andrew Santaguida)
We are becoming so confident in the discovery of exoplanets, that we are now turning our attention to much more detailed examinations of previously discovered examples. For example, many researchers are now focusing on the investigation of exoplanet atmospheres, attempting to discover if they contain traces of chemicals such as carbon monoxide and other organic and complex molecules, and, of course, water. Should these elements be observed it constitutes a clue, a tiny hint, that life may not be unique to our planet.
Thus far, searches for exoplanets have been more effective in finding gas giants, planets similar to Jupiter. But new advances such as the James Webb Space Telescope and the Extremely Large Telescope have researchers salivating at the idea of finding and examining smaller, rocky planets. Planets just like Earth. And of course, the discovery of the Trappist-1 system — containing seven Earth-like rocky planets, three in the so-called ‘habitable zone’ capable of harbouring liquid water — has shown that these planets are definitely out there waiting for us to find them.
As such, exoplanet research stands on the cusp of providing an answer to the question we have all pondered at some point whilst staring at the stars, are we alone in the universe?
Of course, the fact that it took so many years of fruitless searching to begin to successfully spot exoplanets illustrates, these blighters are extremely difficult to observe. This means that astronomers have had to develop extremely precise and sensitive methods of exoplanet detection. These techniques are numerous, each with its own strengths and weaknesses.
It goes without saying that before we spotted the first exoplanet, our experience of observing other planets was restricted to our neighbours in the solar system. This was done exclusively through direct imaging, but this technique becomes much more difficult as the distance to an object increases.
The hindrances imposed on direct imaging increase exponentially when we consider the effect of attempting to spot a dim object next to a much bright one — exactly the scenario faced when attempting to spot a distant planet orbiting its parent star. But, this proximity to an extremely bright object is not always a hindrance to exoplanet detection. In fact, many methods of spotting these planets absolutely depend on it. If a dim object can have an effect of the extremely bright object — then the ability to observe this bright object is a benefit.
This interference arises from the fact that stars with planets orbiting them demonstrate a ‘wobble’ in their motion. This arises from the fact, that despite common belief, planets don’t actually orbit stars. In fact, planets and stars orbit a mutual centre of mass— or barycentre —its location based on the masses of the planets and stars involved. As the usual set-up of a planetary system involves a star that is tremendously more massive than its planets, this mutual point of orbit is usually closer to the star centre of mass — often within the star’s surface.
This huge disparity in mass means that this ‘wobble’ is tiny. As an example, consider our own solar system. As the Sun constitutes more than 99.9% of the total mass of the solar system, the barycentre for our planetary system is located very close to our star’s centre of mass. The most significant gravitational influence on the Sun arises as a result of the solar system’s most mass planet — Jupiter.
Let’s imagine, for simplicity’s sake, that Jupiter is the only planet orbiting the Sun. An observer viewing this reduced solar system and Jupiter’s 12-year orbit from the nearest planetary system — Alpha Centauri, 4.4 light-years away — would see the Sun as a mere point of light. The shift in its position caused by Jupiter would be just 3.7 milliarcseconds. To put this shift into perspective, consider that one pixel in an image from the Advanced Camera for Surveys aboard the Hubble Space Telescope represents 50 milliarcseconds — one pixel! Thus you can see, this ‘wobble’ caused by Jupiter is a tiny, barely perceptible amount of movement, less than 1/10 of a pixel from the nearest star!
Two further things to consider in this hypothetical situation, Jupiter is the most massive planet in the solar system, the wobble caused by Earth viewed from the same position would be smaller by a factor of at least 300. Also, many of the exoplanets that we are attempting to spot are much further afield than 4.4 light-years. That means that any method using this wobble must be incredibly sensitive and precise. Incredibly, despite this tiny effect, the wobble has spawned several methods of exoplanet detection.
One of these methods is astrometry — very effective for detailing high-mass planets in wide orbits around relatively low-mass stars, and thus not well suited to tracking down Earth-like, rocky planets. For an indirect observation method, astrometry is pretty good at pinning down characteristics like mass, and orbital period, shape and width. Unfortunately, it isn’t great at actually identifying planets.
Thankfully there are other indirect techniques that have helped astronomers help find exoplanets — one of which combines a star’s ‘wobble’ with a phenomenon familiar to drivers and pedestrians everywhere.
Sirens, soundwaves and stars. The Doppler Wobble
I’m sure everyone reading this has been in a situation in which an ambulance with sirens blaring has raced towards them, passed their position and continued on its journey. You’ll have likely noticed that as the vehicle approaches the sound of its siren is higher pitched, switching to a lower pitch as it moves away.
This is because as the soundwaves are emitted by the approaching ambulance they are compressed and shorter wavelength sound waves mean a higher-pitched sound. As the siren recedes, the soundwaves are stretched out — resulting in a lower pitch.
This is the Doppler effect, and the key thing for astronomers is, it applies to any kind of wave emitted by a moving object — even light which propagates as a wave. Just as the wavelengths of soundwaves correspond to different pitches, the wavelengths of light correspond to different colours. Longer wavelengths producing a reddening, shorter wavelengths produce bluer light. This is referred to as redshift and blueshift— a crucial phenomenon in astronomy.
Instead of an ambulance, let’s think about a star moving towards us, as the light waves emitted are compressed — causing the light signature of the star to be shifted towards the blue end of the spectrum. As the star moves away, the light is stretched out again — shifting the light signature towards the red end of the electromagnetic spectrum.
If this is the case, why do the lights atop the ambulance as it recedes not appear redder than they were on their approach? This is because the amount of red and blue shift is determined by an object’s speed divided by the speed of light c. As c is so large, an object would have to be moving at tremendous speeds to result in a significant enough change in colour for us to notice.
You might be wondering how exactly scientists can tell that a star’s signature has shifted towards either end of the electromagnetic spectrum. This is because stars don’t emit light in a constant ‘smear’ across the spectrum. There are notable dark bars where light is not emitted — referred to as the absorption spectrum. It is by tracing the shift of these bars that researchers can see if a star is wobbling and by how much, thus inferring the presence of exoplanets.
Of course, you may well have noticed a flaw with this technique. It’s only useful in detecting exoplanets that are causing their star to wobble towards and away from Earth. This gives rise to the method’s alternative name — the radial-velocity method. In addition to this blind-spot in glimpsing planets moving perpendicular to Earth, the Doppler-wobble technique can also only tell us what a planet’s minimum mass is.
But, knowledge of the light signature of a star gives rise to another tool in the exoplanet hunter’s arsenal, one which depends on planets crossing — or transiting — their parent star. The photometry technique.
Don’t cross me!
The photometry technique measures the dip in brightness of a star caused as a planet crosses in front of it, thus allowing us to infer the presence of an exoplanet and even collect details about a few of its characteristics. The method clearly requires searching for rare eclipse events where a planet blocks some of its parent star’s light.
You may be unsurprised to learn that like the other methods detailed above, the photometry technique has to be incredibly sensitive. In this case, that is because the disparity in size between a star and a planet orbiting it is so huge in the star’s favour that the light obscured by this transit is minuscule.
To illustrate this, take a look at this image of Mercury transiting the Sun seen from within the solar system.
This speck, highlighted below, is Mercury. Now imagining the tiny fraction of light this would have obscured. When you’ve done that, imagine viewing this scene from millions of light-years away!
Returning to the example of Jupiter, the largest planet in our solar system, when it transits the Sun it blocks just 1% of the star’s light — making the Sun appear 1% fainter for a period of 12 hours. As small as it is, in comparison to the phenomena exploited by the two methods above this effect is massive.
And again, like its fellow methods of exoplanet detection, the photometric technique has significant limitations that define the situations in which it can be employed. Many planets don’t transit their parent stars and those that do have to be orientated ‘just right’ for the photometry method to work. Also, transits that do occur are incredibly brief, so it takes a lot of good fortune to catch one. That means that the vast majority of exoplanets that we believe exist out there in the depths of space can’t be spotted by this method.
The Earth’s atmosphere and the ‘twinkling effect’ it has on stars is also a major hindrance to the photometry method. This results in its reliance on space-based telescopes. By taking the atmosphere out of the equation, it is possible to not just improve the precision of our measurements but also allows for the continuous monitoring of a star’s brightness without the agony of something as mundane as a rainy-day ruining data.
The future of exoplanet research is extremely bright
With all the limits and drawbacks I’ve listed it may seem like searching for exoplanets is something of a hopeless task, like searching for a needle in a haystack. Except there are 100 billion ‘haystacks’ or stars outside of our analogy in each galaxy. Clearly its a tribute to our advances in science that we have found 4000 or so ‘needles’ thus far.
The astrometry technique, the first tool we examined in the exoplanet hunter’s toolkit isn’t particularly useful, but the second, the doppler technique has been a real boon. It kickstarted exoplanet-hunting as a viable scientific field in the ’90s and provided the majority of discoveries right up into the 2000s. Despite this, its the transit technique — photometry — the last piece of equipment that we turned over, that holds the most promise for the future.
It was a slow starter for sure, reaching maturity much later than the previous two methods mentioned. But, as the use of automated and space-based telescopes has become more prevalent, the ability to keep thousands of stars under constant observation is making the photometry technique the exoplanet-hunting tool that promises to push the boundaries of our understanding of planets elsewhere in the universe.
As our catalogue of exoplanets expands, researchers also now begin to look beyond just spotting these other worlds. The CHEOPS telescope will launch this week (17/12/19) with its mission to spot exoplanets close-by that warrant further investigation. And it is the James Webb Space Telescope, launching in 2021, that will really delve into these selected planets.
Researchers will then use some of the methods I’ve listed above to examine the atmospheres of these planets, a ‘deep-dive’ that would have seemed like little more than a pipe-dream in 1995 when Michel Mayor and Didier Queloz spotted 51 Pegasi b.
Exoplanet research, in many ways, represents one of the ultimate expressions of the drive to perform science. For its pioneers, the men and women that stocked our toolkit, it simply wasn’t enough to lie back staring at the stars, dreaming of other worlds.
The scheduled launch of the European Space Agency’s (ESA) Characterizing Exoplanets Satellite or CHEOPS telescope, set to usher in a new era of exoplanet research was cancelled today.
The launch, which was set to take place at 12:54 am local time (roughly 4am ET) from the spaceport in Kourou, French Guiana was called-off due to what the University of Bern is calling a software error. The institution was set to live stream the event.
The launch has been rescheduled and is expected to take place within the next 24 to 48 hours. The official revised launch time and date will be announced at 6:00pm (ET).
CHEOPS is loaded aboard a Russian Soyuz-FG, which will place it in a low-Earth orbit. The procedure — which will take around 145 minutes to complete — will result in CHEOPS taking a rare pole-to-pole orbit.
The CHEOPS mission is designed to observe exoplanets in relatively close proximity to Earth. The aim of this is to select viable targets for future investigation by the next major development in both the fields of astronomy and exoplanet research — the James Webb Telescope, set to launch in 2021.
It is hoped that by using a combination of these instruments, researchers will finally be able to uncover characteristics of rocky exoplanets, which has been tricky up until now. This will include discovering if such bodies can maintain atmospheres and deduce the chemical compositions of these atmospheres.
It is likely that when the launch does occur, live coverage will be provided by the ESA on its website.
Exoplanet researcher Ignas Snellen — a professor in astronomy at the University of Leiden in the Netherlands — has collected the 2019 Hans Sigrist prize for his innovative work in the field of exoplanet research. The award of the prize to Snellen comes at the conclusion of a year which also marked the Nobel Committee’s recognition of the first observation of an exoplanet orbiting a Sun-like star, awarding its discoverers Michel Mayor and Didier Queloz the 2019 Nobel Prize in Physics.
The message from the scientific community seems to be clear, exoplanet research is a field to watch. With the launch of the CHEOPS satellite, later this month and the James Webb Space Telescope set to launch in 2021, applied science is finally catching up to aspirations held by astronomers for decades–the discovery of more and more diverse worlds outside our solar system.
In addition to this, the tantalizing possibility of catching a fleeting glimpse of a clue that we are not alone in the universe seems closer than ever to realization.
But as Snellen explains, things could have been very different for him, falling into exoplanet research was something of a happy accident: “I was doing very different research, working with galaxies,” he says. “I didn’t really know where my research was going. That’s when I was asked to present a workshop on extrasolar planets.”
Despite the serendipity at play, Snellen says he recognised the potential growth for the young field almost immediately. “I thought ‘wow, what an amazing field!'”
And Snellen’s decision to pursue exoplanet research relates indirectly to Nobel prize winners Mayor and Queloz. “This was in 2001, so exoplanet research was still in its infancy, but the first transiting exoplanet had been discovered as well as a few others.”
Despite the fact that only a handful of exoplanets had been discovered when Snellen began his research in the field less than two decades ago, NASA’s catalog of extrasolar planets now numbers in excess of 4,000. Clearly, this is a stunning illustration of just how rapidly the field has advanced in this relatively short period of time.
Snellen’s work focuses on assessing the atmospheric composition of exoplanets. This possible to do when a planet passes in front of–or ‘transits’– its parent star. The planet’s atmosphere absorbs light from the star at certain wavelengths. As chemical elements absorb and emit light at certain frequencies, the resulting light spectrum forms a distinct ‘fingerprint’ by which they can be identified.
This method of transit spectroscopy holds great promise in terms of identifying potential ‘biomarkers’ such as molecular oxygen, water and carbon monoxide.
As the Hans Sigrist Prize is specifically designated to recognize scientists in the midst of their careers rather than acting as a ‘lifetime achievement’ type award, it is only fitting that its recipient should very clearly have their eyes on future goals. And, fortunately, the future is bright for exoplanet research.
The ESO’s CHEOPS telescope launches on 17th December with its mission to identify nearby, small rocky exoplanets. Snedden points out the mission’s role as an important first step in the exoplanet research, helping select targets for researchers to further investigate.
But the two projects that Snellen is most excited for and the launch of the James Webb Telescope in 2021 and the completion of the aptly named 39-meter diameter Extremely Large Telescope (ELT) scheduled for completion in 2025.
“At the moment we can only observe the atmospheres of large Jupiter-like gas giants,” he explains. “The James Webb will finally allow us to start examining the atmospheres of smaller, rocky, more Earth-like exoplanets.”
These planets will still differ quite a bit from Earth, elaborates Snellen, explaining that they will, for example, be much hotter than our planet. “The exciting thing is, we don’t yet know if these small rocky planets can actually hold an atmosphere,” Snellen says.
The researcher concludes by pointing out that the seven Earth-like planets of the Trappist-1 system are very likely the first targets for further investigation. An exciting prospect, given that at least three of these planets are believed to exist in that system’s ‘habitable zone’–an area where water can exist as a liquid, a key ingredient for life.
One of the most promising prospects for discovering liquid water in the Trappist-1 system is Trappist-1e, an exoplanet that is slightly denser than Earth. As liquid water requires a temperature that is not too hot and not too cold, and also a certain amount of pressure–the fact that Trappist-1e receives roughly the same amount of radiation from its star as Earth and its gravitational influence exerts a similar pressure, it seems a safe bet to predict liquid water will be found there.
Of course, the concept of discovering liquid water amongst the stars and drawing comparisons to Earth leads, inevitably to the question could any of these planets also host life?
Snellen urges caution, remarking that even if these biomarkers are found, it is still a long way from confirming the ‘Holy Grail’ of exoplanet research: the presence of extraterrestrial life.
“It would be a major clue,” Snellen points out. “But it’s too simple to say ‘OK we have molecular oxygen, this is a sign of life.’ As molecular oxygen is difficult to detect though, by the time we can identify it, we should also be able to see lots of other gases.”
The Hans Sigrist Prize was established in 1994 to recognise mid-career scientists who still have a significant time left in their careers to make further major contributions to their field. Thus far, two of the previous recipients have gone on to become Nobel Prize Laureates later in their careers.
In connection with the prize, Snellen will receive 100,000 CHF–around $100,000–to help further his research. Accepting his prize, Snellen first thanked the team of researchers that have supported him in his research over the past decade.
The European Space Agency’s (ESA) space telescope CHEOPS (CHaracterising ExOPlanet Satellite) begins its journey into space aboard the Soyuz rocket on December 17th. In preparation for the launch from French Guiana, collaborators in the mission, the ESA, the University of Geneva and the University of Bern held a press conference on the morning of the 5th December.
The gathered experts from the respective agencies discussed the mission–the ESA’s first ‘S-Class’ or small scale project–the international collaboration that brought it together and the role CHEOPS will play in the investigation of Exoplanets and the search for life elsewhere in the universe.
“After over six years of intensive work, I am, of course very pleased that the launch is finally in sight,” Willy Benz, CHEOPS’s principal investigator and professor of astrophysics at the University of Bern states.
The main role of CHEOPS will be to examine the ever-growing catalog of exoplanets, explains David Ehrenreich, CHEOPS Consortium Mission Scientist from the University of Geneva.
This involves selecting what Ehrenreich describes as ‘golden targets’ or exoplanets that missions such as the James Webb Space Telescope (JWST)–set to launch in 2021 from the same site—can follow-up on in order to perform in-depth examinations. As the JWST will search for signs of habitability–mainly indications of water and methane– it is a massive advantage for it to have preselected targets to study.
CHEOPS will enforce this selection process by examining nearby bright stars that are known to host exoplanets–particularly those with planets in a size range of Earth to Neptune. By measuring the transit depths as these planets cross their host star–the sizes of the planets can be accurately ascertained and then the researchers can also calculate their density and in turn, their composition–if they are rocky or gaseous, for example. The mission should also be able to determine if the planets possess deep oceans–believed to be a key component for the development of life.
A Small Mission Can Answer Big Questions
Kate Issak, a CHEOPS project scientist from the ESA explains how the mission–the first part of the Cosmic Vision 2015-2025 program–differs from previous endeavors undertaken by the agency: “CHEOPS is the first S-class mission for ESA, meaning it has a small budget and a short timeline to completion.
“Because of this, it is necessary for CHEOPS to build on existing technology.”
The cost of CHEOPS is an estimated 50-million Euros and it has taken 5 years to complete after being greenlit in 2014. Whilst this may not seem like a small amount of money or a short period of time, the cost and preparation time of the JWST–about 9 billion Euros and 7 years–very much puts both into perspective.
But neither a short timeline to completion or a small budget nor the fact that it mainly bridges the gap between past and future investigations will stop CHEOPS from attempting to answer some of the biggest lingering questions in exoplanet research.
Ehrenreich lays out some of the big questions that CHEOPS may have the potential to tackle, namely:
How do planets form?
At what rate do planets occur around other stars?
What are the compositions of these planets?
How do these compositions compare with the compositions of planets in the solar system?
Is our solar system unique or common?
And perhaps most interestingly for the general public and scientists alike:
Are any of these worlds habitable?
By tackling these questions CHEOPS and the ESA really get to the heart of both space exploration and exoplanet investigation.
CHEOPS: Empathising collaboration
As is fitting for a mission that probes such fundamental ideas as, how common is life in the universe, the ESA is throwing the use of the CHEOPS equipment out to other institutions and researchers.
Whilst 80% of CHEOPS’s operating time will be determined by the ESA’s mission program, Issak explains, the remaining 20% will be devoted to the wider scientific community. The projects and researchers that will be able to make use of this time will be determined based on merit alone.
“CHEOPS will build on the work of the consortium and benefit the scientific community as a whole,” promises Issak.
The idea of community spirit is built into CHEOPS’s DNA from its genesis, Willy Benz the mission’s principal investigator explains. The project brings together 11 individual nations each of which has made a specific contribution to the equipment aboard the satellite.
Issak adds “CHEOPS is an excellent example of how EU member states can work together.”
The ESA will follow-up on CHEOPS with PLATO (PLAnetary Transits and Oscillation of stars) project in 2026, and ARIEL (Atmospheric Remote-sensing Infrared Exoplanet Large-survey) mission in 2028.
Plato will specialise in the examination of rocky exoplanets orbiting in habitable zones around Sun-like stars, particularly focusing on the potential for these planets to hold liquid water. It will also examine seismic activity in stars–giving insight into the age and evolutionary stage of these planetary systems.
Ariel, meanwhile, will take exoplanet survey and characterisation to a whole new level of detail, enable to perform chemical censuses of a wide variety of planet’s atmospheres.
As the award of this year’s Nobel Prize in Physics to Michel Mayor and Didier Queloz for the discovery of the first exoplanet around a Sun-like star demonstrates, the search for exoplanets and the quest to categorise and understand them is currently one of the hottest research areas in science.
As such CHEOPS puts the ESA at the forefront of the race to discover how common our home planet and the solar system is, and potentially, answer an age-old question: are we alone in the Universe?
NASA is very close to reaching a milestone in the construction of the James Webb Space Telescope (JWST), Hubble’s successor that will be launched in 2018.
The telescope will consist of 18 mirror segments when it’s completed. Each segment can be independently adjusted to bring the starlight into focus. David Higginbotham/Emmett Given/MSFC/NASA
Engineers have almost completely assembled the giant mirror, with a collecting area about five times larger (25 square meters) than Hubble’s – despite being twice as light. When complete, the mirror will look like a giant satellite dish – one that’s two stories high.
“So far, everything — knock on wood — is going quite well,” says Bill Ochs, the telescope’s project manager at Goddard Space Flight Center in Maryland.
Comparison between Hubble’s and James Webb’s mirrors. Wikipedia.
This has been the fastest and most cursive part of the building schedule in what was otherwise a project with many hurdles and delays. This isn’t unexpected though. When Hubble’s construction started in 1972, it had an estimated cost of $300 million – but when it finally went in space in 1990, it cost four times more. But just like Hubble was revolutionary (and still is), so too will James Webb be.
The largest NASA astrophysics mission of its generation, JWST will offer unprecedented resolution and sensitivity from long-wavelength (orange-red) visible light, through near-infrared to the mid-infrared. It will be able to capture light from the first stars and galaxies in the Universe, from billions of light years across.
It will also probe the atmospheres of potentially habitable planets, providing more information on their habitability. It’s bigger and better.
“Every time we build bigger or better pieces of equipment, we find something astonishing,” he says.
Full scale James Webb Space Telescope model at South by Southwest in Austin. Wikipedia.
Unfortunately, the construction of something so large and innovative is bound to have some delays and cost extensions. The first estimates suggested the observatory would cost $1.6 billion and launch in 2011. Now, NASA has scheduled the telescope for a 2018 launch and that seems to be well on track. They even have a generous margin for an October 2018 launch.
“We keep our fingers crossed, but things have been going tremendously well,” said Nasa’s JWST deputy project manager John Durning. “We have eight months of reserve; we’ve consumed about a month with various activities,” he added.
In the past two decades alone, some 900 exoplanets – planets outside our solar system – have been identified, with some 2300 more in queue. Most of these were confirmed using the now discontinued Kepler space telescope. It’s remarkable how much scientists can find out about a distant plant, hundreds of light years away, simply by studying how light emitted by its parent star is manipulated (absorbed, reflected, tugged). For instance, researchers can establish properties like mass, planet and atmosphere composition, surface temperature and more.
As one can imagine, these readings are far from being extremely accurate. A team of researchers at MIT recently made a significant contribution to exoplanet hunting after they demonstrated a new method for assessing exoplanet mass, which they claim should be more accurate. The method is particularly useful for establishing the mass of smaller planets orbiting dimmer stars, something that currently renders skewed results using other methods. Having an accurate reading of a planet’s mass is extremely important since mass influences all the other parameters used to characterize a planet.
“The reason is that the mass of a planet is connected to its internal and atmospheric structure and it affects its cooling, its plate tectonics, magnetic field generation, outgassing, and atmospheric escape,” IT graduate student Julien de Wit said. “Understanding a planet is like dealing with a huge puzzle where knowing the mass is one of the corner pieces, which you really need to get started.”
A new way to measure mass
Artist impression of HD 189733 b and its parent star. Photo: ESA, NASA, M. Kornmesser (ESA/Hubble), and STScI
Typically, the mass of a planet is calculated by studying radial velocity or a measure of how intensely a planets pulls on its star. This method is useful for establishing how many planets orbit a certain star and how large these are, however it’s only accurate in certain conditions, namely for massive planets orbiting around bright star.
The method developed by de Wit and colleagues at MIT, alled MassSpec, employs transmission spectroscopy instead. This works by measuring light from a star passing through an exoplanet’s atmosphere. A key property called pressure-scale height – how quickly the atmospheric pressure changes with altitude – is established. Then, using this data the MIT researchers can determine the planet’s gravity and, in term, mass.
A hellish world
To test the accuracy of the method, the MIT researchers looked at a gas giant HD 189733 b – a huge, Jupiter-like planet in terms of composition which orbits its parent star in only 2.2-days – previously analyzed using conventional methods. Since its a massive planet around a very bright star, measuring the exoplanet’s properties is relatively easy and accurate. After comparing the data coming from the MIT method with those from conventional methods, the results were found to be consisting.
Following the 2018 deployment of the James Webb Telescope, a multi-billion project, much powerful than Kepler, that will peer through dim and small stars, like those classed as M dwarf stars, the MIT method is sure to become truly useful. Considering there are billions of planets in the Milky Way, a new age of astronomic breakthroughs and discoveries may come out.
Two fantastic space telescopes, Hubble and ESA’s Herschel, have teamed up to image one of the most popular astronomical sights in the sky, the “Horsehead” nebula, in infrared as well as longer wavelengths to provide unprecedented insights as to what’s going on in this stunning star hatchery.
Listed in catalogues under “Barnard 33”, but better known as the Horsehead nebula thanks to its distinctive shape, this fabulous molecular gas cloud lies some 1,300 light years away in the constellation Orion. Until recently, optical observations have made the nebula famous, but new infrared imaging shows the Horsehead in unprecedented detail.
Besides being a fabulous sight, the region is also a highly active star formation region, which makes it particularly appealing.
“You need images at all scales and at all wavelengths in astronomy in order to understand the big picture and the small detail,” said Prof Matt Griffin, the principal investigator on Herschel’s SPIRE instrument.
“In this new Herschel view, the Horsehead looks like a little feature – a pimple. In reality, of course, it is a very large entity in its own right, but in this great sweep of a picture from Herschel you can see that the nebula is set within an even larger, molecular-cloud complex where there is a huge amount of material and a great range of conditions,” the Cardiff University, UK, researcher told BBC News.
The image comes ahead of the 23rd anniversary of the telescope’s launch on the space shuttle Discovery on April 24, 1990. Its successor, the James Webb Space Telescope, is due to launch around 2018.
Though hundreds of potentially life harboring exoplanets have been discovered thus far, until the James Webb Space Telescope becomes operational, sometime around 2018, scientists today lack the resources to peer into the guts of these planet and determine a realistic chance of hosting life. Even when the JWT goes live, however, it will take hundreds of hours of observations to come up with solid data for planets orbiting stars similar to the Sun.
Artist impression of a possible Earth-like planet capable of harboring life orbiting around its parent white dwarf star. (c) David A. Aguilar (CfA)
Scientists at the Harvard-Smithsonian Center for Astrophysics have found that, given out current technological limitations, we should concentrate our efforts of finding life harboring planets to those orbiting white dwarf stars. At the end of its evolution, if it isn’t massive enough, a dying star will turn into a white dwarf – a very dense star no longer capable of sustaining nuclear fusion.
Nuclear fusion is what powers most star, including our Sun, allowing energy to spread through sunlight. However, even without fusion a white dwarf can still emanate a considerable amount of residual thermal energy, enough to keep it warm for billions of years until it slowly fades away. Some white dwarfs actually have been found to continue to spread heat even though they’ve been dated from the dawn of the Universe.
What makes the James Web Telescope so important for alien life research is its cutting edge instruments, capable of inspecting the spectral fingerprint of the planet’s atmosphere. With today’s tech, astronomers can establish the orbit, size or mass of a planet based on its transient motion around its parent star. With the James Web Telescope, scientists will also be able to determine key chemical composition elements found in the atmosphere’s of alien worlds.
Starlight shining through the atmosphere of an exoplanet can reveal its chemical composition. (c) ESA
This can be achieved using a technique astronomers call transmission spectroscopy. Chemical elements in a planet’s atmosphere absorb some of the starlight, meaning more light than normal will be blocked at that particular wavelength associated with the element, thus offering a spectrum of the planet.
“Detecting any of these biomarkers in the atmosphere of an Earth-copy planet around a nearby normal star, using JWST, will be extremely challenging, if not impossible,” said Dan Maoz from Tel-Aviv University in Israel. “The difficulty lies in the extreme faintness of the signal, which is hidden in the glare of the ‘parent’ star. The novelty of our idea is that, if the parent star is a white dwarf, that glare is greatly reduced, and one can now realistically contemplate seeing the O2 biomarker. Detecting other biomarkers will require future space telescopes that are even more ambitious than JWST.”
Looking for life around dying stars
The technique seems wonderful, in theory, however in practice it’s a whole lot more difficult to apply. Most parent stars are very bright, causing noise that blocks planetary signals. A white dwarf, though very dim and difficult to detect, offers less resistance to spectroscopy surveys, thus offering the best chance at detecting a possibly life harboring planet. For planets around other types of stars, such as red dwarfs, observation might take hundreds of hours, compared to mere hours in the case of white dwarf stars.
“In the quest for extraterrestrial biological signatures, the first stars we study should be white dwarfs,” said theorist Avi Loeb in a CfA press release.
What are the signals astronomers are looking for? Well, the most important biomarkers are oxygen and methane, since these chemical elements are typically generated by life, on Earth at least, and would quickly degrade were it not for their constant regeneration.
No planets have yet been detected orbiting a white dwarf, due to the difficulty in observing these faint stars, however there is some evidence to suggest that such planets might exist. In the paper published in the journal MNRAS, the researchers believe that in a survey of 500 dwarf stars – if a third of all white dwarfs host an Earth-mass planet within their habitable zones (where liquid water is supported) – one such planet might be found.
First discovered in 2005, and then studied in more depth since 2007, NASA scientists have finally isolated the ethereal glow thought to originate from the very first objects in the Universe with the highest precision yet.
As seen in the image above, depicted in orange and red, the ‘lumpy’ infrared glow was observed using the ever faithful Spitzer Space Telescope, a remarkable device which has so far delivered numerous valuable scientific data about the cosmos. The scientists suggest the glow was given off by wildly massive stars or voracious black holes. The exact source can not be pinpointed with the available technology today, but what seems rather certain is that it originated from the very first objects in the Universe 13 billion years ago, shortly, in cosmic time that is, after the “Big Bang“, which is theorized to had occurred 13.7 billion years ago.
“All we can say is that these sources do not exist among the known galaxy populations, which have been observed to very early times (large distances),” said Alexander “Sasha” Kashlinsky, a NASA scientist who led the team that made the discovery. “This likely puts us within the first half-giga-year of the universe’s evolution, the epoch of first stars.”
The intriguing glow, known as cosmic infrared background, was first sighted by Spitzer in 2005, but only in recent years was the telescope able to isolate it. Scientists directed Spitzer at a region of interest in the sky — near the constellation Boötes — and studied it for over 400 hours, after which they carefully subtracted all of the known stars and galaxies in the images.
What remained were faint patterns of light with several telltale characteristics of the cosmic infrared background.
“These objects would have been tremendously bright,” says Alexander Kashlinsky of NASA’s Goddard Space Flight Center.
“We can’t yet directly rule out mysterious sources for this light that could be coming from our nearby universe, but it is now becoming increasingly likely that we are catching a glimpse of an ancient epoch. Spitzer is laying down a roadmap for NASA’s upcoming James Webb Telescope, which will tell us exactly what and where these first objects were.”
Their first light would have originated at visible or even ultraviolet wavelengths and then, because of the expansion of the universe, stretched out to the longer, infrared wavelengths observed by Spitzer. The telescope, however, has a short-wavelength view and thus can not answer unambiguously whether these objects were stars, black holes, galaxies or some previously unknown celestial formation. The new study measures this cosmic infrared background out to scales equivalent to two full moons – significantly larger than before. They plan to explore more patches of sky in the future.
“We hope to achieve this in the coming years (or months),” Kashlinsky said.
Such investigations would have access to a broader picture, and thus answers as well, once with the deployment of the highly anticipated James Webb Space Telescope, slated for launch in 2018. The James Webb Telescope is a massive, cutting-edge space telescope designed to orbit 1 million miles from Earth, where it would observe the mid-infrared portion of the electromagnetic spectrum. This would make it capable of gazing through some of the earliest forms of the Universe.
“This is one of the reason’s we are building the James Webb Space Telescope,” says Glenn Wahlgren, Spitzer program scientist. “Spitzer is giving us tantalizing clues, but James Webb will tell us what really lies at the era where stars first ignited.”
Artist impression of the "water-world" GJ1214b, orbiting around its red-dward star. The planet represents a whole new type of exoplanet, like nothing ever observed so far in known planetary systems. (c) NASA
The hunt for the second Earth, a similar life-bearing paradise like our own, rages on, and while no candidate came any close so far, scientists have made some extraordinary discoveries in the process. The latest exciting find is a super-Earth, a planet larger than Earth, but no bigger than Neptune, that represents the first of a new class of exoplanets – a steamy waterworld. Quick, someone call Kevin Costner!
Dubbed, GJ 1214b, the exoplanet is a mere 40 light-years away. It was first discovered in 2009 by ground-based telescopes, and a preliminary report was issued in 2010 by a team of scientists lead by Zachory Berta, from the Harvard Smithsonian Center for Astrophysics. Back then, collected data suggested that GJ 1214b’s atmosphere was likely composed primarily by water, however until recently, they couldn’t make a definitive conclusion.
Even from back then, however, Berta and colleagues knew they came across something extraordinary. Fortunately, they managed to have the Hubble Space Telescope’s wide-field camera take a glimpse in the planet’s direction and study it as it crossed in front of its star. The telescope studied the planet as it was in transit, and thus determined the composition of the planet’s atmosphere based on how it filtered the starlight.
“GJ 1214b is like no planet we know of,” study lead author Zachory Berta of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., said in a statement. “A huge fraction of its mass is made up of water.”
“We’re using Hubble to measure the infrared color of sunset on this world,” Berta said. “The Hubble measurements really tip the balance in favor of a steamy atmosphere.”
An alien world filled with water
The planet is about 2.7 times the Earth’s diameter, however its mass is just seven times higher, resulting in 2 grams per cubic centimeter (g/cc) density. Earth’s density is 5.5 g/cc, while that of water is 1 g/cc. It seems GJ 1214b has a lot more water and a lot less rock than our blue marble – a complete new class of alien planet, one the likes have never been found before.
It might seem like we’ve found that other life-supporting paradise, however GJ 1214b orbits its red-dwarf star at a distance of 1.2 million miles (2 million kilometers), which results in an estimated surface temperature of about 446 degrees Fahrenheit (230 degrees Celsius). This boiler-planet has no chance of serving life at its surface, covered in a steamy atmosphere. However, deep underwater might be another story. Even on our planet, biologists have found evidence of life lurking right next to hot, underwater geysers.
“The high temperatures and high pressures would form exotic materials like ‘hot ice’ or ‘superfluid water,’ substances that are completely alien to our everyday experience,” Berta said.
Still, GJ 1214b sounds extremely interesting and considering it’s relative short distance from Earth, it certainly makes an exciting prospect for follow-up observations by modern, future instruments, like the James Webb Space Telescope, slated for launch in 2018.
The study will be published in a future edition of the Astrophysical Journal.
Earlier today Obama’s administration budget plan for the National Aeronautics and Space Administration was proposed to $18.7 billion, at the same amount as in 2010, and puts predominance towards science research, exploration and commercial flight development. The $18.7 billion funding layout is $300 million less than the draft budget approved for 2011 in the NASA Authorization Act last year and $750 million less than the legislation’s blueprint for 2012.
In the layout, $1,8 billion is being diverted from the space operation program, which reflects the end of the space shuttle program, to the space research and technology division occupied with the human space program (more than $1 billion) and science division ($500 million). Part of these costs are intended to cover the overrun costs for the James Webb Space Telescope, which has already amounted $3 billion in spending, the innovative device intended to replace the famous Hubble sometime in the mid-decade.
Also, the White House proposes a $350 million increase in funding for commercial crew transportation programs to $850 million next year. The budget request would also initiate development of a heavy-lift rocket and Orion exploration capsule, calling for $2.8 billion in combined spending on those programs in 2012.
The $18.7 billion White House budget plan is significantly bolder than that of the Republicans, which propose to cut N.A.S.A. funding back to 2008’s level. Early analysis already reports this would mean a scrapping of the James Webb telescope, delay many of Obama’s earth sciences initiative and 75,000 contractors laid off by this September, as reported by the agency.
How much do you personally contribute to the N.A.S.A budget? For another interesting analysis, Space.com reports that a family with the median household income ($49,777 according to the U.S. Census Bureau), which pays $6,629 of federal taxes, pays the space agency … $33.