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;
A group of astronomers at the University of Leeds have identified rich reservoirs of life-giving molecules around young stars in our galaxy — which was previously believed to happen only under rare circumstances. The findings suggest that there could be as much as 100 times more of these molecules in the Milky Way than previously thought.
The researchers published a set of papers in which they detail the discovery of the molecules around disks of gas and dust particles, orbiting around stars. These disks are formed simultaneously with the stars and can eventually form planets. Such as it happened with the disc near the Sun that formed the planets of the Solar Systems.
“These planet-forming disks are teeming with organic molecules, some which are implicated in the origins of life here on Earth,” Kartin Öberg, one of the authors, said in a statement. “This is really exciting. The chemicals in each disk will ultimately affect the type of planets that form and determine whether or not the planets can host life.”
The researchers used the Atacama Large Millimetre/submillimetre Array (or ALMA) radio telescope in Chile to look at the composition of the five discs. ALMA can detect even the weakest signals from molecules in outer space thanks to its 60 antennas. Each molecule emits a light at a different wavelength that scientists can investigate.
The researchers looked for certain organic molecules and found them in four of the five disks, and in much larger numbers than they originally anticipated. These molecules are considered essential to life on Earth. They are believed to have reached the planet through asteroids or comets that crashed into Earth billions of years ago.
The theory of the molecules traveling in asteroids and comets was reaffirmed here, as they were located in the same region that produces space rocks. They weren’t evenly distributed in the discs, with each containing a different mix of molecules. For the researchers, this shows that each planet is created based on a different mix of ingredients.
“ALMA has allowed us to look for these molecules in the innermost regions of these disks, on size scales similar to our Solar System, for the first time. Our analysis shows that the molecules are primarily located in these inner regions with abundances between 10 and 100 times higher than models had predicted,” John Ilee, one of the authors, said in a statement.
The researchers specifically looked for three molecules, cyanoacetylene (HC3N), acetonitrile (CH3CN), and cyclopropenylidene (c-C3H2), in five protoplanetary disks, known as IM Lup, GM Aur, AS 209, HD 163296, and MWC 480. The discs were found 300 to 500 lights years from Earth, with each of them showing signals of on-going planet formation.
The next steps
Following this remarkable discovery, the researchers want to keep on searching for more complex molecules in the protoplanetary disks. They are specifically looking forward to the launch of the James Webb Telescope, so far scheduled for December 18th, as it will help to examine the molecules in much greater detail than before, they added.
“If we are finding molecules like these in such large abundances, our current understanding of interstellar chemistry suggests even more complex molecules should also be observable,” Ilee said in a statement. “If we detect them, then we’ll be even closer to understanding how the raw ingredients of life can be assembled around other stars.”
Astronomers have had their eyes on Europa for some time. At first glance, there’s not much going on in this barren world, but this frozen satellite actually has a lot going for itself. For one, it may not be barren. From ground-based observations, researchers have known that Europa’s surface is mostly covered with water ice, but in recent years, we’ve found compelling evidence of a salty, liquid ocean beneath the frozen crust, as well as active seafloor volcanoes pulsing on the seafloor.
Life as we know it seems to have three main requirements: liquid water, the appropriate chemical elements, and an energy source — and all three may be on Europa.
The problem of radiation
Now, in a new study, a computer model estimates that the surface of Europa has been churned through a process called “impact gardening”. According to the studies, the first 12 inches (30 cm) have been churned over tens of millions of years. This means that the top 30 cm of Europa has been exposed to radiation, which would have likely destroyed all signs of life, should these signs exist.
Life on Earth is shielded from radiation thanks to our atmosphere and magnetic field, which keeps the most harmful parts of solar radiation at bay. Other celestial bodies, like our Moon or Europa, are not as fortunate, and they are constantly bombarded. The ice sheet could protect life forms on Europa if they live deep enough beneath it. But if these life forms (or their chemical signatures) were to reach the surface, they would almost certainly be destroyed.
The atmosphere also protects us from impacts from asteroids and meteorites — that’s why the Moon, for instance, is riddled with impact craters, and the Earth is far less affected because many of these bodies burn up in the atmosphere. These impacts also churn some material to the surface, exposing it to radiation.
So if we want to look for signs of life on Europa, we have to dig a bit deeper.
“If we hope to find pristine, chemical biosignatures, we will have to look below the zone where impacts have been gardening,” said lead author Emily Costello, a planetary research scientist at the University of Hawaii at Manoa. “Chemical biosignatures in areas shallower than that zone may have been exposed to destructive radiation.”
“Even at higher latitudes, at which biosignatures may be preserved against radiation at centimetre depths, impact gardening cycles material upwards to the surface and may thwart the hopes of preservation and sampling at shallow depths,” Costello and her colleagues said in the study.
Impact gardening on Europa has been proposed before, but this new study offers some of the most comprehensive support for it. In addition, it also estimates the depth to which it happens.
This is the first to take into account secondary impacts caused by debris raining back down onto Europa’s surface after being kicked up by an initial impact. The research also suggests that Europa’s mid- to high-latitudes would be less affected by the double whammy of impact gardening and radiation — so that’s where we should probably start looking for signs of life.
“This work broadens our understanding of the fundamental processes on surfaces across the solar system,” said Cynthia Phillips, a Europa scientist at NASA’s Jet Propulsion Laboratory in Southern California and a co-author of the study. “If we want to understand the physical characteristics and how planets in general evolve, we need to understand the role impact gardening has in reshaping them.”
While no mission directly to the surface of Europa is planned, NASA’s Europa Clipper is set for launch in 2024. The spacecraft will conduct a series of close flybys of Europa, carrying instruments to both survey the moon remotely as well as analyze samples of the dust and gases ejected from Europa’s surface.
When the Cassini-Huygens probe analyzed the salty plumes ejected from Saturn’s moon Enceladus, it found something that made a lot of researchers excited: methane. If Enceladus, an ice-covered moon with a subsurface ocean of liquid water, is hosting methane, it may well be hosting life. Now, a new study seems to add more weight to that idea.
There could possibly maybe be life on Enceladus
The more we look at Enceladus, the more interesting it seems. In 2006, researchers first identified massive water plumes shooting hundreds of miles into space at high speeds. The plumes were also found to be salty, and in order for this to happen, it would mean that the satellite hosts a liquid ocean beneath its frozen surface.
Since then, the Cassini spacecraft dove into these plumes several times, gathering information about their composition. A new study published in Nature Astronomy looked at this chemistry and Enceladus’ ability to potentially host life. The study compared the Enceladus plumes with the deep-sea plumes on Earth, where microbial (and even macroscopic) life is known to thrive.
The chemistry data from Cassini’s mass-spectroscopy measurements show relatively high concentrations of methane, carbon dioxide, carbon monoxide, and organic materials.
“We wanted to know: Could Earth-like microbes that ‘eat’ the dihydrogen and produce methane explain the surprisingly large amount of methane detected by Cassini?” study co-lead author Régis Ferrière, an associate professor in the University of Arizona’s Department of Ecology and Evolutionary Biology, said in a statement.
Ferrière and colleagues built a series of mathematical models that assessed the likelihood of the methane on Enceladus being generated biologically. They also analyzed whether the observed chemistry could sustain a population of Enceladus microbes.
The models determined that hydrothermal vent chemistry fits perfectly with the observations, but only with the presence of methanogenic microbes — and this is good news for our search for extraterrestrial life.
“In summary, not only could we evaluate whether Cassini’s observations are compatible with an environment habitable for life, but we could also make quantitative predictions about observations to be expected, should methanogenesis actually occur at Enceladus’ seafloor,” Ferrière said.
However, the results don’t necessarily mean there’s life on Enceladus — but they do suggest it’s fairly possible. It’s still also possible that geochemical, non-biological processes produced the chemistry observed by Cassini.
What the study tells us is that all that’s needed for life is there, and life on Enceladus is at least a plausible idea. Whether or not life actually is there is a bit more difficult to confirm at this point.
“Obviously, we are not concluding that life exists in Enceladus’ ocean,” Ferrière said. “Rather, we wanted to understand how likely it would be that Enceladus’ hydrothermal vents could be habitable to Earth-like microorganisms. Very likely, the Cassini data tell us, according to our models.
“And biological methanogenesis appears to be compatible with the data. In other words, we can’t discard the ‘life hypothesis’ as highly improbable. To reject the life hypothesis, we need more data from future missions,” he added.
A mission that could dive down to Enceladus’ liquid water is not in sight, and likely won’t be for the next 10-20 years — at least. But that doesn’t mean we can’t indirectly assess its habitability in the meantime, like we’ve been doing until now.
Papers like this one help us not just find life on extraterrestrial bodies but also understand these surprising places in our solar system. After all, an icy moon far away from the Sun is not exactly where you’d expect to find life.
The authors also add that an important advance of the paper is its methodology, which can be applied to other settings as well. In other words, researchers could use the same approach and assess the likelihood of life on planets even outside our solar system.
What once seemed like an unlikely but enticing possibility has been all but ruled out. An international group of researchers found that the amount of water in the atmosphere of Venus is so low that even the most drought-tolerant microbes of the Earth wouldn’t be able to survive in those conditions. Essentially, life as we know it just couldn’t exist in these clouds.
The finding dismissed a study published late last year that had theorized microbes could be living in there.
The findings will come as a disappointment to some who have been following the news. Optimistic after the discovery of phosphine, a compound made of atoms of phosphorus and hydrogen that on Earth can be associated with living organisms, in Venus’ atmosphere, researchers had suggested phosphine may be produced by microorganisms living in those clouds. That doesn’t seem to be the case.
In the new study, researchers looked at measurements from probes that flew through the atmosphere of the planet and collected data about temperature, humidity, and pressure in the clouds. From these values, they calculated the so-called water activity – which is the water vapor pressure inside the individual molecules in the clouds.
“We found not only is the effective concentration of water molecules slightly below what’s needed for the most resilient microorganism on Earth, it’s more than 100 times too low. It’s almost at the bottom of the scale, and an unbridgeable distance from what life requires to be active,” John Hallsworth, co-author, told BBC News.
On Earth, microorganisms can survive and proliferate in droplets of water in the atmosphere when temperatures allow. However, the findings of this new study leave virtually a zero chance of anything living in the clouds of Venus. Without being hydrated, living systems including microorganisms can’t be active and proliferate, Hallsworth said.
Previous studies on microorganisms living in extreme conditions on Earth found that life can exist at temperatures as cold as minus 40ºC (minus 40 degrees Fahrenheit). For water activity, measured from 0 to 1, the lowest survivable value is 0.585. The water activity level found in the molecules in the Venusian clouds was a very low 0.004.
NASA astrobiologist Chris McKay, one of the co-authors of the paper, said in a news conference that the findings of the study were conclusive. “It’s not a model, it’s not an assumption,” she said. For McKay, the fleet of space missions currently being prepared for Venus won’t change anything about the hope for life on Earth’s closest neighbor.
In the study, the researchers also analyzed data from other planets too and found that the clouds of Jupiter provide sufficient water activity to theoretically support life. Water activity value sits at 0.585, which is above the threshold, while temperatures are also just about survivable, at around 40 degrees Fahrenheit, according to data from the Galileo probe.
McKay said there’s “at least” a layer in the clouds of Jupiter where the water requirements aren’t met. Still, high levels of ultraviolet radiation or lack of nutrients, could prevent potential life from thriving, she added. Completely new measurements will be necessary in the future to find out whether life could thrive there or not.
Around the world, social media users are reporting seeing a mysterious row of bright lights gliding across the sky — which many claim to be UFOs. Exciting as it may sound, it’s likely something far less exciting: a chain of Starlink satellites developed by Elon Musk’ SpaceX.
Last week, Starlink launched its latest wave of 52 satellites from Kennedy Space Center in Florida. It has already launched more than 600 of its 12,000 planned satellites, usually set off in batches of 60. They are usually described as “megaconstellations” because they are a group of satellites moving together.
Paul Lynam, a resident astronomer at Lick Observatory on Mount Hamilton, told The San Francisco Chronicle said the satellites were “catching and reflecting sunlight either in the couple hours after sunset or before sunrise” — which is what a growing number of people are reporting seeing. The sightings are becoming more common as SpaceX continues to populate its constellation space,” he added.
Over the last few years, more people seem to have been seeing these strange lights. In Canada, for example, there has been a notable surge in the number of calls to 911 dispatchers, with people calling to report UFO sightings near their homes.
“We were getting a lot of calls with the SpaceX satellite launches. They’re a very specific pattern in the sky, they’re not hitting the ground, and we can just explain very quickly to people that there are actual satellites,” Tracy Duval, a dispatcher, told CityNews. We have situations where people are saying that the aliens are coming.”
While seeing these satellites in the sky can be an exciting experience and fuel the imagination (sparking images of aliens and UFOs), astronomers around the world are very concerned about the megaconstellations of SpaceX satellites. They worry that these satellites will be too bright and will interfere with visibility for scientific observations. But for people around the world, the satellites can be a godsend.
Under Starlink, SpaceX is developing a satellite network to provide global broadband coverage for high-speed internet access, particularly for people across the world in rural and remote areas. The service is now being beta tested by a limited number of users. It’s reportedly 47% faster than fiber-optic cable internet, the company has said.
The US Federal Communications Commission (FCC) has granted SpaceX permission to fly 12,000 satellites, and perhaps as many as 30,000 eventually. This is massive. There are now only 2,000 active satellites orbiting the Earth that are key to modern life, from mobile phones to internet. Less than 9,000 have ever been launched in all of history.
The Starlink satellites orbit at an altitude of 550 kilometers, which is low enough to get pulled down to Earth by atmospheric drag and burn up in a few years. This means they won’t become space junk once they die, which was an initial concern. Each weighs about 227 kilograms and measures about the size of a typical coffee table.
Musk and his company have been questioned by the astronomical community due to their brightness and potential to disrupt observations of the night sky. This is because the satellites are brighter than most of the stars visible to the human eye and also move faster through the sky. This leaves a trail that can pollute astronomer’s data.
In response, SpaceX started equipping its satellites with a blackened sunshade called VisorSat. The company says it will lower the satellite’s apparent brightness by reducing the amount of sunlight that’s reflected. Initial efforts included launching a satellite with a black antireflecting coating, which was half as bright as a standard satellite.
If noticing a UFO was difficult, the satellites are making it more difficult. Still, don’t lose hope. There might still be a green guy out there waiting for us yet.
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
The star system of Trappist-1 is home to the largest group of Earth-like planets ever discovered elsewhere in the Universe by astronomers. This means that investigating these seven rocky worlds gives us a good idea of how common exoplanets with similar compositions to our own are in the Milky Way and the wider cosmos.
New research has revealed that these planets, which orbit the Trappist-1 star 40 light-years away from Earth, all have remarkably similar compositions and densities. Yet, all are less dense than Earth.
The results could indicate these are worlds with much more water than is found on earth, or possibly even that these planets are composed almost entirely of rust.
This similarity between the exoplanets makes the Trappist-1 system significantly different from our own solar system which consists of planets with radically compositions and densities. Trappist-1’s worlds are dense, meaning they are like the rocky planets in our solar system, Earth, Mars, Venus, and Mercury. The system seems to be lacking larger gas dominated planets like Jupiter, Saturn, Uranus and Neptune.
The finding, documented in a paper published in the Planetary science Journal shows how the system, first discovered in 2016, offers insight into the wide variety of planetary systems that could fill the Universe.
“The new observations allowed us to use transit data from a much longer time span than was available to us for the 2018 calculations,” explains Simon Grimm of the University of Bern, who as well as being involved in the current study, was part of a 2018 team that provided the most accurate calculation of the masses of the seven planets thus far. “With the new data, we were able to refine the mass and density determinations of all seven planets.
“It turned out that the derived densities of the planets are even more similar than we had previously expected.”
Seven Exoplanets with Similar Densities
The similarity in densities observed in the Trappist-1 exoplanets seen by the astronomers hailing from the Universities of Bern, Geneva and Zurich, indicates that there is a good chance they are composed of the same materials at similar ratios.
These are the same materials that we believe form most terrestrial planets, iron, oxygen, magnesium, and silicon. But there is a significant difference between our terrestrial world and the Trappist-1 exoplanets.
The planets in the Trappist-1 system appear to be about 8% less dense than the Earth. This suggests that the materials that comprise them exist in different ratios than they do throughout our home planet.
This difference in density could be the result of several different factors.
One of the possibilities being investigated by the team is that the surfaces of the Trappist-1 exoplanets could be covered with water, reducing their overall density. Combining the planetary interior models with the planetary atmosphere models, the team was able to evaluate the water content of the seven TRAPPIST-1 planets with what Martin Turbet, an astrophysicist at the University of Geneva and co-author of the study describes as “a precision literally unprecedented for this category of planets.”
For the Trappist-1 system’s four outermost planets, should water account for the difference in density, the team has estimated that water would account for 5% of their overall masses. This is considerably more than the 0.1% of Earth’s total mass made up of water.
Rust Nevers Sleeps for the Trappist-1 Planets
Another possibility that could explain why the Trappist-1 exoplanets have lower densities than Earth is the fact that they could be composed of less iron than our planet is–21% rather than the 32% found in the Earth.
It’s also possible that the iron within the seven exoplanets could be bonded with oxygen forming iron oxides–commonly known as rust. This additional oxygen would reduce the planet’s densities.
Iron oxides give Mars its rust-red colour, but they are pretty much confined to its surface. Its core is comprised of non-oxidized iron like the solar system’s other terrestrial planets. If iron-oxide accounts for the seven exoplanet’s lower densities it implies that these worlds are rusty throughout and lacking solid non-oxidized iron cores.
“The lower density might be caused by a combination of the two scenarios – less iron overall than and some oxidized iron,” explains Eric Angol, an astrophysicist at the University of Washington and lead author of the new study. “They might contain less iron than Earth and some oxidized iron like Mars.”
Angol also points out that the Trappist-1 planets are likely to have a low-water content, an idea supported by previous research. “Our internal and atmospheric structure models show that the three inner planets of the TRAPPIST-1 system are likely to be waterless and that the four outer planets have no more than a few per cent water, possibly in liquid form, on their surfaces,” says Turbet.
This seems to favour the theory that the lower density of the Trappist-1 planets is a result of one or both of the iron scenarios suggested by the researchers.
There’s Still a Lot to Learn from Trappist-1
Since its discovery in 2o16, the Trappist system has been the subject of a wealth of observations made by both space and ground-based telescopes alike. Before it was decommissioned at the start of January 2020 the team used the Spitzer Space Telescope to collect their data. This telescope, operated by NASA’s Jet Propulsion Laboratory, alone has clocked in more than 1,000 hours of targeted observations of the exoplanets.
This new study demonstrated the importance of studying systems such as Trappist-1 for extended periods of time.
Caroline Dorn, an astrophysicist at the University of Zurich also highlights the fact that studying systems like this could answer questions about the habitability of exoplanets and the possibility of life elsewhere in the Universe.
“The TRAPPIST-1 system is fascinating because around this one star we can learn about the diversity of rocky planets within a single system,” concludes Dorn. “And we can actually learn more about an individual planet by studying its neighbours as well, so this system is perfect for that.”
“The night sky is full of planets, and it’s only been within the last 30 years that we’ve been able to start unravelling their mysteries, also for determining the habitability of these planets.”
Agol. E., Dorn. C., Grimm. S. L., et al, ‘Refining the transit timing and photometric analysis of TRAPPIST-1: Masses, radii, densities, dynamics, and ephemerides,’ Planetary Science Journal, [https://arxiv.org/abs/2010.01074]
Life-sustaining water could have existed miles beneath the surface of Mars thanks to the melting of thick ice sheets by geothermal heat, new research has found. The discovery, made by a team led by Rutgers University scientists, suggests that 4 billion years ago the most likely place for life to prosper on the Red Planet was beneath its surface.
The study, published in the latest edition of the journal Science Advances, could solve a problem that also has implications for the existence of liquid water–and thus the early development of life–on our planet too. Thus far, researchers looking into the existence of liquid water early in both Earth and Mars’histories have been puzzled by the fact that the Sun would have been up to 70% less intense in its stellar-youth.
This lack of intensity coupled with findings of liquid water at this stage in the solar system’s history is referred to as ‘the faint-sun paradox,’ and should mean that Mars conditions were cold and arid in its deep history. This conclusion was contradicted by geological evidence of liquid water on the young planet. The problem could now be solved, for Mars at least, by geothermal activity.
“Even if greenhouse gases like carbon dioxide and water vapour are pumped into the early Martian atmosphere in computer simulations, climate models still struggle to support a long-term warm and wet Mars,” explains lead author Lujendra Ojha, assistant professor in the Department of Earth and Planetary Sciences in the School of Arts and Sciences at Rutgers University, New Brunswick. “We propose that the faint young sun paradox may be reconciled, at least partly, if Mars had high geothermal heat in its past.”
The status of Mars climate billions of years ago and if freshwater could have existed its this point early in its history has been a source of heated debate in the scientific community for decades. The discussion has been further complicated by the question of whether water would have existed on the planet’s surface or deep underground? Climate models produced for Mars thus far have suggested average surface temperatures below the melting point of water at this point in its history.
Ojha and his team investigated this seeming contradiction in our understanding of Mars by modelling the average thickness of ice deposits in the Red Planet’s southern highlands. They also examined data collected by NASA’s InSight lander, which has been measuring the ‘vitals’ of the Red Planet since 2018.
Discovering that the thickness of these ice deposits did not exceed an average thickness of 2 kilometres, the team complemented this finding with estimates of both the planet’s average annual surface temperature and the flow of heat from its interior to its surface. The aim of this was to discover if the surface heat flow would have been strong enough to melt Mars’ ice sheets.
Indeed, the study seems to show that the flow of heat from both the crust and mantle of Mars would have been intense enough to begin melting at the base of its ice sheets.
Did Life on Mars prosper Beneath its Surface?
The wider implication of this revelation is that whatever the climate of Mars was like billions of years in its history if life once existed on the Red Planet, its subsurface would have been its most habitable region. Thus, life could have prospered, say the team, miles beneath the surface of our neighbour, sustained by the flow of freshwater.
Significantly, this supply of water would have existed even as Mars lost its magnetic field and its atmosphere was stripped away by harsh solar winds and blistering radiation. The process which ultimately deprived Mars of its surface liquid water. This means that life could have survived on the planet, hidden miles underground for much longer than the surface remained habitable.
“At such depths, life could have been sustained by hydrothermal activity and rock-water reactions,” says Ojha. “So, the subsurface may represent the longest-lived habitable environment on Mars.”
A new study has revealed the detection of water in the upper atmosphere of Mars for the first time. The discovery gives scientists a good idea of the mechanism that is currently stripping the Red Planet of its water.
The surface of Mars is cold and dry —bereft of liquid water — but this wasn’t always the case. Studies of the Martian surface have discovered the tell-tale tracks of long dry ancient rivers and sedimentary deposits that indicate lake beds into which water once flowed. This poses the question of how the Red Planet lost its liquid water?
A study published in the journal Science suggests a new mechanism that could have driven Mars’ water loss. A team of astronomers has used data collected from Mars’ atmosphere by NASA’s Neutral Gas and Ion Mass Spectrometer on the Mars Atmosphere and Volatile Evolution spacecraft (MAVEN) to discover water in the planet’s upper atmosphere.
“For the first time, we have seen water in the upper atmosphere of Mars, at around 150 km above the surface. Other scientists have previously observed water in the middle atmosphere,” Shane Wesley Stone, a PhD. Candidate in Planetary Sciences at the Lunar and Planetary Laboratory, University of Arizona, and one of the paper’s authors tells ZME Science. “Water in the upper atmosphere is quickly destroyed and can escape to space, which is why our observations of water in the upper atmosphere are significant.”
Water transported to the upper atmosphere of Mars is converted to atomic hydrogen, which is then so-light that it is lost to space. This process could have been driving Mars’ water loss for billions of years. Water had previously been detected in the lower atmosphere, where scientists believed it was confined, but this is the first detection of water in the upper atmosphere, which caught the team by surprise.
“We did not know that water makes it all the way to the upper atmosphere, so we did not know how important this upward transport of water is to the escape of hydrogen to space and thus to water lost from Mars,” Stone says, explaining that water higher in the atmosphere would be broken down much more rapidly than happens closer to the martian surface. “Water which makes it to the upper atmosphere is destroyed in about 4 hours. This destruction of water would be ten times slower in the middle atmosphere, where most of the products of this destruction would be transported downward back toward the surface.”
Rising Damp: How Does Water Make its Way to Mars’ Upper Atmosphere?
Stone explains that the team is not yet certain what processes are lifting water to Mars’ upper atmosphere, but their study has yielded some good clues as to what may be the major players in this phenomenon.
“We see a seasonal trend in the upper atmospheric water abundance,” says the planetary chemist. “During summer in the southern hemisphere, the water abundance in the upper atmosphere is largest. During summer in the northern hemisphere, the water abundance in the upper atmosphere is smallest but is still significant.”
Stone explains that this seasonal trend is caused by two things. Firstly, during southern summer, Mars is closer to the Sun than it is during the rest of the Martian year. Secondly, this is also the season of dust storms on Mars. He adds: “Relatively close proximity to the Sun and dust storms both lead to heating in the atmosphere, which leads to greater transport of water to the upper atmosphere.”
The researcher points to a massive Martian dust storm that occurred in 2018 as being a major contributing factor to water in the upper atmosphere. The storm was first spotted by NASA’s Mars Reconnaissance Orbiter (MRO) on May 30th 2018 and by June of that year, it had grown to a planet encompassing event.
“Dust storms lead to a sudden splash of water into the upper atmosphere: during the global dust storm of 2018, the water abundance in the upper atmosphere increases by 20x relative to the nominal seasonal abundance,” Stone says. “Smaller surges of water are observed during regional dust storms that occur every Mars year of 687 days. Global storms occur about once every 10 Earth years.”
The team believe that water is moving upward past what planetary scientists call the hygropause — a cold layer in the atmosphere at which water condenses from vapour to liquid, forming clouds. “This because, as we and other scientists have found, the Martian hygropause is not as efficient at trapping water close to the surface as the hygropause on Earth,” Stone says. “The hygropause on Mars is not as efficient because it is too warm: when Mars is closest to the Sun and when dust storms occur, heating caused by these processes warms the hygropause, allowing water to move upward.”
The mechanism their finding reveals is currently the main way that Mars loses water, but Stone points out that this likely wasn’t always the case.
The Changing Picture of Water Loss on Mars
Water transported to Mars’ upper atmosphere by seasonal effects and dust storms where it is broken down to hydrogen and then lost to space is currently the predominant mechanism of water loss on Mars, but the team says this is only because of the Red Planet’s current environment. The water loss mechanisms that have proceeded for billions of years were likely different in the past in terms of both dominance and the speed at which they proceed.
“This process we describe is an important factor in Martian water loss today. However, this water could only be transported to the upper atmosphere relatively recently, over the last billion years or so,” Stone says. “Much of Mars’ atmosphere was lost to space before this time, leading to the weak hygropause which allows water into the upper atmosphere. All escape processes we observe today were likely faster in the past.”
The team reached this conclusion due to the fact that when all the water loss rates of the present-day escape processes are summed, their current escape rate is too slow to explain all the water loss that scientists know must have occurred over the last few billion years.
“We know that over 4 billion years, Mars lost about 66% of its atmosphere to space,” Stone explains. “If we talk about water specifically, Mars has lost 10s to 100s of meters of a ‘global equivalent layer’ of water — equivalent to spreading all of the water lost by Mars over its surface to form an even layer and then reporting how deep this layer would be.”
The process the team describe is responsible for the loss of 44 cm of H2O over the last billion years, and global dust storms are responsible for the loss of an additional 17 cm on top of this over the last billion years.
“In the present epoch, during most of the Martian year, this process we describe is just as important as the ‘classical process’ — the basic process scientists thought responsible for the transport of hydrogen to the upper atmosphere since the first work on this topic in the early 1970s,” Stone says. “During global storms, this water which makes it to the upper atmosphere produces 10x more escaping hydrogen than does the classical process.”
Big Surprises and Future Investigations
Stone describes that the next steps for this research involve figuring out exactly how important this new water loss mechanism has been throughout the history of Mars.
“Extrapolating back over billions of years is extremely difficult and doing it correctly takes time. We still need to understand better the specific transport processes responsible for delivering this water to the upper atmosphere,” he says, adding that the team’s findings came as something as a shock even to them. “The entire project was a huge surprise to us: we were surprised to see water this high in the atmosphere, we were surprised to see the seasonal trend in the water abundance, and we were surprised by just how big an effect the global dust storm has on the upper atmospheric water abundance.”
Researching water loss from Mars is likely to be an important step in understanding how abundant water is throughout the Universe, as Dimitra Atri, a researcher from the Space Science at NYU Abu Dhabi (NYUAD), recently told ZME Science:“Since it is extremely difficult to observe the escape process in exoplanets, we are planning to study this phenomenon in great detail on Mars with the UAE’s Hope mission.”
Thus, this type of study could tell us how unique Earth is in terms of the possession of liquid water in the Universe. Something that could, in turn, tell us about the chances of life on exoplanets.
“Mars used to look like Earth: warmer and wetter with a thick atmosphere and abundant liquid water on its surface,” Stone concludes. “But over the history of the solar system, Mars’ water was lost to space, leaving behind the cold, dry, red planet we see today. Regardless, Mars will be the next planet on which humans step foot.”
As humanity continues to explore planets beyond the solar system — exoplanets — investigations into conditions on these worlds become increasingly complex. This includes the question of whether these exoplanets can support life.
New research has identified which stars would be most likely to host planets with the necessary conditions for habitability, based upon that star’s stellar activity and crucially the rate at which such activity strips away a planet’s atmosphere.
“We wanted to figure out how planets lose their atmospheres from extreme ultraviolet radiation and estimate their impact on their potential to host life,” Dimitra Atri, a researcher from the Space Science at NYU Abu Dhabi (NYUAD), tells ZME Science. “We focused on a channel of escape called hydrodynamic escape where stellar radiation heats up the planet’s atmosphere and a part of it escapes into space.”
Atri is the author of a paper published in the journal Monthly Notices of Royal Astronomical Society: Letters, which analyzes flare emissions using data collected by NASA’s Transiting Exoplanet Survey Satellite (TESS) observatory ultimately helping to determine where else in the Universe life is most likely to prosper.
Harbouring Life: A Question of Water Retention
Planet habitability is closely associated with that world’s ability to hold liquid water. That means that factors which can boil away that water or cause it to be lost to space reduce that habitability. The habitable zone of a star’s environment is defined as the range at which a planet can orbit and still possess liquid water. This means not too hot or too cold — criteria that led to the alternative name for such regions, the Goldilocks zone.
Yet, distance and a star’s luminosity are not the only factors which can affect a planet’s ability to hold liquid water. Space weather — including solar flares — is another determining element, one that as of yet is not well understood. “Flares erode planetary atmospheres,” Atri says. “A substantial atmosphere is needed to sustain liquid water on a planet’s surface. Flares reduce those chances and make planets less habitable.”
What Atri, alongside coauthor and graduate student Shane Carberry Mogan, discovered was that whilst luminosity from a star was still the primary driving factor in atmosphere stripping, flares were a more important factor for some stars than others. In particular, they discovered that flares from M0-M4 stars — cool, red stars like Betelgeuse — were more likely to strip an orbiting planet’s atmosphere.
The duo determined that more frequent, lower energy flares in the extreme ultraviolet region (XUV) of the electromagnetic spectrum were more effective at stripping a planet’s atmosphere and thus reducing its habitability than less frequent, higher energy outbursts. XUV radiation strikes a planet’s atmosphere heating it. This causes hydrodynamic escape, pushing out light atoms first, which through collision and other drag effects also pull out heavier molecules.
“We find that for most stars, luminosity-induced escape is the main loss mechanism, with a minor contribution from flares,” Atri explains. “However, flares dominate the loss mechanism of around 20 per cent of M4–M10 stars.
“M0–M4 stars are most likely to completely erode both their proto- and secondary atmospheres, whilst M4–M10 stars are least likely to erode secondary atmospheres.”
The study also highlights the fact that better modelling of the factors that affect an exoplanet’s atmosphere is needed. Determining the systems and planets most likely to harbour life will play an important factor in selecting targets for the upcoming James Webb Space Telescope — set to launch on October 31st 2021 — and the ESO’s Extremely Large Telescope (ELT) currently under construction in the Acatma desert, Chile.
“The next research step would be to expand our data set to analyze stellar flares from a larger variety of stars to see the long-term effects of stellar activity, and to identify more potentially habitable exoplanets,” adds Atri.
The researcher also points out that the continued investigation of how planets lose their atmosphere could also focus on a target closer to home, our nearest neighbour, Mars. “Since it is extremely difficult to observe the escape process in exoplanets, we are planning to study this phenomenon in great detail on Mars with the UAE’s Hope mission,” the researcher says, explaining how observations from Mars missions can be used to better understand atmospheric escape and how this knowledge can be applied to exoplanets.“We will then apply our understanding of atmospheric escape to exoplanets and estimate the impact of extreme UV radiation on planetary habitability.”
Further to the question of habitability, the study begins to address the wider question of the dynamics of stars and their planetary systems and the evolution of such arrangements. “Given the close proximity of exoplanets to host stars, it is vital to understand how space weather events tied to those stars can affect the habitability of the exoplanet,” Atri concludes. “Stars and planets are very tightly coupled in a number of ways and an improved understanding of this coupling are absolutely necessary to find habitable planets in our Galaxy and beyond.”
Finding microbial life thriving in some of the most extreme environments on Earth is usually a reason for celebration for researchers, as it can guide their search for life on other planets — especially on Mars, their most recent focus of attention.
Newly discovered single-celled creatures living deep beneath the seafloor have given clues about where life on Mars could be found. The bacteria were discovered by the University of Tokyo geomicrobiologist Yohey Suzuki, after a decade examining ancient rocks pulled from the depth of the sea.
Suzuki hypothesized that the cracks in these rocks are home to a community of bacteria as dense as that of the human gut, about 10 billion bacterial cells per cubic centimeter. In contrast, the average density of bacteria living in mud sediment on the seafloor is estimated to be 100 cells per cubic centimeter. The hypothesis turned out to be true.
“I am now almost over-expecting that I can find life on Mars. If not, it must be that life relies on some other process that Mars does not have, like plate tectonics,” Suzuki said in a statement. “I thought it was a dream, seeing such rich microbial life in rocks.”
Undersea volcanoes spew out lava at approximately 1,200 degrees Celsius (2,200 degrees Fahrenheit), which eventually cracks as it cools down and becomes rock. The cracks are narrow and over millions of years, those cracks fill up with clay minerals. Somehow, bacteria find their way into those cracks and multiply.
“These cracks are a very friendly place for life. Clay minerals are like a magic material on Earth; if you can find clay minerals, you can almost always find microbes living in them,” explained Suzuki. “Honestly, it was a very unexpected discovery. I was very lucky because I almost gave up.”
Suzuki and his colleagues discovered the bacteria in rock samples that he helped collect in late 2010 during the Integrated Ocean Drilling Program (IODP), which took researchers to the tropical island of Tahiti in the Pacific Ocean. They used a metal tube to reach the ocean floor and obtain core samples.
Depending on the location, the rock samples were estimated to be 13.5 million, 33.5 million, and 104 million years old. The collection sites were not near any hydrothermal vents or sub-seafloor water channels, so researchers are confident the bacteria arrived in the cracks independently rather than being forced in by a current.
Whole-genome DNA analysis identified the different species of bacteria that lived in the cracks. Samples from different locations had similar, but not identical, species of bacteria. Rocks at different locations have different ages, which may affect what minerals have had time to accumulate therein and therefore what bacteria are most common.
Suzuki and his colleagues speculate that the clay mineral-filled cracks concentrate nutrients that the bacteria use as fuel. This might explain why the density of bacteria in the cracks is eight orders of magnitude greater than the density of bacteria living freely in mud sediment where seawater dilutes the nutrients.
“Minerals are like a fingerprint for what conditions were present when the clay formed. Neutral to slightly alkaline levels, low temperature, moderate salinity, iron-rich environment, basalt rock — all of these conditions are shared between the deep ocean and the surface of Mars,” said Suzuki.
The researchers are now collaborating with NASA’s Johnson Space Center to design a plan to examine rocks collected from the Martian surface by rovers. Ideas include keeping the samples locked in a titanium tube and using a CT (computed tomography) scanner, a type of 3D X-ray, to look for life inside clay mineral-filled cracks.
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?
An entomologist says photos taken by the Curiosity rover depict bugs. His critics say he has pareidolia.
William Romoser, an entomologist and a professor at Ohio University, presented a research poster at a conference in St Louis and said he has evidence of current life on Mars. The said there are “insect-like” and “reptile-like” forms on the planet, which he claimed has a “surprising abundance of higher life forms.”
Romoser spent a few years studying photos from Mars he obtained online. He claimed to have found on them several examples of insect-like forms with a structure similar to bees as well as reptile-like forms including fossils and living organisms.
“There has been and still is life on Mars,” Romoser said. “There is apparent diversity among the Martian insect-like fauna which display many features similar to Terran insects that are interpreted as advanced groups – for example, the presence of wings, wing flexion, agile gliding/flight, and variously structured leg elements.”
The researcher said the photos show images of arthropod body segments as well as legs, antennae, and wings. He claimed to have carefully studied the photos and not to have removed or added content to them, having variated photographic parameters such as contrast and saturation.
“Once a clear image of a given form was identified and described, it was useful in facilitating recognition of other less clear, but none-the-less valid, images of the same basic form,” Romoser said. “An exoskeleton and jointed appendages are sufficient to establish identification as an arthropod.”
That’s it — you’re basically seeing it above. Romoser’s claims are based on the images and the images alone.
Great claims require great proof, and this really isn’t great proof — that’s putting it lightly.
The research was widely questioned in social media and the academic world. Amanda Kooser, CNET writer, said Romoser suffers from pareidolia, a human tendency to see recognizable shapes in random patterns – something commonly found among alien enthusiasts.
Romoser dedicated most of his academic life to studying insects, so he could be seeing insects where there are none. He also has a history of bold (and quite fringe) claims regarding Mars. He published two past reporters where he claimed to have found evidence of intelligent life forms on the red planet.
Even this is putting it lightly: Twitter had a field day with Romoser’s claims.
Romoser is an accomplished entomologist — but if he wants people to take these claims more seriously, substantially more evidence is required.
However, it should be said that he presented the claims at the Entomology conference — and conferences are exactly where preliminary results should be presented. It remains to be seen whether these Martian bugs will pass the test of serious scientific screening — but I wouldn’t bet on it.
While exploring the far side of the moon, China’s Chang’e-4 lunar rover has discovered an unusually colored, ‘gel-like’ substance. The discovery led to scientists postponing the driving plans for the rover and instead focus on discovering what the strange material is.
On July 28, the Yutu-2 science team at the Beijing Aerospace Control Center was preparing to power down the rover, a process that prevents the delicate machinery from overheating when the Sun is directly overhead.
member Yu Tianyi noticed something unusual in the crater while checking a
panorama photographed by Yutu-2. So, the researchers kept the rover awake just
a little bit longer, rolling it over to the crater for a better look.
carefully approached the crater and then targeted the unusually colored
material and its surroundings. The rover examined both areas with its Visible
and Near-Infrared Spectrometer (VNIS), which detects light that is scattered or
reflected off materials to reveal their makeup.
According to the rover’s drive diary, this material differed from the surrounding regolith in shape, color, and texture. No photos of the finding have been released yet, only one of the rover heading to the crater to look at what it’s inside.
scientists haven’t offered any indication as to the nature of the colored
substance and have said only that it is “gel-like” and has an
“unusual color.” One possible explanation, outside researchers
suggested, is that the substance is melt glass created from meteorites striking
the surface of the moon.
This is not
the first-time scientists get surprised by a lunar discovery. Apollo 17
astronaut Harrison Schmitt discovered orange-colored soil near the mission’s
Taurus-Littrow landing site in 1972. Lunar geologists eventually concluded that
the orange soil was created during an explosive volcanic eruption 3.64 billion
The Chinese lunar rover launched in early December 201 and made the first-ever soft landing on the far side of the moon in January. 3. The Yutu-2 rover had covered a total of 890 feet (271 meters) by the end of lunar day 8. Now, during lunar day 9, Yutu-2 will continue its journey west.
The use of ultraviolet flares from red suns and biofluorescence may provide astronomers with vital life signs in the universe
A new method of searching for life in the cosmos has been pioneered by astronomers from Cornell University.
The team propose that astronomers could utilise harsh ultraviolet radiation flares from red suns — once thought to destroy surface life on planets — to assist in the discovery of hidden biospheres. The team’s study — published in the journal Monthly Notices of the Royal Astronomical Society — suggests that ultraviolet radiation could trigger biofluorescence — a protective glow — from life on exoplanets.
Jack O’Malley-James, a researcher at Cornell’s Carl Sagan Institute and the study’s lead author, says: “This is a completely novel way to search for life in the universe.
“Just imagine an alien world glowing softly in a powerful telescope.”
Some undersea coral on Earth use a similar form of biofluorescence that the team intend to utilise in the search for life. The coral does this in order to render the sun’s harmful ultraviolet radiation into harmless visible wavelengths, in the process, creating a beautiful radiance.
“Maybe such life forms can exist on other worlds too, leaving us a telltale sign to spot them,” points out Lisa Kaltenegger, associate professor of astronomy and director of the Carl Sagan Institute.
She points out that in our search for exoplanets, we have searched for ones which look like our own planet. This research plays off the idea the biofluorescence may not have evolved on Earth exclusively.
In fact, as this is a form of defence from harsh UV radiation, logic suggests that its usefulness — and thus, the chance of development — would be increased around stars where UV flares are commonplace.
A large fraction of exoplanets — planets beyond our solar system — reside in the habitable zone of M-type stars. This type of star — the most commonly found in the universe — frequently flare, and when those ultraviolet flares strike their planets, biofluorescence could paint these worlds in beautiful colours.
The next generation of Earth- or space-based telescopes can detect the glowing exoplanets — should they exist.
Ultraviolet rays are transformed into less-energetic and therefore less harmful wavelengths through a process called “photoprotective biofluorescence.” This should leave a very specific signal which astronomers can search for.
Kaltnegger continues: “Such bio fluorescence could expose hidden biospheres on new worlds through their temporary glow when a flare from a star hits the planet.”
The astronomers used emission characteristics of common coral fluorescent pigments from Earth to create model spectra and colours for planets orbiting active M stars to mimic the strength of the signal and whether it could be detected for life.
Proxima b — a potentially habitable world found orbiting the active M star Proxima Centauri in 2016 could qualify as a target for such a search. The rocky exoplanet has been one of the most optimal space travel destinations due to the proximity of the star it orbits — although such jaunts are a concern for the far-future.
Jack O’Malley-James, continues: “These biotic kinds of exoplanets are very good targets in our search for exoplanets, and these luminescent wonders are among our best bets for finding life on exoplanets.”
Large, land-based telescopes that are being developed now for 10 to 20 years into the future may be able to spot this glow.
Kaltenegger concludes: “It is a great target for the next generation of big telescopes, which can catch enough light from small planets to analyze it for signs of life, like the Extremely Large Telescope in Chile.”
Artistic depiction of a snowball Earth. Image credits: NASA.
Whenever astronomers announce the discovery of a new planet, our thoughts inexorably fly to potential habitability. Every planet is remarkable in its own way and helps us learn even more about the universe, but something about a planet being potentially habitable makes it incredibly exciting.
The vast majority of planets, however, are not habitable. To put it this way, almost all exoplanets we’ve ever discovered are very uninhabitable. The main criterium for habitability, it first needs to orbit around a specific type of star, at a specific distance from it. This is so that the planet can support liquid water, an essential requirement of all life as we know it. But this is hardly sufficient.
The planet’s surface temperature is affected by several factors, especially its atmosphere. Too much CO2 in the atmosphere could raise temperatures dramatically, and not enough greenhouse gases can make it freezing cold. The chemistry needs to be just right, but even so, there are other complications.
Jupiter’s satellite Europa, for instance, is completely frozen. It’s also a satellite, not even a planet — and yet, there is strong evidence that it hosts liquid water beneath its frozen surface, and is also shielded for radiation, which makes it an excellent candidate for extraterrestrial life.
In a new study, researchers argue that snowball exoplanets (planets similar to Earth, but with all the oceans frozen) can be similarly well-suited for life.
A key argument for that is that the Earth itself is thought to have gone through snowball phases. Some 715 million years ago the entire planet was encased in snow and ice — and this is approximately when the first animals are thought to have evolved. A snowball phase is different from an ice age — in the former, the oceans are completely frozen, whereas in the latter, some liquid ice remains at the equator area. The Earth is believed to have gone through several of these phases, although some researchers argue that some water still remained liquid — the so-called “slushball” Earth versus the snowball Earth theories. At any rate, life on Earth managed to survive in these conditions, so couldn’t it have done the same thing somewhere else?
You have these planets that traditionally you might consider not habitable and this <new study> suggests that maybe they can be,” says Adiv Paradise, an astronomer and physicist at the University of Toronto, Canada.
“We know that Earth was habitable through its own snowball episodes, because life emerged before our snowball episodes and life remained long past it,” Paradise said in a press release. “But all of our life was in our oceans at that time. There’s nothing about the land.”
Paradise and colleagues wanted to know if some areas of land on snowball planets could still be hot (or rather, not-cold) enough to support life. They used computer models, tweaking different variables such as the amount of sunlight and the continent configuration.
Carbon dioxide was a key parameter. Although we now have too much of it in our atmosphere and it’s getting too hot, CO2 is a vital component of a habitable planet, as it keeps the planet warm enough to avoid freezing. Basically, the reason why a planet becomes a snowball Earth in the first place is that it has too little carbon dioxide. Here on Earth, this process notably happened when the continents started eroding. Water absorbs carbon dioxide, turns it into carbonic acid, which further interacts and gets absorbed by rocks during erosion. The carbon binds with the minerals and is stored on the seafloor. Planets exit the snowball phase when this carbon is re-released into the atmosphere — but there’s no guarantee that this will happen, the new study shows.
Earth-like planets can become stuck in a snowball state under some conditions, the models suggested. However, they also showed that in some conditions, some areas of snowball planets can still host life.
Land areas in the center of continents, away from the frozen oceans, can reach temperatures of 10 degrees Celsius (50 degrees Fahrenheit) — which is sufficient to allow life to survive and reproduce.
The findings suggest that a planet’s habitability is not as clear as we once thought. The habitability boundary is not always clear — in fact, in the case of snowball planets at least, it’s a bit fuzzy, Paradise concludes.
Gale Crater could have supported life 3.5 billion years ago — and the Curiosity Rover is excellently placed to study it.
A view from the “Kimberley” formation on Mars taken by NASA’s Curiosity rover. The layers indicate the flow of water toward a basin that existed before the larger bulk of the mountain formed. Image credits: NASA/JPL-Caltech/MSSS.
Looking at the photos taken by Curiosity, it’s hard to see Mars as anything else than a barren landscape. Yet study after study, we’ve learned that the Red Planet wasn’t always like this. Billions of years ago, it was a temperate, water-rich planet, and Gale Crater is a prime example of that past.
Gale Crater is a dried-up lake bed. The crater’s geology is notable for characteristics. For starters, it contains both clays and sulfate minerals, which form in water conditions, and may also preserve signs of past life. Gale also contains a number of fans and deltas which would have been excellent hotspots for ancient life on Mars.
These pebbles got their rounded shapes after rolling in a river in Gale Crater. (NASA/JPL-Caltech).
Penn State researcher Christopher House says that Gale Crater would have had plenty of time to develop life.
“The water would have persisted for a million years or more,” he says. But the entire groundwater system lasted for way longer than that.
“The whole system, including the groundwater that ran through it, lasted much longer, perhaps even a billion or more years,” he said. “There are fractures filled with sulfate, which indicates that water ran through these rocks much later, after the planet was no longer forming lakes.”
But just because the planet may have had the right conditions to host life (which is in itself a debate) doesn’t necessarily mean that it did host life. This is why House and other scientists are looking for sulfate and sulfide minerals. If they wound find a mineral such as pyrite, for instance, this would indicate that the environment could have supported life.
Curiosity samples the rocks at Gale Crater. Image credits: NASA/JPL-Caltech/MSSS/Ken Kremer/Marco Di Lorenzo.
House is also working in the sedimentology and stratigraphy team — which, as the name implies, studies how the rock layers on Mars formed. The goal is to understand the environment in which they formed, to better understand the geological evolution of our planetary neighbor.
“Missions like this have shown habitable environments on Mars in the past,” House said. “Missions have also shown Mars to continue to be an active world with potentially methane releases and geology, including volcanic eruptions, in the not too distant past. There’s definitely great interest in Mars as a dynamic terrestrial world that is not so different than our Earth as some other worlds in our solar system,” House adds.
However, working remotely via Curiosity is no easy feat. The brave rover has been going strong since August 2012 and despite some minor issues, it shows no signs of stopping, although it has long surpassed its original planned mission.
This rover is on another planet, going strong for more than 2,500 days. Here it is taking a selfie. Image credits: NASA/JPL-CALTECH/Malin Space Science Systems.
In its almost 7 years of activity, Curiosity has covered 20.73 km (12.88 mi). It might not seem like much to us, but every step of the way is carefully planned and analyzed. The day-to-day operations and scientific tests are planned with painstaking care and detail. Researchers need to carefully address all the information that’s presented to them and additionally, Curiosity has a limited amount of power.
“Each time we drive, we wake up to an entirely new field of view with new rocks and new questions to ask,” he said.
“It’s sort of a whole new world each time you move, and so often you’re still thinking about the questions that were happening months ago, but you have to deal with the fact that there’s a whole new landscape, and you have to do the science of that day as well.”
However, so far, the results have been extremely rewarding. Mars is not the boring, desolate environment we once thought it to be. Mars is a fascinating world, one that we’ve learned much about, we still have even more to learn. Is there — or was there — life on Mars? We don’t know yet. But in this case, the journey is just as exciting as the destination.
“Each time we drive, we wake up to an entirely new field of view with new rocks and new questions to ask,” he said. “It’s sort of a whole new world each time you move, and so often you’re still thinking about the questions that were happening months ago, but you have to deal with the fact that there’s a whole new landscape, and you have to do the science of that day as well,” House concludes.
Researchers at the University of Illinois at Chicago (UoI) have designed a nuclear-powered ‘tunnelbot’ to explore Europa, Jupiter’s ice-bound moon.
Artist’s rendering of the Europa “tunnelbot.” Image credits Alexander Pawlusik / LERCIP Internship Program, NASA Glenn Research Center.
Europa (the moon, not the continent) has captured the imaginations of space buffs around the world since 1995. That year saw NASA’s Galileo spacecraft’s first flyby around the moon which, along with subsequent investigations in 2003, pointed without a doubt to a liquid ocean beneath the icy surface.
All that water makes Europa a very strong candidate for alien microbial life or at least evidence of now-extinct microbial life. Needless to say, researchers were very thrilled about paying the moon a visit. However, we simply didn’t have any machine capable of pushing through the crust and then braving the oceans beneath — at least, not until now.
We all live in a nuclear submarine
“Estimates of the thickness of the ice shell range between 2 and 30 kilometers [1.2 and 18.6 miles], and is a major barrier any lander will have to overcome in order to access areas we think have a chance of holding biosignatures representative of life on Europa,” said Andrew Dombard, associate professor of earth and environmental sciences at the University of Illinois at Chicago.
Dombard and his spouse, D’Arcy Meyer-Dombard, associate professor of earth and environmental sciences at UoI, are part of the NASA Glenn Research COMPASS team, a multidisciplinary group of scientists and engineers tasked with designing technology and solutions for space exploration and science missions. Together with the team, Dombard presented their new design — a nuclear-powered tunnelling probe — at the American Geophysical Union meeting in Washington, D.C. this week.
The so-called “tunnelbot” is meant to pierce through Europa’s ice shell, reach the top of its oceans, and deploy instruments to analyze the environment and search for signs of life. The team didn’t worry about how the bot “would make it to Europa or get deployed into the ice,” Dombard said, instead focusing on “how it would work during descent to the ocean.”
Such a tunnelbot should be able to take ice samples as it passes through the moon’s shell, water samples at the ocean-ice interface, and it should be able to search the underside of this ice for microbial biofilms, the team explains. Finally, it should also be capable of searching for and investigating liquid water “lakes” within the ice shell.
Two designs were considered for the job: one version of the robot powered by a small nuclear reactor, and another powered by General Purpose Heat Source bricks (radioactive heat source modules designed for space missions). In both cases, heat generated by the power source would be used to melt through the ice shell. Communications would be handled by a string of “repeaters” connected to the bot by optic fibre cables.
NASA is very interested in visiting Europa, particularly because of its potential to harbor life. However, the bot designed by Dombard’s team isn’t an official ‘go’ sign for such an expedition. Whether NASA will plan tunneling, and if one of these designs would be selected for the job, remains to be seen.