Tag Archives: orbit

A new approach to cleaning space junk is being tested in space right now

A rocket blasted off last Saturday from the Baikonur Cosmodrome in Kazakhstan, and it could lead to a much cleaner orbit around our planet.

One of the satellites involved in the mission. Image credits ESA.

Known as the End-of-Life Services by Astroscale or ELSA-d, the mission aims to test a theoretical approach to cleaning out space junk. The craft will look for dead satellites around our planet, attach to them, and slowly push them towards our planet so they burn up in our atmosphere. According to Astroscale, the Japan-based company behind this mission, there are over 8,000 tons of debris in the Earth’s orbit, which represents a very real threat for services such as weather forecasting, telecommunications, and GPS systems.

Decommission mission

The mission will be trying out a new approach that involves using magnetic docking to capture space junk. While no actual junk will be captured just yet, two satellites — a ‘servicer’ and a ‘client’ satellite — were launched into orbit to test the approach. As part of ELSA-d, the servicer will release and then try to re-capture the client, which, essentially, serves as a mock piece of space junk.

This catch and release process will be repeated over the next six months. The UK-based ground team will use data from this step to improve the satellite’s ability to lock onto and dock with its targets.

One important thing to note is that the satellite isn’t meant to remove the clutter that is already in orbit. Rather, the team is after future satellites that, they say, will be equipped with special docking clamps before launch.

Space debris are a growing problem, one which can impact our lives in quite unpleasant ways. Taken to the extreme, such cluttering could even prevent us from ever leaving the Earth again — but we’re not there yet. For now, they just risk impacting and downing our satellites, meaning services that rely on orbital networks, such as GPS and mobile phones, are also at risk. They’re also a hazard to astronauts and other missions.

According to NASA, there are at least 26,000 pieces of space junk in orbit about the size of a softball. Going on along at roughly 17,500 mph, each could “destroy a satellite on impact”. Apart from that, another 500,000 pieces of debris represent “mission-ending threats”, the report adds. The rest, estimated at more than 100 million pieces, are around the same size as a grain of sand. That’s not to say they’re harmless, however — each could pierce a spacesuit

Clearing the Earth’s orbit would go a long way towards keeping us safe and happy, both on the surface and in space. Taking down what’s already there is, obviously, a very sensible approach; but so is limiting how much junk we’ll be putting there in the future. Missions such as ELSA-d showcase how we can prepare for a more sustainable use of outer space, an element that will only grow in importance as humanity makes bolder steps towards the stars.

Venus might be a hellscape today because of Jupiter

While Venus is boiling-hot today, this wasn’t always the case. And the culprit, new research suggests, could be our largest neighbor.

Image credits Pablo Carlos Budassi via Wikimedia.

Jupiter, the colossus of our solar system, likely altered the orbit of Venus in the past, condemning it to a state of lifelessness. The findings come from a new study that aimed to understand why Venus’ orbit around the sun is so circular.

Big players

“One of the interesting things about the Venus of today is that its orbit is almost perfectly circular,” said UCR astrobiologist Stephen Kane, who led the study.

“With this project, I wanted to explore whether the orbit has always been circular and if not, what are the implications of that?”

Jupiter is by far the largest planet in our vicinity, with a mass over two-and-a-half times greater than that of all other planets in the solar system combined. As such, it can wield quite a lot of (gravitational) influence upon them.

During its early days, Jupiter moved towards the sun and then away from it again. This isn’t really a very peculiar case — observations from other systems show that giant planets follow such orbits pretty often during their formation.

In our corner of space, Jupiter’s motion affected the orbit of Venus. This put it on the path to becoming the planet it is today. Kane says that while it’s very likely that Venus lost some of its water due to other reasons, the passing of Jupiter irrevocably changed its climate and drained its reserves of liquid water. Researchers mostly consider any planet lacking liquid water to be incapable of spawning life, or at least, life as we know it.

“As Jupiter migrated, Venus would have gone through dramatic changes in climate, heating up then cooling off and increasingly losing its water into the atmosphere,” Kane said.

Kane created a model of the solar system during the early days of planetary formation, calculating where each of them was and how their gravitational pull influenced one another. This model showed that Venus used to have a much less circular (more ‘eccentric’) orbit than today. A planet’s eccentricity is denoted by a number between 0 and 1, with the first meaning perfectly circular and 1 meaning completely linear. Kane explains that a planet with an eccentricity of 1 would “simply launch into space”.

Currently, the orbit of Venus has an eccentricity of 0.006, making it the most circular in the whole Solar System. However, the model holds that this value used to be 0.3 before Jupiter came around. Kane says Venus had a much higher probability of being habitable at that time. The recent discovery of phosphine in the atmosphere of Venus — a gas that is typically produced by microbes — could be the signature of “the last surviving species on a planet that went through a dramatic change in its environment.”

Still, any surviving microbes would have needed to live in the clouds of sulfuric acid that drape the planet for over a billion years without liquid water.

“There are probably a lot of other processes that could produce the gas that haven’t yet been explored,” Kane said.

“I focus on the differences between Venus and Earth, and what went wrong for Venus, so we can gain insight into how the Earth is habitable, and what we can do to shepherd this planet as best we can.”

The findings “Could the Migration of Jupiter Have Accelerated the Atmospheric Evolution of Venus?” have been published in The Planetary Science Journal.

NASA cancels maneuver to get Juno closer to Jupiter due to faulty fuel valves — but that’s not bad news

NASA’s Science Mission Directorate has canceled a planned tightening of Juno’s orbit around Jupiter after system checks revealed faulty fuel valves on board the probe.

Image credits NASA / JPL.

Last year on July 4, the Juno probe reached its destination and settled in a comfortable 53-day orbit around Jupiter. On the closest point to the giant during every pass, it would deploy its sensor array and take as many measurements as possible, beaming the data back to Earth for study.

Researchers hoped to reduce Juno’s orbit around the gas giant down to just 14 days to speed up data acquisition from the craft. To do this, they planned on firing the craft’s main engine to reduce its speed and get it closer to Jupiter. Operational tests performed before the braking however showed the two helium check valves which supply the engine did not operate as expected when the system was fully pressurized.

“Telemetry from the spacecraft indicated that it took several minutes for the valves to open, while it took only a few seconds during past main engine firings,” a NASA status report on Friday read.

Rather than risk to lose control on Juno’s current orbit, NASA postponed the maneuver. Since then, researchers have been hard at work looking into how the burn can safely be performed in light of the new technical difficulties.

But it seems they weren’t very confident in their chances. Last week, NASA announced it will abort the maneuver rather than risk to irrevocably alter Juno’s flight path. The probe will maintain its current orbit around Jupiter.

“We looked at multiple scenarios that would place Juno in a shorter-period orbit, but there was concern that another main engine burn could result in a less-than-desirable orbit,” said project manager Rick Nybakken with NASA’s Jet Propulsion Laboratory in Pasadena, California. “The bottom line is a burn represented a risk to completion of Juno’s science objectives.”

The good news is that the probe can still perform its task, it will just take a little longer to do so. Both orbits would yield the same quality of data, as they would both take Juno just as close to Jupiter — some 2,600 miles (4,200 km) above the gas giant’s clouds.

Which is not a bad place to be at all, judging from the view.
Image credits Credits: NASA/JPL-Caltech/SwRI/MSSS/Roman Tkachenko.

“The worst-case scenario is I have to be patient and get the science slowly,” lead researcher Scott Bolton, with the Southwest Research Institute in San Antonio, Texas, said after the engine problem surfaced in October.

“The science will be just as spectacular as with our original plan,” he added on Friday’s release.

“In fact, the longer orbit provides new opportunities that allow further exploration of the far reaches of space dominated by Jupiter’s magnetic field, increasing the value of Juno’s research,” the statement added.

Another upside of canceling the burn is that a more distant orbit will extend the craft’s operational life. Jupiter’s massive radiation belts were the main killer for Juno, and staying well away from them should better protect its systems.

In light of its extended operational life, Nybakken will probably request additional funding for the US$1.13 billion mission, currently scheduled to end on July 31, 2018 — when Juno would have completed its observations and become inoperable under the effects of radiation. The extended mission now aims at completing 12 close approaches.

Juno has proven instrumental in our understanding of how gas giants form and behave. If you want to take a more active part in its research, you can vote on which features of the planet will be imaged during each flyby in the JunoCam project set up by NASA. It’s the closest you’ll ever get to be an astronaut without even leaving your chair.

First artwork to be made in space is now orbiting above all our heads

Art has found its way to space! On Friday, a 3D printer aboard the ISS launched a sculpture of the human laugh into space.

Image credits NASA.

It’s not the first time art has gone to space — but it’s the first time it’s been made up there, as part of project #Laugh. This collaboration between Israeli artist Eyal Gever and California-based company Made In Space (the guys that build and operate the ISS’s Additive Manufacturing Facility/3D printer), started back in Dec. 2016 when Gever launched an app that converts the users’ unique laugh soundwave into a 3D-model.

Gever let all the app’s users vote on their favorite ‘laugh star’ — the winner was Naughtia Jane Stanko of Las Vegas, whose model was beamed up to the ISS and printed out Friday. But it’s not just a pretty shape — the star carries symbolic significance, Gever said.

“We live in epic times, where continuous disruption and rapid change exists against a backdrop of extremely volatile cultural shifts constantly challenging our human conscience,” he said in a statement.

“A laugh star floating in space, above all our heads, is my attempt to create a contemporary metaphor for the hanging ‘Sword of Damocles,’ a reminder that the beauty of human life is so fragile.”

The AMF is usually put to work printing spare parts, tool, and a whole wide range of stuff the astronauts need aboard their orbiting lab. Made in Space were more than happy to expand on its usual range of applications for the project however.

“It’s important for the world to see that technology and art are not independent of one another,” Made In Space President and CEO Andrew Rush said in the same statement.

“We’ve enjoyed being a part of this project, and hope that it communicates to the world that innovation and creativity are the driving forces behind humanity’s future in space.”

Gever and Made In Space Chief Technology Officer Jason Dunn will showcase the laugh star on March 13 at the South by Southwest Festival in Austin, Texas.

A new model to explain the Moon’s weird orbit suggests a much more violent genesis

A new paper might explain how the Moon got some of its surprising features.

Image credits NASA.

As far as moons go, our own is very peculiar. In fact, it’s one of the strangest planetary bodies in the whole Solar System. It orbits the Earth but at an unusually long distance and with a large orbital tilt. Scientists have yet to come up with a model for the Moon’s formation that explains all of these characteristics. A paper published Oct. 31 in the journal Nature attempts to solve this issue by using numerical models to study the moon’s explosive formation and how it evolved together with our planet.

The model suggests that the Earth was sent spinning much faster, and at a much steeper tilt than it does today. The complex Moon-Earth-Sun interactions in the several billion years after this event allowed many of these changes to revert closer to their original state, resulting in the system we see today. The remaining anomalies, such as the large tilt, are relics of the Moon’s explosive birth.

“Evidence suggests a giant impact blasted off a huge amount of material that formed the moon,” said Douglas Hamilton, professor of astronomy at the University of Maryland and a co-author of the Nature paper.

“This material would have formed a ring of debris first, then the ring would have aggregated to form the moon. But this scenario does not quite work if Earth’s spin axis was tilted at the 23.5 degree angle we see today.”

According to collisional physics, this ring of debris should stabilize on the Earth’s equatorial plane — and thus, the moon’s orbit after formation. As the satellite began to distance itself from the Earth, its orbit should have shifted to the planet’s ecliptic plane — the Earth’s orbit around the Sun. Today however, the Moon is tilted five degrees from this plane.

“This large tilt is very unusual. Until now, there hasn’t been a good explanation,” Hamilton said. ” But we can understand it if Earth had a more dramatic early history than we previously suspected.”

Hamilton and his team tried many different scenarios for how the Moon formed. The one that fit best called for a moon-forming impact which sent the planet spinning almost twice as fast as what other models predict. It also heavily impacted Earth’s tilt, knocking it off to somewhere between 60 and 80 degrees. This high tilt allowed our planet to shake off its excess speed more easily.

It also explains the five degree tilt of the Moon. Because of how the Earth’s axis was shifted during the impact, the Moon couldn’t transition smoothly from our planet’s equatorial to the ecliptic plane. This transition was abrupt, leaving the Moon with a large tilt relative to the former — one much larger than what we can see today.

In this model, the young moon began its orbit within Earth’s equatorial plane. In the top panel, Earth’s tilt began near the current value of 23.5 degrees. In the lower panel, the Earth had a much higher tilt after the impact (~75 degrees, lower panel). This is consistent with the moon’s current 5-degree orbital tilt away from the ecliptic.
Image credits Douglas Hamilton et al., (2016).

“As the moon moved outward, Earth’s steep tilt made for a more chaotic transition as the sun became a bigger influence,” Cuk said.

“Subsequently, and over billions of years, the moon’s tilt slowly decayed down to the five degrees we see today. So today’s five degree tilt is a relic and a signature of a much steeper tilt in the past.”

The team agrees that their model doesn’t answer every question about the Moon’s orbit — but the model’s strength, Hamilton says, is that it forms a solid framework from which this questions can be answered in the future.

“There are many potential paths from the moon’s formation to the Earth-moon system we see today. We’ve identified a few of them, but there are sure to be other possibilities,” Hamilton said.

“What we have now is a model that is more probable and works more cleanly than previous attempts. We think this is a significant improvement that gets us closer to what actually happened.”

The full paper “Tidal evolution of the Moon from a high-obliquity, high-angular-momentum Earth” has been published in the journal Nature.

Too big to orbit: Jupiter is so massive it doesn’t actually orbit the Sun

The fifth planet from the Sun and owner of the most iconic stormy swirl in the Solar Sistem, Jupiter is nothing if not massive. So massive, in fact, that the planet doesn’t simply orbit our sun, but drags it along for the ride.

Image via pixabay

What?

It’s all a matter of physics and Newton’s universal law of gravitation. It’s the one which says objects pull on each other with a force proportional to the product of their masses and inversely proportional to the square of the distance between them. So more mass means a stronger gravitational pull, but as you move away from said mass this pull drops exponentially. This is why gravity can keep your feet on the ground but isn’t strong enough to pull every comet in the universe down on our heads.

Now because of this, in theory, whenever two objects in space meet and start orbiting, it’s not one body going round a fixed other — they both move around a central point whose position is determined by the relative masses of the objects. Think of how the Moon causes ebb and flow. It also pulls on the rocks and soil that make up our planet, pulling it as a whole towards the Moon. The ISS also pulls on Earth with its own very weak gravitational field. In both cases, the centre of gravity is so close to our planet’s centre that the effect is negligible. Earth doesn’t seem to move, and the Moon and ISS make perfect circles around it.

When talking about out neighbouring planets, the gravitational centre is so close to the Sun’s centre that we don’t even bother with it. Not even Saturn has a noticeable effect on its position in space. So, for all intents and purposes, we consider the centre of the Sun to be the point around which everything in our system orbits around.

Except Jupiter, Tech Insider reports.

Because of the sheer mass of the gas giant (Jupiter has two and a half times the mass of all other planets in the solar system combined) it’s centre of mass with the Sun is 1.07 solar radii outside the middle of the star. So the central point around which both Jupiter and the Sun orbit, the “barycenter” as it is known, lies 7 percent of the Sun’s radius above its surface. Both the Sun and Jupiter orbit around that point in space.

This gif NASA put together shows what I’m talking about.

This is, in essence, how Jupiter and the Sun move through space together – though the distances and sizes aren’t to scale. Jupiter is still only a fraction of the Sun’s size.

NASA’s Juno spacecraft sends back first color image of Jupiter from orbit

Image credit NASA/JPL-Caltech/SwRI/MSSS

Image credit NASA/JPL-Caltech/SwRI/MSSS

NASA’s Juno spacecraft has sent back the first image of Jupiter since it entered its orbit last week, capturing the planet’s famous Great Red Spot as well as three of its moons – Europa, Ganymede and Io. The probe was approximately 2.7 million miles away from Jupiter when it snapped the spectacular photo.

“This scene from JunoCam indicates it survived its first pass through Jupiter’s extreme radiation environment without any degradation and is ready to take on Jupiter,” said Scott Bolton of the Southwest Research Institute in San Antonio and Juno principal investigator. “We can’t wait to see the first view of Jupiter’s poles.

It took Juno five years to reach the massive planet, eventually entering its orbit on July 4. On July 6, the team powered up the probe’s instruments and on July 10 they turned on the JunoCam, a color, visible-light camera specially designed to take pictures of Jupiter’s poles and cloud tops.

Although the JunoCam will help give context to the data gained from the other instruments on the probe, it’s main purpose is to engage the public. It is not considered to be one of the mission’s main scientific instruments.

The Juno spacecraft is currently making its way away from Jupiter towards the farthest reaches of its elliptical, 53-day orbit, where it will continue to snap photos along its journey. However, the main goal of the mission is to examine the giant planet’s magnetic and gravitational fields, as well as its composition and internal structure. Scientists are hopeful that data from the missions will help them better understand how Jupiter and the solar system formed and evolved over the years.

“JunoCam will continue to take images as we go around in this first orbit,” said Candy Hansen of the Planetary Science Institute in Tucson, Arizona and Juno co-investigator. “The first high-resolution images of the planet will be taken on August 27, when Juno makes its next close pass to Jupiter.”

The Juno mission is set to end in February 2018 with one final plunge into Jupiter’s hazy atmosphere. All photos from the JunoCam will continue to be posted on the mission’s official website.

New class of star-stripped super-Earths discovered

Astrophysicists have discovered a new class of exoplanets whose atmospheres and volatile elements have been blown away by the star they’re orbiting. Their findings help cover a previously uncharted gap in planetary populations and offers valuable insight for locating new worlds to colonize.

Too close for comfort.
Image credits: ESO/ .Calcada

There’s an old Latin saying along the lines of “dosage makes the poison,” and that holds true even on immense scales. Planets are on the receiving end of a huge amount of energy emitted by their host star as heat, radiation and charged particles — commonly known as solar winds. Earth sits comfortably in the Goldilocks zone, close enough to the sun so it won’t freeze over but not too close, so it doesn’t bake and burn. It’s also far enough from the sun to allow its magnetic field to effectively repel much of these particles and radiation. But not all earth-like planets are so fortunate.

By using data from NASA’s Kepler space telescope, astrophysicists from the University of Birmingham have discovered a new class of ‘stripped’ rocky planets. These Earth-like planets orbit very close to their stars, and are subjected to a torrent of high-energy radiation and extreme temperatures. Over time, this heat causes the volatile substances in the rocks to escape into the atmosphere. Radiation, in turn, strips the outer gaseous layer, leaving only a shrunk rocky core exposed.

‘For these planets it is like standing next to a hairdryer turned up to its hottest setting,” said Dr Guy Davies, from the University of Birmingham’s School of Physics and Astronomy. “There has been much theoretical speculation that such planets might be stripped of their atmospheres. We now have the observational evidence to confirm this, which removes any lingering doubts over the theory.’

The team used asteroseismology to characterize the stars and their planets they were investigating much more accurately than ever before. Asteroseismology uses the natural resonances of stars to reveal their properties and inner structures.

The findings are important in helping us understand how stellar systems evolve over time. It also highlights the crucial role the host star plays in shaping the planets orbiting it.

Dr Davies added: ‘Our results show that planets of a certain size that lie close to their stars are likely to have been much larger at the beginning of their lives. Those planets will have looked very different,’ Dr Davies added.

The full paper, titled “Hot super-Earths striped by their host stars” has been published online in the journal Nature Communications and can be read here.

Water detected in a planet outside our solar system

Astronomers have recently discovered water in the atmosphere of a planet outside our solar system, using a novel technique – they believe that this new method could reveal more and more planets which feature water; so far, all life as we know it, is based on water. They made their discovery on a Jupiter-like planet that is orbiting the nearby star tau Boötis.

An artist’s conception of a hot-Jupiter extrasolar planet orbiting a star similar to tau Boötes. Credit: David Aguilar, Harvard-Smithsonian Center for Astrophysics

Researchers had already discovered water vapor on a handful of planets – but there were only two ways of doing this, both pretty limited:

– the first one worked only if the studied planet has an orbit that passes it in front of its star, when viewed from Earth.
– the other method worked only if he planet is sufficiently far away from its host star.

Needless to say, most of the exoplanets don’t fill into either of these categories – so it was virtually impossible to find water.

Chad Bender, a research associate in the Penn State Department of Astronomy and Astrophysics and a co-author of the paper, talked about their discovery:

“We now are applying our effective new infrared technique to several other non-transiting planets orbiting stars near the Sun,” Bender said. “These planets are much closer to us than the nearest transiting planets, but largely have been ignored by astronomers because directly measuring their atmospheres with previously existing techniques was difficult or impossible.” With the new detection technique and more-powerful future telescopes such as the James Webb Space Telescope and the Thirty Meter Telescope, the astronomers expect to be able to examine the atmospheres of planets that are much cooler and more distant from their host stars, where liquid water is even more likely to exist.

Tau Boötis b is an extrasolar planet approximately 51 light-years away – while extremely far away per se, it’s relatively close in astronomic terms; it is one of the very first exoplanets ever discovered. It’s a so-called hot Jupiter, with a mass approximately 4 times larger than that of Jupiter, and it orbits its star in a so-called “torch orbit”, at a distance from the star less than one seventh that of Mercury’s from the Sun. An orbital revolution (a “year”) takes only 3 days 7.5 hours to complete. Although it hasn’t been directly calculated, it seems very safe to assume that the planet is made of gas, and it also seems extremely unlikely that the planet holds life – the estimated temperature is over 1.300 degrees Celsius (over 2400 Fahrenheit).

“Planets like tau Boötes b, which are as massive as Jupiter but much hotter, do not exist in our solar system. Our detection of water in the atmosphere of tau Boötes b is important because it helps us understand how these exotic hot-Jupiter planets form and evolve. It also demonstrates the effectiveness of our new technique, which detects the infrared radiation in the atmospheres of these planets.”

Bender is leading a larger project to characterize the atmospheres of many hot-Jupiter extrasolar planets. Hopefully, as they develop and refine the technique more and more, they will be able to apply it to more Earth-like planets – ultimately, discovering which planets have the biggest chances of hosting life.

Journal Reference:

  1. Alexandra C. Lockwood, John A. Johnson, Chad F. Bender, John S. Carr, Travis Barman, Alexander J. W. Richert, Geoffrey A. Blake. Near-IR Direct Detection of Water Vapor in tau Boötis b. The Astrophysical Journal, 2014; 783 (2): L29 DOI: 10.1088/2041-8205/783/2/L29

Extrasolar hot Jupiter sheds some light on our own solar system

Since 1995, over 500 planets that don’t orbit our Sun have been discovered, with the numbers increasing more and more in the past years. But only recently did astrophysicists observe that in some of these cases, the star seems to be spinning in one direction, and the planet orbits it in the totally opposite direction – totally counterintuitive and against what we generally believe about planetary formation.

“That’s really weird, and it’s even weirder because the planet is so close to the star,” said Frederic A. Rasio, a theoretical astrophysicist at Northwestern University. “How can one be spinning one way and the other orbiting exactly the other way? It’s crazy. It so obviously violates our most basic picture of planet and star formation.”

The size and proximity to the star is what led to the ‘hot Jupiter’ name, but aside from this information, researchers didn’t really know that much about them; so they set out to study what can cause such a flipped rotation, and why these hot Jupiters have such close orbits.

“Once you get more than one planet, the planets perturb each other gravitationally,” Rasio said. “This becomes interesting because that means whatever orbit they were formed on isn’t necessarily the orbit they will stay on forever. These mutual perturbations can change the orbits, as we see in these extrasolar systems.”

The thing is, typically enough, astrophysicists have considered our solar system to be typical for the Universe, but observations don’t seem to confirm this belief.

“We had thought our solar system was typical in the universe, but from day one everything has looked weird in the extrasolar planetary systems,” Rasio said. “That makes us the odd ball really. Learning about these other systems provides a context for how special our system is. We certainly seem to live in a special place.”

The physics they used to solve this issue is basically orbital mechanics, but the approach they needed, and the amount of detail and successful approximation is absolutely stunning.

“It was a beautiful problem,” said Naoz, “because the answer was there for us for so long. It’s the same physics, but no one noticed it could explain hot Jupiters and flipped orbits.”

“Doing the calculations was not obvious or easy,” Rasio said, “Some of the approximations used by others in the past were really not quite right. We were doing it right for the first time in 50 years, thanks in large part to the persistence of Smadar.”

Of course, a computer model was necessary, but the steps that have to be taken until that computer model are the most important. It takes a sharp mind, and a correct approach to take everything from paper and put it on a hard disk.

“It takes a smart, young person who first can do the calculations on paper and develop a full mathematical model and then turn it into a computer program that solves the equations,” Rasio added. “This is the only way we can produce real numbers to compare to the actual measurements taken by astronomers.”

In their model, they created a simple solar system with a star similar to the Sun and two planets; one of them is a Jupiter-like planet that forms far from the star, where this kind of planets are thought to form. The other planet is even farther away from the sun than the inner planet, and it interacts gravitationally with it, shaking the whole system.

The effects of this model are the exact ones they were trying to get: the inner gas giant moves closer and closer towards the Sun and starts orbiting in the opposite direction of the star’s spin. These changes occur because (according to the model) the two orbits are exchanging angular momentum, and the inner one loses energy via strong tides. The gravitational couple forces the inner planet to adopt an eccentric, needle-like orbit; in order for this to happen, it has to lose a lot lot of angular momentum, giving it away to the outer planet, and thus its orbit gradually shrinks because of all the dissipated energy, pulling it closer and closer to the star, and sometimes flipping its orbit in the process.

Messenger succesfully enters Mercury orbit

Messenger around Mercury. NASA artist's rendering.

As reported earlier on Thursday morning, the Messenger NASA spacecraft was scheduled for an evening jump into Mercury’s orbit through a tricky maneuver which involved a “burn” – essentially “riding its brakes” by firing its main thruster – to slow the spacecraft enough to be captured by Mercury’s gravity.

At 8:45 p.m. ET, the procedure was commenced. At 9:10 p.m. engineers confirmed that the burn had occurred. By 9:45 p.m. the probe had turned its antenna back toward Earth and began transmitting more detailed data showing that the 15-minute burn was “clean”. Since then Messenger in successfully anchored into Mercury’s orbit!

This is indeed an incredible feat, especially for the mission control team at the Johns Hopkins Applied Physics Laboratory in Maryland which was monitoring MESSENGER’s progress from 96 million miles.

This is going to be a long night; they’ve got a lot of data to look at. But so far, it’s been a great night,” said Michael Paul, a mission engineer providing color commentary from a nearby auditorium where lab personnel were following the crucial phase of the mission.

About 40 minutes later, mission lead engineer Eric Finnegan announced that the spacecraft was in a near-perfect orbit. “Right down the alley,” he said. “We hit the trajectory to within half a sigma, for my engineer friends in the crowd. It was right on the money.”

Since its launch in 2004, Messenger has flown by Earth once and Venus twice on a circuitous 4.9-billion-mile journey, and made three high-speed flybys of Mercury in 2008 and 2009. However, during its flybys the craft was able only to capture about 45% of the planet’s surface filled with craters.

Now, in orbit, Messenger will be able to take incredibly high-resolution images of the planet’s surface in a year long mission, during which it will orbit Mercury twice every 24 hours—conducting the equivalent of two flybys a day – and sending back reams of data from a suite of onboard cameras and spectrographs. The first data gathered by Messenger is expected in early April.

Space Shuttle Discovery heads home after final mission

When launched in 1984, Discovery was top notch; it was the best available around, and only the third operational orbiter; now, after 3 flights, over five thousand orbits and no less than 365 days spent in space, during which it traveled 150 million miles Discovery left the International Space Station (ISS) for the last time; it is still, for a few days, the oldest orbiter still working. It was a sentimental moment for many people, and station skipper Scott Kelly rang his ship’s bell in true naval tradition, paying tribute to the shuttle after its last departure.

“Discovery departing,” he called out.

Discovery is due to Earth on Wednesday, after which it wil be retired and sent to the Smithsonian Institution for display. Discovery’s astronauts got a special greeting from actor William Shatner, who portrayed captain James Kirk on the original “Star Trek” TV series.

ZME Science would like to take a bow and pay homage to Discovery, and thank all the people who were involved in any way in it’s remarkable achievements !

Picture sources: 1 2 3 4