Posted on by David Dickinson

New Finds From Kepler: 8 New Worlds Discovered in the Habitable Zone

An artist's conception of one of the newly released exo-worlds, a planet orbiting an ancient planetary nebula. Credit: David A. Aguilar/CfA.

A fascinating set of finds was announced today at the 225th meeting of the American Astronomical Society (AAS), currently underway this week in Seattle, Washington. A team of astronomers announced the discovery of eight new planets potentially orbiting their host stars in their respective habitable zones. Also dubbed the ‘Goldilocks Zone,’ this is the distance where — like the tempting fairytale porridge — it’s not too hot, and not too cold, but juuusst right for liquid water to exist.

And chasing the water is the name of the game when it comes to hunting for life on other worlds. Two of the discoveries announced, Kepler-438b and Kepler-442b, are especially intriguing, as they are the most comparable to the Earth size-wise of any exoplanets yet discovered.

“Most of these planets have a good chance of being rocky, like Earth,” said Guillermo Torres in a recent press release. Guillermo is the lead author in the study for the Harvard-Smithsonian Center for Astrophysics (CfA).

This also doubles the count of suspected terrestrial exo-worlds — planets with less than twice the diameter of the Earth — inferred to orbit in the habitable zone of their host stars.

Fans on exoplanet science will remember the announcement of the first prospective Earth-like world orbiting in the habitable zone of its host star, Kepler-186f announced just last year.

The Kepler Space Telescope looks for planets used a technique known as the transit method. If a planet is orbiting its host star along our line of sight, a small but measurable dip in the star’s brightness occurs. This has advantages over the radial velocity technique because it allows researchers to pin down the hidden planet’s orbit and size much more precisely. The transit method is biased, however, to planets close in to its host which happen to lie along our solar system-bound line of sight. Kepler may miss most exo-worlds inclined out of its view, but it overcomes this by staring at thousands of stars.

Kepler launch
The launch of Kepler from the Cape in 2009. Credit: NASA/Kim Shiflett.

Launched in 2009, Kepler has wrapped up its primary phase of starring at a patch of sky along the plane of the Milky Way in the directions of the constellations of Cygnus, Lyra and Hercules, and is now in its extended K2 mission using the solar wind pressure as a 3rd ‘reaction wheel’ to carry out targeted searches along the ecliptic plane.

Both newly discovered worlds highlighted in today’s announcement orbit distant red dwarf stars. Kepler-438 b is estimated to be 12% larger in diameter than the Earth, and Kepler-442 b is estimated by the team to be 33% larger. These worlds have a 70% and 60% chance of being rocky, respectively. For comparison, Ice giant planet Uranus is 4 times the diameter of the Earth, and over 14 times more massive.

A comparison of the new exoplanet finds between Earth and Jupiter. Credit: NASA/Kepler.
A comparison of the new exoplanet finds between Earth and Jupiter. Credit: NASA/Kepler.

“We don’t know for sure whether any of the planets in our sample are truly habitable,” Said CfA co-researcher in the study David Kipping. All we can say is that they’re promising candidates.”

The idea of habitable worlds around red dwarf stars is a tantalizing one. These stars are fainter and cooler than our Sun, and 7.5% to 50% as massive. They also have two primary factors going for them: they’re the most common type of stars in the universe, and they have life spans measured in trillions of years, much longer than the current age of the universe. If life could go from muck to making microwave dinners here on Earth in just a few billion years, it’s had lots longer to do the same on worlds orbiting red dwarf stars.

There is, however, one catch: the habitable zone surrounding a red dwarf is much closer in to its host star, and any would-be planet is subject to frequent surface-sterilizing flares. Perhaps a world with a synchronous rotation might be spared this fate and feature a habitable hemisphere well inside the snow line permanently turned away from its host.

The team made these discoveries by sifting though Kepler’s preliminary finds that are termed KOI’s, or Kepler Objects of Interest. Though these potential discoveries were far too small to pin down their masses using the traditional method, the team employed a program named BLENDER to statically validate the finds. BLENDER has been employed before in concert with backup observations for extremely tiny exoplanet discoveries. Torres and Francois Fressin developed the BLENDER program, and it is currently run on the massive Pleiades supercomputer at NASA Ames.

It was also noted in today’s press conference that two KOIs awaiting validation — 5737.01 and 2194.03 — may also prove to be terrestrial worlds  orbiting Sun-like stars that are possibly similar in size to the Earth.

The proposed target regions for the Kepler K2 mission. Credit: NASA/Kepler.
The proposed target regions for the Kepler K2 mission. Credit: NASA/Kepler.

But don’t plan on building an interstellar ark and heading off to these newly found worlds just yet. Kepler-438b sits 470 light years from Earth, and Kepler-442b is even farther away at 1,100 light years. And we’ll also add our usual caveat and caution that, from a distance, the planet Venus in our own solar system might look like a tempting vacation spot. (Spoiler alert: it’s not).

Still, these discoveries are fascinating finds and add to the growing menagerie of exoplanet systems. These will also serve as great follow up targets for TESS, Gaia and LSST survey, all set to add to our exoplanet knowledge in the coming decade.

The LSST mirror in the Tuscon Mirror Lab. (Photo by author).
The LSST mirror in the Tuscon Mirror Lab. (Photo by author).

And to think, I remember growing up as a child of the 1970s reading that exoplanet detections were soooo difficult that they might never occur in our lifetime… now, fast-forward to 2015, and we’re beginning to classify and characterize other brave new solar systems in the modern Age of Exoplanet Science.

-Looking to observe red dwarf stars with your backyard scope? Check out our handy list.

Posted on by Elizabeth Howell

Could Mercury Get A Meteor Shower From Comet Encke?

Artist's concept of the planet Mercury orbiting through a debris trail from Comet Encke that may cause a meteor shower. Credit: NASA's Goddard Space Flight Center

We’re sure going to miss the MESSENGER spacecraft at Mercury when it concludes its mission in 2015, because it keeps bringing us really unexpected news about the Sun’s closest planet. Here’s the latest: Mercury may get a periodic meteor shower when it passes through the debris trail of Comet Encke.

Why do scientists suspect this? It’s not from patiently watching for shooting stars. Instead, they believe the signature of calcium in Mercury’s tenuous atmosphere may be pointing to a pattern.

MESSENGER (which stands for MErcury Surface, Space ENvironment, GEochemistry, and Ranging) has been orbiting the planet for three Earth years and sees regular “surges” in calcium abundance on a predictable schedule. The researchers suspect it’s because of bits of dust colliding with Mercury and ricocheting bits of calcium up from the surface.

Mercury also picks up bits of dust from interplanetary debris, but the scientists say it’s not enough to account for the amounts of calcium they see. Extrapolating, the researchers suspect it must occur as the planet passes through debris left behind from a comet or asteroid. There are a small number of such small bodies that do this, and the scientists narrowed it down to Encke.

Illustration of MESSENGER in orbit around Mercury (NASA/JPL/APL)
Illustration of MESSENGER in orbit around Mercury (NASA/JPL/APL)

Computer simulations of the comet’s debris showed a slight difference from what researchers predicted, but they believe it’s because of variations in Mercury’s orbit as it gets tugged by larger planets, particularly Jupiter. Encke itself takes about 3.3 years to do one lap around the Sun, and has been photographed by MESSENGER in the past.

“The possible discovery of a meteor shower at Mercury is really exciting and especially important because the plasma and dust environment around Mercury is relatively unexplored,” stated lead author Rosemary Killen, a planetary scientist at NASA’s Goddard Space Flight Center in Maryland.

MESSENGER, meanwhile, is burning off the last of its fuel to stay in orbit; the final engine maneuver is expected for Jan. 21. Once that’s finished, the spacecraft will slowly spiral down towards the planet for an expected impact in March, ending the mission.

Source: NASA

Posted on by Elizabeth Howell

A Martian Blue Snake, Brought To You By Canadians And A Spacecraft

A false-color image of part of Cerberus Fossae on Mars. The view shows two rifts intersecting with each other, with sand (in deep blue) and dust. Credit: NASA/JPL-Caltech/University of Arizona/Western University Planetary Sciences Division

Here’s the awesome thing about space and social media: in some cases, you can often follow along with a mission almost as soon as the images come to Earth. A group of Canadians is taking that to the next level this month as they take control of the 211th imaging cycle of a powerful camera on the Mars Reconnaissance Orbiter.

While some images need to be kept back for science investigations, the team is sharing several pictures a day on Twitter and on Facebook portraying the views they saw coming back from the High Resolution Imaging Science Experiment (HiRISE) camera. The results are astounding, as you can see in the images below.

“It’s mind-blowing to realize that when the team, myself included, first look at the images, we are likely the first people on Earth to lay eyes upon a portion of the Martian surface that may have not been imaged before at such high resolution,” stated research lead Livio Tornabene, who is part of Western University’s center for planetary science and exploration.

The team will capture up to 150 images between Nov. 30 and Dec. 12, and already have released close to two dozen to the public. Some of the best are below.

Posted on by Elizabeth Howell

Venus Express Spacecraft, Low On Fuel, Does Delicate Dance Above Doom Below

Artist's impression of Venus Express performing aerobreaking maneuvers in the planet's atmosphere in June and July 2014. Credit: ESA–C. Carreau

It’s been an interesting year for Venus Express. A few months ago, controllers deliberately dipped the spacecraft into the atmosphere of the planet — for science purposes, of course. The daring maneuver was approved because the spacecraft is near the end of its mission. It’s nearly out of fuel and will fall into Venus — sometime. Likely in 2015. No one knows exactly when, however.

Until Dec. 30, European Space Agency operators are going to boost the spacecraft’s orbit to try to get a little more productivity out of it. After that, all depends on what gas is left in the tank.

The push against the dense atmosphere revealed a few surprises. In a recent blog post, ESA said the atmosphere was changing more than expected. Between different altitudes, controllers sometimes saw a steady rise in pressure and sometimes multiple peaks. The spacecraft’s journeys took it as low as 129.2 kilometers (80 miles) above the surface, but mostly involving a month of “surfing” between 131 km and 135 km (81.4 miles and 83.9 miles).

Artist's conception of Venus Express doing an aerobraking maneuver in the atmosphere in 2014. Credit: ESA–C. Carreau
Artist’s conception of Venus Express doing an aerobraking maneuver in the atmosphere in 2014. Credit: ESA–C. Carreau

“One possible explanation is that we detected atmospheric waves,” stated Håkan Svedhem, Venus Express project scientist.

“These features can be caused when high speed winds travel over mountain ranges. The waves then propagate upwards. However, such waves have never before been detected at such heights – twice the altitude of the cloud deck that blankets Venus.”

ESA observed that the atmospheric density increased 1,000 times between 165 km and 130 km (102.5 miles and 80.8 miles) and that it also changed when the spacecraft moved from day to night (specifically, it was four times greater on the sunlit side.) Measurements were also taken of high-energy particles and Venus’ magnetic fields, which are still being examined.

False colour composite of a ‘glory’ seen on Venus on 24 July 2011. The image is composed of three images at ultraviolet, visible, and near-infrared wavelengths from the Venus Monitoring Camera. The images were taken 10 seconds apart and, due to the motion of the spacecraft, do not overlap perfectly. The glory is 1200 km across, as seen from the spacecraft, 6000 km away. Credit: ESA/MPS/DLR/IDA.
False colour composite of a ‘glory’ seen on Venus on 24 July 2011. The image is composed of three images at ultraviolet, visible, and near-infrared wavelengths from the Venus Monitoring Camera. The images were taken 10 seconds apart and, due to the motion of the spacecraft, do not overlap perfectly. The glory is 1200 km across, as seen from the spacecraft, 6000 km away. Credit: ESA/MPS/DLR/IDA.

But now, the end is indeed near for the spacecraft after eight years at Venus — four times longer than its primary mission. Although it is healthy and performing routine science operations, fuel is only standing at around 3 kilograms (6.6 pounds) and oxidizer at 5 kg (11 lbs). It’s possible not all of it is accessible due to propellant movement in the tanks, ESA said. The new maneuvers are expected to subtract 1.4 kg of fuel and 2 kg of oxidizer from these totals.

“Unfortunately, we do not know how much fuel remains in its tanks, but we are intending to continue the up-down process as long as possible, until the propellant runs out,” Svedhem added.

“We have yet to decide whether we shall simply continue until we lose control, allowing it to enter the atmosphere and burn up naturally, or whether we attempt a controlled descent until it breaks up.”

Source: European Space Agency (here and here)

Posted on by Elizabeth Howell

‘Double Earths’ Could Be Fun Exoplanets To Hunt For — If They Exist

Artist's conception of binary Earths. Credit: NASA

One big driver in the search for exoplanets is whether life can exist elsewhere in the Universe. In fact, a major goal of the Kepler space telescope is to discover an Earth-like planet in the habitable zone of a star like our Sun.

But what about having two Earths orbiting close to each other for billions of years? Is this even possible? A new study suggests that yes, this could happen. Imagine the implications for planetary searches if a double Earth is possible.

With current technology it’s hard to spot an Earth-sized planet, let alone resolve two, but if such planets exist it presents interesting questions. Could they be habitable? How do they form? More study is needed.

The study says double Earths can happen if they form at least half a Sun-Earth distance from their star. In what scientists say is the first-ever study considering binary Earths they suggest a scenario where two rocky bodies get close to each other early in their Solar System’s formation. They don’t collide (such as what likely formed our Moon), but they’re close enough to be within three or so radii of each other.

Artist's conception of two celestial bodies smacking into each other. Such a collision is believed to have formed Earth's moon. Credit: NASA/JPL-Caltech
Artist’s conception of two celestial bodies smacking into each other. Such a collision is believed to have formed Earth’s moon. Credit: NASA/JPL-Caltech

“There is a good reason to believe terrestrial binary planetary systems may be possible,” read a press release from the California Institute of Technology. “In a grazing collision the angular momentum is too high to be contained within a single rotating body (it would fission) and if the bodies barely touch then they could retain their identity. However, it requires an encounter where the bodies are initially approaching each other at low enough velocity.”

Scientists simulated these planetary encounters using a simulation, dubbed Smooth Particle Hydrodynamics, which has been used in the past for scenarios such as the collision that created the Moon. The scenarios showed that a collision between two Earth-sized planets would only produce a Moon. However, if the bodies came close enough to produce tidal distortion on each other, the planets could form a binary system.

The research was presented at the Division for Planetary Sciences meeting of the American Astronomical Society this week by undergraduate Keegan Ryan, graduate student Miki Nakajima, and planetary science researcher David Stevenson, all of the California Institute of Technology. A press release did not disclose plans for publication, or if the research is peer-reviewed.

Source: California Institute of Technology

Posted on by Elizabeth Howell

Uranus Bland? Nope, It’s A Stormy Planet With Interesting Insides

A composite image of Uranus in two infrared bands, showing the planet and its ring system. Picture taken by the Keck II telescope and released in 2007. Credit: W. M. Keck Observatory (Marcos van Dam)

Sometimes first impressions are poor ones. When the Voyager 2 spacecraft whizzed by Uranus in 1986, the close-up view of the gas giant revealed what appeared to a be a relatively featureless ball. By that point, scientists were used to seeing bright colors and bands on Jupiter and Saturn. Uranus wasn’t quite deemed uninteresting, but the lack of activity was something that was usually remarked upon when describing the planet.

Fast-forward 28 years and we are learning that Uranus is a more complex world than imagined at the time. Two new studies, discussed at an American Astronomical Society meeting today, show that Uranus is a stormy place and also that the images from Voyager 2 had more interesting information than previously believed.

Showing the value of going over old data, University of Arizona astronomer Erich Karkoschka reprocessed old images of Voyager 2 data — including stacking 1,600 pictures on top of each other.

He found elements of Uranus’ atmosphere that reveals the southern hemisphere moves differently than other regions in fellow gas giants. Since only the top 1% of the atmosphere is easily observable from orbit, scientists try to make inferences about the 99% that lie underneath by looking at how the upper atmosphere behaves.

“Some of these features probably are convective clouds caused by updraft and condensation. Some of the brighter features look like clouds that extend over hundreds of kilometers,” he stated in a press release.

Voyager 2. Credit: NASA
Voyager 2. Credit: NASA

“The unusual rotation of high southern latitudes of Uranus is probably due to an unusual feature in the interior of Uranus,” he added. “While the nature of the feature and its interaction with the atmosphere are not yet known, the fact that I found this unusual rotation offers new possibilities to learn about the interior of a giant planet.”

It’s difficult to get more information about the inner atmosphere without sending down a probe, but other methods of getting a bit of information include using radio (which shows magnetic field rotation) or gravitational fields. The university stated that Karkoschka’s work could help improve models of Uranus’ interior.

So that was Uranus three decades ago. What about today? Turns out that storms are popping up on Uranus that are so large that for the first time, amateur astronomers can track them from Earth. A separate study on Uranus shows the planet is “incredibly active”, and what’s more, it took place at an unexpected time.

Summer happened in 2007 when the Sun shone on its equator, which should have produced more heat and stormy weather at the time. (Uranus has no internal heat source, so the Sun is believed to be the primary driver of energy on the planet.) However, a team led by Imke de Pater, chair of astronomy at the University of California, Berkeley, spotted eight big storms in the northern hemisphere while looking at the planet with the Keck Telescope on Aug. 5 and 6.

Infrared images of Uranus showing storms at 1.6 and 2.2 microns obtained Aug. 6, 2014 by the 10-meter Keck telescope. Credit: Imke de Pater (UC Berkeley) & Keck Observatory images.
Infrared images of Uranus showing storms at 1.6 and 2.2 microns obtained Aug. 6, 2014 by the 10-meter Keck telescope. Credit: Imke de Pater (UC Berkeley) & Keck Observatory images.

Keck’s eye revealed a big, bright storm that represented 30% of light reflected by the planet at a wavelength of 2.2 microns, which provides information about clouds below the tropopause. Amateurs, meanwhile, spotted a storm of a different sort. Between September and October, several observations were reported of a storm at 1.6 microns, deeper in the atmosphere.

“The colors and morphology of this [latter] cloud complex suggests that the storm may be tied to a vortex in the deeper atmosphere similar to two large cloud complexes seen during the equinox,” stated Larry Sromovsky, a planetary scientist at the University of Wisconsin, Madison.

What is causing the storms now is still unknown, but the team continues to watch the Uranian weather to see what will happen next. Results from both studies were presented at the Division for Planetary Sciences meeting of the American Astronomical Society in Tucson, Arizona today. Plans for publication and whether the research was peer-reviewed were not disclosed in press releases concerning the findings.

Posted on by Elizabeth Howell

Dusty Baby Solar System Gives Clues On How Our Sun And Planets Grew Up

Artist's conception of early planetary formation from gas and dust around a young star. Outbursts from newborn and adolescent stars might drive planetary water beneath the surface of rocky worlds. Credit: NASA/NASA/JPL-Caltech

This isn’t a clone of our Solar System, but it’s close enough. Scientists eagerly scrutinized a young star system called HD 95086 to learn more about how dust belts and giant planets grow up together. This is an important finding for our own neighborhood, where the gas giants of Jupiter, Saturn, Uranus and Neptune are also wedged between dusty areas.

“By looking at other star systems like these, we can piece together how our own Solar System came to be,” stated lead author Kate Su, an associate astronomer at the University of Arizona, Tucson.

The system is about 295 light-years from Earth, and is suspected to have two dust belts: a warmer one (similar to our asteroid belt) and a cooler one (similar to the Kuiper Belt that has icy objects.) The system is host to at least one planet that is five times the mass of Jupiter, and other planets could also be hiding between the dusty lanes. This planet, called HD 95086 b, was imaged by the European Southern Observatory’s Very Large Observatory in 2013.

Planet HD95086 b is shown at lower left in this picture. Astronomers blocked out the light of the star (center) to image the exoplanet. The blue circle represents the equivalent orbit of Neptune in this star system. Credit: ESO/J. Rameau
Planet HD95086 b is shown at lower left in this picture. Astronomers blocked out the light of the star (center) to image the exoplanet. The blue circle represents the equivalent orbit of Neptune in this star system. Credit: ESO/J. Rameau

The next step was a comparison study with another star system called HR 8799, which also has two dusty rings and in this case, at least four planets in between. These planets have also been caught on camera. Comparing the structure of the two systems indicates that HD 95086 may have more planets lurking for astronomers to discover.

“By knowing where the debris is, plus the properties of the known planet in the system, we can get an idea of what other kinds of planets can be there,” stated Sarah Morrison, a co-author of the paper and a PhD student at the University of Arizona. “We know that we should be looking for multiple planets instead of a single giant planet.”

The researchers presented their work at the Division for Planetary Science Meeting of the American Astronomical Society in Tucson, Arizona. A press release did not disclose publication plans or if the work was peer-reviewed.

Source: NASA

Posted on by Elizabeth Howell

Martian Permafrost And Dust-Sculpted Surface Captured By NASA Spacecraft

Frost deposits in Louth Crater appears to remain through the year, as found in Mars Reconnaissance Orbiter HiRISE photos of the region. Credit: NASA/JPL/University of Arizona

Mars was once thought to be a fairly unchanging planet, similar to the Moon. But now we know it is a planet that was shaped by water and other forces in the past — and that these forces still come into play today.

Above is a picture of permafrost deposits just discovered in Louth Crater. This find comes from NASA’s Mars Reconnaissance Orbiter’s High Resolution Imaging Science Experiment (HiRISE) and you can see some of its latest water- and dust- shaped environments imaged below.

“A still-unexplained feature of this crater is the diffuse dark smudges visible on the crater floor,” read an update on the University of Arizona HiRISE website explaining this image. “These resemble ‘defrosting spots’ which are visible on carbon dioxide ice in the early spring, but they occur on frost-free areas and survive throughout the summer.”

The frost was caught in a HiRISE image early in the summer, and it persisted as controllers watched it through the summer — indicating that it is permanent. Its size did diminish somewhat, however. Scientists are pretty sure that this is water ice, as carbon dioxide can’t survive the summer.

See more new HiRISE photos below.

A close-up of "chaotic terrain" in Valles Marineris imaged by the Mars Reconnaissance Orbiter's HiRISE camera. Wind or fluid may have further shaped this region, which could be related to possible signs of an ancient lake found in other regions of Valles Marineris. Credit: NASA/JPL/University of Arizona
A close-up of “chaotic terrain” in Valles Marineris imaged by the Mars Reconnaissance Orbiter’s HiRISE camera. Wind or fluid may have further shaped this region, which could be related to possible signs of an ancient lake found in other regions of Valles Marineris. Credit: NASA/JPL/University of Arizona
A section of the vast Valles Marineris ravine called Melas Chasma, a spot where sulfates (minerals formed in water) have been found before. The image shows layers of deposits that were formed before and after the formation of VAlles Marineris. Credit: NASA/JPL/University of Arizona
A section of the vast Valles Marineris ravine called Melas Chasma, a spot where sulfates (minerals formed in water) have been found before. The image shows layers of deposits that were formed before and after the formation of Valles Marineris. Credit: NASA/JPL/University of Arizona
A section of Eastern Elysium Planitia imaged by the Mars Reconnaissance Orbiter's HiRISE camera showing a possible old lava field near dust avalanches stirred up more recently. Credit: NASA/JPL/University of Arizona
A section of Eastern Elysium Planitia imaged by the Mars Reconnaissance Orbiter’s HiRISE camera showing a possible old lava field near dust avalanches stirred up more recently. Credit: NASA/JPL/University of Arizona
Posted on by Elizabeth Howell

Ice Alert! Mercury’s Deposits Could Tell Us More About How Water Came To Earth

A view of the crater Prokofiev on Mercury. The crater is the largest one on the planet's north pole area to have "radar-bright" material, a probable sign of ice. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington.

New pictures of water ice at Mercury’s north pole — the first such optical images ever — could help scientists better understand how water came to planets in the rest of the Solar System, including Earth. The image you see above came courtesy of NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft.

Mercury is a hot planet (it’s the closest one to the Sun), so the only way the ice survives is in deep shadow. This makes it hard to spot unless scientists use some clever techniques. In this case, they examined some scattered light from Prokofiev, the biggest crater in Mercury’s north pole suspected to hold the deposits.

The pictures show that Prokofiev’s surface water ice likely arrived after the craters underneath. And in an intriguing find, there is probably other water ice sitting under dark materials believed to be “frozen organic-rich compounds,” stated the Johns Hopkins University Applied Physics Laboratory.

“This result was a little surprising, because sharp boundaries indicate that the volatile deposits at Mercury’s poles are geologically young, relative to the time scale for lateral mixing by impacts,” stated lead researcher Nancy Chabot, the Instrument Scientist for MESSENGER’s Mercury dual imaging system.

Illustration of MESSENGER in orbit around Mercury (NASA/JPL/APL)
Illustration of MESSENGER in orbit around Mercury (NASA/JPL/APL)

“One of the big questions we’ve been grappling with is ‘When did Mercury’s water ice deposits show up?’ Are they billions of years old, or were they emplaced only recently?”, added Chabot, who is a planetary scientist at the Johns Hopkins University Applied Physics Laboratory in Maryland. “Understanding the age of these deposits has implications for understanding the delivery of water to all the terrestrial planets, including Earth.”

Another intriguing property comes when scientists compare Mercury to the Moon: because the ice looks different on both relatively atmosphere-less bodies, scientists believe the water came more recently to the Moon. But more study is required.

Results were published recently in the journal Geology.

Source: Johns Hopkins University Applied Physics Laboratory

Posted on by Shannon Hall

MAVEN Spacecraft’s First Look at Mars Hints at Promising Results

Three views of an escaping atmosphere, obtained by MAVEN’s Imaging Ultraviolet Spectrograph. By observing all of the products of water and carbon dioxide breakdown, MAVEN's remote sensing team can characterize the processes that drive atmospheric loss on Mars. Image Credit: University of Colorado/NASA

It’s been less than a month since NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft slipped into orbit. But it’s already provided mission scientists their first look at Mars’ tenuous atmosphere.

“Everything is performing well so far,” said Bruce Jakosky, the mission’s principle investigator, in a news release. “All the instruments are showing data quality that is better than anticipated at this early stage of the mission. The spacecraft is performing beautifully. It’s turning out to be an easy and straightforward spacecraft to fly, at least so far. It really looks as if we’re headed for an exciting science mission.”

Data collected by MAVEN will answer a longstanding puzzle among planetary scientists. There’s ample evidence that early in the Red Planet’s history it had a much denser atmosphere. Rain fell from the sky and water carved its surface. But then the atmosphere vanished, and scientists are unsure why.

One leading theory is that the gas escaped to space, stripped away by the solar wind rushing past. (Click here to see a cool animation of that process.) Here on Earth, our magnetosphere helps protect our atmosphere from the solar wind. But once Mars lost its own magnetosphere, billions of years ago, its atmosphere became vulnerable.

MAVEN’s spectrometers will attempt to determine if hydrogen atoms, torn from water molecules by ultraviolet sunlight, are escaping to space and at what rate. Already, the spacecraft has observed the edges of the Martian atmosphere using its Imaging Ultraviolet Spectrograph (IUVS) camera, which is sensitive to the sunlight reflected by the atoms.

“With these observations, MAVEN’s IUVS has obtained the most complete picture of the extended Martian upper atmosphere ever made,” said team member Mike Chaffin from Colorado University at Boulder.

So far scientists have used IUVS to create a map of Mars’ ozone. “With these maps we have the kind of complete and simultaneous coverage of Mars that is usually only possible for Earth,” said team member Justin Deighan, also from CU-Boulder.

There will be about two weeks of additional instrument calibration and testing before MAVEN starts its primary science mission in early to mid-November. It will then likely take a few additional months to build up enough measurements to have a clear sense of what’s going on. But the initial results are promising.