Posted on by Jason Major

A Crescent Moon in the Martian Sky

Raw image of Phobos above Mars, taken by Curiosity's Mastcam in September 2012. Credit: NASA/JPL-Caltech

Mars’ moon Phobos is captured in a daytime image by Curiosity (NASA/JPL-Caltech/MSSS)

A raw image taken on September 21 by Curiosity’s right Mastcam shows a daytime view of the Martian sky with a crescent-lit Phobos in the frame… barely visible, yes, but most certainly there. Very cool!

The image above is a crop of the original, contrast-enhanced and sharpened to bring out as much detail as possible.

The 13-km-wide Phobos has been spotted several times before by Mars rovers, most recently during a solar transit on September 13 (sol 37) but I’m not sure if it’s ever been clearly captured on camera during the day before (i.e., not passing in front of the Sun.) If not, this will be a first!

See the latest news from the Curiosity mission here.

Added 9/28: According to Universe Today publisher Fraser Cain, this is “the most dramatic space picture of the year”… whether you agree or not, hear what he had to say on this and other recent news during the September 27 episode of the Weekly Space Hangout.

Posted on by John Williams

Finding Life in All the Unlikely, Unexpected Places

Just one of several weather stations set up at Chott El Jerid, a Tunisian saltpan, measuring temperature, humidity, ultraviolet radiation, wind direction and velocity. Image credit: Felipe Goméz/Europlanet

From orbit and on the ground, Mars looks inhospitable. But it doesn’t look much different than the freezing Antarctic plains, sun-baked saltpans in Tunisia or Spain’s corrosively acidic Rio Tinto, according to a few explorers from the Centro de Astrobiología (CAB) in Madrid, who today presented some of their findings of life during a press conference at the European Planetary Science Congress.

The biggest difference, however, is that life still thrives in these extreme locales on Earth.

“The big questions are: what is life, how can we define it and what the requirements for supporting life?” asks project leader Dr. Felipe Goméz. “To understand the results we receive back from missions like Curiosity, we need to have detailed knowledge of similar environments on Earth. Metabolic diversity on Earth is huge. We have found a range of complex chemical processes that allow life to survive in unexpected places.”

Over the past four years, Goméz and his colleagues have checked Earth’s most inhospitable locales; the Chott el Jerid saltpan in Tunisia, the Atacama Desert in Chile, Rio Tinto in southern Spain and Deception Island in Antarctica.

While visiting Chott el Jerid, the team tracked huge changes in environmental conditions throughout the day but it was a small rise in surface temperature after dusk that caught their eye. “We found that this is caused by water condensing on the surface and hydrating salts which releases heat in an exothermic reaction,” he said in the press release. This is very interesting from the perspective of the REMS instrument on Curiosity — it gives us away to follow when liquid water might be present on the surface.”

The team also built a three-dimensional picture of the subsurface in the saltpan by measuring the electrical properties of the soil. While drilling several meters into the subsurface at Chott el Jerid and in the Atacama Desert, researchers found bacteria at depth that was completely isolated from the surface. The researchers found not only bacteria, but also single-celled halophilic organisms that are able to oxidize metabolites under both aerobic and anaerobic conditions.

Along the surface of Chott El Jerid, which is made up of very pure sodium chloride with a trace of other salts, the team found small pieces of organic matter within the salt crystals. Once analyzed, they found populations of halophilic, salt-loving, dormant bacteria. In the laboratory, they were able to rehydrate the samples and bring the bacteria back to life, Goméz said.

Another unexpected find occurred while studying outcrops of the mineral jarosite at Rio Tinto in Spain. Jarosite, found on the surface of Mars by the Mars Exploration Rover Opportunity, forms only in the presence of water that contains high concentrations of metals, such as iron. The outcrops at Rio Tinto also are extremely corrosive. Yet, sandwiched between layers in the salt crusts, the team found photosynthetic bacteria. Unexpectedly, iron in the salt crust seems to protect bacteria from ultraviolet radiation, Goméz said. Samples of bacteria with iron present were exposed with high levels of ultraviolet radiation. They survived while bacteria samples without iron were destroyed.

“What the bacteria we found in Rio Tinto show is that the presence of ferric compounds can actually protect life. This could mean that life formed earlier on Earth than we thought. These effects are also relevant for the formation of life on the surface of Mars,” says Goméz. The team also found that salt provides stable conditions that can allow life to survive in very hard environments.

“Within salts, the temperature and humidity are protected from fluctuations and the doses of ultraviolet radiation are very low,” explained Goméz. “In the laboratory, we placed populations of different bacteria between layers of salt a few millimetres thick and exposed them to Martian conditions. Nearly 100% of deinoccocus radiodurans, a hardy type of bacteria survived being irradiated. But fascinatingly, about 40% of acidithiobacillus ferrooxidans – a very fragile variety of bacteria – also survived when protected by a salt crust.”

The findings have implications not only for studying possible life on Mars, but also for the development of life on early Earth.

Source: European Planetary Science Congress (EPSC) 2012 Press Release

Image Details: Photosynthetic bacteria at Rio Tinto. Credit: Felipe Goméz

About the author: John Williams is owner of TerraZoom, a Colorado-based web development shop specializing in web mapping and online image zooms. He also writes the award-winning blog, StarryCritters, an interactive site devoted to looking at images from NASA’s Great Observatories and other sources in a different way. A former contributing editor for Final Frontier, his work has appeared in the Planetary Society Blog, Air & Space Smithsonian, Astronomy, Earth, MX Developer’s Journal, The Kansas City Star and many other newspapers and magazines. Follow John on Twitter @terrazoom

Posted on by Nancy Atkinson

Astrophoto: A Year of Mars Observations by Efrain Morales

Mars from July, 2011 to June 2012. Credit: Efrain Morales, Jaicoa Observatory

Superman has nothing on this big “S” created by putting together views of Mars for one full year. Efrain Morales from the Jaicoa Observatory in Puerto Rico compiled just a few images of Mars he captured from July of 2011 to June of 2012, and this collage shows the size differences in how Mars appeared in a telescope as the planet moved toward and then reached opposition in March of 2012, and how it appeared during the months afterward. Also visible is how the North Polar Cap decreased in size as the seasons changed on the red Planet.

Equipment: LX200ACF 12 inch, OTA, CGE mount, Flea3 CCD, TeleVue 3x barlows, Astronomik LRGB filter set. See more of Efrain’s work at his website.

Want to get your astrophoto featured on Universe Today? Join our Flickr group or send us your images by email (this means you’re giving us permission to post them). Please explain what’s in the picture, when you took it, the equipment you used, etc.

Posted on by Jason Major

Curiosity Shows Off Its Credentials

Plaque on the exterior of Mars Science Laboratory, aka “Curiosity” (NASA/JPL-Caltech/MSSS)

Curiosity drops a few rather big names in recent images taken with its MAHLI (Mars Hand Lens Imager) camera: here we see a plaque affixed to its surface bearing the names and signatures of U.S. President Barack Obama, Vice President Joe Biden, Office of Science and Technology Director John Holdren, NASA Administrator Charles Bolden and other key figures responsible for making the Mars Exploration Program possible.

You never know… even on another planet it can’t hurt to have friends in high places!

The image was captured by MAHLI on September 19, the 44th sol of the MSL mission. (See the original raw downlink here.)

The rectangular plaque is made of anodized aluminum, measuring 3.94 inches (100 mm) high by 3.23 inches (82 mm) wide. It’s attached to the front left side of Curiosity’s deck with four bolts. (Explore Curiosity in 3D here.)

Dust, pebbles and variously-sized bits of Mars can be seen scattered around the plaque and deck, leftover detritus from the rover’s landing.

The complete list of signatures is:

Barack Obama, President, United States of America

Joe Biden, Vice President

John P. Holdren, Director, Office of Science and Technology Policy

Charles F. Bolden, Jr., Administrator, National Aeronautics and Space Administration

Edward J. Weiler, Associate Administrator, Science Mission Directorate (2008–2011)

James Green, Director, Planetary Sciences Division

Doug McCuistion, Director, Mars Exploration Program

Michael Meyer, Program Scientist, Mars Exploration Program

David Lavery, Program Executive, Mars Science Laboratory

In another image taken on the same sol, Curiosity shows some national pride with a circular medallion decorated with the stars and stripes of the American flag. The 68-mm-wide circular aluminum plate is affixed to one of the rover’s rocker arms. It’s just one of its four “mobility logos” — the others having the NASA logo, the JPL logo and the Curiosity mission logo.

Curiosity’s “stars and stripes” American flag mobility logo (NASA/JPL-Caltech/MSSS)

The main purpose of Curiosity’s MAHLI camera is to acquire close-up, high-resolution views of rocks and soil at the rover’s Gale Crater field site. Developed for NASA by Malin Space Science Systems in San Diego, CA, the camera is capable of focusing on any target at distances of about 0.8 inch (2.1 centimeters) to infinity, providing versatility for other uses, such as views of the rover itself from different angles.

Get more technical information about the MAHLI camera here.

Posted on by Jason Major

Curiosity Captures a Martian Eclipse

Yes, Mars gets eclipses too! This brief animation, made from ten raw subframe images acquired with Curiosity’s Mastcam on September 13 — the 37th Sol of the mission — show the silhouette of Mars’ moon Phobos as it slipped in front of the Sun’s limb.

The entire animation spans a real time of about 2 minutes.

As a moon Phobos really is an oddity. In addition to its small size – only 8 miles (13 km) across at its widest – and irregular shape, it also orbits its parent planet at a very low altitude, only 5,840 miles (9,400 km) and thus needs to travel at a relatively high velocity in order to even stay in orbit. Phobos actually orbits Mars over three times faster than Mars rotates, appearing to rise in Mars’ western sky. And its orbit is so low that it can’t even be seen from the polar regions!

Since Phobos, and its even more petite sibling Deimos, are so small, the Mars rovers won’t ever see a total solar eclipse. In fact these events are often referred to as transits rather than actual eclipses.

This isn’t the first time an eclipse was captured by a Mars Exploration Rover; Opportunity witnessed a similar partial eclipse of the Sun by Phobos in December 2010, and Spirit caught a lunar (or “Phobal?”) eclipse on camera back in 2005, when the moon passed into the shadow of Mars.

Curiosity’s find was no accident, either, as mission engineers had the Mastcam already positioned to capture the event. Preparation really pays off!

See the latest images and news from the MSL mission here.

Images: NASA/JPL-Caltech/Malin Space Science Systems. Animation by Jason Major. Inset image: Phobos as seen by Mars Express ESA/DLR/FU Berlin (G. Neukum)

UPDATE 9/19/12: See a close-up animation of the eclipse event here.

Posted on by Jason Major

In Fact It’s Cold As Hell: Mars Isn’t As Earthlike As It Might Look

The slopes of Gale Crater as seen by Curiosity are reminiscent of the American southwest (NASA/JPL-Caltech)

“Mars ain’t no kind of place to raise your kids; in fact it’s cold as hell” sang Elton John in “Rocket Man”, and although the song was released in 1972 — four years before the first successful landing on Mars — his weather forecast was spot-on. Even though the fantastic images that are being returned from NASA’s Curiosity rover show a rocky, ruddy landscape that could easily be mistaken for an arid region of the American Southwest one must remember three things: this is Mars, we’re looking around the inside of an impact crater billions of years old, and it’s cold out there.

Mars Exploration Program blogger Jeffrey Marlow writes in his latest “Martian Diaries” post:

Over the first 30 sols, air temperature has ranged from approximately -103 degrees Fahrenheit (-75 Celsius) at night to roughly 32 degrees Fahrenheit (0 Celsius) in the afternoon. Two factors conspire to cause such a wide daily range (most day-night fluctuations on Earth are about 10 to 30 degrees Fahrenheit). The martian atmosphere is very thin; with fewer molecules in the air to heat up and cool down, there’s more solar power to go around during the day, and less atmospheric warmth at night, so the magnitude of temperature shifts is amplified. There is also very little water vapor; water is particularly good at retaining its heat, and the dryness makes the temperature swings even more pronounced. 

In that way Mars is like an Earthly desert; even after a blisteringly hot day the temperatures can plummet at night, leaving an ill-prepared camper shivering beneath the cold glow of starlight. Except on Mars, where the Sun is only 50% as bright as on Earth and the atmosphere only 1% as dense, the nighttime lows dip to Arctic depths.

“Deserts on Earth have very extreme temperature ranges,” says Mars Science Laboratory Deputy Project Scientist, Ashwin Vasavada. “So if you take a desert on Earth and put it in a very thin atmosphere 50% farther from the Sun, you’d have something like what we’re seeing at Gale Crater.”

And although the afternoon temperatures in Gale may climb slightly above freezing that doesn’t mean liquid water will be found pooling about in any large amounts. Curiosity’s in no danger from flash floods on Mars… not these days, anyway.

With atmospheric pressure just above water’s thermodynamic triple point, and temperatures occasionally hovering around the freezing point, it is likely that local niches are seeing above-zero temperatures, and Vasavada acknowledges, “liquid water could exist here over a tiny range of conditions.” But don’t expect a Culligan water plant in Gale Crater any time soon. “We wouldn’t expect for Curiosity to see liquid water, because it would evaporate or re-freeze too quickly,” explains Vasavada. “With so little water vapor in the atmosphere, any liquid water molecules on the surface would quickly turn to gas.”

So when on Mars, drink your coffee quickly. (And pack a blanket.)

“Gale Crater may look like the dusty, basaltic basins of the American southwest, but one look at the thermometer will send you running for the winter coat.”

– Jeffrey Marlow, Martian Diaries

Read Marlow’s full article here.

Image: Sunset on Mars seen by the MER Spirit from Gusev Crater in 2005 (NASA/JPL-Caltech)

Posted on by John Williams

Say Ahhh to Mars

Take a deep breath because this new panorama from Mars enthusiast Stu Atkinson will take it away.

“Anyway, a whole bunch of these came down, like I said, and to my delight they all linked up to form a big, biiiiiiiig panoramic mosaic,” said Stu on his blog “The Gale Gazette.” “And here it is. Obviously you’ll need to click on it to enlarge it… and I’ll warn you, it’s a big image, you can kiss the next few minutes goodbye because you’ll be panning around it for a while…”

Zoom in and you can see actual rocks. Click that little button at the right of the toolbar and Mars will take over your screen.

So far, Curiosity has rolled across a barely dusty plain in Gale Crater. Here’s a look of things to come. In black-and-white image from Curiosity, there appear to be big dunes to cross to get to the foothills of Aeolis Mons, or Mount Sharp.

A black-and-white but still breathtaking view of the dusty terrain between Curiosity’s current location and the foothills of Aeolis Mons, or Mount Sharp. Credit: NASA/JPL/Stu Atkinson

Curiosity has nearly finished robotic arm tests. Once complete, the rover will be able to touch and examine its first Mars rock.

“We’re about to drive some more and try to find the right rock to begin doing contact science with the arm,” said Jennifer Trosper, Curiosity mission manager at NASA’s Jet Propulsion Laboratory in Pasadena, Calif, in a press release.

This image from NASA’s Curiosity rover shows the open inlet where powered rock and soil samples will be funneled down for analysis. It was taken by the Mars Hand Lens Imager (MAHLI) on Curiosity’s 36th Martian day, or sol, of operations on Mars (Sept. 11, 2012). MAHLI was about 8 inches (20 centimeters) away from the mouth of the Chemistry and Mineralogy (CheMin) instrument when it took the picture. The entrance of the funnel is about 1.4 inches (3.5 centimeters) in diameter. The mesh screen is about 2.3 inches (5.9 centimeters) deep. The mesh size is 0.04 inches (1 millimeter). Once the samples have gone down the funnel, CheMin will be shooting X-rays at the samples to identify and quantify the minerals.

Engineers and scientists use images like these to check out Curiosity’s instruments. This image is a composite of eight MAHLI pictures acquired at different focus positions and merged onboard the instrument before transmission to Earth; this is the first time the MAHLI performed this technique since arriving at Curiosity’s field site inside Gale Crater. The image also shows angular and rounded pebbles and sand that were deposited on the rover deck during landing on Aug. 5, 2012 PDT (Aug. 6, 2012 EDT).

Two science instruments, a camera called Mars Hand Lens Imager, or MAHLI, that can take close-up color images and a tool called Alpha Particle X-ray Spectrometer (APXS) that can determine the elemental composition of a rock, also have passed tests. The instruments are mounted on a turret at the end of the robotic arm and can be placed in contact with target rocks. The adjustable focus MAHLI camera produced images this week of objects near and far; of the underbelly of Curiosity, across inlet ports and a penny that serves as a calibration target on the rover.

This close-up image shows tiny grains of Martian sand that settled on the penny that serves as a calibration target on NASA’s Curiosity rover. The larger grain under Abraham Lincoln’s ear is about 0.2 millimeters across. The grains are classified as fine to very fine sand.

The Mars Hand Lens Imagery (MAHLI) on the Curiosity rover taken by the Mast Camera on the 32nd Martian day, or sol, of operations on the surface. Engineers imaged MAHLI to inspect the dust cover and to ensure that the tool’s LED lights are functional. Scientists enhanced the image to show the scene as it would appear under Earth’s lighting conditions. This helps in analyzing the background terrain.

Check out more images from the Mars Science Laboratory teleconference.

Image credit: NASA/JPL-Caltech/MSSS

Posted on by Paul Scott Anderson

Opportunity Rover Finds Intriguing New Spherules at Cape York

Mosaic image of the spherules in the rock outcrop on Cape York at Endeavour crater. Credit: NASA / JPL-Caltech / Stuart Atkinson

One of the most interesting discoveries made so far by the Opportunity rover on Mars has been the small round spherules or “blueberries” as they are commonly referred to, covering the ground at the rover’s landing site. Typically only a few millimetres across, some lie loose on the soil while others are imbedded in rock outcrops.

Analysis by Opportunity indicates that they are most likely a type of concretion, which are also found on Earth. These Martian concretions have been found to contain the mineral hematite, which explains its detection in this region from orbit, and one of the main reasons that the rover was sent to this location in Meridiani Planum in the first place. They are similar to the Moqui Marbles, iron-oxide concretions in the outcrops of Navajo Sanstone in Utah, which formed in groundwater.

Now, the rover (eight years later and still going!) has found what may be a different type of spherule. These ones generally resemble the previous ones, but are quite densely packed in an unusual rock outcrop that is on the eastern side of Cape York, the small island-like ledge on the rim of the huge Endeavour crater. With brittle-looking “fins” of material, the outcrop is an an area that from orbit has been identified as containing small clay deposits. There are also more substantial clay deposits farther south along Endeavour’s rim at the much larger Cape Tribulation, the next major destination of Opportunity.

Whether this outcrop actually has any clay in it isn’t known yet, but the examination of it by Opportunity continues at the time of this writing. Some spherules have apparently broken off the outcrop, exposing their inside structure. The new close-up images of the spherules were taken by the Microscopic Imager (MI) on the rover.

A portion of the rock outcrop. Credit: NASA / JPL-Caltech / Stuart Atkinson

What makes these spherules of interest is the possibility that they may be connected somehow to the clay deposits. Their dense concentration in the outcrop and the physical nature of the outcrop itself may indicate a different origin than the other spherules seen previously, as well as the fact that no hematite signature has been seen from orbit in this specific area (although there may be smaller amounts of hematite here as well). We will just have to wait for the results of the rover’s analysis to come back, but they should be interesting.

Opportunity is specifically looking for the clay deposits in this area, as they could have formed in non-acidic (or pH neutral) water as often happens on Earth. As we have seen in just the last few days though, the origin of Martian clays is itself still a subject of debate.

The whitish gypsum veins already seen at Cape York and examined by Opportunity also indicate the presence of liquid water at this location in the distant past. There are some interesting light-coloured veins in this same outcrop as well; whether they are also gypsum or something else isn’t known yet.

Thanks also to Stuart Atkinson for his excellent mosaic images made from the original Opportunity photos.

Posted on by Nancy Atkinson

Sputtering: How Mars May Have Lost Its Atmosphere

Artist depiction of the MAVEN spacecraft. Credit: NASA

Why is Mars cold and dry? While some recent studies hint that early Mars may have never been wet or warm, many scientists think that long ago, Mars once had a denser atmosphere that supported liquid water on the surface. If so, Mars might have had environmental conditions to support microbial life. However, for some reason, most of the Martian atmosphere was lost to space long ago and the thin wispy atmosphere no longer allows water to be stable at the surface. Scientists aren’t sure how or why this happened, but one way a planet can lose its atmosphere is through a process called ‘sputtering.’ In this process, atoms are knocked away from the atmosphere due to impacts from energetic particles.

Since Mars doesn’t have a strong intrinsic magnetic field, the atmosphere could have been eroded by interactions with the solar wind, and this video shows how that occurs. Also, the conditions in the early solar-system conditions enhanced the sputtering loss, and so the loss of Martian atmosphere could be caused by a complex set of mechanisms working simultaneously.

An upcoming mission could tell us what happened to Mars’ atmosphere. The Mars Atmosphere and Volatile Evolution spacecraft or MAVEN is equipped with eight different sensors designed to sort out what happened to the planet’s atmosphere.

MAVEN will be the first spacecraft ever to make direct measurements of the Martian atmosphere, and is the first mission to Mars specifically designed to help scientists understand the past – also the ongoing — escape of CO2 and other gases into space. MAVEN will orbit Mars for at least one Earth-year, about a half of a Martian year. MAVEN will provide information on how and how fast atmospheric gases are being lost to space today, and infer from those detailed studies what happened in the past.

Studying how the Martian atmosphere was lost to space can reveal clues about the impact that change had on the Martian climate, geologic, and geochemical conditions over time, all of which are important in understanding whether Mars had an environment able to support life.

The MAVEN will carry eight science instruments that will take measurements of the upper Martian atmosphere during one Earth year, equivalent to about half of a Martian year.

MAVEN is scheduled to launch in 2013, with a launch window from Nov. 18 to Dec 7, 2013. Mars Orbit Insertion will be in mid-September2014.

Posted on by Nancy Atkinson

It Only Happens on Mars: Carbon Dioxide Snow is Falling on the Red Planet

Observations by NASA’s Mars Reconnaissance Orbiter have detected carbon-dioxide snow clouds on Mars and evidence of carbon-dioxide snow falling to the surface. Image credit: NASA/JPL-Caltech

In 2008, we learned from the Phoenix Mars lander that it snows in Mars northern hemisphere — perhaps quite regularly – from clouds made of water vapor. But now, Mars Reconnaissance Orbiter data has revealed the clearest evidence yet of carbon-dioxide snowfalls on Mars. Scientists say this is the only known example of carbon-dioxide snow falling anywhere in our solar system.

“These are the first definitive detections of carbon-dioxide snow clouds,” said Paul Hayne from the Jet Propulsion Laboratory, lead author of a new study published in the Journal of Geophysical Research. “We firmly establish the clouds are composed of carbon dioxide — flakes of Martian air — and they are thick enough to result in snowfall accumulation at the surface.”

Scientists have known for decades that carbon-dioxide exists in ice in Mars’ seasonal and permanent southern polar caps. Frozen carbon dioxide, sometimes called “dry ice” here on Earth, requires temperatures of about -125 Celsius (- 193 degrees Fahrenheit), which is much colder than needed for freezing water.

Even though we like to think Mars is a lot like Earth, findings like this remind us that Mars is indeed quite different. But just as the water-based snow falls during the winter in Mars’ northern hemisphere, the CO2 snowfalls occurred from clouds around the Red Planet’s south pole during winter in the southern hemisphere.

“Swiss Cheese Terrain” on Mars South Pole residual CO2 ice cap. Credit: NASA/JPL/University of Arizona

Hayne and six co-authors analyzed data gained by looking at clouds straight overhead and sideways with the Mars Climate Sounder, one of six instruments on the Mars Reconnaissance Orbiter. This instrument records brightness in nine wavebands of visible and infrared light as a way to examine particles and gases in the Martian atmosphere. The analysis was conducted while Hayne was a post-doctoral fellow at the California Institute of Technology in Pasadena.

The data provide information about temperatures, particle sizes and their concentrations. The new analysis is based on data from observations in the south polar region during southern Mars winter in 2006-2007, identifying a tall carbon-dioxide cloud about 500 kilometers (300 miles) in diameter persisting over the pole and smaller, shorter-lived, lower-altitude carbon dioxide ice clouds at latitudes from 70 to 80 degrees south.

“One line of evidence for snow is that the carbon-dioxide ice particles in the clouds are large enough to fall to the ground during the lifespan of the clouds,” co-author David Kass of JPL said. “Another comes from observations when the instrument is pointed toward the horizon, instead of down at the surface. The infrared spectra signature of the clouds viewed from this angle is clearly carbon-dioxide ice particles and they extend to the surface. By observing this way, the Mars Climate Sounder is able to distinguish the particles in the atmosphere from the dry ice on the surface.”

Mars’ south polar residual ice cap is the only place on the Red Planet where frozen carbon dioxide persists on the surface year-round. Just how the carbon dioxide from Mars’ atmosphere gets deposited has been in question. It is unclear whether it occurs as snow or by freezing out at ground level as frost. These results show snowfall is especially vigorous on top of the residual cap.

“The finding of snowfall could mean that the type of deposition — snow or frost — is somehow linked to the year-to-year preservation of the residual cap,” Hayne said.

Images from the Phoenix lander show water vapor clouds on Mars are producing snow. Credit: NASA/JPL-Caltech/University of Arizona/Texas A&M University
Clouds on Mars are producing snow. Credit: NASA/JPL-Caltech/University of Arizona/Texas A&M University

In 2008, science teams from the Phoenix mission were able to observe water-ice clouds in the Martian atmosphere and precipitation that fell to the ground at night and sublimate into water in the morning. Phoenix scientist James Whiteway and his colleagues said that clouds and precipitation on Mars play a role in the exchange of water between the ground and the atmosphere and when conditions are right, snow falls regularly on Mars.

“Before Phoenix we did not know whether precipitation occurs on Mars,” Whiteway said. “We knew that the polar ice cap advances as far south as the Phoenix site in winter, but we did not know how the water vapor moved from the atmosphere to ice on the ground. Now we know that it does snow, and that this is part of the hydrological cycle on Mars.”

It will be interesting to follow up on this discovery and learn more about Mars CO2 cycle and how it might affect the Martian atmosphere and surface processes.

Source: NASA