Universe Today

December 12, 2013December 23, 2015 by Jason Major

Hubble Discovers Water Plumes Erupting from Europa

UV observations from Hubble show the size of water vapor plumes coming from Europa's south pole (NASA, ESA, and M. Kornmesser)

It’s been known since 2005 that Saturn’s 300-mile-wide moon Enceladus has geysers spewing ice and dust out into orbit from deep troughs that rake across its south pole. Now, thanks to the Hubble Space Telescope (after 23 years still going strong) we know of another moon with similar jets: Europa, the ever-enigmatic ice-shelled moon of Jupiter. This makes two places in our Solar System where subsurface oceans could be getting sprayed directly into space — and within easy reach of any passing spacecraft.

(Psst, NASA… hint hint.)

The findings were announced today during the meeting of the American Geophysical Union in San Francisco.

“The discovery that water vapor is ejected near the south pole strengthens Europa’s position as the top candidate for potential habitability,” said lead author Lorenz Roth of the Southwest Research Institute (SwRI) in San Antonio, Texas. “However, we do not know yet if these plumes are connected to subsurface liquid water or not.”

The 125-mile (200-km) -high plumes were discovered with Hubble observations made in December 2012. Hubble’s Space Telescope Imaging Spectrograph (STIS) detected faint ultraviolet light from an aurora at the Europa’s south pole. Europa’s aurora is created as it plows through Jupiter’s intense magnetic field, which causes particles to reach such high speeds that they can split the water molecules in the plume when they hit them. The resulting oxygen and hydrogen ions revealed themselves to Hubble with their specific colors.

Unlike the jets on Enceladus, which contain ice and dust particles, only water has so far been identified in Europa’s plumes. (Source)

Rendering showing the location and size of water vapor plumes coming from Europa's south pole. — Rendering showing the location and size of water vapor plumes coming from Europa’s south pole.

The team suspects that the source of the water is Europa’s long-hypothesized subsurface ocean, which could contain even more water than is found across the entire surface of our planet.

“If those plumes are connected with the subsurface water ocean we are confident exists under Europa’s crust, then this means that future investigations can directly investigate the chemical makeup of Europa’s potentially habitable environment without drilling through layers of ice,” Roth said. “And that is tremendously exciting.”

One other possible source of the water vapor could be surface ice, heated through friction.

Cassini image of ice geysers on Enceladus (NASA/JPL/SSI)

In addition the Hubble team found that the intensity of Europa’s plumes, like those of Enceladus, varies with the moon’s orbital position around Jupiter. Active jets have been seen only when Europa is farthest from Jupiter. But the researchers could not detect any sign of venting when Europa is closer.

One explanation for the variability is Europa undergoes more tidal flexing as gravitational forces push and pull on the moon, opening vents at larger distances from Jupiter. The vents get narrowed or even seal off entirely when the moon is closest to Jupiter.

Still, the observation of these plumes — as well as their varying intensity — only serves to further support the existence of Europa’s ocean.

“The apparent plume variability supports a key prediction that Europa should tidally flex by a significant amount if it has a subsurface ocean,” said Kurt Retherford, also of SwRI.

(Science buzzkill alert: although exciting, further observations will be needed to confirm these findings. “This is a 4 sigma detection, so a small uncertainly that the signal is just noise in the instruments,” noted Roth.)

“If confirmed, this new observation once again shows the power of the Hubble Space Telescope to explore and opens a new chapter in our search for potentially habitable environments in our solar system.”

– John Grunsfeld, NASA’s Associate Administrator for Science

So. Who’s up for a mission to Europa now? (And unfortunately in this case, Juno doesn’t count.)

“Juno is a spinning spacecraft that will fly close to Jupiter, and won’t be studying Europa,” Kurt Retherford told Universe Today. “The team is looking hard how we can optimize, maybe looking for gases coming off Europa and look at how the plasma interacts with environment, so we really need a dedicated Europa mission.”

We couldn’t agree more.

The findings were published in the Dec. 12 online issue of Science Express.

Sources: Hubble news releases (US and ESA)

Image credits:
Graphic Credit: NASA, ESA, and L. Roth (Southwest Research Institute and University of Cologne, Germany)
Science Credit: NASA, ESA, L. Roth (Southwest Research Institute and University of Cologne, Germany), J. Saur (University of Cologne, Germany), K. Retherford (Southwest Research Institute), D. Strobel and P. Feldman (Johns Hopkins University), M. McGrath (Marshall Space Flight Center), and F. Nimmo (University of California, Santa Cruz)

December 12, 2013December 23, 2015 by Elizabeth Howell

UPDATE: NASA Pushes Back Cygnus Launch Decision Due To Space Station Cooling Problem

A view of the International Space Station as seen by the last departing space shuttle crew, STS-135. Credit: NASA

The decision to launch a cargo flight to the International Space Station next week has been pushed back until Monday (Dec. 16) because of a cooling problem on station that forced the shutdown of redundant systems, according to a NASA update.

Orbital Sciences’ Cygnus commercial spacecraft is expected to blast off on Dec. 18 from the Wallops Flight Facility in Virginia. However, with some station systems offline, the launch does not now meet certain “commit criteria” to make its journey to space next week, said Kenny Todd, the space station’s mission integration and operations manager.

“We haven’t lost any primary functionality,” he said in a NASA Television update today (Dec. 12), emphasizing that the six-person Expedition 38 crew is fine. “There is some redundancy that we’re down right now, but that’s not something I would call critical to day-to-day station operations.”

While a spacewalk is a possibility to fix the problem, it’s too early to say what NASA and other space station partners will decide to do.

NASA controllers spent the night examining a control valve blamed for causing an ammonia pump to shut down yesterday (Dec. 12). The space station uses liquid ammonia to maintain its temperature, pumping the ammonia through external radiators to bleed off heat. Astronauts have made periodic spacewalks to repair parts of the ammonia system, most recently in May when Expedition 35 replaced a pump controller box on the P6 (far port) truss just days before some crew members went home.

Expedition 35 Flight Engineers Chris Cassidy (left) and Tom Marshburn on a spacewalk on May 11 to inspect and replace a pump controller box on the International Space Station’s far port truss (P6) leaking ammonia coolant. Credit: NASA.

“The pump module on one of ISS two external cooling loops automatically shut down today when it got too cold,” stated the NASA Johnson Space Center Twitter feed yesterday (Dec. 11).

“The pump was brought back online, but they think a valve may not be working correctly inside it. Some of the station’s internal electrical systems were moved over to the second loop, and some noncritical things were powered down. The crew was always safe and will work with the ground teams as they figure out what caused the issue.”

Non-critical systems were powered down in the Harmony node, Columbus Laboratory and Japanese Kibo laboratory. After confirming that the new configuration was stable, controllers began this morning (EST) to move the troublesome valve to several positions and monitor the effect on cooling temperatures, according to a NASA TV update.

The Japanese Kibo module on the International Space Station as photographed by a member of the Expedition 38 crew in 2013. Credit: NASA

The crew is going about their activities as much as possible, although they’re on a “reduced timeline” because some of the experiments aren’t running as usual. (Science collected up to now is “not at risk”, Todd said.)

Responding to questions on social media, NASA astronaut Douglas Wheelock — who led three unplanned spacewalks in 2010 to replace a broken ammonia pump module on the S1 truss in the same cooling loop — said he is working with Mission Control to see what needs to be done next.

Of note, NASA has suspended spacewalks after a water leak in one of its spacesuits forced Italian astronaut Luca Parmitano back to the airlock during work in July. (Crewmate Chris Cassidy, who was on the spacewalk at the same time, later said he felt Parmitano was in no immediate danger, but felt the prudent thing to do was stop.)

NASA astronaut Douglas Wheelock during a contingency spacewalk Nov. 16, 2010 after an ammonia cooling pump failed aboard the International Space Station. During this spacewalk, Wheelock and fellow Expedition 24 crew member Tracy Caldwell installed a spare ammonia pump module on the S1 Truss on the space station. The duo did three contingency spacewalks during the mission to address the problem. Credit: NASA

Astronauts have been troubleshooting the suit periodically on board station, but NASA is planning to send it back on the next SpaceX Dragon flight to Earth for further investigation. SpaceX isn’t planning to get to the station again until late February, media reports say. Russian spacewalks can still continue as they use a separate suit; the most recent one took place in November with the Olympic torch.

While Todd didn’t quite say the ban on spacewalks has been lifted, he added that NASA has new procedures in place to guard against another crew member facing the same water issue. He did not elaborate on what those procedures are.

The current launch window for Cygnus extends as far as Dec. 21 and “possibly” the 22nd, Todd said, but emphasized more time is needed to come to a decision. “At this point, for lack of a better term, we’re going to kick the can a little bit and let the team work a little bit more,” he said.

Updates will follow as the situation and fix progresses.

December 12, 2013March 14, 2017 by Fraser Cain

Is Everything in the Universe Expanding?

The Universe is expanding. Distant galaxies are moving away from us in all directions. It’s natural to wonder, is everything expanding? Is the Milky Way expanding? What about the Solar System, or even objects here on Earth. Are atoms expanding?

Nope. The only thing expanding is space itself. Imagine the Universe as loaf of raisin bread rising in the oven. As the bread bakes, it’s stretching in all directions – that’s space. But the raisins aren’t growing, they’re just getting carried away from each other as there’s more bread expanding between them.

Space is expanding from the Big Bang and the acceleration of dark energy. But the objects embedded in space, like planets, stars, and galaxies stay exactly the same size. As space expands, it carries galaxies away from each other. From our perspective, we see galaxies moving away in every direction. The further galaxies are, the faster they’re moving.

There are a few exceptions. The Andromeda Galaxy is actually moving towards the Milky Way, and will collide with us in about 4 billion years.In this case, the pull of gravity between the Milky Way and Andromeda is so strong that it overcomes the expansion of the Universe on a local level.

Within the Milky Way, gravity holds the stars together, and same with the Solar System. The nuclear force holding atoms together is stronger than this expansion at a local scale. Is this the way it will always be? Maybe. Maybe not.

A few decades ago, astronomers thought that the Universe was expanding because of momentum left over from the Big Bang. But with the discovery of dark energy in 1998, astronomers realized there was a new possibility for the future of the Universe. Perhaps this accelerating dark energy might be increasing over time.

In billions years from now, the expansive force might overcome the gravity that holds galaxies together. Eventually it would become so strong that star systems, planets and eventually matter itself could get torn apart.This is a future for the Universe known as the Big Rip. And if it’s true, then the space between stars, planets and even atoms will expand in the far future.

This image shows the Hubble Ultra Deep Field 2012, an improved version of the Hubble Ultra Deep Field image featuring additional observation time. The new data have revealed for the first time a population of distant galaxies at redshifts between 9 and 12, including the most distant object observed to date. These galaxies will require confirmation using spectroscopy by the forthcoming NASA/ESA/CSA James Webb Space Telescope before they are considered to be fully confirmed. — The space between the galaxies is expanding. Credit: NASA/HST

Is this going to happen? Astronomers don’t know. Their best observations so far can’t rule it out, or confirm it. And so, future observations and space missions will try to calculate the rate of dark energy’s expansion.

So no, matter on a local level isn’t expanding. The spaces between planets and stars isn’t growing. Only the distances between galaxies which aren’t gravitationally bound to each other is increasing. Because space itself is expanding.

December 12, 2013December 23, 2015 by Elizabeth Howell

Mars Water Could Have Carved These ‘Mystery Mounds’

Layered deposits in Juventae Chasma as seen by the European Space Agency's Mars Express orbiter's high-resolution stereo camera in November 2013. Credit: ESA/DLR/FU Berlin (G. Neukum)

Above is a time capsule of more than three billion years of Mars history. The right-hand side shows a bunch of blocky-looking things that formed after volcanic activity made the walls of Juventae Chasma collapse. In the center are what the European Space Agency calls “mystery mounds” made up of sulphate materials (indicating that they were changed by water a long time ago.)

“The mounds contain numerous layers that were most likely built up as lake-deposits during the Chasma’s wet epoch. But ice-laden dust raining out from the atmosphere – a phenomenon observed at the poles of Mars – may also have contributed to the formation of the layers,” ESA stated.

“While the water has long gone, wind erosion prevails, etching grooves into the exposed surfaces of the mounds and whipping up the surrounding dust into ripples.”

The picture was snapped Nov. 4 by the European Space Agency’s Mars Express mission. There’s been a lot of talk about water on Mars this past week, between this possible salty water find at the equator and news of the Mars Curiosity rover stumbling on to an ancient lake that could have supported life.

Mars Express has been humming along for 10 years and counting above the Red Planet. Check out some of its top discoveries in the past decade in this past article by Universe Today’s Ken Kremer.

Mars Express over water-ice crater. ESA Celebrates 10 Years since the launch of Mars Express. This artists concept shows Mars Express set against a 35 km-wide crater in the Vastitas Borealis region of Mars at approximately 70.5°N / 103°E. The crater contains a permanent patch of water-ice that likely sits upon a dune field – some of the dunes are exposed towards the top left in this image. Copyright ESA/DLR/FU-Berlin-G.Neukum — This artist’s concept shows Mars Express set against a 35 km-wide crater in the Vastitas Borealis region of Mars at approximately 70.5°N / 103°E. The crater contains a permanent patch of water-ice that likely sits upon a dune field – some of the dunes are exposed towards the top left in this image. Copyright ESA/DLR/FU-Berlin-G.Neukum

December 11, 2013December 23, 2015 by Elizabeth Howell

The Search For Life On Europa Could Center On Celestial Party-Crashers

Jupiter's moon, Europa, appears to have clay-like minerals on it (visible in blue in the false-color patch, amid red-colored water ice). The information came from new data analysis from NASA's Galileo mission, which concluded in 2003. The backdrop is a mosaic of visual-light images from Galileo's Near-Infrared Mapping Spectrometer. Credit: NASA/JPL-Caltech/SETI

The cool thing about space missions is long after they conclude, the data can yield the most interesting information. Here’s an example: Jupiter’s moon Europa may have a ripe spot for organic materials to take root.

Scouring the data from NASA’s past Galileo mission — which ended a decade ago — scientists unveiled an area with “clay-like minerals” on it that came to be after an asteroid or comet smashed into the surface. The connection? These celestial party-crashers often carry organics with them.

“Organic materials, which are important building blocks for life, are often found in comets and primitive asteroids,” stated Jim Shirley, a research scientist at NASA’s Jet Propulsion Laboratory. “Finding the rocky residues of this comet crash on Europa’s surface may open up a new chapter in the story of the search for life on Europa.”

Reprocessed Galileo image of Europa's frozen surface by Ted Stryk (NASA/JPL/Ted Stryk) — Reprocessed Galileo image of Europa’s frozen surface by Ted Stryk (NASA/JPL/Ted Stryk)

Europa is considered one of the best spots in our solar system to look for life, due to the ocean lurking beneath its icy surface, surface salts that can provide energy, and a source of heat as the mighty Jupiter squeezes and releases the moon like a tennis ball.

The minerals (called phyllosilicates) emerged after Shirley’s team ran a new analysis on infrared pictures snapped by Galileo in 1998, basically working to refine the signal out of the images (which are much lower quality than what we are capable of today).

After the analysis, the phyllosilicates appeared in a “broken ring”, NASA stated, about 75 miles (120 kilometers) away from a crater site. The crater itself is about 20 miles (30 kilometers) in diameter. Scientists are betting that the ring of phyllosilicates is debris (“splash back of material”, NASA says), after a celestial body struck at or around a 45 degree angle from vertical. It’s unlikely the phyllosilicates came from Europa’s ocean given the crust, which can be as thick as 60 miles (100 kilometers).

Europa Report was a 2013 film that focused on a human mission to the Jovian moon. Poster by Start Motion Pictures.

“If the body was an asteroid, it was likely about 3,600 feet (1,100 meters) in diameter. If the body was a comet, it was likely about 5,600 feet (1,700 meters) in diameter. It would have been nearly the same size as the comet ISON before it passed around the sun a few weeks ago,” NASA stated.

To be clear, nobody has found organic materials on Europa directly, and even if they were detected it would then be another feat of science to determine if they related to life or not. This does, however, lend credence to theories that life came to Earth through comets and asteroids.

Ample fodder to consider as the community waits for the European Space Agency’s JUICE (JUpiter ICy moons Explorer) to get going to Europa and Jupiter upon its expected launch in 2022. The probe should arrive there in 2030.

Shirley will give a talk on this topic at the American Geophysical Union’s fall meeting on Friday.

Source: NASA

December 11, 2013December 23, 2015 by Nancy Atkinson

Turn on Your Heart Light and Meet NASA’s “Superhero” Robot

A concept drawing of what eventually became Valkyrie, Johnson Space Center's entry in the DARPA Robotics Challenge. Credit: NASA, via DARPA.

Here’s a new DARPA-inspired, NASA-built robot, complete with a glowing NASA Meatball in its chest, reminiscent of ET’s heart light. The robot’s name is Valkyrie and she was created by a team at the Johnson Space Center as part of the DARPA Robotics Challenge, a contest designed to find the life-saving robot of the future. While NASA’s current robot — Robonaut 2 – is just now getting a pair of legs, “Val” (officially named “R5″ by NASA) is a 1.9 meter tall, 125 kilogram, (6-foot 2-inch, 275-pound) rescue robot that can walk over multiple kinds of terrain, climb a ladder, use tools, and even drive.

According to an extensive article about the new robot in IEEE Spectrum, “This means that Valkyrie has to be capable of operating in the same spaces that a person would operate in, under the control of humans who have only minimal training with robots, which is why the robot’s design is based on a human form.”

Why is NASA building more robots? The thinking is that NASA could send human-like robots to Mars before they send humans. Right now, Valkyrie is not space-rated, but the team at JSC is just getting started.

She’s loaded with cameras, LIDAR, SONAR, is strong and powerful, and is just a great-looking robot.

“We really wanted to design the appearance of this robot to be one that was, when you saw it you’d say, wow, that’s awesome.” Nicolaus Radford, Project and Group Lead at the Dexterous Robotics Lab and JSC.

December 11, 2013December 23, 2015 by Nancy Atkinson

Win the Perfect Holiday Gift: The Year in Space Calendar

What’s the perfect holiday gift for any space fan? It’s the 2014 version of Steve Cariddi’s wonderful Year in Space Wall Calendar, which is now available to order, and thanks to Steve, Universe Today has another 5 copies to give away! This calendar is full of amazing color images, daily space facts, historical references, and it even shows you where you can look in the sky for all the best astronomical sights.

This is a gorgeous wall calendar that has over 120 beautiful photos of space, as well as in-depth info on human space flight, planetary exploration, and deep sky wonders. This calendar is huge — much larger than a traditional wall calendar — and last year it was named “Science Geek Gift of the Year” at Alan Boyle’s NBC “Cosmic Log” website.

For our giveaway, to be entered into the drawing, just put your email address into the box below (where it says “Enter the Giveaway”) before Monday, December 16, 2013.

Update: This giveaway is now closed.

These calendars normally sell for $16.95, but Universe Today readers can buy the calendar for only $12.95 or less (using the “Internet” discount), and get free U.S. shipping and discounted international shipping.

There’s also the 144-Page Desk Calendar at a similar discounts.

You can preview the entire calendar at the Year in Space Calendar website.

It’s published in cooperation with The Planetary Society, with an introduction by Bill Nye. Our thanks to Steve Cariddi for providing this giveaway opportunity for our readers!

Other features of this calendar:
– Background info and fun facts
– A sky summary of where to find naked-eye planets
– Space history dates
– Major holidays (U.S. and Canada)
– Daily Moon phases
– A mini-biography of famous astronomer, scientist, or astronaut each month

If this is the first time you’re registering for a giveaway from Universe Today, you’ll receive a confirmation email immediately where you’ll need to click a link to be entered into the drawing. For those who have registered previously, you’ll receive an email later where you can enter this drawing.

December 11, 2013March 14, 2017 by Fraser Cain

Where Should We Look for Life in the Solar System?

Emily Lakdawalla is the senior editor and planetary evangelist for the Planetary Society. She’s also one of the most knowledgeable people I know about everything that’s going on in the Solar System. From Curiosity’s exploration of Mars to the search for life in the icy outer reaches of the Solar System, Emily can give you the inside scoop.

In this short interview, Emily describes where she thinks we should be looking for life in the Solar System.

Follow Emily’s blog at the Planetary Society here.
Follow her on Twitter at @elakdawalla
And Circle her on Google+
Continue reading “Where Should We Look for Life in the Solar System?”

December 11, 2013December 23, 2015 by Elizabeth Howell

Foom! Morpheus Project Lander Roars In Free Flight Test

NASA's Morpheus Project -- a prototype for vertical landing and takeoff for other planets -- during a free flight test Dec. 10, 2013. Credit: NASA (@MorpheusLander Twitter feed)

What an otherworldly experience, without having to leave Earth! The Morpheus Project wrapped up a successful free-flight test yesterday. That picture above is just to whet your appetite for the actual video, which you can see (and definitely hear) after the jump below.

“WOOOOHOOOOO! How about them apples?!” the @MorpheusLander Twitter feed said shortly after the test wrapped up with a takeoff, hover and landing at NASA’s Kennedy Space Center. “Successful #FREEFLIGHT @NASAKennedy today!” the feed added later. “Get ready for us to #increasetheawesome as we progress through our tests!”

The team is of course analyzing the data to see how successful this free flight was for the planetary landing prototype that NASA is testing.

NASA’s goal with Morpheus is to demonstrate landing technologies at low cost, to possibly bring on to planetary missions in the future — and ultimately, human ones as well.

The project has had some setbacks, with one prototype crashing and burning last year. Redesigns were implemented. One test in June also saw a “soft abort” as the lander moved out of a safety zone, but then a fully successful test shortly afterwards.

“The Morpheus project and the Autonomous Landing and Hazard Avoidance Technology (ALHAT) project provide technological foundations for key components of the greater exploration architecture necessary to move humans beyond low Earth orbit (LEO),” the project stated on its website.

December 11, 2013December 23, 2015 by Elizabeth Howell

Is There Martian Salty Water At The Red Planet’s Equator? These Lines May Be The Smoking Gun

A series of images from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter show how the appearance of dark markings on Martian slope changes with the seasons. Image credit: NASA/JPL-Caltech/Univ. of Arizona.

Get ready, because here are some more findings about possible water on Mars. This picture above from the Mars Reconnaissance Orbiter is a series showing changing dark lines on an equatorial hillside — which could be an indication of salty water, scientists said.

As MRO circled the planet and peered at the lines with its High Resolution Imaging Science Experiment (HiRISE) camera, it tracked these changes at five locations in Valles Marineris, the biggest canyon our solar system has to offer. The lines were on slopes that faced the north and the south, and most intriguingly, they activated when the sun hit their respective sides.

“The equatorial surface region of Mars has been regarded as dry, free of liquid or frozen water, but we may need to rethink that,” stated Alfred McEwen of the University of Arizona in Tucson.

“The explanation that fits best is salty water is flowing down the slopes when the temperature rises,” added McEwen, who is HiRISE principal investigator. “We still don’t have any definite identification of water at these sites, but there’s nothing that rules it out, either.”

A 2010 image of ice excavated on Mars after a recent meteorite impact. Image from the Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment (HiRISE) camera. Credit: NASA/JPL-Caltech/Univ. of Arizona — A 2010 image of ice excavated on Mars after a recent meteorite impact. Image from the Mars Reconnaissance Orbiter’s High Resolution Imaging Science Experiment (HiRISE) camera. Credit: NASA/JPL-Caltech/Univ. of Arizona

Scientists first spotted these types of features two years ago in the mid-latitudes of Mars, but in that case these were small features (usually less than 16 feet or five meters wide). The slopes observed here range as wide as 4,000 feet (1,200 meters).

Salt can keep water flowing even in temperatures where more pure water gets frozen, and also reduce the evaporation rate. NASA also noted it used data from two other MRO instruments (Compact Reconnaissance Imaging Spectrometer for Mars and the Context Camera) and the Mars Oddysey’s Thermal Emission Imaging System.

That’s not all, however. Scientists also reported 15 fresh craters that excavated ice that used to be hidden underneath the soil of Mars.

A radar on NASA's Mars Reconnaissance Orbiter has detected widespread deposits of glacial ice in the mid-latitudes of Mars.NASA/JPL-Caltech/ASI/University of Rome/Southwest Research Institute — A radar on NASA’s Mars Reconnaissance Orbiter has detected widespread deposits of glacial ice in the mid-latitudes of Mars.NASA/JPL-Caltech/ASI/University of Rome/Southwest Research Institute

“The more we find, the more we can fill in a global map of where ice is buried,” stated Colin Dundas of the United States Geological Survey in Flagstaff, Ariz.

“We’ve now seen icy craters down to 39 degrees north, more than halfway from the pole to the equator. They tell us that either the average climate over several thousand years is wetter than present or that water vapor in the current atmosphere is concentrated near the surface. Ice could have formed under wetter conditions, with remnants from that time persisting today, but slowly disappearing.”

Results were presented at the American Geophysical Union’s fall meeting this week.

Source: NASA