Posted on by Nancy Atkinson

Launch Pad Repairs to Begin; Hubble Repair Mission Should Go As Scheduled

Work will begin on Friday to repair damaged sections of Kennedy Space Center’s launch pad 39A that was damaged during the last space shuttle launch on May 31. On Thursday, (June 26) NASA managers approved a plan that would complete the repairs by the third week of August. Therefore the mission schedule shouldn’t be impacted. The next space shuttle flight, the high-profile final mission to repair the Hubble Space Telescope is scheduled to launch on October 8, and if all goes well with the repairs, space shuttle Atlantis would crawl its way out to the pad on August 29. “We really like the plan,” said shuttle Program Manager John Shannon. “We expect to start moving out on it right away.”

During shuttle Discovery’s launch in May more than 3,500 fire-resistant bricks lining the northeast wall of the “flame trench” at pad 39A were blasted away. Radar tracking showed some of the bricks shot out of the trench at about 1,000 feet per second, or about 680 mph. But NASA officials said the incident did not pose a threat to the space shuttle. Computer simulations run by engineers showed that none of the bricks flew up near the pad surface, and therefore couldn’t have hit the shuttle.

“It’s not a flight [safety] issue at all,” said Rita Willcoxon, space shuttle processing manager, during a teleconference on Thursday.

The work is estimated to cost less than $2.7 million.
A detailed inspection found that many of the anchor plates used to secure the interlocking fire bricks to the 3-foot-thick concrete back wall were heavily eroded due to decades of exposure to severe pressures and acidic rocket exhaust. Additionally, epoxy used to help secure the bricks to the wall was degraded or not consistently applied when the pad was built in the mid 1960s. As a result, the outer brick wall was not tightly locked to the underlying concrete wall it was designed to protect.

To fix the trench, a two different sections of the trench wall will be stripped of bricks.. A steel mesh-like structure will be erected over the exposed backwall and then covered in sprayed-on Fondu Fyre, a material used to protect the massive flame deflector directly under the shuttle’s boosters and main engines.

Working two 10-hour shifts per day, the repair team expects to have the brick removed by July 19. After that, the mesh will be erected and the Fondue Fyre applied.
Officials said the repaired flame trench will be inspected after every launch, but is expected to hold up through the end of shuttle operations in 2010.

The other shuttle pad, 39B may have similar deficiencies in its flame trench. But no major repairs are scheduled for that pad, as all 10 remaining shuttle flights are scheduled to use pad 39A. NASA will have a shuttle ready at 39B for a rescue mission should Atlantis suffer major damage during the Hubble flight, since the shuttle couldn’t reach the International Space Station as a safe haven, which is in a different orbit than Hubble.

News Sources: CBS News Space Place, Space.com

Posted on by Ian O'Neill

Phoenix: Mars Soil Can Support Life

Phoenix delivers regolith to the wet lab (NASA/UA)

Another groundbreaking discovery from Mars: Phoenix has analysed martian regolith containing minerals more commonly found in soil here on Earth, and the acidity is not a hindrance for life to thrive. These new and very exciting results come after preliminary analyses of a scoop of regolith by the landers “wet lab” known as the Microscopy, Electrochemistry and Conductivity Analyzer (MECA) instrument. Although more data collecting needs to be done, trace levels of nutrients have already been detected. This, with the recent discovery of water ice, has amazed mission scientists, likening these new results to “winning the lottery.”

The MECA instrument is carrying out the first ever wet-chemical analysis on a planet other than Earth, and these first results are tantalisingly close to providing answers for the question: “Can Mars support life?” Taken from a scoop of top-soil, the robotic digger managed to excavate a 2 cm deep ditch, delivering the sample to the MECA where analysis could be carried out. The first results from the two-day wet-lab experiment are flooding in and mission scientists are excited by the results. “We are awash in chemistry data,” said Michael Hecht of NASA’s Jet Propulsion Laboratory and lead scientist for the MECA.

The salts discovered contain magnesium, sodium, potassium and chlorine, indicating these minerals had once been dissolved in water. The knowledge that these elements exist in martian regolith is nothing new, but the fact that they would be soluble in water means they would have been available for life to form. In fact, there are some strong similarities between the mineral content and pH level of the martian surface and soils more commonly found here on Earth.

“This soil appears to be a close analog to surface soils found in the upper dry valleys in Antarctica. The alkalinity of the soil at this location is definitely striking. At this specific location, one-inch into the surface layer, the soil is very basic, with a pH of between eight and nine. We also found a variety of components of salts that we haven’t had time to analyze and identify yet, but that include magnesium, sodium, potassium and chloride.” – Sam Kounaves, Phoenix co-investigator, Tufts University.

From the question “Has Mars supported life?” to “Can Mars support life?” – The answer seems to be an overwhelming “Yes.” Although nitrates have yet to be detected, the Mars soil appears to have an alkalinity commonly found in terrestrial soils. At a pH of eight or nine, a zoo of bacteria and plants can live comfortably. Vegetables such as asparagus and turnips are farmed in soils to this degree of alkalinity. Besides, extreme forms of bacteria have been discovered in environments that resemble the alkalinity of bleach, exceeding a pH of 12. The martian surface has suddenly become a little more hospitable for life to thrive.

“Over time, I’ve come to the conclusion that the amazing thing about Mars is not that it’s an alien world, but that in many aspects, like mineralogy, it’s very much like Earth.” – Kounaves.

Although these first results are very exciting, mission scientists are staying realistic. This is only one of several tests, plus it is a sample from a single location. As the digger only scooped a sample 2 cm deep, scientists are keen to see if the regolith deeper down has similar chemistry, so the intention is to dig deeper into the same location, possibly including ice.

Aside: The term “Mars soil”, up to this point, hasn’t been technically accurate. If we look at the definition of “soil” we get:

The material on the surface of the ground in which plants grow; earth
– Cambridge Dictionaries.
The top layer of the earth’s surface, consisting of rock and mineral particles mixed with organic matter.
– Answers.com

The stuff with a red hue on Mars is actually regolith, pulverized grains of rock from hundreds of millions of years of meteorite impacts, geological activity and weathering. Until Phoenix produced these new findings, the most accurate way to describe Mars “soil” was to call it regolith. But now, it seems, Mars regolith fulfils most of the characteristics of being a soil. It contains rock, it contains minerals and it appears to have a pH capable of sustaining plant growth. But does it already contain organic matter? Whether it contains anything “organic” now is open to debate, but it might do in the future…

Sources: Phoenix (UA), New Scientist

Posted on by Fraser Cain

Carnival of Space #60

The Pantheon.

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This week the Carnival of Space moves to Slacker Astronomy.

Click here to read the Carnival of Space #60

And if you’re interested in looking back, here’s an archive to all the past carnivals of space. If you’ve got a space-related blog, you should really join the carnival. Just email an entry to [email protected], and the next host will link to it. It will help get awareness out there about your writing, help you meet others in the space community – and community is what blogging is all about. And if you really want to help out, let me know if you can be a host, and I’ll schedule you into the calendar.

Finally, if you run a space-related blog, please post a link to the Carnival of Space. Help us get the word out.

Posted on by Ian O'Neill

LCROSS Passes Pre-Flight Tests Before Kamikaze Mission to Find Water on Moon

LCROSS separation above the Moon (NASA)

The Lunar Crater Observation and Sensing Satellite (LCROSS) is a very exciting mission for lunar exploration. Since the discovery of water on Mars by Phoenix last week, focus is turning on other planetary bodies and natural satellites for the possibility they may hold a supply of water too. First stop for any manned mission will be our return trip to the Moon by 2020, so it would be very advantageous if we could find a frozen reservoir of H2O hiding within the craters of the lunar surface. LCROSS is going to hitch a ride with the Lunar Reconnaissance Orbiter (LRO) later this year on board an Atlas V rocket. It has just passed some gruelling pre-launch tests before it sets out on a suicide mission that will end in collision with the lunar surface…

To make sure LCROSS can stand up to the huge temperature gradients it will experience during its lunar adventure, engineers have subjected it to rigorous heating and cooling cycles at the Northrop Grumman facility in Redondo Beach, California. These tests come after successful completion of thermal vacuum testing at the start of this month. LCROSS has also been given the thumbs up after passing a launch acoustic vibration simulation intended to see how the integrity of the spacecraft copes with the violence of an Atlas V blast-off.

This new round of tests heated the spacecraft to 230°F (110°C) and then cooled it to -40°F (-40°C) over 13.5 days to simulate the extremes of temperature it will experience en-route to the Moon and flyby.

“The spacecraft steadily has taken shape since Ames delivered the science payload in January. It is a testament to the hard work, perseverance and expertise of the NASA and Northrop Grumman teams that the spacecraft has completed these critical tests ahead of schedule.” – Daniel Andrews, LCROSS project manager, NASA’s Ames Research Center, California.

When in orbit around the Moon in 2009, LCROSS will create two impact plumes in the lunar surface. The target will be a crater near the lunar polar region that is constantly in shadow. This is the perfect location for water ice to form, if there’s any at all.

The Atlas V’s Centaur upper stage rocket will carry LCROSS to the Moon and execute a lunar flyby. It will then enter an elongated Earth orbit, putting the probe in the correct trajectory, ready for LCROSS-Centaur separation. The Centaur stage will then be instructed to carry out a suicidal plunge into the surface so the resulting plume of dust and gas that will rise into the orbital path for LCROSS to analyse. Once data about the plume is relayed to Earth, LCROSS itself will make the ultimate sacrifice, ploughing into the Moon’s surface, creating a second plume of debris for Earth-based observatories to analyse.

It is hoped this trailblazer mission will unlock some of the lunar secrets as to whether water ice is present in any great quantities inside this polar crater, possibly the source for a future manned lunar base.

Source: LCROSS, Physorg

Posted on by Nicholos Wethington

Dark Matter is Denser in the Solar System

Dark matter was theorized to exist relatively recently, and we’ve come a long way in understanding what makes up a whopping 23% of our Universe. Our own galaxy is surrounded by a halo of dark matter that adds to its mass. A recent paper on the dark matter closer to home – right here in our own Solar System – reveals that it is denser and more massive than in the galactic halo.

Dark matter is just plain weird stuff. It doesn’t give off light, has mass and reacts gravitationally with “normal” matter – the stuff that we and our planet and the stars are composed of. Just like normal matter, it “clumps” up, or accretes, because of this gravitational attraction; we find more dark matter near galaxies than in the vast expanses between them.

Dark matter isn’t just far off in the Milky Way or somewhere on the other side of the Universe, though: it’s right here at home in our Solar System. In a recent paper submitted to Physical Review D, Ethan Siegel and Xiaoying Xu of the University of Arizona analyzed the distribution of dark matter in our Solar System, and found that the mass of dark matter is 300 times more than that of the galactic halo average, and the density is 16,000 times higher than that of the background dark matter.

Over the history of the Solar System, Xu and Siegel calculate that 1.07 X 10^20 kg of dark matter have been captured, or about 0.0018% the mass of the Earth. To get a handle on this number, the mass of Ceres – the largest object in the asteroid belt between Mars and Jupiter – is about 9 times this amount.

Siegel and Xu calculated how much dark matter the Solar System has swept up over it’s 4.5 billion-year lifespan by modeling the composition of the background dark matter halo in the orbit of the Solar System around the galaxy, and calculating just how much dark matter would be trapped by the Solar System as it moves through this halo. They ran this calculation for the Sun and each one of the eight planets separately, giving the distribution of the matter throughout the Solar System, as well as the total amount captured.

Much like when you drive your car through a light snowfall, dark matter “sticks” to the Solar System when it is gravitationally bound by the Sun and planets. Just as some of the snow melts on your windshield (hopefully), some doesn’t stick to the hood and most just flies right by, dark matter isn’t distributed evenly throughout our Solar System, either. Some planets have more dark matter surrounding them than others, depending on where they are. Shown below is the density distribution of the dark matter in the Solar System

The first spike is Mercury, and the next two spikes are Venus and Earth (Mars doesn’t show up). The next is Jupiter, followed by a small bump from Saturn and finally Uranus and Neptune combined create the last small bump.

How does the local dark matter effect interactions in the Solar System? Well,it doesn’t have a large effect on the orbits of the planets, nor does it slow down the Solar System in its orbit around the galactic center appreciably.

“Planetary orbits, if there were enough dark matter present, would have their perihelia precess faster than if there were no dark matter. The amount of dark matter allowed from these observations is considerably greater than the amount I predict. The errors on the measurements of perihelion precession are in units of hundredths of an arc second per century…Even if you assume the dark matter is at rest with respect to the galaxy that the Solar System moves through (which is the extreme example), the Sun is of order 10^30 kg; capturing a 10^20 kg clump of dark matter will slow you down by about 20 microns/second over the lifetime of the Solar System. So that would be small.” – Ethan Siegel in an email interview.

And, alas, the mystery of the Pioneer anomaly is not going to be solved by this revelation, as the mass of the captured dark matter is not enough to explain the odd motions of that spacecraft.

The discovery of a higher density and mass of dark matter in our neighborhood may aid in the study and detection of dark matter, though. Knowing the mass and density distribution of the local dark matter – and thus knowing how much and where to look for it – will provide astronomers looking into solving exactly what it’s made up of with more information .

“Our determination of the local dark matter density and velocity distribution are of great importance to direct detection experiments. The most recent calculations that have been carried out assume that the properties of dark matter at the Sun’s location are derived directly from the galactic halo. By comparison, we find that terrestrial experiments should also consider a component of dark matter with a density 16,000 times greater than the background halo density,” wrote Xu and Siegel.

Source: Arxiv, email interview with Ethan Siegel

Posted on by Tammy Plotner

Reaching for the Ring: M57 by Dietmar Hager

M57 Close-up - Dr. Dietmar Hager

For those of us old enough to remember riding on an old fashioned carousel, there was once a quaint custom where the operator would hold a brass ring out and the lucky contestant who captured it could ride again for free. Before you dismiss this astrophotograph as just another colorful look at a Messier, perhaps you better step inside the workings of the merry-go-round to learn more about what you’re really seeing here… Because this ring is pure gold.

Discovered by Antoine Darquier de Pellepoix in January of 1779 and independently discovered and cataloged by Charles Messier just a few days later, the famous comet hunter himself described it as being “a dull nebula, but perfectly outlined; as large as Jupiter and looks like a fading planet.” Perhaps it was that very description which coaxed Uranus’ discoverer – Sir William Herschel – to have a look for himself and class such objects as “planetary nebula“. Fortunately, Herschel’s telescope resolved M57 to a far greater degree and his descriptions were “a perforated ring of stars… none seems to belong to it.” Since that time, astronomers have been turning an eye towards this “curiosity of the heavens” in a great effort to not only understand its cause – but to capture it as well.

In 1800, German astronomer Friedrich von Hahn was the first to resolve out the Ring’s central star – a planet-sized white dwarf variable star which has an average magnitude of 15. At one point in its Mira-like life, it began shedding its outer layers in what we now believe to be a cylindrical shape and what we see is the bright torus of light from our point of view. Of course, none of this is particularly new news about the 2,300 light year distant M57. Nor is the knowledge when we are looking down this tunnel of expelled gas that we are seeing a decreasing ionization level as the distance from the central star increases. For all who have seen the Ring with their own eyes the innermost region appears dark – the result of only ultra-violet radiation. What we can capture visually is the inner ring, glowing brightly with the greenish forbidden light of doubly ionized oxygen and nitrogen. Where the true prize lay is much like a carousel – it’s just outside where only the red light of hydrogen can be excited.

In 1935 an astronomer named J.C. Duncan discovered something a bit more about the Ring than we knew – an extended halo of material which is all the remains of the star’s earlier stellar winds. It took the power of the Hubble telescope to resolve out dust filaments and globules, but now I invite you to take a closer look at which took 40,000 years in the making and spans 500 times the size of our own solar system.

M57 Closeup - Dr. Dietmar Hager

It took Dr. Dietmar Hager a full month of work to compile some 12 hours of exposure time to reveal what you see here, but the results from StarGazer Observatory are nothing less than amazing. Like the Hubble Telescope images of M57, this image reveals small clouds of dark dust which have flowed out from the central star and are captured in silhouette against the glowing walls of the planetary shell. According to what we know, “These small, dense dust clouds are too small to be seen with ground-based telescopes, but are easily revealed by Hubble.” What’s more, the outer filaments only recently came to public light as ” The Spitzer Space Telescope’s powerful infrared vision detected this material expelled from the withering star.”

Congratulations, Dr. Hager. You have managed with a 9″ Earth-based refractor to capture for us what took two space telescopes to first reveal – along with a distant background galaxy in the full sized image. At least in my book, that means you’ve done far more than just reach for the brass ring…

You’ve captured pure gold.

Posted on by Nancy Atkinson

Twin Spiral Galaxies Dance Together

This incredible image looks like space art, or a trick done with Photoshop, but its an actual image of twin galaxies dancing together in the sky. The image was obtained, appropriately enough by the Gemini South telescope in Chile using GMOS, the Gemini Multi-Object Spectrograph. These two nearly identical spiral galaxies are in Virgo, 90 million light years distant, in the early stages of a gentle gravitational embrace.

Like two dancers grabbing hands while passing, NGC 5427 (the nearly open-faced spiral galaxy at lower left) and its southern twin NGC 5426 (the more oblique galaxy at upper right), are in the throes of a slow but disturbing interaction – one that could take a hundred million years to complete.

At a glance, these twin galaxies — which have similar masses, structures, and shapes and are together known as Arp 271 – appear undisturbed. But recent studies have shown that the mutual pull of gravity has already begun to alter and distort their visible features.

Typically, the first sign of a galaxy interaction is the formation of a bridge-like feature. Indeed, the two spiral arms on the western (upper) side of NGC 5426 appear as long appendages that connect with NGC 5427. This intergalactic bridge acts like a feeding tube, allowing the twins to share gas and dust with one other across the 60,000 light years (less than one galaxy diameter) of space separating them.

Colliding gases caused by the interaction may have also triggered bursts of star formation (starbursts) in each galaxy. Star-forming, or HII, regions appear as hot pink knots that trace out the spiral patterns in each galaxy. HII regions are common to many spiral systems, but the giant ones in NGC 5426 are curiously knotted and more abundant on the side of the galaxy closest to NGC 5427. Starburst activity can also be seen in the galaxy’s connecting bridge.

Once thought to be unusual and rare, gravitational interactions between galaxies are now known to be quite common (especially in densely populated galaxy clusters) and are considered to play an important role in galaxy evolution. Most galaxies have probably had at least one major, if not many minor, interactions with other galaxies since the advent of the Big Bang some 13 billion years ago. Our own Milky Way, a spiral galaxy like those in this image, is, in fact, performing its own stately dance. Both with the nearby dwarf galaxy, called the Large Magellanic Cloud and a future interaction with the large spiral galaxy M-31 or the Great Andromeda Galaxy, which is now located about 2.6 million light years away from the Milky Way. This new Gemini image is possibly a preview of things to come for our own galaxy. Ultimately the end result of these types of collisions will be a large elliptical galaxy.

Original news source: Gemini Observatory

Posted on by Ian O'Neill

Ares V Rocket Gets an Upgrade: It will be Bigger and Stronger for 2020 Moon Mission (Video)

The future of space travel - Artist impression of Ares V on the launchpad (NASA)

NASA announced on Wednesday that the original Constellation project’s principle rocket, the Ares V, will need to be designed to carry a larger payload for manned missions to the Moon by the year 2020. This means the original concept will need to have a length extension of 20 feet (6 metres) and will need to use six main engines at its base, rather than the current five. This upgrade will be capable of sending far more instrumentation into space, an extra 15,600 lb (7,000 kg, or the equivalent mass of a male African elephant)…

When the Shuttle is retired in 2010, there is going to be a five-year gap before the Constellation Program prepares its first Ares launch. There can therefore be little room for setbacks in the design phase of the Ares rocket system as there are already concerns for the US dependence on Russia to provide access to space between 2010 and 2015.

In a move to make the heavy-lift vehicle more robust (predicting an increased launch thrust requirement) to send four astronauts, a lunar lander plus supplies, NASA has announced the Ares V rocket will be “beefed up” to cater for our future needs to get man back to the Moon. This huge vehicle is now designed to carry payloads of over 156,600 lb (71,000 kg), some 15,600 lb (or 10%) more than the original concept. Ares V was originally designed to be approximately the same length as the original Saturn V lunar rocket (361 feet or 110 metres long), but to accommodate an extra booster engine and extra payload volume, Ares V will be 381 feet (116 metres) long. That’s the height of a 38-story building. This increased capability will obviously be of huge benefit to the future lunar and Mars missions.

These design alterations were announced after a nine-month study to investigate whether NASA could succeed in its goal to be ready for a return mission to the Moon in 2020, and a manned mission to Mars afterwards. Constellation program manager Jeff Hanley is upbeat about the study’s findings. “This extensive review proves we are ready for the next phase: taking these concepts and moving forward,” he said.

The Constellation Program will use a two-step method for getting man and machine into space. The Ares V will launch heavy payloads, using its superior power, whilst the smaller Ares I will be used as a general low-mass/manned transit vehicle. For large missions, both Ares V and Ares I launch vehicles will be used, allowing astronauts to dock with their equipment in space before travelling to the Moon and beyond.

View the excellent NASA visualization of what it will be like to see the Ares V and Ares I rockets launch and enter Earth orbit and dock before beginning their mission »

All I know is, whether Constellation is completed on time or not, I’ll be at the launch to watch the awesome Ares V lift off from Cape Canaveral…

Source: Space.com

Posted on by Nancy Atkinson

Two Faces of Mars Explained

Mars has two faces. No, not those kind of faces, but the notable differences between the northern and southern hemisphere. Mars has lowlands in the north and highlands in the south. This disparity has long puzzled planetary scientists, but most concurred that early in Mars history, impacts shaped the planet’s two-faced landscape. But many disagreed whether several small impacts or one big one were responsible for sculpting Mars’ surface. Now scientists at the California Institute of Technology have shown through computer modeling that the Mars dichotomy, as the divided terrain has been termed, can indeed be explained by one giant impact early in the planet’s history.

“The dichotomy is arguably the oldest feature on Mars,” said Oded Aharonson from Caltech. Scientists believe the differences in hemispheric features arose more than four billion years ago.

Previously, scientists discounted the idea that a single, giant impactor created the lower elevations and thinner crust of Mars’s northern region, says Margarita Marinova, a graduate student at Caltech, and one of the lead authors of the study.

For one thing, Marinova explained, it was thought that a single impact would leave a circular footprint, but the outline of the northern lowlands region is elliptical. There is also a distinct lack of a crater rim: topography increases smoothly from the lowlands to the highlands without a lip of concentrated material in between, as is the case in small craters. Finally, it was believed that a giant impactor would obliterate the record of its own occurrence by melting a large fraction of the planet and forming a magma ocean.

“We set out to show that it’s possible to make a big hole without melting the majority of the surface of Mars,” Aharonson says. The team modeled a range of projectile parameters that could yield a cavity the size and ellipticity of the Mars lowlands without melting the whole planet or making a crater rim.

The team ran over 500 computer simulations combining various energies, velocities, and impact angles. Finally, they were able to narrow in on a “sweet spot”–a range of single-impact parameters that would make exactly the type of crater found on Mars. Their dedicated supercomputer allowed them to run simulations not run in the past. “The ability to search for parameters that allow an impact compatible with observations is enabled by the dedicated machine at Caltech,” Aharonson said.

The favored simulation conditions outlined by the sweet spot suggest an impact energy of around 1029 joules, which is equivalent to 100 billion gigatons of TNT. The impactor would have hit Mars at an angle between 30 and 60 degrees while traveling at 6 to 10 kilometers per second. By combining these factors, Marinova calculated that the projectile was roughly 1,600 to 2,700 kilometers across.

Estimates of the energy of the Mars impact place it squarely between the impact that is thought to have led to the extinction of dinosaurs on Earth 65 million years ago and the one believed to have extruded our planet’s moon four billion years ago.

Marinova said the timing of formation of our moon and the Mars dichotomy is not coincidental. “This size range of impacts only occurred early in solar system history,” she says. The results of this study are also applicable to understanding large impact events on other heavenly bodies, like the Aitken Basin on the moon and the Caloris Basin on Mercury.

This report, published in the June 26 issue of Nature, goes along with two other papers on the Mars dichotomy. One published by Jeffrey Andrews-Hanna and Maria Zuber of MIT and Bruce Banerdt of JPL examine the gravitational and topographic signature of the dichotomy with information from the Mars orbiters. Another accompanying report, from a group at UC Santa Cruz led by Francis Nimmo, explores the expected consequences of mega-impacts.

Original News Source: EurekAlert

Posted on by Nancy Atkinson

Mars Atmosphere Once Held Enough Moisture for Dew or Drizzle

Data from Mars orbiters and landers have suggested that any past water on the Red Planet’s surface probably came from subsurface moisture bubbling up from underground. But a new study of Martian soil data implies that Mars’ atmosphere was once thick enough to hold moisture and that dew or even drizzle hit the ground. Geoscientists at the University of California Berkeley combined data from the Viking 1 and 2 landers, the Pathfinder rover, and the current rovers Spirit and Opportunity. The scientists say tell-tale signs of this type of moisture are evident on the planet’s surface.

“By analyzing the chemistry of the planet’s soil, we can derive important information about Mars’ climate history,” said Ronald Amundson, UC Berkeley professor of ecosystem sciences and the study’s lead author. “The dominant view, put forward by many now working on the Mars missions, is that the chemistry of Mars soils is a mix of dust and rock that has accumulated over the eons, combined with impacts of upwelling groundwater, which is almost the exact opposite of any common process that forms soil on Earth. In this paper, we try to steer the discussion back by re-evaluating the Mars data using geological and hydrological principles that exist on Earth.”

The team says soil at the various spacecraft landing sites have lost significant fractions of the elements that make up the rock fragments from which the soil was formed. This is a sign, they say, that water once moved downward through the dirt, carrying the elements with it. Amundson also pointed out that the soil also shows evidence of a long period of drying, as evidenced by surface patterns of the now sulfate-rich land. The distinctive accumulations of sulfate deposits are characteristic of soil in northern Chile’s Atacama Desert, where rainfall averages approximately 1 millimeter per year, making it the driest region on Earth.

Researchers compared images such as this image of the Atacama Desert with the above image taken by the Opportunity rover on Mars, which show similar surface patterns.

“The Atacama Desert and the dry valleys of Antarctica are where Earth meets Mars,” said Amundson. “I would argue that Mars has more in common geochemically with these climate extremes on Earth than these sites have in common with the rest of our planet.”

Amundson noted that sulfate is prevalent in Earth’s oceans and atmosphere, and is incorporated in rainwater. However, it’s so soluble that it typically washes away from the surface of the ground when it rains. The key for the distinctive accumulation in soil to appear is for there to be enough moisture to move it downward, but not so much that it is washed away entirely.

The researchers also noted that the distribution of the chemical elements in Martian soil, where sulfates accumulate on the surface with layers of chloride salt underneath, suggest atmospheric moisture.

“Sulfates tend to be less soluble in water than chlorides, so if water is moving up through evaporation, we would expect to find chlorides at the surface and sulfates below that,” said Amundson. “But when water is moving downward, there’s a complete reversal of that where the chlorides move downward and sulfates stay closer to the surface. There have been weak but long-term atmospheric cycles that not only add dust and salt but periodic liquid water to the soil surface that move the salts downward.”

Amundson pointed out that there is still debate among scientists about the degree to which atmospheric and geological conditions on Earth can be used as analogs for the environment on Mars. He said the new study suggests that Martian soil may be a “museum” that records chemical information about the history of water on the planet, and that our own planet holds the key to interpreting the record.

“It seems very logical that a dry, arid planet like Mars with the same bedrock geology as many places on Earth would have some of the same hydrological and geological processes operating that occur in our deserts here on Earth,” said Amundson. “Our study suggests that Mars isn’t a planet where things have behaved radically different from Earth, and that we should look to regions like the Atacama Desert for further insight into Martian climate history.”

Original News Source: EurekAlert