On this day in science history: Mars 5 launched

In 1973, the USSR launched Mars 5, on a Proton SL-12/D-1-e booster. It was one of several Soviet Mars probes - Mars 4, 5, 6, and 7 - launched in Jul-Aug 1973. The Mars 5 mission was to orbit Mars, which was achieved on 12 Feb 1974. Each orbit took about 25 hours. It was designed to return information on the composition, structure, and properties of the martian atmosphere and surface. However, after only 22 orbits, the mission ended prematurely due to loss of pressurization in the transmitter housing. Before the failure, data for a small portion of the martian southern hemisphere was captured with about 60 images forwarded over a nine day period. The probe also sent more measurements made by other instruments.

Mars in natural colour in 2007. By ESA - European Space Agency & Max-Planck Institute for Solar System Research for OSIRIS Team ESA/MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA [CC BY-SA 3.0-igo (http://creativecommons.org/licenses/by-sa/3.0-igo)], via Wikimedia Commons

Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, after Mercury. Named after the Roman god of war, it is often referred to as the "Red Planet" because the iron oxide prevalent on its surface gives it a reddish appearance. Mars is a terrestrial planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the valleys, deserts, and polar ice caps of Earth.

The rotational period and seasonal cycles of Mars are likewise similar to those of Earth, as is the tilt that produces the seasons. Mars is the site of Olympus Mons, the largest volcano and second-highest known mountain in the Solar System, and of Valles Marineris, one of the largest canyons in the Solar System. The smooth Borealis basin in the northern hemisphere covers 40% of the planet and may be a giant impact feature. Mars has two moons, Phobos and Deimos, which are small and irregularly shaped. These may be captured asteroids, similar to 5261 Eureka, a Mars trojan.

There are ongoing investigations assessing the past habitability potential of Mars, as well as the possibility of extant life. Liquid water cannot exist on the surface of Mars due to low atmospheric pressure, which is less than 1% of the Earth's, except at the lowest elevations for short periods. The two polar ice caps appear to be made largely of water. The volume of water ice in the south polar ice cap, if melted, would be sufficient to cover the entire planetary surface to a depth of 11 meters (36 ft). In November 2016, NASA reported finding a large amount of underground ice in the Utopia Planitia region of Mars. 

The volume of water detected has been estimated to be equivalent to the volume of water in Lake Superior.

Mars can easily be seen from Earth with the naked eye, as can its reddish coloring. Its apparent magnitude reaches −2.91, which is surpassed only by Jupiter, Venus, the Moon, and the Sun. Optical ground-based telescopes are typically limited to resolving features about 300 kilometers (190 mi) across when Earth and Mars are closest because of Earth's atmosphere.

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Mission control: salty diet makes you hungry, not thirsty

We've all heard it: eating salty foods makes you thirstier. But what sounds like good nutritional advice turns out to be an old-wives' tale. In a study carried out during a simulated mission to Mars, an international group of scientists has found exactly the opposite to be true. "Cosmonauts" who ate more salt retained more water, weren't as thirsty, and needed more energy.

Salt shaker, by Dubravko Sorić SoraZG on Flickr [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

For some reason, no one had ever carried out a long-term study to determine the relationship between the amount of salt in a person's diet and his drinking habits. Scientists have known that increasing a person's salt intake stimulates the production of more urine - it has simply been assumed that the extra fluid comes from drinking. Not so fast! say researchers from the German Aerospace Center (DLR), the Max Delbrück Center for Molecular Medicine (MDC), Vanderbilt University and colleagues around the world. Recently they took advantage of a simulated mission to Mars to put the old adage to the test. Their conclusions appear in two papers in the current issue of The Journal of Clinical Investigation.

What does salt have to do with Mars? Nothing, really, except that on a long space voyage conserving every drop of water might be crucial. A connection between salt intake and drinking could affect your calculations - you wouldn't want an interplanetary traveler to die because he liked an occasional pinch of salt on his food. The real interest in the simulation, however, was that it provided an environment in which every aspect of a person's nutrition, water consumption, and salt intake could be controlled and measured.

The studies were carried out by Natalia Rakova (MD, PhD) of the Charité and MDC and her colleagues. The subjects were two groups of 10 male volunteers sealed into a mock spaceship for two simulated flights to Mars. The first group was examined for 105 days; the second over 205 days. They had identical diets except that over periods lasting several weeks, they were given three different levels of salt in their food.

The results confirmed that eating more salt led to a higher salt content in urine - no surprise there. Nor was there any surprise in a correlation between amounts of salt and overall quantity of urine. But the increase wasn't due to more drinking - in fact, a salty diet caused the subjects to drink less. Salt was triggering a mechanism to conserve water in the kidneys.

Before the study, the prevailing hypothesis had been that the charged sodium and chloride ions in salt grabbed onto water molecules and dragged them into the urine. The new results showed something different: salt stayed in the urine, while water moved back into the kidney and body. This was completely puzzling to Prof. Jens Titze, MD of the University of Erlangen and Vanderbilt University Medical Center and his colleagues. "What alternative driving force could make water move back?" Titze asked.

Experiments in mice hinted that urea might be involved. This substance is formed in muscles and the liver as a way of shedding nitrogen. In mice, urea was accumulating in the kidney, where it counteracts the water-drawing force of sodium and chloride. But synthesizing urea takes a lot of energy, which explains why mice on a high-salt diet were eating more. Higher salt didn't increase their thirst, but it did make them hungrier. Also the human "cosmonauts" receiving a salty diet complained about being hungry.

The project revises scientists' view of the function of urea in our bodies. "It's not solely a waste product, as has been assumed," Prof. Friedrich C. Luft, MD of the Charité and MDC says. "Instead, it turns out to be a very important osmolyte - a compound that binds to water and helps transport it. Its function is to keep water in when our bodies get rid of salt. Nature has apparently found a way to conserve water that would otherwise be carried away into the urine by salt."

The new findings change the way scientists have thought about the process by which the body achieves water homeostasis - maintaining a proper amount and balance. That must happen whether a body is being sent to Mars or not. "We now have to see this process as a concerted activity of the liver, muscle and kidney," says Jens Titze.

"While we didn't directly address blood pressure and other aspects of the cardiovascular system, it's also clear that their functions are tightly connected to water homeostasis and energy metabolism."

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https://en.wikipedia.org/wiki/Salt

Mercury's journey across Sun under way

Skywatchers across the globe are observing Mercury transit the Sun, the little planet's third such pass of 14 it will make this century.

Mercury's sojourn between Earth and our star lasts from 11:12 until 18:42 GMT.

It will not make another transit until 2019 and then 2032.

The event is impossible - and dangerous - to view with the naked eye or binoculars, but astronomy groups worldwide are offering the chance view it through filtered telescopes.

Live views from space and ground telescopes are also available online.

They show Mercury as a tiny black circle, smaller but darker than many sunspots, slowly traversing the Sun's giant yellow disc.

Mercury in colour by NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington. Edited version of Image:Mercury in color - Prockter07.jpg by jjron (cropped to square). (NASA/JPL [1]) [Public domain], via Wikimedia Commons

Mercury spins around the Sun every 88 days, but its orbit is tilted relative to the Earth's. It is that discrepancy which makes it relatively rare for the three bodies to line up in space.

From western Europe, north-western Africa and much of the Americas, Mercury's seven-and-a-half-hour glide across the Sun will be visible in its entirety. A further swathe of the planet will catch part of the transit, depending on local sunrise and sunset times.

The only land masses to miss out completely are Australasia, far eastern Asia and Antarctica.

Because Mercury is so small - just one-third as big as Earth and, from our perspective, 1/150th of the Sun's diameter - its transit can only be glimpsed under serious magnification; the "eclipse glasses" used by thousands of people to view last year's solar eclipse will be useless.

And to avoid permanent eye damage, any telescope must be fitted with a solar filter before being trained on the Sun. The British Astronomical Association explains on its website how amateur stargazers can enjoy the spectacle safely.

Open University's Prof David Rothery said the celestial event would not present any novel scientific opportunities - but was special nonetheless.

"From this transit, we're unlikely to learn anything we don't already know," he told BBC Inside Science. "But what a wonderful event for showing people Mercury. It's a hard planet to see.

"Historically, transits were of immense importance."

In the 1700s, for example, it was observations of Mercury and Venus slipping across the Sun that allowed astronomers, led by Edmund Halley, to pin down the dimensions of the known Solar System.

Prof Rothery is a Mercury expert and a leading scientist on the European Space Agency's BepiColombo mission to the diminutive planet, which will launch in 2017 or 2018.

Mercury has already been visited by two Nasa probes: Mariner 10 flew past in 1974 and 1975 and Messenger spent four years in orbit until its planned crash landing in 2015.

Messenger spent four years in orbit taking images and measurements of Mercury

"[Messenger] told us an awful lot. It really told us we don't understand Mercury - because there's a lot of things which just don't stack up," Prof Rothery said.

"It's an airless body, with lots of craters... But there's been a long history of volcanic activity, fault activity - and the composition, that began to be revealed by Messenger, is weird.

"There's very little iron at the surface but it must have a ginormous iron core, because it generates a magnetic field - which Venus, Mars and the Moon don't."

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ExoMars: 'giant nose' to sniff out life on Mars prepares for launch

Space engineers are making final preparations for the launch of a robot spacecraft designed to sniff out signs of life on Mars.

The probe, ExoMars 2016 – the first of a two-phase exploration of the Red Planet by European and Russian scientists – is scheduled to be blasted into space on a Proton rocket from Baikonour cosmodrome in Kazakhstan at 0931 GMT on Monday.

The spacecraft consists of a module called Schiaparelli that will test heat shields and parachutes in preparation for future probe landings on Mars and a second main component, the Trace Gas Orbiter or TGO, that will analyse the planet’s atmosphere. In particular it will seek out the presence of the gas methane which, on Earth, is produced by living organisms.

“Essentially our spacecraft is a giant nose in the sky,” said Jorge Vago, an ExoMars project scientist based with the European Space Agency (Esa). “We are going to use it to sniff out the presence of methane on Mars and determine if it is being produced by biological processes.”

Methane is normally destroyed by ultraviolet radiation within a few hundred years of its creation. Its presence on Mars would therefore suggest life had recently been active there. The US robot rover Curiosity, which landed on Mars in 2012, initially found no sign of methane. Subsequent analyses in 2014 did report the presence of methane in the Martian atmosphere in one area. However, some scientists have argued that it may have been created by non-biological means.

On Earth most methane is generated biologically, but it can be made by chemical processes under the surface. To differentiate between these two processes, the ExoMars trace gas detector will not only analyse methane levels in more detail than any previous mission but also study other gases that will provide information about its likely source. “If methane is found in the presence of other complex hydrocarbon gases, such as propane or ethane, that will be a strong indication that biological processes are involved,” said another project scientist, Manish Patel, of the Open University.

“However, if we find methane in the presence of gases such as sulphur dioxide, a chemical strongly associated with volcanic activity on Earth, that will be a pretty sure sign that we are dealing with methane that has come from the ground and is a byproduct of geological processes.”

By NASA, ESA, and The Hubble Heritage Team (STScI/AURA) [Public domain], via Wikimedia Commons

ExoMars is expected to arrive at the Red Planet on 19 October after a journey of 308m miles (496m km) across space, and will be followed by a second ExoMars mission, a Mars rover, scheduled for launch in 2018 – although Esa officials have warned that it may be delayed by budget problems.

On Friday, Russian engineers completed the rollout of the giant Proton rocket that will carry ExoMars to its destination, and on Saturday, staff at Esa’s mission control centre in Darmstadt, Germany – which will run the mission once in space – conducted a dress rehearsal for the launch. “We do a similar dress rehearsal for every launch,” said Paolo Ferri, head of mission operations for Esa. “It’s a milestone that caps off several years of preparation for any complex mission – designing, building and testing the ground systems, preparing the flight operations procedures and then finally an intensive period of team training.”

Finally, on Monday, the spacecraft is scheduled take off from Baikonour. Then, when it has reached orbit, the TGO, still linked to the Schiaparelli test lander, will separate from the fourth stage of its Proton launcher and begin its seven-month journey to the Red Planet.

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New Mars rover findings revealed - much higher concentrations of silica indicate 'considerable water activity'

New findings by NASA's Mars Curiosity rover are the focus of a press conference this morning at the American Geophysical Union (AGU) meeting in San Francisco, Calif. A group of scientists, including one from Los Alamos National Laboratory, revealed that the Curiosity rover found much higher concentrations of silica at some sites the rover has investigated in the past seven months than anywhere else it has visited since landing on Mars 40 months ago. Silica makes up nine-tenths of the composition of some of the rocks.

Mars, by NASA, ESA, and The Hubble Heritage Team (STScI/AURA)

"The high silica was a surprise," said Jens Frydenvang of Los Alamos National Laboratory and the University of Copenhagen, also a Curiosity science team member. "While we're still working with multiple hypotheses on how the silica got so enriched, these hypotheses all require considerable water activity, and on Earth high silica deposits are often associated with environments that provide excellent support for microbial life. Because of this, the science team agreed to make a rare backtrack to investigate it more."

The first discovery was as Curiosity approached the area "Marias Pass," where a lower geological unit contacts an overlying one. ChemCam, the rover's laser-firing instrument for checking rock composition from a distance, detected bountiful silica in some targets the rover passed along the way to the contact zone. The ChemCam instrument was developed at Los Alamos in partnership with the French IRAP laboratory in Toulouse and the French Space Agency.

Adding information about silica clues was a major emphasis in rover operations over a span of four months and a distance of about one-third of a mile (half a kilometer). It involves many more readings from ChemCam, plus elemental composition measurements by the Alpha Particle X-ray Spectrometeter (APXS) on the rover's arm and mineral identification of drilled rock-powder samples analyzed by the Chemistry and Mineralogy (CheMin) instrument inside the rover.

Curiosity's science team is working with two main hypotheses to explain the recent findings on Mount Sharp, both of which require water. Water that is acidic would tend to carry other ingredients away and leave silica behind. Alkaline or neutral water could bring in dissolved silica that would be deposited from the solution. Apart from presenting a puzzle about the history of the region where Curiosity is working, the recent findings on Mount Sharp have intriguing threads to what an earlier rover, Spirit, found halfway around Mars. There, signs of sulfuric acidity were observed.

Adding to the puzzle, some of the silica found at one rock Curiosity drilled, called "Buckskin," is in a mineral named tridymite, which is found in Bandelier tuff, common in New Mexico but rare elsewhere, and never before seen on Mars. The usual origin of tridymite on Earth involves high temperatures in igneous or metamorphic rocks, but the finely layered sedimentary rocks examined by Curiosity have been interpreted as lakebed deposits.

Curiosity has been studying geological layers of Mount Sharp, starting from the bottom, since 2014, following two years of productive work on the plains surrounding the mountains. The mission delivered evidence in its first year that lakes in the area billions of years ago offered favorable conditions for life, if microbes ever lived on Mars. As Curiosity studies successively younger layers up Mount Sharp's slopes, the mission is investigating how ancient environmental conditions evolved from lakes, rivers and deltas to the harsh aridity of today's Mars.

Buckskin was the first of three rocks where drilled samples were collected during that period. The CheMin identification of tridymite prompted the team to look at possible explanations for it: "We could solve this by determining whether trydymite in the sediment comes from a volcanic source or has another origin," said Liz Rampe, of Aerodyne Industries at NASA's Johnson Space Center. "A lot of us are in our labs trying to see if there's a way to make tridymite without such a high temperature."

Beyond Marias Pass, ChemCam and APXS readings showed a pattern of high silica in pale zones along fractures in the bedrock, linking the silica enrichment there to alteration by fluids that flowed through the fractures and permeated into the bedrock. CheMin analyzed drilled material from a target called "Big Sky" in bedrock away from a fracture and from a fracture-zone target called "Greenhorn." Greenhorn indeed has much more silica, but not any in the form of tridymite. Much of it is in the form of noncrystalline opal, which can form in many types of environments, including hot springs, acid leaching and other wet settings.

"What we're seeing on Mount Sharp is dramatically different from what we saw in the first two years of the mission," said Curiosity Project Scientist Ashwin Vasavada of JPL. "There's so much variability within relatively short distances. The silica is one indicator of how the chemistry changed. It's such a multifaceted and curious discovery, we're going to take a while figuring it out."

The ChemCam has just passed 300,000 laser shots on Mars, each of which returns a color spectrum of the resulting plasma.

For more about Curiosity, which is examining sand dunes this month, visit the Mars Science Laboratory webpage: mars.jpl.nasa.gov/msl/

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Europe and Russia mission to assess Moon settlement

The European and Russian space agencies are to send a lander to an unexplored area at the Moon's south pole.

It will be one of a series of missions that prepares for the return of humans to the surface and a possible permanent settlement.

The spacecraft will assess whether there is water, and raw materials to make fuel and oxygen.

BBC News has obtained exclusive details of the mission, called Luna 27, which is set for launch in five years' time.

The mission is one of a series led by the Russian federal space agency, Roscosmos, to go back to the Moon.

These ventures will continue where the exploration programme that was halted by the Soviet Union in the mid 1970s left off, according to Prof Igor Mitrofanov, of the Space Research Institute in Moscow, who is one of the lead scientists.

"We have to go to the Moon. The 21st Century will be the century when it will be the permanent outpost of human civilisation, and our country has to participate in this process," he told BBC News.

But unlike efforts in the 1960s and 70s, when the Soviet Union was working in competition with the US and other nations, he added, "we have to work together with our international colleagues".

Full moon: Gregory H. Revera

Bérengère Houdou, who is the head of the lunar exploration group of at Esa's European Space Research and Technology Centre (Estec), just outside Amsterdam, has a similar strategy.

"We have an ambition to have European astronauts on the Moon. There are currently discussions at international level going on for broad cooperation on how to go back to the Moon."

One of the first acts of the new head of the European Space Agency, Johann-Dietrich Wörner, was to state that he wants international partners to build a base on the Moon's far side.

The initial missions will be robotic. Luna 27 will land on the edge of the South Pole Aitken (SPA) basin. The south polar region has areas which are always dark. These are some of the coldest places in the Solar System. As such, they are icy prisons for water and other chemicals that have been shielded from heating by the Sun.

According to Dr James Carpenter, Esa's lead scientist on the project, one of the main aims is to investigate the potential use of this water as a resource for the future, and to find out what it can tell us about the origins of life in the inner Solar System.

"The south pole of the Moon is unlike anywhere we have been before," he said.

"The environment is completely different, and due to the extreme cold there you could find large amounts of water-ice and other chemistry which is on the surface, and which we could access and use as rocket fuel or in life-support systems to support future human missions we think will go to these locations."

Back in the heady days of the Apollo missions, it seemed almost inevitable that those astounding but brief trips to the Moon would be followed by something more permanent. But the notion of colonies soon proved to be science fantasy. After the last of 12 astronauts left their boot prints in the lunar dust in 1972, the US government and taxpayers collectively declared, "been there, done that". America had scored a dazzling point over the Soviet Union but at eye-watering cost, so the final three planned Apollo missions were cancelled.

For a while, our nearest neighbour in space seemed rather unappealing. But then, over recent years, came a series of discoveries about the lunar dust itself, suggesting that the Moon holds water and minerals that could conceivably help support a settlement, if anyone has the appetite to pay for it. So a new batch of missions is under way. China seems to be particularly eager, launching increasingly capable robotic craft that could pave the way for human flights, sometime in the 2030s.

In all probability, the next boots on the Moon will be Chinese. One of China's leading space scientists told me how he even envisages opening lunar mines to extract valuable resources such as Helium-3. Throughout history, humanity has gazed at the Moon through different eyes. In the 1960s, it was the scene for Cold War rivalry. Now it is seen as a potential staging-post for longer journeys and as a rock waiting to be dug up and exploited.

Prof Mitrofanov says that there are scientific and commercial benefits to be had by building a permanent human presence on the lunar surface.

"It will be for astronomical observation, for the utilisation of minerals and other lunar resources and to create an outpost that can be visited by cosmonauts working together as a test bed for their future flight to Mars."

Esa and its industrial collaborators are developing a new type of landing system able to target areas far more precisely than the missions in the 1960s and 70s. 

The so-called "Pilot" system uses on-board cameras to navigate and a laser guidance system which is able to sense the terrain while approaching the surface and be able to decide for itself whether the landing site is safe or not, and if necessary to re-target to a better location.

Europe is also providing the drill which is designed to go down to 2m and collect what might be hard, icy samples. According to Richard Fisackerly, the project's lead engineer, these samples might be harder than reinforced concrete and so the drill will need to be extremely strong.

"We are currently looking at the technologies we would need to penetrate that type of material and are looking at having both rotation and hammering functions. The final architecture has yet to be decided - but this combination of rotation, hammering and depth is a step beyond what we have already flown or is in development today," he told BBC News.

Esa will also provide the onboard miniaturised laboratory, called ProSPA. It will be similar to the instrument on the Philae lander, which touched down on the surface of Comet 67P last year. But ProSPA will be tuned to searching for the key ingredients with which to make water, oxygen, fuel and other materials that can be exploited by future astronauts.

The instrument will help scientists discover out how much of these critical resources are under the surface, and, crucially, whether they can be extracted easily.

Europe's participation in the mission is due to receive final approval at a meeting of ministers in late 2016. It has the strong support of Esa and Roscosmos hierarchy, and the scientists involved in Luna 27 are confident that it is not a question of if but when humans go back to the lunar surface.

"This whole series of missions feels like the beginning of the return to the Moon but it is also starting something new in terms of overall exploration of the Solar System," says Mr Fisackerly.

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Liquid water flows on today's Mars: NASA confirms evidence

New findings from NASA's Mars Reconnaissance Orbiter (MRO) provide the strongest evidence yet that liquid water flows intermittently on present-day Mars.

Using an imaging spectrometer on MRO, researchers detected signatures of hydrated minerals on slopes where mysterious streaks are seen on the Red Planet. These darkish streaks appear to ebb and flow over time. They darken and appear to flow down steep slopes during warm seasons, and then fade in cooler seasons. They appear in several locations on Mars when temperatures are above minus 10 degrees Fahrenheit (minus 23 Celsius), and disappear at colder times.

Martian slopes. Credit: NASA/JPL-Caltech/Univ. of Arizona

"Our quest on Mars has been to 'follow the water,' in our search for life in the universe, and now we have convincing science that validates what we've long suspected," said John Grunsfeld, astronaut and associate administrator of NASA's Science Mission Directorate in Washington. "This is a significant development, as it appears to confirm that water -- albeit briny -- is flowing today on the surface of Mars."

These downhill flows, known as recurring slope lineae (RSL), often have been described as possibly related to liquid water. The new findings of hydrated salts on the slopes point to what that relationship may be to these dark features. The hydrated salts would lower the freezing point of a liquid brine, just as salt on roads here on Earth causes ice and snow to melt more rapidly. Scientists say it's likely a shallow subsurface flow, with enough water wicking to the surface to explain the darkening.

"We found the hydrated salts only when the seasonal features were widest, which suggests that either the dark streaks themselves or a process that forms them is the source of the hydration. In either case, the detection of hydrated salts on these slopes means that water plays a vital role in the formation of these streaks," said Lujendra Ojha of the Georgia Institute of Technology (Georgia Tech) in Atlanta, lead author of a report on these findings published Sept. 28 by Nature Geoscience.

Ojha first noticed these puzzling features as a University of Arizona undergraduate student in 2010, using images from the MRO's High Resolution Imaging Science Experiment (HiRISE). HiRISE observations now have documented RSL at dozens of sites on Mars. The new study pairs HiRISE observations with mineral mapping by MRO's Compact Reconnaissance Imaging Spectrometer for Mars (CRISM).

The spectrometer observations show signatures of hydrated salts at multiple RSL locations, but only when the dark features were relatively wide. When the researchers looked at the same locations and RSL weren't as extensive, they detected no hydrated salt.

Ojha and his co-authors interpret the spectral signatures as caused by hydrated minerals called perchlorates. The hydrated salts most consistent with the chemical signatures are likely a mixture of magnesium perchlorate, magnesium chlorate and sodium perchlorate. Some perchlorates have been shown to keep liquids from freezing even when conditions are as cold as minus 94 degrees Fahrenheit (minus 70 Celsius). On Earth, naturally produced perchlorates are concentrated in deserts, and some types of perchlorates can be used as rocket propellant.

Perchlorates have previously been seen on Mars. NASA's Phoenix lander and Curiosity rover both found them in the planet's soil, and some scientists believe that the Viking missions in the 1970s measured signatures of these salts. However, this study of RSL detected perchlorates, now in hydrated form, in different areas than those explored by the landers. This also is the first time perchlorates have been identified from orbit.

MRO has been examining Mars since 2006 with its six science instruments.

"The ability of MRO to observe for multiple Mars years with a payload able to see the fine detail of these features has enabled findings such as these: first identifying the puzzling seasonal streaks and now making a big step towards explaining what they are," said Rich Zurek, MRO project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California.

For Ojha, the new findings are more proof that the mysterious lines he first saw darkening Martian slopes five years ago are, indeed, present-day water.

"When most people talk about water on Mars, they're usually talking about ancient water or frozen water," he said. "Now we know there's more to the story. This is the first spectral detection that unambiguously supports our liquid water-formation hypotheses for RSL."

The discovery is the latest of many breakthroughs by NASA's Mars missions.

"It took multiple spacecraft over several years to solve this mystery, and now we know there is liquid water on the surface of this cold, desert planet," said Michael Meyer, lead scientist for NASA's Mars Exploration Program at the agency's headquarters in Washington. "It seems that the more we study Mars, the more we learn how life could be supported and where there are resources to support life in the future."

For more information visit:-

http://www.sciencedaily.com/releases/2015/09/150928094114.htm

https://www.prlabs.co.uk/lab-supplies.php?N=regeneration-salt&Id=62072

What happened to early Mars' atmosphere? New study eliminates one theory

Scientists may be closer to solving the mystery of how Mars changed from a world with surface water billions of years ago to the arid Red Planet of today.

A new analysis of the largest known deposit of carbonate minerals on Mars suggests that the original Martian atmosphere may have already lost most of its carbon dioxide by the era of valley network formation.

"The biggest carbonate deposit on Mars has, at most, twice as much carbon in it as the current Mars atmosphere," said Bethany Ehlmann of the California Institute of Technology and NASA Jet Propulsion Laboratory, both in Pasadena. "Even if you combined all known carbon reservoirs together, it is still nowhere near enough to sequester the thick atmosphere that has been proposed for the time when there were rivers flowing on the Martian surface."

Carbon dioxide makes up most of the Martian atmosphere. That gas can be pulled out of the air and sequestered or pulled into the ground by chemical reactions with rocks to form carbonate minerals. Years before the series of successful Mars missions, many scientists expected to find large Martian deposits of carbonates holding much of the carbon from the planet's original atmosphere. Instead, these missions have found low concentrations of carbonate distributed widely, and only a few concentrated deposits. By far the largest known carbonate-rich deposit on Mars covers an area at least the size of Delaware, and maybe as large as Arizona, in a region called Nili Fossae.

Christopher Edwards, a former Caltech researcher now with the U.S. Geological Survey in Flagstaff, Arizona, and Ehlmann reported the findings and analysis in a paper posted online by the journal Geology. Their estimate of how much carbon is locked into the Nili Fossae carbonate deposit uses observations from numerous Mars missions, including the Thermal Emission Spectrometer (TES) on NASA's Mars Global Surveyor orbiter, the mineral-mapping Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) and two telescopic cameras on NASA's Mars Reconnaissance Orbiter, and the Thermal Emission Imaging System (THEMIS) on NASA's Mars Odyssey orbiter.

Edwards and Ehlmann compare their tally of sequestered carbon at Nili Fossae to what would be needed to account for an early Mars atmosphere dense enough to sustain surface waters during the period when flowing rivers left their mark by cutting extensive river-valley networks. By their estimate, it would require more than 35 carbonate deposits the size of the one examined at Nili Fossae. They deem it unlikely that so many large deposits have been overlooked in numerous detailed orbiter surveys of the planet. While deposits from an even earlier time in Mars history could be deeper and better hidden, they don't help solve the thin-atmosphere conundrum at the time the river-cut valleys formed.

The modern Martian atmosphere is too tenuous for liquid water to persist on the surface. A denser atmosphere on ancient Mars could have kept water from immediately evaporating. It could also have allowed parts of the planet to be warm enough to keep liquid water from freezing. But if the atmosphere was once thicker, what happened to it? One possible explanation is that Mars did have a much denser atmosphere during its flowing-rivers period, and then lost most of it to outer space from the top of the atmosphere, rather than by sequestration in minerals.

"Maybe the atmosphere wasn't so thick by the time of valley network formation," Edwards said. "Instead of Mars that was wet and warm, maybe it was cold and wet with an atmosphere that had already thinned. How warm would it need to have been for the valleys to form? Not very. In most locations, you could have had snow and ice instead of rain. You just have to nudge above the freezing point to get water to thaw and flow occasionally, and that doesn't require very much atmosphere."

NASA's Curiosity Mars rover mission has found evidence of ancient top-of-atmosphere loss, based on the modern Mars atmosphere's ratio of heavier carbon to lighter carbon. Uncertainty remains about how much of that loss occurred before the period of valley formation; much may have happened earlier. NASA's MAVEN orbiter, examining the outer atmosphere of Mars since late 2014, may help reduce that uncertainty.

Arizona State University, Tempe, provided the TES and THEMIS instruments. The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland., provided CRISM. JPL, a division of Caltech, manages the Mars Reconnaissance Orbiter and Mars Odyssey project for NASA's Science Mission Directorate, Washington, and managed the Mars Global Surveyor project through its nine years of orbiter operations at Mars. Lockheed Martin Space Systems in Denver built the three orbiters.

For more information about the Mars Reconnaissance Orbiter mission, visit:

http://mars.nasa.gov/mro

For more information about the Mars Odyssey mission, visit:

http://mars.nasa.gov/odyssey

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The above post is reprinted from materials provided by NASA/Jet Propulsion Laboratory. Note: Materials may be edited for content and length.

For more information visit:-

http://www.sciencedaily.com/releases/2015/09/150903121019.htm

https://www.prlabs.co.uk/lab-supplies.php?N=gastube-carbon-dioxide-hr-05-20&Id=11735