Tag: Mars (page 1 of 3)

Sample Return in the Time of Coronavirus

 

Sample return from Mars. Artist rendering of a Mars sample return mission. The mission would use robotic systems and a Mars ascent rocket to collect and send samples of Martian rocks, soils and atmosphere to Earth for detailed chemical and physical analysis.  No rocket has ever taken off from Mars and this NASA and European Space Agency (ESA) project is in early planning stages. Still, blue-ribbon science panels have recommended efforts to begin preparing the public for an eventual Mars sample return. ( Wickman Spacecraft & Propulsion)

For space scientists of all stripes, few goals are as crucial as bringing pieces of Mars, of asteroids, of other planets and moons back to Earth for the kind of intensive study only possible here.  Space missions can, and have, told us many truths about the solar system,  but having a piece of Mars or Europa or an asteroid to study in a lab on Earth is considered the gold standard for learning about the actual composition of other bodies, their histories and whether they could — or once did — harbor life.

In keeping with this ambition, the last National Research Council Decadal Survey listed a Mars “sample return” as the top science priority for large Flagship missions.  And the Perseverance rover that NASA is scheduled to send to Mars next month will — among many other tasks — identify compelling rock samples, collect and cache them so a subsequent mission can pick them up and fly them to Earth.

Two asteroid sample return missions are also in progress, the NASA’s OSIRIS-REx mission to Bennu and the Japan Aerospace Exploration Agency (JAXA’s)  Hayabusa2 mission to the Ryugu.  Both spacecraft are at or have already left their intended targets now and are expected to return with rock samples later this decade, with Hayabusa2 scheduled to complete its round trip later this year.

An illustration of the coronavirus. (Centers of Disease Control)

So sample return is in our future.  And in the case of Mars the samples will not with 100 percent certainty be lifeless — a major difference from the samples brought back from the moon during the Apollo missions and the samples coming from asteroids.

This possibility of a spacecraft bringing back something biological — as in the 1969 book “The Andromeda Strain” — has always been viewed as a very low probability but high risk hazard, and much thinking has already gone into how to bring samples back safely.… Read more

Theorized Northern Ocean of Mars; now long gone.  (NASA)

Change is the one constant in our world– moving in ways tiny and enormous,  constructive and destructive.

We’re living now in a time when a rampaging pandemic circles the globe and when the climate is changing in so many worrisome and potentially devastating ways.

With these ominous  changes as a backdrop, it is perhaps useful to spend a moment with change as it happens in a natural world without humans.  And just how complete that change can be:

For years now, planetary scientists have debated whether Mars once had a large ocean across its northern hemisphere.

There certainly isn’t one now — the north of Mars is parched, frigid and largely featureless.  The hemisphere was largely covered over in a later epoch by a deep bed of lava, hiding signs of its past.

The northern lowlands of Mars, as photographed by the Viking 2 lander. The spacecraft landed in the Utopia Planitia section of northern Mars in 1976. (NASA/JPL)

Because our sun sent out significantly less warmth at the time of early Mars (4.2-3.5  billion years ago,) climate modelers have long struggled to come up with an explanation for how the planet — on average, 137 million miles further out than Earth — could have been anything but profoundly colder than today. And if that world was so unrelentingly frigid, how could there be a surface ocean of liquid water?

But discoveries in the 21st century have strongly supported the long-ago presence of water on a Mars in the form of river valleys, lakes and a water cycle to feed them.  The work done by the Curiosity rover and Mars-orbiting satellites has made this abundantly clear.

An ocean in the northern lowlands is one proposal made to explain how the water cycle was fed.

And now, In a new paper in Journal of Geophysical Research: Planets,  scientists from Japan and the United States have presented modelling and analysis describing how and why Mars had to have a large ocean early in its history to produce the geological landscape that is being found.

Lead author Ramses Ramirez, a planetary scientist with the Earth-Life Science Institute in Tokyo, said it was not possible to determine how long the ocean persisted, but their team concluded that it had to be present  in that early period around 4 billion to 3.5 billion years ago.  That is roughly when what are now known to be river valleys were cut in the planet’s southern highlands.… Read more

How Long Were the Wet Periods on Early Mars, and Was That Water Chemically Suitable For Life?

 

An artist rendering, based on scientific findings, of Gale Crater in Mars during one of its ancient, wet periods. (NASA)

There is no doubt that early Mars had long period of warmer and much wetter climates before its atmosphere thinned too much to retain that liquid H20 on the surface.

As we know from the Curiosity mission to Gale Crater and other orbital findings, regions of that warmer and wetter Mars had flowing water and lakes periodically over hundreds of millions of years.  That’s one of the great findings of planetary science of our times.

But before approaching the question of whether that water could have supported life, a lot more needs to be known than that water was present.  We need answers to questions like how acidic or basic that water likely was?  Was it very salty? Did it have mineral and elemental contents that could provide energy to support any potential life?

And most especially, how long did those wet periods last, and the dry periods as well?

In a recent paper for Nature Communications, some more precise answers are put forward based on data collected at Gale Crater and interpreted based on geochemical modeling and Earth-based environmental science.

The water, say geochemist Yasuhito Sekine of the Earth-Life Science Institute (ELSI) in Tokyo and colleagues from the U.S. and Japan, had many important characteristics supportive of life.  It was only mildly salty, it had a near-neutral pH, it contained essential minerals and elements in state of disequilibrium — meaning that they could give and receive the electrons needed to provide life-supporting energy.   The  area was hardly lush — more like the semi-arid regions of Central Asia and Utah’s Great Salt Lake — but it contained water that was plausibly life supporting.

Based on an analysis of the patterns and quantities of salt remains, they estimate the water was present numerous times for between 10,000 to one million years each period.

Were those warm eras long enough for life to emerge, and the dry period short enough for it to survive?

“We don’t have a clear answer,” Sekine said. “But it is now more clear that the key question is which is more important:  the chemistry of the water or the duration of its presence?”

And the way to address the question, he said, is through a mix of planetary science and environmental science.

“This is a first step in the application of environmental chemistry to Mars,” Sekine said.… Read more

PIXL: A New NASA Instrument For Ferreting Out Clues of Ancient Life on Mars

 

Extremely high definition images of the com ponents of rocks and mud as taken by PIXL, the Planetary Instrument for X-ray Lithochemistry .   On the Mars 2020 rover, PIXL  will have significantly greater capabilities than previous similar instruments sent to Mars.  Rather than reporting bulk compositions averaged over several square centimeters, it will identify precisely where in the rock each element resides. With spatial resolution of about 300 micrometers, PIXL will conduct the first ever petrology investigations on Mars, correlating elemental compositions with visible rock textures . (NASA)J

The search for life, or signs of past life beyond Earth is now a central issue in space science, is central to the mission of NASA, and is actually a potentially breakthrough discovery in the making  for humanity.    The scientific stakes could hardly be higher.

But identifying evidence of ancient microbial life – and refuting all reasonable non-biological explanations for that evidence — is stunningly difficult.

As recent wrangling over Earth’s oldest rocks in Greenland has shown, determining the provenance of a deep-time biosignature even here on Earth is extraordinarily difficult. In 2016, scientists reported discovery of 3,700 million yr-old stromatolites in the Isua geological area of Greenland.

Just three years later, a field workshop held at the Isua discovery site brought experts from around the world to examine the intriguing structures and see whether the evidence cleared the very high bar needed to accept a biological interpretation. While the scientists who published the initial discovery held their ground, not one of the other scientists felt convinced by the evidence before them.  Watching and listening as the different scientists presented their cases was a tutorial in the innumerable factors involved in coming to any conclusion.

Now think about trying to wrestle with similar or more complex issues on Mars, of how scientists can reach of level of confidence to report that a sign (or hint) of past life has apparently been found.

As it turns out, the woman who led the Greenland expedition — Abigail Allwood of NASA’s Jet Propulsion Lab — is also one of the key players in the upcoming effort to find biosignatures on Mars.  She is the principal investigator of the Planetary Instrument for X-ray Lithochemistry (PIXL) that will sit on the extendable arm of the rover, and it has capabilities to see in detail the composition of Mars samples as never before.

The instrument has, of course, been rigorously tested to understand what it can and cannot do. … Read more

If Bacteria Could Talk

 

Hawaiian lava cave microbial mats appear to have the highest levels and diversity of genes related to quorum sensing so far.  (Stuart Donachie, University of Hawai`i at Mānoa)

Did you know that many bacteria — some of the oldest lifeforms on Earth — can talk?  Really.

And not only between the same kind of single-cell bacteria, but  back and forth with members of other species, too.

Okay, they don’t talk in words or with sounds at all.  But they definitely communicate in a meaningful and essential way, especially in the microbial mats and biofilms (microbes attached to surfaces surrounded by mucus) that constitute their microbial “cities.”

Their “words” are conveyed via chemical signaling molecules — a chemical language — going from one organism to another,  and are a means to control when genes in the bacterial DNA are turned “on” or “off.”  The messages can then be translated into behaviors to protect or enhance the larger (as in often much, much larger) group.

Called “quorum sensing,” this microbial communication was first identified several decades ago.  While the field remains more characterized by questions than definitive answers, is it clearly growing and has attracted attention in medicine, in microbiology and in more abstract computational and robotics work.

Most recently,  it has been put forward as chemically-induced behavior that can help scientists understand how bacteria living in extreme environments on Earth — and potential on Mars —  survive and even prosper.  And the key finding is that bacteria are most successful when they form communities of microbial mats and biofilms, often with different species of bacteria specializing in particular survival capabilities.

Speaking at the recent Astrobiology Science Conference in Seattle,  Rebecca Prescott, a National Science Foundation  Postdoctoral Research Fellow in Biology said this community activity may make populations of bacteria much more hardy than otherwise might be predicted.

 

Quorum sensing requires a community. Isolated Bacteria (and Archaea) have nobody to communicate with and so genes that are activated by quorum sensing are not turned “on.”

“To help us understand where microbial life may occur on Mars or other planets, past or present, we must understand how microbial communities evolve and function in extreme environments as a group, rather than single species,” said Prescott,

“Quorum sensing gives us a peek into the interactive world of bacteria and how cooperation may be key to survival in harsh environments,” she said.

Rebecca Prescott  is a National Science Foundation Postdoctoral Fellow in Biology (1711856) and is working with principal investigator Alan Decho of the University of South Carolina on a NASA Exobiology Program grant.

Read more

Curiosity Rover as Seen From High Above by Mars Orbiter

A camera on board NASA’s Mars Reconnaissance Orbiter recently spotted the Curiosity rover in Gale Crater.  The image is color-enhanced to allow surface features to become more visible. (NASA/JPL-Caltech)

This is Apollo memory month, when the 50th anniversary arrives of the first landing of astronauts on the moon.  It was a very big deal and certainly deserves attention and applause.

But there’s something unsettling about the anniversary as well, a sense that the human exploration side of NASA’s mission has disappointed and that its best days were many decades ago.   After all, it has been quite a few years now since NASA has been able to even get an astronaut to the International Space Station without riding in a Russian capsule.

There have been wondrous (and brave) NASA human missions since Apollo — the several trips to the Hubble Space Telescope for emergency repair and upgrade come to mind — but many people who equate NASA with human space exploration are understandably dismayed.

This Many Worlds column does not focus on human space exploration, but rather on the science coming from space telescopes, solar system missions, and the search for life beyond Earth.

And as I have argued before, the period that following the last Apollo mission and began with the 1976 Viking landings on Mars has been — and continues to be — the golden era of space science.

This image of Curiosity,  which is now exploring an area that has been named Woodland Bay in Gale Crater, helps make the case.

Taken on May 31 by the HiRISE camera of NASA’s Mars Reconnaissance Orbiter (MRO), it shows the rover in a geological formation that holds remains of ancient clay.  This is important because clay can be hospitable to life, and Curiosity has already proven that Mars once had the water, organic compounds and early climate to support life.

The MRO orbits between 150 and 200 miles above Mars, so this detailed image is quite a feat.

The arm of the Curiosity rover examines the once-watery remains at Woodland Bay, Gale Crater. (NASA/JPL-Caltech)

Curiosity landed on Mars for what was planned as a mission of two years-plus. That was seven years ago this coming August.

The rover has had some ups and downs and has moved more slowly than planned, but it remains in motion — collecting paradigm-shifting information, drilling into the Mars surface, taking glorious images and making its way up the slopes of Gale Crater. … Read more

Methane on Mars. Here Today, Gone Tomorrow

On the 2,440th Martian day at Gale Crater, the Curiosity rover detected a large spike in the presence of the gas methane. It was by far the largest plume detected by the rover, and parallels an earlier ground-based discovery of an even larger plume of the gas.  (NASA, JPL-Caltech, MSSS)

The presence — and absence — of methane gas on Mars has been both very intriguing and very confusing for years.  And news coming out last week and then on Monday adds to this scientific mystery.

To the great surprise of the Curiosity rover team, their Sample Analysis on Mars instrument sent back a measurement of 21 parts per billion of methane on Thursday — by far the highest measurement since the rover landed at Gale Crater.

As Paul Mahaffy, principal investigator of the instrument that made the measurement, described it yesterday at a large astrobiology conference in Seattle, “We were dumbfounded.”

And then a few days later, all the methane was gone.   Mahaffy, and NASA headquarters, reported that the readings went down quickly to below 1 part per billion.

These perplexing findings are especially important because methane could — and also could not — be a byproduct of biology.  On Earth, more than 90 percent of methane is produced via biology.  On Mars — at this point, nobody knows.  But the question has certainly gotten scientists’ attention.

The most recent finding of a return to low methane levels suggests that last week’s methane detection was one of the transient methane plumes that have been observed in the past. While Curiosity scientists have noted background levels rise and fall seasonally, they haven’t found a pattern in the occurrence of these transient plumes.

“The methane mystery continues,” said Ashwin Vasavada, Curiosity’s project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California. “We’re more motivated than ever to keep measuring and put our brains together to figure out how methane behaves in the Martian atmosphere.”

This image was taken by the left Navcam on the Curiosity Mars rover on June 18, 2019, the day when a methane plume was detected.  It shows part of “Teal Ridge,” which the rover has been studying within a region called the “clay-bearing unit.” (NASA/JPL-Caltech)

The nature and size of this most recent methane plume will, by chance, be the most widely observed so far.

That’s because the Mars Express orbiter happened to be performing spot tracking observations at the Gale Crater right around the time Curiosity detected the methane spike. … Read more

A Significant Advance: Primitive Earth Life Survives an 18-Month Exposure to Mars-Like Conditions in Space

The European Space Agency’s BIOMEX array, outside the Russian Zvezda module of the ISS. (ESA)

The question of whether simple life can survive in space is hardly new, but it has lately taken on a new urgency.

It is not only a pressing scientific question — might life from Mars or another body have seeded life on Earth?  Might organisms similar to extreme Earth life survive Mars-like conditions? — but it is also has some very practical implications.  If humans are going to some day land and live on the moon or on Mars, they will need to grow food to survive.

So the question is pretty basic:  can Earth seeds or dormant life survive a long journey to deep space and can they then  grow in the protected but still extreme radiation, temperature, and vacuum  of deep space?

It was with these questions in mind that the European Space Agency funded a proposal from the German Institute of Planetary Research to send samples of a broad range of simple to more complex life to the International Space Station in 2014, and to expose the samples to extreme conditions outside the station.

Some of the findings have been reported earlier,  but last month the full results of the Biomex tests (Biology on Mars Experiment) were unveiled in the journal Astrobiology.

And the answer is that many, though certainly not all, of the the samples of snow and permafrost algae, cyanobacteria, archaea, fungi, biofilms, moss and lichens in the  did survive their 533 days of living dangerous in their dormant states.  When brought back to Earth and returned to normal conditions, they returned to active life.

“For the majority of the chosen organisms, it was the first and the longest time they ever were exposed to space and Mars-like conditions,” Jean-Pierre Paul de Vera, principal investigator of the effort, wrote to me.  And the results were promising.

 

For the BIOMEX experiment, on 18 August 2014, Russian cosmonauts Alexander Skvortsov and Oleg Artemyev placed several hundred samples in an experiment container on the exterior of the Zvezda’Russian ISS module. The containers, open to the surrounding space environment, held primitive terrestrial organisms such as mosses, lichens, fungi, bacteria, archaea and algae, as well as cell membranes and pigments.

 

A microbiologist and planetary researcher at the German Space Agency’s Institute of Planetary Research in Berlin, de Vera and his team went from Antarctica to the parched Atacama desert in Chile, from the high Alps to the steppe highlands of central Spain to find terrestrial life surviving in extreme conditions (extremophiles.)Read more

Ancient Mars Water. Ever More of It, and Flowing Ever Longer on the Surface

A photo of a preserved river channel on Mars with color overlaid to show different elevations (blue is low, yellow is high).
(Courtesy of NASA/JPL/Univ. Arizona/Univ. Chicago)

 

Rather like a swollen river overflowing its banks, the story of water on Mars keeps on rising and spreading in quite unpredictable ways.

While the planet is now inarguable parched — though with lots of polar and subsurface ice and, perhaps, some seasonal surface trickles — data from the Curiosity rover, the Mars Reconnaissance Orbiter and other missions have proven quite reliably that the planet was once much wetter and warmer.  But how much wetter, and for how long,  remains of subject of hot debate.

On one side, Mars climate modelers have struggled to find mechanisms to keep the planet wetter and warmer for more than it’s earliest period — perhaps 500 million years.  Their projections flow from the seemingly established conclusion that Mars lost much of its atmosphere by 3.5 billion years ago, and without that protection warmer and wetter appear to be impossible.

But the morphology of the planet, the gorges, the fossil lakes, the riverbeds and deltas that are visible  because of 21st century technology and missions,  appears to tell a different and more wide-ranging story of Mars water.

 

Mudstone at the “Kimberley” formation on Mars taken by NASA’s Curiosity rover. The strata in the foreground dip towards the base of Mount Sharp, indicating the ancient depression that existed before the larger bulk of the mountain formed.
Credit:NASA/JPL-Caltech/MSSS

And now, in one of the most expansive interpretations of the Martian water story, University of Chicago planetary scientist and Mars expert Edwin Kite and colleagues report in a Science Advances paper that the planet not only once had many, many lakes and rivers, but that they were filled as part of a water cycle involving precipitation, rather than primarily through the sporadic melting of primordial ice as a result of incoming meteorites or other astrophysical events.

What’s more, they write, the rivers continued to sporadically flow well past the time when the Martian surface has been assumed to be dead dry.

The era when Mars has been most often described as going from wet-to-dry is around 3.5 billion years ago, but their interpretation of when precipitation-filled rivers stopped running is about 3 billion years ago.  In other words, Kite’s team now says the rivers ran — often quite actively — for more than one billion years.… Read more

How Creatures End Up Miles Below the Surface of Earth, and Maybe Mars Too

Poikilolaimus oxycercus is a microscopic nematode, or roundworm, found alive and well more than a mile below the surface in South Africa, where its ancestors had lived for hundreds or thousands of years. (Gaetan Borgonie)

 

When scientists speculate about possible life on Mars, they generally speak of microbial or other simple creatures living deep below the irradiated and desiccated surface.  While Mars long ago had a substantial period that was wetter and warmer when it also had a far more protective atmosphere,  the surface now is considered to be lethal.

But the suggestion that some potential early Martian life could have migrated into the more protected depths is often discussed as a plausible, if at this point untestable possibility.  In this scenario, some of that primitive subsurface life might even have survived the eons in their buried, and protected, environments.

This thinking has gotten some support in the past decade with the discovery of bacteria and nematodes (roundworms) found as far down as three miles below the surface of South Africa, in water dated as being many thousands or millions years old.  The lifeforms have been discovered by a team that has regularly gone down into the nation’s super-hot gold and platinum mines to search for life coming out of boreholes in the rock face of deep mine tunnels.

 

Borgonie setting up a water collector for a borehole at the Driefontein mine in the Witwatersrand Basin  of South Africa.  He said he stopped counting his journeys into the deep mines at 50, but that the number now is much higher. (Courtesy of Borgonie)

Now a  new paper describes not only the discovery of additional deep subsurface life, but also tries to explain how the distant ancestors of the worms and bacteria and algae might have gotten there. 

Their conclusion:  many were pulled down when fractures opened in the aftermath of earthquakes and other seismic events.  While many lifeforms were swept down, only a small percentage were able to adapt, evolve and thus survive.

The is how Gaetan Borgonie, lead author of the paper in Scientific Reports, explained it to me via email:

“After the discovery of multicellular animals in the deep subsurface up to 3.8 km (2.5 miles) in South Africa everyone was baffled and asked the question how did they get that deep? This question more or less haunted us for more than a decade as we were unable to get our head around it.Read more

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