Category: Astrobiology (page 2 of 7)

Breakthrough Findings on Mars Organics and Mars Methane

The Curiosity rover on Mars takes a selfie at a site named Mojave. Rock powdered by the rover drill system and then intensively heated rock and then heated to as much as 800 degrees centigrade produced positive findings for long-sought organics. (NASA/JPL-Caltech/MSSS.)

A decades-long quest for incontrovertible and complex Martian organics — the chemical building blocks of life — is over.

After almost six years of searching, drilling and analyzing on Mars, the Curiosity rover team has conclusively detected three types of naturally-occurring organics that had not been identified before on the planet.

The Mars organics Science paper, by NASA’s Jennifer Eigenbrode and much of the rover’s Sample Analysis on Mars (SAM) instrument team, was twinned with another paper describing the discovery of a seasonal pattern to the release of the simple organic gas methane on Mars.

This finding is also a major step forward not only because it provides ground truth for the difficult question of whether significant amounts of methane are in the Martian atmosphere, but equally important it determines that methane concentrations appear to change with the seasons. The implications of that seasonality are intriguing, to say the least.

In an accompanying opinion piece in Science, Inges Loes ten Kate of Utrecht University in  Netherlands wrote of the two papers: “Both these findings are breakthroughs in astrobiology.”

The clear conclusion of these (and other) recent findings is that Mars is not a “dead” planet where little ever changes.  Rather, it’s one with cycles that appear to produce not only methane but also sporadic surface water and changing dune formations.

Remains of 3.5 billion-year old lake that once filled Gale Crater. NASA scientists concluded early in the Curiosity mission that the planet was habitable long ago based on the study of mudstone remains like these. (NASA/JPL-Caltech/MSSS)

Finding organic compounds on Mars has been a prime goal of the Curiosity rover mission.

Those carbon-based compounds surely fall from the sky on Mars, as they do on Earth and everywhere else, but identifying them has proven illusive.

The consequences of that non-discovery have been significant.  Going back to the Viking missions of 1976, scientists concluded that life was not possible on Mars because there were no organics, or none that were detected.

Jen Eigenbrode, research astrobiologist at NASA’s Goddard Space Flight Center. (NASA/W. Hrybyk)

But the reasons for the disappearing organics are pretty well understood.  Without much of an atmosphere to protect it, the Martian surface is bombarded with ultraviolet radiation, which can destroy organic compounds. … Read more “Breakthrough Findings on Mars Organics and Mars Methane”

Joining the Microscope and the Telescope in the Search for Life Beyond Earth

 

Niki Parenteau of NASA’s Ames Research Center is a microbiologist working in the field of exoplanet and Mars biosignatures. She adds a laboratory biology approach to a field generally known for its astronomers, astrophysicists and planetary scientists. (Marisa Mayer, Stanford University.)

 

The world of biology is filled with labs where living creatures are cultured and studied, where the dynamics of life are explored and analyzed to learn about behavior, reproduction, structure, growth and so much more.

In the field of astrobiology, however, you don’t see much lab biology — especially when it comes to the search for life beyond Earth.  The field is now largely focused on understanding the conditions under which life could exist elsewhere, modeling what chemicals would be present in the atmosphere of an exoplanet with life, or how life might begin as an organized organism from a theoretical perspective.

Yes, astrobiology includes and learns from the study of extreme forms of life on Earth, from evolutionary biology, from the research into the origins of life.

But the actual bread and butter of biologists — working with lifeforms in a lab or in the environment — plays a back seat to modeling and simulations that rely on computers rather than actual life.

Niki Parenteau with her custom-designed LED array, can reproduce the spectral features of different simulated stellar and atmospheric conditions to test on primitive microbes. (Marc Kaufman)

There are certainly exceptions, and one of the most interesting is the work of Mary “Niki” Parenteau at NASA’s Ames Research Center in the San Francisco Bay area.

A microbiologist by training, she has been active for over five years now in the field of exoplanet biosignatures — trying to determine what astronomers could and should look for in the search for extraterrestrial life.

Working in her lab with actual live bacteria in laboratory flasks, test tubes and tanks, she is conducting traditional biological experiments that have everything to do with astrobiology.

She takes primitive bacteria known to have existed in some form on the early Earth, and she blasts them with the radiation that would have hit the planet at the time to see under what conditions the organisms can survive.  She has designed ingenious experiments using different forms of ultraviolet light and a LED array that simulate the broad range of radiations that would come from different types of stars as well.

What makes this all so intriguing is that her work uses, and then moves forward, cutting edge modeling from astronomers and astrobiologists regarding thick photochemical hazes understood to have engulfed the early Earth — making the planet significantly colder but also possibly providing some protection from deadly ultraviolet radiation.… Read more “Joining the Microscope and the Telescope in the Search for Life Beyond Earth”

The Just-Approved European ARIEL Mission Will Be First Dedicated to Probing Exoplanet Atmospheres

 

This column was written by my colleague Elizabeth Tasker, now at the Japan Aerospace Exploration Agency (JAXA), Institute of Space and Astronautical Sciences (ISAS).  Trained as an astrophysicist, she researches planet and galaxy formation and also writes on space science topics.  Her book, “The Planet Factory,” came out last year.

 

The Ariel space telescope will explore the atmospheres of exoplanets. (Artist impression, ESA)

The European Space Agency (ESA) has approved the ARIEL space mission—the world’s first dedicated exoplanet atmosphere sniffer— to fly in 2028.

ARIEL stands for the “Atmospheric Remote-sensing Infrared Exoplanet Large-Survey mission.” It is a space telescope that can detect which atoms and molecules are present in the atmosphere of an exoplanet.

The mission was selected as a medium class mission in the ESA Cosmic Vision program; the agency’s decadal plan for space missions that spans 2015 – 2025.

One of the central themes for Cosmic Vision is uncovering the conditions for planet formation and the origins of life. This has resulted in three dedicated exoplanet missions within the same decadal plan. ARIEL will join CHEOPS (in the small class mission category) and PLATO (another medium class mission) in studying worlds beyond our own sun.

Yet ARIEL is a different type of telescope from the other exoplanet-focused missions. To understand why, we need to examine what properties we can observe of these distance exo-worlds.

Exoplanet missions can be broadly divided into two types. The first type are the exoplanet hunter missions that search the skies for new worlds.

These are spacecraft and instruments such as the NASA Kepler Space Telescope. Since it launched in 2009, Kepler has been an incredibly prolific planet hunter. The telescope has found thousands of planets, modeled their orbits and told us about the distribution of their sizes.

From Kepler, we have learnt that planet formation is common, that it can occur around stars far different from our own sun, and that these worlds can have a vast range of sizes and myriad of orbits quite unlike our own Solar System.

 

Current and future (or proposed) space missions with capacities to identify and characterize exoplanets. (NASA,ESA: T. Wynne/JPL, composited by Barbara Aulicino)

 

However, the information Kepler is able to provide about individual planets is very limited. The telescope monitors stars for the tiny drop in light as the planet crosses (or “transits”) the star’s surface. From this, astronomers can measure the radius of the planet and its orbital period but nothing about the planet’s surface conditions.… Read more “The Just-Approved European ARIEL Mission Will Be First Dedicated to Probing Exoplanet Atmospheres”

A Reprieve for Space Science?

View of WFIRST focusing on supernova SN1995E in NGC 2441. The high-priority but embattled space telescope would, if congressional support continues, add greatly to knowledge about dark energy and dark matter, supernovae, and exoplanets.  (NASA)

 

A quick update on a recent column about whether our “golden age” of space science and discovery was in peril because of cost overruns and Trump administration budget priorities that emphasized human space travel over science.

The 2018 omnibus spending bill that was passed Wednesday night by the House of Representatives and Thursday night by the Senate represents a major push back against the administration’s earlier NASA budget proposals.  Not only would the agency receive $1.6 billion more funding than proposed by the administration, but numerous projects that had been specifically eliminated in that proposal are back among the living.

They include four Earth science satellites, a lander to accompany the Europa Clipper mission to that potentially habitable moon and, perhaps most important, the Wide Field Infrared Survey Telescope (WFIRST) space telescope.

Funding for that mission, which was the top priority of the space science community and the National Academy of Sciences for the 2020s, was eliminated in the proposed 2019 Trump budget, but WFIRST received $150 million in the just-passed omnibus bill.

A report accompanying the omnibus bill is silent about the proposed cancellation and instructs NASA to provide to Congress in 60 days a cost estimate for the full life cycle of the mission, including any additions that might be needed.  So there appears to be a strong congressional desire to see WFIRST launch and operate.

Still hanging fire is the fate of the James Webb Space Telescope, which has fallen behind schedule again and is in danger of crossing the $8 billion cap put into place by Congress in 2011.  NASA officials said this week that they will soon announce their determination about whether a breach of the program’s cost cap will occur as a result of further delays.

NASA has a fleet of 18 Earth science missions in space, supported by aircraft, ships and ground observations. Together they have revolutionized understanding of the planet’s atmosphere, the oceans, the climate and weather. The Obama administration emphasized Earth studies, but the Trump administration has sought to eliminate future Earth missions. This visualization shows the NASA fleet in 2017, from low Earth orbit all the way out to the DSCOVR satellite taking in the million-mile view.

Read more “A Reprieve for Space Science?”

Space Science In Peril

NASA’s decades-long success at enabling ground-breaking discoveries about our planet, our solar system, our galaxy, our origins and the billions of other planets out there is one of the crown jewels of our nation’s collective inventiveness and will, and surely of our global soft power.

Others have of course made major contributions as well.  But from the Viking Mars landings of the 1970s on to the grand space observatories Hubble and Spitzer and Chandra, to the planetary explorations such as Cassini (Saturn), Galileo and Juno (Jupiter), New Horizons (Pluto and beyond) and Curiosity (Mars), to the pioneering exoplanet census of Kepler, the myriad spacecraft enhancing our understanding of our own planet and the sun, and the pipeline confidently filled with of missions to come, NASA has been the consistent and essential world leader.

What we know of our world writ large has just exploded in these decades, and we’re far richer for it.

But of late, the future of these efforts to ever expand our knowledge of the logic and make-up of our universe has become worryingly unclear.

First there are the recently revealed new problems with the James Webb Space Telescope, initially scheduled to launch years ago and now reportedly unlikely to meet its launch date next year.  It is also over budget again and under serious threat.

This news came as Congress wrestled with the White House decision to scuttle the WFIRST dark energy, planet and star formation, and exoplanet mission, planned as NASA’s major flagship mission of the 2020s.

And perhaps most worrisome, NASA now wants to fold its Space Technology Mission Directorate into the Human Exploration and Operations Directorate, surely to support the administration’s goal of setting up a human colony on the moon.

This is an Apollo-sized, many-year and very costly effort that would have to take funds away from potential space science missions unless the NASA budget was growing substantially. But the proposed 2019 NASA budget would cap spending for the next four years.

Might our Golden Era of space discovery be winding down?

 

An illustration of the James Webb Space Telescope after deploying in space.  The pioneering technology of the JWST is both its great promise and recurring pitfall. (NASA)

 

First the JWST situation.  The telescope, far more powerful and complex than anything sent into space, is expected to open up new understandings about the origins of the universe, xxx, and exoplants.… Read more “Space Science In Peril”

The Northern Lights, the Magnetic Field and Life

Northern Lights over a frozen lake in Northern Norway, inside the Arctic Circle near Alta. The displays can go on for hours, or can disappear for days or weeks. It all depends on solar flares. (Ongajok.no)

May I please invite you to join me in the presence of one of the great natural phenomena and spectacles of our world.

Not only is it enthralling to witness and scientifically crucial, but it’s quite emotionally moving as well.

Why? Because what’s before me is a physical manifestation of one of the primary, but generally invisible, features of Earth that make life possible. It’s mostly seen in the far northern and far southern climes, but the force is everywhere and it protects our atmosphere and us from the parched fate of a planet like Mars.

I’m speaking, of course, of the northern lights, the Aurora Borealis, and the planet’s magnetic fields that help turn on the lights.

My vantage point is the far northern tip of Norway, inside the Arctic Circle. It’s stingingly cold in the silent woods, frozen still for the long, dark winter, and it’s always an unpredictable gift when the lights show up.

But they‘re out tonight, dancing in bright green and sometimes gold-tinged arches and spotlights and twirling pinwheels across the northerly sky. Sometimes the horizon glows green, sometimes the whole sky fills with vivid green streaks.

It can all seem quite other-worldly. But the lights, of course, are entirely the result of natural forces.

 

Northern Lights over north western Norway. Most of the lights are green from collisions with oxygen, but some are purple from nitrogen. © Copyright George Karbus Photography

It has been known for some time that the lights are caused by reactions between the high-energy particles of solar flares colliding in the upper regions of our atmosphere and then descending along the lines of the planet’s magnetic fields. Green lights tell of oxygen being struck at a certain altitude, red or blue of nitrogen.

But the patterns — sometimes broad, sometimes spectral, sometimes curled and sometimes columnar — are the result of the magnetic field that surrounds the planet. The energy travels along the many lines of that field, and lights them up to make our magnetic blanket visible.

Such a protective magnetic field is viewed as essential for life on a planet, be it in our solar system or beyond.

But a magnetic field does not a habitable planet make.… Read more “The Northern Lights, the Magnetic Field and Life”

False Positives, False Negatives; The World of Distant Biosignatures Attracts and Confounds

This artist’s illustration shows two Earth-sized planets, TRAPPIST-1b and TRAPPIST-1c, passing in front of their parent red dwarf star, which is much smaller and cooler than our sun. NASA’s Hubble Space Telescope looked for signs of atmospheres around these planets. (NASA/ESA/STScI/J. de Wit, MIT)

What observations, or groups of observations, would tell exoplanet scientists that life might be present on a particular distant planet?

The most often discussed biosignature is oxygen, the product of life on Earth.  But while oxygen remains central to the search for biosignatures afar, there are some serious problems with relying on that molecule.

It can, for one, be produced without biology, although on Earth biology is the major source.  Conditions on other planets, however, might be different, producing lots of oxygen without life.

And then there’s the troubling reality that for most of the time there has been life on Earth, there would not have been enough oxygen produced to register as a biosignature.  So oxygen brings with it the danger of both a false positive and a false negative.

Wading through the long list of potential other biosignatures is rather like walking along a very wet path and having your boots regularly pulled off as they get captured by the mud.  Many possibilities can be put forward, but all seem to contain absolutely confounding problems.

With this reality in mind, a group of several dozen very interdisciplinary scientists came together more than a year ago in an effort to catalogue the many possible biosignatures that have been put forward and then to describe the pros and the cons of each.

“We believe this kind of effort is essential and needs to be done now,” said Edward Schwieterman, an astronomy and astrobiology researcher at the University of California, Riverside (UCR).

“Not because we have the technology now to identify these possible biosignatures light years away, but because the space and ground-based telescopes of the future need to be designed so they can identify them. ”

“It’s part of what may turn out to be a very long road to learning whether or not we are alone in the universe”.

 

Artistic representations of some of the exoplanets detected so far with the greatest potential to support liquid surface water, based on their size and orbit.  All of them are larger than Earth and their composition and habitability remains unclear. They are ranked here from closest to farthest from Earth. 

Read more “False Positives, False Negatives; The World of Distant Biosignatures Attracts and Confounds”

Putting Together a Community Strategy To Search for Extraterrestrial Life

I regret that the formatting of this column was askew earlier; I hope it didn’t make reading too difficult.  But now those problems are fixed.

The scientific search underway for life beyond Earth requires input from many disciplines and fields. Strategies forward have to hear and take in what scientists in those many fields have to say. (NASA)

Behind the front page space science discoveries that tell us about the intricacies and wonders of our world are generally years of technical and intellectual development, years of planning and refining, years of problem-defining and problem-solving.  And before all this, there also years of brainstorming, analysis and strategizing about which science goals should have the highest priorities and which might be most attainable.

That latter process is underway now in regarding the search for life in the solar system and beyond, with numerous teams of scientists tackling specific areas of interest and concern and turning their group discussions into white papers.  In this case, the white papers will then go on to the National Academy of Sciences for a blue-ribbon panel review and ultimately recommendations on which subjects are exciting and mature enough for inclusion in a decadal survey and possible funding.

This is a generally little-known part of the process that results in discoveries, but scientists certainly understand how they are essential.  That’s why hundreds of scientists contribute their ideas and time — often unpaid — to help put together these foundational documents.

With its call for extraterrestrial habitability white papers, the NAS got more than 20 diverse and often deeply thought out offerings.  The papers will be studied now by an ad hoc, blue ribbon committee of scientists selected by the NAS, which will have the first of two public meetings in Irvine, Calif. on Jan. 16-18.

Shawn Domagal-Goldman, a leader of many NASA study projects and a astrobiologist at NASA’s Goddard Space Fight Center. (NASA)

Then their recommendations go up further to the decadal survey teams that will set formal NASA priorities for the field of astronomy and astrophysics and planetary science.  This community-based process that has worked well for many scientific disciplines since they began in the late 1950s.

I’m particularly familiar with two of these white paper processes — one produced at the Earth-Life Science Institute (ELSI) in Tokyo and the other with NASA’s Nexus for Exoplanet System Science (NExSS.)  What they have to say is most interesting.Read more “Putting Together a Community Strategy To Search for Extraterrestrial Life”

Two Tempting Reprise Missions: Explore Titan or Bring Back a Piece of A Comet

Dragonfly is a quadcopter lander that would take advantage of the environment on Titan to fly to multiple locations, some hundreds of miles apart, to sample materials and determine the composition of the surface.  A central goal would be to analyze Titan’s organic chemistry and assess its habitability. (NASA)

Unmanned missions to planets and moons and asteroids in our solar system have been some of NASA’s most successful efforts in recent years, with completed or on-going ventures to Mars, Saturn, Jupiter, the asteroid Bennu, our moon, Pluto, Mercury and bodies around them all.   On deck are a funded mission to Europa, another to Mars and one to the unique metal asteroid 16 Psyche orbiting the sun between Mars and Jupiter.

We are now closer to adding another New Frontiers class destination to that list, and NASA announced this week that it will be to either Saturn’s moon Titan or to the comet 67P/Churyumov-Gerasimenko.

After assessing 12 possible New Frontiers proposals, these two made the cut and will receive $4 million each to further advance their proposed science and technology. One of them will be selected in spring of 2019 for launch in the mid 2020s.

With the announcement, associate administrator for NASA’s Science Mission Directorate Thomas Zurbuchen described the upcoming choice as between two “tantalizing investigations that seek to answer some of the biggest questions in our solar system today.”

Those questions would be:  How did water and other compounds essential for life arrive on Earth?  Comets carry ancient samples of both, and so can potentially provide answers.

And with its large inventories of nitrogen, methane and other organic compounds, is Titan potentially habitable?  Then there’s the added and very intriguing prospect of visiting the methane lakes of that frigid moon.

The CAESAR mission would return to the nucleus of  comet explored by the European Space Agency’s Rosetta mission, and its lander Philae.  (NASA)

Both destinations selected have actually been visited before.

The European Space Agency’s Rosetta mission orbited the comet 67P/Churyumov-Gerasimenko comet for two years and deployed a lander, which did touch down but sent back data for only intermittently for several days.

And the NASA’s Cassini-Huygens mission to Saturn passed by Titan regularly during its decade exploring that system, and the ESA’s Huygens probe did land on Titan and sent back information for a short time.

So both Rosetta and Cassini-Huygens began the process of understanding these distant and potentially revelatory destinations, and now NASA is looking to take it further.… Read more “Two Tempting Reprise Missions: Explore Titan or Bring Back a Piece of A Comet”

A New Way to Find Signals of Habitable Exoplanets?

Scientists propose a new and more indirect way of determining whether an exoplanet has a good, bad or unknowable chance of being habitable.  (NASA’s Goddard Space Flight Center/Mary Pat Hrybyk)

The search for biosignatures in the atmospheres of distant exoplanets is extremely difficult and time-consuming work.  The telescopes that can potentially take the measurements required are few and more will come only slowly.  And for the current and next generation of observatories, staring at a single exoplanet long enough to get a measurement of the compounds in its atmosphere will be a time-consuming and expensive process — and thus a relatively infrequent one.

As a way to potentially improve the chances of finding habitable conditions on those exoplanets that are observed, a new approach has been proposed by a group of NASA scientists.

The novel technique takes advantage of the frequent stellar storms emanating from cool, young dwarf stars. These storms throw huge clouds of stellar material and radiation into space – traveling near the speed of light — and the high energy particles then interact with exoplanet atmospheres and produce chemical biosignatures that can be detected.

The study, titled “Atmospheric Beacons of Life from Exoplanets Around G and K Stars“, recently appeared in Nature Scientific Reports

“We’re in search of molecules formed from fundamental prerequisites to life — specifically molecular nitrogen, which is 78 percent of our atmosphere,” said Airapetian, who is a solar scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and at American University in Washington, D.C. “These are basic molecules that are biologically friendly and have strong infrared emitting power, increasing our chance of detecting them.”

The thin gauzy rim of the planet in foreground is an illustration of its atmosphere. (NASA’s Goddard Space Flight Center)

So this technique, called a search for  “Beacons of Life,” would not detect signs of life per se, but would detect secondary or tertiary signals that would, in effect, tell observers to “look here.”

The scientific logic is as follows:

When high-energy particles from a stellar storm reach an exoplanet, they break the nitrogen, oxygen and water molecules that may be in the atmosphere into their individual components.

Water molecules become hydroxyl — one atom each of oxygen and hydrogen, bound together. This sparks a cascade of chemical reactions that ultimately produce what the scientists call the atmospheric beacons of hydroxyl, more molecular oxygen, and nitric oxide.… Read more “A New Way to Find Signals of Habitable Exoplanets?”

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