Category: Astrobiology (page 2 of 18)

Icy Moons, And Exploring The Secrets They Hold

Voyager 2’s flew by the Uranian moon Miranda in 1986 and the spacecraft spent 17 minutes taking  photos to make this high-resolution portrait.  Miranda has three oval and trapezoid coronae, tectonic features whose origins remain debated. (NASA / JPL / Ted Stryk)

When it come to habitable environments in our solar system, there’s Earth, perhaps Mars billions of years ago and then a slew of ice-covered moons that are likely to have global oceans under their crusts.  Many of you are familiar with Europa (a moon of Jupiter) and Enceladus (a moon of Saturn) — which have either been explored by NASA or will be in the years ahead.

But there quite a few others icy moons that scientists find intriguing and just possibly habitable.  There is Ganymede,  the largest moon of Jupiter and larger than Mercury but only 40 percent as dense, strongly suggesting a vast supply of water inside rather than rock.

There’s Saturn’s moon Titan, which is known for its methane lakes and seas on the surface but which has a subterranean ocean as well.  There is Callisto, the second largest moon of Jupiter and an subsurface-ocean candidates and even Pluto and Ceres, now called dwarf planets that show signs of having interior oceans.

And of increasing interest are several of the icy moons of Uranus, particularly Ariel and Miranda.  Each has features consistent with a subsurface ocean and even geological activity.  Although Uranus is a distant planet, well past Jupiter and Saturn and would take more than a decade to just get there, the possibility of a future Uranus mission is becoming increasingly real.

The National Academy of Sciences (NAS) Decadal Survey for planetary science rated a Uranus mission as the highest priority in the field, and just today (Aug. 18) NASA embraced the concept.

At a NASA Planetary Science Division town hall meeting, Director Lori Glaze said the agency was “very excited” about the Uranus mission recommendation from the National Academy and that she hoped and expected some studies could be funded and begun in fiscal 2024.

If a Uranus mission is fully embraced,  it would be the first ever specifically to an ice giant system — exploring the planet and its moons.  This heightened interest reflects the fact that many in the exoplanet field now hold that ice giant systems are the most common in the galaxy and that icy moons may well be common as well.… Read more

Despite Everything, American-Russian Relations on the International Space Station Appear To Be Solid

The International Space Station, which orbits 248 miles above Earth,  in what is called low-Earth orbit. Its long success as an international collaboration has been tested by the Ukraine war. (NASA)

Late last month, it appeared that Russian participation in the International Space Station would end in 2024 — or so seemed to say the head of the Russian space agency, Roscosmos  Thirty years of unusual and successful cooperation would be coming to a close as the Ukraine war appeared to make longer-term commitments impossible, or undesirable for the Russian side.

But on a day when the Ukraine war raged for its 163rd day, when new Western sanctions were being put into place, when a Russian judge gave WNBA star Brittney Griner a provocative 9-year prison term for carrying small amounts of cannabis oil as she left Moscow, and just a short time after what seemed to be the Russian announcement of that 2024 departure,  NASA officials held a commodious press conference with Roscosmos Executive Director for Human Space Programs Sergei Krikalev and others involved with the ISS.

Together they spoke yesterday (August 4) of expanding American-Russian cooperation on the mission and discounted talk of a 2024 Russian exit.

“We always talk of spaceflight as being team support,” said Kathy Lueders, NASA’s associate administrator of NASA’s Space Operations, which oversees the ISS. “And this news conference will exemplify how it is a team sport.”

She then discussed  how and why a Russian cosmonaut would soon take a SpaceX flight to the ISS as part of a new program under which Russian cosmonauts and American astronauts can fly on each other’s ISS-and-homeward-bound spacecraft.  The flight by veteran cosmonaut Anna Kikina will mark the first time a Russian has flown on an American spacecraft.

In the press conference, Krikalev then insisted that Russia had no intention of leaving the station in 2024 but rather would begin looking at the logistics of departing at that time — with an eye to leaving for their own planned space station in the years ahead.

“As far as the statement for 2024, perhaps something was lost in translation,” he said. “The statement actually said Russia will not pull out until after 2024.  That may be in 2025, 2028 or 2030.”   He said the timetable “will depend on the technical condition of the station.”

In the good-natured spirit of the press conference, Krikalev said that he was “happy to see so many faces I’ve known for many years.” 

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Reports From Inside the Sun’s Corona

This movie is built from images taken over 10 days during the full perihelion encounter when the spacecraft was nearing the Sun’s corona. The perihelion is a brief moment during the encounter time, when the spacecraft is at its closest point to the Sun. The movie is from orbit 10 and dates and distances are on the frames, and changing locations of planets are in red.  (AHL/JHU; NASA)

To borrow from singer Paul Simon, these are definitely days of miracles and wonders — at least when it comes to exploring and understanding our Sun.

The Parker Solar Probe has been swinging further and further into the Sun’s corona, having just finished its 12th of 24 descents into a world of super-heated matter (plasma) where no human creation has ever gone.

The probe has dipped as close as 5.3 million miles from the surface of the sun — Mercury is 32 million miles from that solar surface — and is flying through the solar wind, through streamers (rays of magnetized solar material)  and even at times through coronal mass ejections, those huge eruptions of magnetized plasma flying at speeds up to nearly 2,000 miles per second.

This is all a goldmine for solar scientists, an opportunity to study our star — and by extension all stars — up close and to learn much more about how it works.

At a four-day conference at the Johns Hopkins University Applied Physics Lab late last month, scores of scientists described the results of their early observations and analyses of the measurements and images coming from the Parker Probe via its The Wide-Field Imager (WISPR) and instruments that measure energy and magnetic flows.  The results have often surprising and, as some scientists said, “thrilling.”

“Parker Solar Probe was developed to answer some of the biggest puzzles, biggest questions about our Sun,” said Nour Raouafi, project scientist for the Parker Solar Probe.

“We have learned so much that we believe we are getting close to finding some important answers.  And we think the answers will be quite big for our field, and for science.”

The Parker Solar Probe had observed many switchbacks in the corona— traveling disturbances in the solar wind that cause the magnetic field to bend back on itself.  They are an as-yet unexplained phenomenon that might help scientists uncover more information about how the solar wind is accelerated from the Sun. (NASA’s Goddard Space Flight Center/Conceptual Image Lab/Adriana Manrique Gutierrez)

Among the many unexpected solar features and forces detected by the Parker Probe is the widespread presence of switchbacks, rapid flips of the Sun’s magnetic field moving away from the Sun. … Read more

Mars Was Once Wetter and Warmer And It Had Life-Essential Organic Carbon. Was There Enough for Life to Emerge?

Yellowknife Bay in Gale Crater, Mars, was extensively studied by the Curiousity rover in 2011-12 and was declared to have been “habitable” long ago.  But the amount of life-essential organic carbon at the site appeared to be low, and now has been measured in detail. (NASA)

In the early days of the Curiosity mission on Mars, scientists were excited by what they found in what was once a mud-flat they called Yellowknife Bay.  After months of drilling and testing, the mission team concluded that the site once had the roughly neutral water, an array of chemicals that could support metabolism and the organic carbon compounds needed for life.  So Yellowknife Bay and the surrounding Gale Crater were deemed to have once been “habitable.”

The finding of organic carbon was a major step forward because it is essential as a building block for the emergence of life as we know it.  The readings were clear that the organic carbon was present, but it has taken a decade to produce the first measurement of how much of the precious organic carbon was present.

The results, published late last month in the Proceedings of the National Academy of Sciences, show higher organic carbon levels than in some “low-life” environments on Earth.  But those levels are still quite reduced and point to an unwelcoming Mars even in an area declared to be habitable billions of years ago when Mars was wetter and warmer.

“Total organic carbon is one of several measurements that help us understand how much material is available as feedstock for prebiotic chemistry and potentially biology,” said Jennifer Stern of NASA’s Goddard Space Flight Center.

“We found at least 200 to 273 parts per million of organic carbon. This is comparable to or even more than the amount found in rocks in very low-life places on Earth, such as parts of the Atacama Desert in South America, and more than has been detected in Mars meteorites.”

The Atacama is one of the driest places on Earth, but it does support some life — bacteria under the surface of the desert and even some desert flowers in areas that experience fog.  Not surprisingly, NASA and other scientists often use the Atacama when they study conditions on ancient Mars.

The Atacama desert in Chile is one of the driest places on Earth and is often studied as a Mars analog. (Shudderstock)

This carbon data has been a long time coming.

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Evolving Views of Our Heliosphere Home

Does this model show of the actual shape of the heliosphere, with lines of magnetic fields around it? New research suggests so. The size and shape of the magnetic “force field” that protects our solar system from deadly cosmic rays has long been debated by astrophysicists. (Merav Opher, et. al)

We can’t see the heliosphere.  We know where it starts but not really where it ends.  And we are pretty certain that most stars, and therefore most planetary systems, are bounded by heliospheres, or “astropheres,” as well.

It has a measurable physical presence, but it is always changing.  And although it is hardly well known, it plays a substantial role in the dynamics of our solar system and our lives.

As it is studied further and deeper, it has become apparent that the heliosphere might be important — maybe even essential – for the existence of life on Earth and anywhere else it may exist.  Often likened to an enormous bubble or cocoon, it is the protected space in which our solar system and more exists.

Despite the fact that it is the largest physical system in the entire solar system, the heliosphere was only discovered at the dawn of the space age in the late 1950’s, when it was theorized by University of Chicago physicist Eugene Parker as being the result of what he termed the solar wind.

It took another decade for satellite measurements to confirm its existence and to determine some of its properties — that it is made up of an endless supply of charged particles that are shot off the sun — too hot to form into atoms. Together these particles,  which are superimposed with the interplanetary magnetic field, constitute the ingredients of he heliosphere.

Just as the Earth’s magnetic fields protect us from some of the effects of the Sun’s hazardous emanations, the heliosphere protects everything inside its bubble from many, though not all, of the incoming and more hazardous high-energy cosmic rays headed our way.

As measurable proof that the heliosphere does offer significant protection, when the Voyager 1 spacecraft left the heliosphere in 2012 and entered the intersellar medium, instruments onboard detected a tripling of amount of cosmic radiation suddenly hitting the spacecraft.

A comet-shaped traditional view of the structure of the heliosphere, with the sun in the middle of the circle, planets orbiting around and the solar wind trailing as the Sun orbits the Milky Way.  

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NASA’s Perseverance Rover on Mars; an Update

 

The composite images of “Delta Scarp” in Jezero Crater reveal that billions of years ago, when Mars had an atmosphere thick enough to support water flowing across its surface, Jezero’s fan-shaped river delta apparently experienced a late-stage flooding events that carried rocks and debris into it from the highlands well outside the crater. (RMI: NASA/JPL-Caltech/LANL/CNES/CNRS/ASU/MSSS).

NASA’s Perseverance rover has been on Mars for fifteen months now and is about to begin its trek into the fossil delta of Jezero Crater.  It’s a big deal for the mission, because the delta is where water once flowed long enough and strongly enough to smooth, round and move large rocks.

Since proof of the long-ago presence of water means the area was potentially habitable — especially a delta that spreads out into what were once calm rivulets — this is where the astrobiology goals of the mission come to the fore.

Or so the Perseverance team thought it would play out.

But the big surprise of the mission so far has been that the rover landed on igneous rock, formed in the Martian interior, spewed out and crystalized and solidified on the surface.

That Perseverance would land on igneous rock was always seen as a possibility, but a more likely outcome was landing on sedimentary rock as in  Gale Crater, where the Curiosity rover continues its decade-long explore. Sedimentary rock is laid down in layers in the presence of water.

Perseverance takes a selfie in Jezero. The rover is a twin of the Curiosity rover, but with some upgrades and new instruments (NASA/JPL-Caltech/MSSS)

As explained last week at the Ab-Sci-Con 2022 conference in Atlanta, the deputy program scientist for the mission — Katie Stack Morgan of NASA’s Jet Propulsion Lab — from the mission’s perspective the presence of both igneous and nearby sedimentary rock offers the best of both worlds.

While sedimentary rock is traditionally where scientists look for signs of ancient life, igneous rock can date the site more exactly and it can potentially better preserve any signs of early microbial life.

And in the context of Perseverance, the presence of accessible and compelling igneous formations provides for the diversity of rock samples called for in the Mars Sample Return effort — another central part of the rover’s mission.

“We did a lot of work with our different instruments to come to the conclusion that we landed on  igneous rock,” Stack Morgan later said in an interview. … Read more

New Findings Suggest the Building Blocks For Life’s Genetic Structure May Well Have Arrived From Above

Conceptual image of meteoroids delivering nucleobases to ancient Earth. The nucleobases are represented by structural diagrams with hydrogen atoms as white spheres, carbon as black, nitrogen as blue and oxygen as red. (NASA Goddard/CI Lab/Dan Gallagher)

All of life, from simplest to most complex, contains five information-passing compounds that allow the genetic code to work.  These nitrogen-based compounds, called nucleobases, are found in all the the DNA and RNA that  provide the instructions to build and operate every living thing on Earth.

How these compounds are formed, or where they come from, has long been a key question in astrobiology and the search for the origin of life.

Numerous theories have been advanced to explain their presence, including that they arrived on Earth via meteorites and the infall of dust.  But until recently, only three of these nucleobases have been found embedded in meteorites but, puzzlingly, the two others have not been found.

Now an international team centered in Japan has completed the search for nucleobases in meteorites by finding the remaining two, and so it appears possible that all these building blocks of the genetic code could have arrived on very early Earth from afar.

Yasuhiro Oba of the University of Hokkaido, and lead author of the new study in Nature Communications, said that  extraterrestrial material arrived in much greater quantities on the early Earth — during what is called the period of “late heavy bombardment” — and so the discovery “of all five primary nucleobases in DNA/RNA indicates that these components should have been provided to the early Earth with such extraterrestrial materials.”

This certainly does not mean that fully formed DNA or RNA was delivered to Earth.  Oba said the process of making those nucleic acids from components parts, including nucleobases, is under active study but is not particularly well understood.  But it does mean that essential building blocks for the genetic backbone of life clearly did arrive from space for possible use in the life-forming process.

“We don’t know how life first started on the Earth, but the discovery of extraterrestrial nucleobases in meteorites provides additional support for the theory that meteorite delivery could have seeded the early Earth with the fundamental units of the genetic code found in DNA and RNA in all life today,” said co-author Daniel Glavin of NASA’s Goddard Spaceflight Center.

“These nucleobases are highly soluble in liquid water, so over time, any meteorite fragments exposed to water on the early Earth would be extracted from the meteorites into the water and could therefore contribute to the chemical inventory of the prebiotic soup from which life emerged.”… Read more

A Clue Into The Makeup of Jupiter’s Moon Europa Provided by the Greenland Ice Sheet

Double ridge ice formations seen on Europa are similar to formations detected on the Greenland Ice Sheet. This artist’s rendering shows how double ridges on the surface of Jupiter’s moon Europa may form over shallow, refreezing water pockets within the ice shell. This mechanism is based on the study of an analogous double ridge feature found on Earth’s Greenland Ice Sheet. (Justice Blaine Wainwright)

Europa’s ice crust is crossed by thousands of double ridges, pairs of long parallel raised lines with a small valleys in between, sometimes as much as hundreds of miles long and skyscraper-height tall rims. While these double ridges are ubiquitous on Europa’s surface, how they form remains something of a mystery to scientists.

Dustin Schroeder, an associate professor of geophysics at Stanford University’s School of Earth, Energy & Environmental Sciences, was working on an issue related to climate change when he saw double ridges similar to those seen on Europa here on Earth.  The ridges, in Northwest Greenland, were tiny when compared with those on Europa, but the found the same “M”-shaped crest as found everywhere on that Jovian moon.

“We were working on something totally different related to climate change and its impact on the surface of Greenland when we saw these tiny double ridges – and we were able to see the ridges go from ‘not formed’ to ‘formed,’ ” Schroeder said.

Could the double ridges be forming as a result of processes similar to those that form the double ridges on Europa?

If so, then Greenland would provide a possibly important new window into a central question about Europa:  Is that thick ice shell surrounding the subsurface ocean completely solid, or does it have what are called “water sills” within the shell?

This is important because, as the Nature Communications paper concludes, “If the same process is responsible for Europa’s double ridges, our results suggest that shallow liquid water is spatially and temporally ubiquitous across Europa’s ice shell.”

Or as Schroeder put it, “If the mechanism we see in Greenland is how these things happen on Europa, it suggests there’s water everywhere,” he said in a release.

They can make this inference because the double ridges formed in Greenland are the known, and detectable, result of the dynamics of subsurface water surrounded by the ice sheet.

Surface imagery comparison of a double ridge on Europa (a) and on Earth (b), on the Northwest Greenland Ice Sheet.

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“Nature Has Become More Beautiful.” Physicist Eugene Parker and his Life Unlocking Secrets Of The Sun

 

Parker with an image of the solar corona, the outermost portion of Sun’s atmosphere.  Parker brought new understanding to the nature and workings of the corona and the solar wind, which originates in the corona. (University of Chicago)

When  Eugene Parker was 16 years old,  he decided he didn’t want to spend the summer hanging out in suburban Detroit.  So Parker went up to the state capital looking to buy some tax delinquent land held by the state.

He selected a 40-acre piece of woods in far-off Cheboygan County, not far from Mackinac Island.  There was nothing on the land but trees.  He bought it with $120 from his own earlier summertime earnings.

Over the next three summers, Parker, his younger brother and sometimes a cousin and a friend constructed a log cabin on the land.  Because this was during World War II and gas was strictly rationed,  they couldn’t ask their parents for a ride up, and so they often bicycled the more than 300 miles to their homestead.

The cabin still doesn’t have electricity or indoor running water, but it has been used regularly by Parker and his family for almost 80 years.  And in many ways, that cabin reflects the basic character, the drive and the profound originality of the boy who built it and went on to become one of the great theoretical physicists of the 20th century.

The young Parker atop a birch  tree in 1943, on the site where his northern Michigan cabin would be built. (Courtesy of the Parker family.)

Eugene Parker, who passed away earlier this month at 94, has been hailed as the father of solar physics and is perhaps best known as the man who — basically single-handedly and despite many eminent critics –came up with the theory of the “solar wind,” a torrent of charged particles and magnetic fields that always and in all directions is blasting out from the Sun.

Parker’s innumerable achievements in his field, as well as his old-school civility and demeanor, earned him the first and only honor of its kind given by NASA — having a major space mission named after him while alive.

Ailing and aged 91, he nonetheless went with his family down to Florida in 2018 to watch the launch of the Parker Solar Probe — an extraordinary mission that flies through the blast furnace of the Sun’s corona in its effort to learn more about the origins of the solar wind and the forces at play that produce that still mysterious solar corona.… Read more

The World’s Most Capable Space Telescope Readies To Observe. What Will Exoplanet Scientists Be Looking For?

This artist’s concept shows what the TRAPPIST-1 planetary system may look like, based on available data about the planets’ diameters, masses and distances from the host star.  The James Webb is expected to begin science observations this summer. (NASA/JPL-Caltech)

The decades-long process of developing, refining, testing, launching, unfurling and now aligning and calibrating the most capable space telescope in history is nearing fruition.  While NASA has already released a number of “first light” images of photons of light moving through the James Webb Space Telescope’s optical system, the  jaw-dropping “first light” that has all the mirrors up and running together to produce an actual scientific observation is a few months off.

Just as the building and evolution of the Webb has been going on for years, so has the planning and preparation for specific team observation “campaigns.”   Many of these pertain to the earliest days of the universe, of star and galaxy formation and other realms of cosmology,  but an unprecedented subset of exoplanet observations is also on its way.

Many Worlds earlier discussed the JWST Early Release Science Program, which involves observations of gigantic hot Jupiter planets to both learn about their atmospheres and as a way to collect data that will guide exoplanet scientists in using JWST instruments in the years ahead.

Now we’ll look at a number of specific JWST General Observation and Guarantreed Time efforts that are more specific and will collect brand new information about some of the major characteristics and mysteries of a representative subset of the at least 100 billion exoplanets in our galaxy.

This will be done by using three techniques including transmission spectroscopy — collecting and analyzing the light that passes through an exoplanet’s atmosphere as it passes in front of its Sun.  The JWST will bring unprecedented power to characterizing the wild diversity of exoplanets now known to exist; to the question of whether “cool” and dim red dwarf stars (by far the most common in the galaxy) can maintain atmospheres; to newly sensitive studies of the chemical makeup of exoplanet atmospheres; and to the many possibilities of the TRAPPIST-1 exoplanets, a seven rocky planet solar system that is relatively nearby.

An artist’s interpretation of GJ 1214b,one of a group of super-Earth to mini-Neptune sized planets to be studied in the JWST Cycle1 observations. The planet is known to be covered by a thick haze which scientists expect the JWST to pierce as never before and allow them to study atmospheric chemicals below.

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