Category: Astrobiology (page 1 of 15)

A Red Supergiant Star Is Caught Going Explosively Supernova, A First

Supernova (SN) 2020tlf, identified by red markers, in the act of exploding 120 million light years away. The bright white region to the upper right is the crowded center of the star’s galaxy, the oval-shaped NGC 5731. This direct image was captured using the Pan-STARRS camera at the Haleakala Observatory, Hawai’i.  It shows the supernova in optical light. (Pan-STARRS/YSE)

When a large star reaches the end of its life it runs out of fuel, collapses and explodes into a supernova. The explosion releases enormous amounts of energy and light, turning a luminous object that is small at a distance into a large glowing ball.

Supernova temperatures have been modeled to reach 6,000 times higher than the core temperature of our Sun. Much of the matter in the star is sent flying into space and, in moments, the gigantic eruption is over. These cataclysmic events — the most energetic explosions ever seen by humans — are known to send far into the cosmos shock waves of compressed gas clouds that eventually birth new stars.

Supernova are stupendous astrophysical events which are of great interest to astronomers.  And over the past several years an international team including the University of California, Berkeley and the University of Hawai’i  have actually captured such an explosion of a red supergiant star — the first such imaging of its kind.

“For the first time, we watched a red supergiant star explode!” said Wynn Jacobson-Galán, a National Science Foundation Graduate Research Fellow at UC Berkeley and lead author of the study in The Astrophysical Journal. “This is a breakthrough in our understanding of what massive stars do moments before they die.”

“It’s like watching a ticking time bomb,” said senior author Raffaella Margutti, an associate professor of astronomy at UC Berkeley, and one of those who monitored the star for several months before it exploded.

“We’ve never confirmed such violent activity in a dying red supergiant star, where we see it produce such a luminous emission then collapse and combust. Until now.”

An artist’s video rendering of a red supergiant star transitioning into a Type II supernova, emitting a violent eruption of radiation and gas on its dying breath before collapsing and exploding.  (W. M. Keck Observatory/Adam Makarenko)

A supernova of the type and size of the one just observed are known to occur periodically,  but predicting when massive stars will reach that final violent stage and having telescopes in place to observe it has been a bridge too far.… Read more

The Amazing Unfurling Of The James Webb Space Telescope

The last view of the JWST and its unfurled solar arrays after it separated from the Ariane 5 launch vehicle and started it’s month-long and extraordinarily complicated deployment. (NASA)

Over the next three weeks-plus, the James Webb Space Telescope will play out an unfurling and deployment in deep space unlike anything this world has seen before.

It took decades to perfect the observatory — a segmented telescope on a heat shield  the length of a tennis court that was squeezed for launch into a rocket payload compartment less than 30 feet in diameter.  The unfurling has begun and will continue over 25 more days, with 50 major deployments and 178 release mechanisms to set the pieces free.

The process has been likened to the undoing of an origami creation, or like the opening of a massive, many-featured Swiss army knife but without a human to pull the parts out.

Adding to the stress of these days,  the JWST will be much further out into space than the Hubble Space Telescope, which is in a very close orbit around the Earth at an altitude of about 340 miles.  The JWST will be over 930,000 miles away from Earth at the stable orbital point called the second Lagrange point 2 (L2) — way too far away for any manual fixes or upgrades like the ones accomplished by astronauts for the Hubble.

Four days after liftoff, the observatory has unfurled some of its solar panels, has deployed some of the pallet that will hold the sunshield and has extended the tower assembly about 6 feet from its storage space.   Here is a video from the Goddard Space Flight Center illustrating all the steps needed to make JWST whole:

 

And here is a more detailed depiction of the many stages of deployment, what is being deployed and how.

JWST will  have the largest telescope mirror ever sent into space — 21 feet in diameter compared with the Hubble’s 8-foot diameter.  Because it is so large, it had to be divided into 18 hexagonal segments of the lightweight element beryllium, each one roughly the size of a coffee table. Together, the segments must align almost perfectly, moving in alignment within a fraction of a wavelength of light.

Webb mission systems engineer Mike Menzel, of NASA’s Goddard Space Flight Center, said in a deployment-explaining video called “29 Days on the Edge” that every single releases and deployment must work.… Read more

A Huge Watery Reservoir May Lie Beneath the Surface of The “Grand Canyon” of Mars

The Valles Marineris in equatorial Mars and is one of the the largest canyon in the solar system.  It is surpassed in length only by the rift valleys of Earth. (NASA)

That early Mars was much wetter and warmer than it is today has been well established by numerous missions.  Water ice is visible at the poles and many fossil rivers have been found in the southern highlands of Mars.  The Curiosity rover found as well that the large crater where it landed — Gale Crater – once had a lake and in-flowing streams.

But the presence of water, or proof that water once flowed, has been missing in the equatorial latitudes  of the planet.

However, now a paper based on data from the European/Russian Trace Gas Orbiter (TGO) strongly suggests that the Candor Chasma, located near the heart of the massive canyon system called Valles Marineris, has either large deposits of a kind of permafrost water ice just below its surface or of rocks formed in water and now containing that H2O in their structure.

The article to appear in the journal Icarus says that the discovery of large amounts of hydrogen in the region speaks of this aqueous  past.

“We found a central part of Valles Marineris to be packed full of water – far more water than we expected,” Alexey Malakhov, of the Russian Space Research Institute and a co-author of the study, said in a statement.

“This is very much like Earth’s permafrost regions, where water ice permanently persists under dry soil because of the constant low temperatures.”

 

Valles Marineris, seen at an angle of 45 degrees to the surface in near-true color and with four times vertical exaggeration. The image covers an area of about 400,000 square miles. The largest portion of the canyon, which spans right across the image, is known as Melas Chasma. Candor Chasma is the connecting trough immediately to the north. The digital terrain model was created from 20 images taken by the High Resolution Stereo Camera of the Mars Express Orbiter. (ESA)

Valles Marineris is 10 times longer and 4 times deeper than our Grand Canyon.  Geologists have theorized that Valles Marineris began to open along geological faults about 3.5 billion years ago. The faulting may have been caused by the tectonic activity that accompanied the growth of the giant volcanoes in Tharsis, lying just to the west.Read more

What The James Webb Space Telescope Can Do For Exoplanet Science and What It Cannot Do

The James Webb Space Telescope, as rendered by an artist. The telescope is scheduled to launch later this month. (NASA)

When the James Webb Space Telescope finally launches (late this month, if the schedule holds) it will forever change astronomy.

Assuming that its complex, month-long deployment in space works as planned, it will become the most powerful and far-seeing observatory in the sky.  It will have unprecedented capabilities to probe the earliest days of the universe, shedding new light on the formation of the first stars and galaxies.  And it will observe in new detail the most distant regions of our solar system.

Deep space astrophysics is what JWST was first designed for in the early 1990s, and that will be its transformative strength.

But much is also being made of what JWST can do for the study of exoplanets and some are even talking about how it just might be able to find biosignatures — signs of distant life.

While it is probably wise to never say never regarding an observatory with the power and capabilities of JWST,  the reality is that it was not designed to look for the exoplanets most likely to be habitable.  Actually, when it was first proposed, the observatory had no exoplanet-studying capabilities at all because no exoplanets had yet been found.

What was added on is substantial and exoplanet scientists say JWST can help advance the field substantially.  But there are definite limits and finding biosignatures — life — is almost certainly a reach too far for JWST.

When starlight passes through a planet’s atmosphere, certain parts of the light are absorbed by the atmosphere’s elements. By studying which parts of light are absorbed, scientists can determine the composition of the planet’s atmosphere. (Christine Daniloff/MIT, Julien de Wit)

Astronomer Jacob Bean of the University of Chicago, who has played a leadership role in planning JWST exoplanet observations for the telescope’s early day, says that people need to know these limitations so the pioneering exoplanet science that will be possible with JWST is not seen as somehow disappointing.

As he explained, it is essential to understand that the kind of exoplanet observing that the JWST will mostly do is “transit spectroscopy.”  This involves staring at a star when an exoplanet is expected to transit in front of it.  When that happens, light from the star will pass through the atmosphere of the exoplanet (if there is one) and through spectroscopy scientists can determine what molecules are in that hoped-for atmosphere.… Read more

Why Does Our Solar System Have No Super-Earths, and Other Questions for Comparative Planetology

An artist’s impression of the exoplanet LHS 1140b, which orbits a red dwarf star 40 light-years from Earth. Using the European Southern Observatory’s telescope at La Silla, Chile, and other telescopes around the world, an international team of astronomers discovered this super-Earth orbiting in the habitable zone around the faint star LHS 1140. This world is a little larger and much more massive than the Earth. (ESO)

Before the explosion in discovery of extrasolar planets, the field of comparative planetology was pretty limited  — confined to examining the differences between planets in our solar system and how they may have come to pass.

But over the past quarter century, comparative planetology and the demographics of planets came to mean something quite different.  With so many planets now identified in so many solar systems, the comparisons became not just between one planet and another but also between one solar system and another.

And the big questions for scientists became the likes of:  How and why are the planetary makeups of distant solar systems often so different from our own and from each other; what does the presence  or absence of large planets in a solar system do to the distribution of smaller planets;  how large can a rocky planet can get before it turns to a gas giant planet; and on a more specific subject, why do some solar systems have hot Jupiters close to the host star and others have cold Jupiters much further out like our own

Another especially compelling question involves our own solar system, though as something of an outlier rather than a prototype.

That question involves the absence in our solar system of anything in the category of a “super-Earth” — a rocky or gaseous extrasolar planet with a mass greater than Earth’s but substantially below those of our solar system’s planets next in mass,  Uranus and Neptune.

The term “super-Earth” refers only to the mass and radii of the planet, and so does not imply anything about the surface conditions or habitability. But in the world of comparative planetology “super-Earths” are very important because they are among the most common sized exoplanets found so far and some do seem to have planetary characteristics associated with habitability.

Yet they do not exist in our solar system.  Why is that?

Artist rendition of Earth in comparison to one of the many super-Earth planets. (NASA)

In a recent article in The Astrophysical Journal Letters,  planetary demographer Gijs D.… Read more

NASA Should Build a Grand Observatory Designed to Search For Life Beyond Earth, Top Panel Concludes

The National Academy of Sciences has released it’s “Decadal Survey,” with guidance and recommendations for the fields of astronomy, astrobiology and astrophysics.(NASA)

NASA should begin developing a mission that can tell us whether life in the near galaxy is abundant, rare or essentially absent, The National Academy of Sciences recommended yesterday.

The call for a next Grand Observatory telescope with this ambitious goal represents the first time that the Academy, in its Decadal Survey for Astronomy and Astrophysics, has given top priority to the science of  exoplanets and the search for life far beyond Earth.

The long-awaited NAS survey did not select a single mission concept, although several NASA-commissioned studies were extensively researched and assembled for the Decadal over the past four years.

Rather, they set the science goal of giving an answer – as complete as possible – to the eternally-asked question of whether life exists solely on Earth or can be found on the billions of other planets we now know orbit their own suns.

Decadal steering committee co-chair Robert Kennicutt Jr., a professor at University of Arizona and Texas A & M University, said that a flood of discoveries and astronomical and technological advances in recent decades made clear that the time for such a mission had come.

“We’re laying down a marker here,” Kennicutt said  in a press conference.  “We think that progress in this field has taken us to the point that within the planning horizon of this survey, we can really contemplate imaging  Earth-like planets in their habitable zones around other stars and spectroscopically studying them for atmospheric composition, perhaps including biomarkers. with the ultimate goal of answering one of the most profound questions:  Are we alone in the universe?”

The proposed mission, he said, would as a result have the transformative scientific power of the Hubble Space Telescope and the James Webb Space Telescope, which is scheduled to launch next month.  It would change the way that scientists and citizens see the world.

The telescope envisioned by Decadal Survey would search for small rocky planets in the habitable zone of heir sun — where the temperatures would allow for liquid water to exist rather than just water vapor or ice.  This artist’s concept ia of Kepler-452b, the first near-Earth-size world found in the habitable zone of a distant sun-like star. ( NASA/Ames/JPL-Caltech.)

But the road to an actual mission will be long and definitely uphill.… Read more

A Call To Action on Ensuring That Extraordinary Claims About ET Life Come With Extraordinary Evidence

An artist’s rendering of the sweep of cosmic events important to astrobiology.  They include the formation of molecular clouds of gas and dust where stars are born, the subsequent evolving of a protoplanetary disk surrounding the new star, and then the organizing of a cleaned-up solar systems with planets and moons. (National Radio Astronomy Observatory and Dina Clark/University of California, Santa Cruz)

The global scientific search for signs of life beyond Earth has produced cutting-edge and paradigm-shifting science for several decades now, and it has clearly found eager audiences around the world.  This search is a high-priority goal of NASA and other space agencies, as well as institutions, universities and companies.

While the successes in this broadly defined field of astrobiology are legion, the field has also struggled with a problem that flows precisely from its high-impact subject.

That problem is how to best keep its scientific claims evidence based and how to take into account all the myriad factors that can undermine the strength of a “finding.”  And then comes the question of how to best communicate with the public the nature of the findings and all the caveats involved.

There appears to be a widely-held view that some scientific claims and media reports about potential life beyond Earth have become not only a distraction in the field, but have served to undermine some public confidence in the endeavor.

NASA Chief Scientist Jim Green is the lead author of a Nature paper calling for heightened standards for all extraterrestrial life detection science. With discoveries coming in so fast, he said, some formal new standards are needed to increase scientific and public confidence. (NASA /Carla Cioffi)

And some of the leading figures in the field have written a paper, released today by the journal Nature, that calls for the creation of some as yet undefined guardrails or confidence scales to make exciting scientific findings and news about astrobiology more consistently dependable.

The goal is to find ways to make sure that papers meet the widely-embraced Carl Sagan standard that  “extraordinary claims require extraordinary evidence”.

This is how the authors introduce the paper:

“Ours could realistically be the generation to discover evidence of life beyond Earth. With this privileged potential comes responsibility.”

“The magnitude of the question, “are we alone?”, and the public interest therein, opens the possibility that results may be taken to imply more than the observations support, or than the observers intend.… Read more

Many Planets Form in a Soup of Life-Friendly Organic Compounds

Artist’s depiction of a protoplanetary disk with young planets forming around a star. The right-side panel zooms in to show various organic molecules that are accreting onto a planet. (M.Weiss/Center for Astrophysics | Harvard & Smithsonian)

One of the more persuasive arguments in favor of the potential existence of life beyond Earth is that the well-known chemical building blocks of that life are found throughout the galaxy.  These chemical components aren’t all present in all examined solar systems and planets, but they are common and behave in ways familiar to scientists here.

And when it comes elements and compounds found on distant planets but not found here, there just aren’t many. That doesn’t mean they don’t exist — some unstable compounds in interstellar space, for instance — but rather that the cosmos holds many surprises but none have involved extraterrestrial elements or compounds near planets or stars.

This is in large part the result of how elements are formed in the universe.  Other than hydrogen and helium, all other elements are forged in the thermonuclear explosion of stars that have exhausted their supply of fuel.  These massive explosions (supernovae) then shoot the newly-formed elements out into space where they can and do collect in gas and dust clouds that will form other new stars.  They are spread throughout the disks that form around new stars and over time they become components of new planets in formation.

This galactic evolution includes the bonding together of carbon-based organic compounds — the building blocks of life as we know it.  They are an essential component to any theory of a planet’s habitability and,  while their presence in space and star nurseries has been known for some time,  they have remained a subject of great interest but limited detailed knowledge.

That is why an international team from the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass. set out to intensively study five disks forming around young stars to determine more precisely what organic compounds were present and available for objects developing into planets.

And the results are striking:  The abundance of organic material detected was 10 to 100 times more than expected.

“These planet-forming disks are teeming with organic molecules, some of which are implicated in the origins of life here on Earth,” said team leader Karin Öberg. “This is really exciting; the chemicals in each disk will ultimately affect the type of planets that form and determine whether or not the planets can host life.”… Read more

Frigid Europa Holds a Huge and Maybe Habitable Ocean Beneath Its Thick Ice Covering. How is That Possible?

Europa has one of the smoothest surface of any body in the solar system.  A moon as old as Europa that did not have an ice cover — and a likely ocean inside — would be pocked with asteroid craters.  On Europa, these craters appear to be absorbed into the icy surface via geologic and thermal processes.  Giant lakes trapped in Europa’s crust also bust up the icy surface. (NASA)

Jupiter’s moon Europa is almost five times as far away from the sun as Earth is, with surface temperatures that don’t rise above minus 260 degrees Fahrenheit.  It’s slightly smaller than our moon and orbits but 400,000 miles from the solar system’s largest planet, which it takes but 3.5 Earth days to orbit.  As a result it is tidally locked, always showing the same face to Jupiter.

When it comes to potentially habitable objects in our solar system, Europa would not seem to be a terribly likely possibility.

But, of course, it is.  And in three years NASA’s Europa Clipper mission will launch to explore what would appear to be one of the most unlikely yet possible places in our solar system to find potential signs of life.

The reason why is that scientists are almost certain that under Europa ‘s 10-to 15 mile ice covering is a deep, global ocean of salty water.

The size of the ocean has not been well determined yet, with estimates of between 40 and 100 miles of depth.  But a  consensus has been reached that the ocean is likely to be global, and contains two to three times as much liquid water as found on Earth.

This then raises a question with great significance for Europa, other moons in the solar system and quite likely planets and moons well beyond us:  How can there be so much liquid water inside such frigid places?

The spot toward the lower left is one Europa, against the backdrop of Jupiter.  Images from Voyager in 1979 bolster the modern hypothesis that Europa has an underground ocean and is therefore a good place to look for extraterrestrial life. The dark spot on the upper right is a shadow of another of Jupiter’s large moons. Sixteen frames from Voyager 1’s 1979 Jupiter flyby were recently reprocessed and merged to create this image.  (NASA, Voyager 1, JPL, Caltech; Processing & License: Alexis Tranchandon / Solaris)

There are numerous possible answers to that question, and it’s likely that all or most played some role.… Read more

Sample Return from Mars Begins in Earnest

This image taken by NASA’s Perseverance rover on Sept. 7, 2021 shows two holes where the rover’s drill obtained chalk-size samples from a rock nicknamed “Rochette.” They are the first physical manifestations of the NASA’s long-planned Mars Sample Return Mission. (NASA/JPL-Caltech.)

For the first time ever, a sample of pulverized rock from another planet has been drilled, collected and stored for eventual delivery to the highest-tech labs on Earth.

Yes, a storehouse of rocks were collected on the moon by Apollo astronauts and delivered to Houston, and some small samples of two asteroids and one comet were snatched by three spacecraft (two Japanese and one American) and their contents were brought here for study.

But never before has the surface of another planet been the source of precious extraterrestrial material that some day, if all goes well, will be received on Earth for intensive analysis.

The feat was accomplished by the team that operates the Perseverance rover on Mars.  After an unsuccessful effort to drill what turned out to be a very soft rock in August , the rover drill succeeded in digging into a briefcase-sized hard volcanic rock twice this month and pulling out samples to be tubed and stored for later pick-up by a different mission.

That next step isn’t scheduled for another half decade and the samples would not arrived on Earth until well after that.  But a long-dreamed and highly-ambitious effort to bring some of Mars to Earth (called Mars Sample Return) has now formally begun.

“This is a truly historic achievement, the very first rock cores collected on another terrestrial planet — it’s amazing,” Meenakshi Wadhwa, Mars sample return principal scientist at NASA’s Jet Propulsion Laboratory, said during a news conference held Friday

“In our science community, we’ve talked about Mars sample return for decades,” Wadhwa said. “And now it’s actually starting to feel real.”

Perseverance’s first cored-rock sample of Mars is seen inside its titanium container tube in this image taken by the rover’s Sampling and Caching System Camera, known as CacheCam. (NASA/JPL-Caltech)

The press conference was a victory lap of sorts for leaders of a team with many members who have worked eight to ten years for this moment.  Lori Glaze, NASA’s director of the Planetary Science Division, also called it an historic achievement –the culmination of advances pioneered by many other NASA missions to Mars and elsewhere and a milestone for NASA’s Mars program.… Read more

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