Author: Marc Kaufman (page 1 of 21)

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

Introducing Hycean Planets

A so-called Hycean planet is one featuring large oceans and a hydrogen atmosphere. A new report from the University of Cambridge suggests this kind of planet, sized between a super-Earth and a mini-Neptunes, could potentially support life. The image features a red dwarf star as the planet’s host star. (Artist rendering by Amanda Smith, University of Cambridge)

Planets beyond our solar system, we now know, come in all shapes, sizes and consistencies.  There are rocky planets, water worlds, gaseous planets, super-Earths, hot Jupiters, tidally locked planets, planets in orbital resonance with each other,  and so much more.

A group of exoplanet researchers at the University of Cambridge have recently proposed a new category of planet, one that has seldom been considered even potentially habitable.  They call them Hycean planets due to the presence of substantial hydrogen in the atmospheres and large oceans (hydrogen and ocean = Hycean) on their surfaces.

And in an article in The Astrophysical Journal, they make the case that under certain conditions, some Hycean planets could, indeed, be habitable.

“Hycean planets open a whole new avenue in our search for life elsewhere,” said Nikku Madhusudhan from Cambridge’s Institute of Astronomy, who led the research.

Many of the prime Hycean candidates identified by the researchers are bigger and hotter than Earth, but the researchers argue that they still have the characteristics to host large oceans that could support microbial life similar to that found in some of Earth’s most extreme watery environments.

Hycean planets, Madhusudhan said in a release, offer a new paradigm for the search for life beyond Earth.

“Essentially, when we’ve been looking for these various molecular signatures, we have been focusing on planets similar to Earth, which is a reasonable place to start,”  he said. “But we think Hycean planets offer a better chance of finding several trace biosignatures.”

Co-author Anjali Piette, also from Cambridge, added: “It’s exciting that habitable conditions could exist on planets so different from Earth.”

An artist rendering of what a possible Hycean planet would look like.  This image is of K2-18b, which has a radius twice that of Earth and is more than eight times as massive as our planet.  The heavy hydrogen atmosphere is present, as is the red dwarf star that it orbits. (Alex Boersma)

There are no planets of this size and type in our solar system, but planets in the Hycean range are quite common in the galaxy.… Read more

Findings Suggest that Red Dwarf Stars May Not Sterilize Many Exoplanets As Feared

An illustration of a red dwarf star with orbiting exoplanet. The question of whether this very common type of star can support habitable planets is a much debated one. (NASA)

Red dwarf suns are the most common in the universe, and many of the exoplanets officially discovered so far orbit this type of “cool” star.  Red dwarfs are much smaller and less powerful than the G type stars such as our own sun, and it is easier to detect exoplanets orbiting them because of their reduced size and energy.

As a result, a number of relatively nearby red dwarf stars — in the Trappist-1 system, Proxima Centauri and Barnard’s star, for instance — are avidly studied for their potential habitability.  The exoplanets of red dwarfs tend to orbit much closer than around other larger stars, but the suns have that lower radiative power and so some are considered habitable candidates.  And if they are indeed habitable, they could be for a very long time because red dwarfs live much longer than most other stars.

But there have been two (at least) problems with the habitable red dwarf exoplanet scenario.  The first is that many of the planets so close to their star are tidally locked, meaning that only one side ever faces the sun.  Some have argued a tidally locked planet can still be habitable, but it would not be easy.

More crucial, however, is that red dwarf stars are known for sending out many, many powerful solar flares, especially during their solar infancy and childhood.  These high radiation and particle flares could and would potentially kill any life emerging on a dwarf exoplanet, and the stellar flares could even sterilize the planets’ atmosphere for all time.  Although direct observations have not shown this deadly scenario to be inevitable or even present, the red dwarf flaring is well documented.  And so potentially the flares have seemed to rule out, or make improbable, life on an estimated 75 percent of the stars in our galaxy.

This is why there is interest in the astrobiology world about a new paper that addresses a particular kind of stellar flare that would hit red dwarf exoplanets.  Such studies of how the behavior of a star effects orbiting planets is one of the less well studied aspects of the exoplanet field, and so the paper is especially welcomed.

And the results suggests that the red dwarf flares would strike orbiting exoplanets from an angle rather than straight on, and therefore would land in a way that would theoretically minimize damage to potential atmospheres and life.… Read more

The Many Ways The James Webb Space Telescope Could Fail

Artist rendering of the James Webb Space Telescope when it has opened and is operating. The telescope is scheduled to launch in November, 2021. (NASA)

When a damaged Apollo 13 and its crew were careening to Earth, mission control director Gene Kranz famously told the assembled NASA team that “failure is not an option.”  Actually, the actor playing Kranz in the “Apollo 13” movie spoke those words, but by all accounts Kranz and his team lived that phrase, with a drive that became a reality.

That kind of hard-driving confidence now seems to be built into NASA’s DNA, and with some tragic exceptions it has served the agency well in its myriad high-precision and high-drama ventures.

So it was somewhat surprising (and a bit refreshing)  to read the recent blog post from Thomas Zurbuchen,  NASA’s Associate  Administrator for the Space Science Directorate, on the subject of the scheduled November launch of the James Webb Space Telescope.

Thomas Zurbuchen, NASA’s Associate Administrator of the Space Science Directorate, with the new eyeglasses he introduced in his blog. (NASA)

“Those who are not worried or even terrified about (the challenges facing the JWST mission) are not understanding what we are trying to do,” he wrote.

“For most missions, launch contributes the majority of mission risk – if the spacecraft is in space, most risk is behind us. There are few types of missions that are very much different with most risk coming after launch.

“We have already performed one such mission in February when we landed on Mars. For the Perseverance rover, only 10-20% of the risk was retired during launch, perhaps 50% during the landing, and we are in the middle of the residual risk burn down as we are getting ready to drill and collect the precious Mars samples with the most complex mechanical system ever sent to another planet.

“The second such mission this year is Webb. Like a transformer in the movies, about 50 deployments need to occur after launch to set up the huge system. With 344 so-called single point failures – individual steps that have to work for the mission to be a success – this deployment after launch will keep us on edge for 3 weeks or so. For comparison, this exceeds single point failures for landing on Mars by a factor of 3, and that landing lasted only 7 minutes.”

Zurbuchen is confident that the Webb team and technology is up to the challenge but still, that is quite a risk profile.… Read more

A Young Planet Found That May Well Be Making Moons

An image made by the Very Large Telescope in Chile shows a forming planet, the bright spot at right. The overpowering light of the host star is blocked out by a coronagraph inside the telescope. (ESO/A. Müller et al.)

Astronomers have many theories about how planets are formed within the gas, dust, pebbles and gradually rocks of the circumstellar disks that encircle a star after it has been born.  While the general outlines of this remarkable process are pretty well established, many questions large and small remain unanswered.

One is how and when exomoons are formed around these planets, with the assumption that the process that forms planets must also give birth moons.  But the potential moons have been far too small for the current generation of space and ground telescopes to identify.

Now astronomers have detected something almost as significant:  a circumplanetary disk surrounding a young planet that appears to be in the process of making moons.  The moon itself has not been detected, but a forming planet has been found with a ring of dust and gas that surrounds it.  And within that circumplanetary disk, astronomers infer, a moon is possibly being formed.

“Our work presents a clear detection of a disk in which satellites could be forming,” said Dr. Myriam Benisty, an astronomer at the University of Grenoble and the University of Chile.

“The new … observations were obtained at such exquisite resolution that we could clearly identify that the disk is associated with {the exoplanet} and we are able to constrain its size for the first time,” she said in a release.

While the first detection of the planet was made via the European Southern Observatory’s Very Large Telescope in Chile, the more granular observation of the forming planet and its moon-forming disk was made with the Atacama Large Millimeter/submillimeter Array (ALMA), also in Chile.

This ALMA image shows the young PDS 70 planetary system. The system features a star at its center and at least two planets orbiting it, PDS 70b (not visible in the image) and PDS 70c, surrounded by a circumplanetary disk (the dot to the right of the star). Image credit: ALMA / ESO / NAOJ / NRAO / Benisty et al.)

The finding, published in the Astrophysical Journal Letters, came via direct imaging — in effect through extremely high power photography rather through the indirect methods much more common in exoplanet astronomy.… Read more

Earth as a Transiting Exoplanet

A view of Earth and Sun from thousands of miles above our planet. Stars that enter and exit a position where they can see Earth as a transiting planet around our Sun are brightened. (OpenSpace/American Museum of Natural History)

Exoplanet scientists and enthusiasts spend a lot of time trying to find, measure and understand distant planets that can — under specific conditions — be detected as passing in front of their host star.  A majority of the 4000-plus exoplanets discovered so far were indirectly detected this way, by measuring the diminishing of stellar light as the exoplanet passes between the star and us.

In a conceptual turnaround, two researchers have now asked the question of how common it might be for beings on distant exoplanets to be able to similarly detect and measure Earth as it transits in front of our sun.

Astronomers call this special vantage point in space – the point from which Earth transits can be seen – the Earth transit zone.  Because the cosmos is dynamic and ever-changing, they looked for not only stars that are in that zone now, but have also passed through over the past 5,000 years and will in the next 5,000 years.

“From the exoplanets’ point-of-view, we are the aliens,” said Lisa Kaltenegger, director of the Carl Sagan Institute at Cornell University.

“We wanted to know which stars have the right vantage point to see Earth, as it blocks the sun’s light.  And because stars move in our dynamic cosmos, this vantage point is gained and lost.”


Transit data are rich with information. By measuring the depth of the dip in brightness and knowing the size of the star, scientists can determine the size or radius of the planet. The orbital period of the planet can be determined by measuring the elapsed time between transits. Once the orbital period is known, Kepler’s Third Law of Planetary Motion can be applied to determine the average distance of the planet from its stars. (NASA/Ames)

How many stars (and their orbiting planets) have this proper vantage point, have had in the past and will in the future?

In Kaltenegger’s paper, published in Nature with Jackie Faherty of the astrophysics department of the American Museum of Natural History, the numbers reported are quite low.

They found that since the earliest human civilization about 5,000 years ago, only 1,715 stars among the 300,000-plus that shine within 300 light years of our sun are in the right geometric alignment for an observation of Earth passing in front of our sun. Read more

Will The Habitable Exoplanet Observatory (HabEx) — Or Something Like It — Emerge As NASA’s Next Great Observatory?

Artist impression of HabEx spacecraft and a deployed starshade 47,000 miles away, with an exoplanet made visible by the starshade’s blocking of stellar light. (NASA)

Some time later this summer, it is predicted, the National Academy of Sciences will release its long-awaited Decadal Survey for astrophysics, which is expected to recommend the science and architecture that NASA should embrace for its next “Great Observatory.”

Many Worlds earlier featured one of the four concepts in the running — LUVOIR or the Large UV/Optical/IR Surveyor.  With a segmented mirror potentially as wide as 50 feet in diameter, it would revolutionize the search for habitable exoplanets and potentially could detect one (or many) distant planets likely to support life.

Proposed as a “Great Observatory” for the 2030s in the tradition of the Hubble Space Telescope and the James Webb Space Telescope (scheduled to launch later this year), LUVOIR would allow for transformative science of not only exoplanets but many other fields of astronomy as well.

Also under serious consideration is the Habitable Exoplanet Observatory, HabEx, which would also bring unprecedented capabilities to the search for life beyond Earth.  Its mirror would be considerably smaller than that proposed for LUVOIR and it would have fewer chances to find an inhabited world.

But it is nonetheless revolutionary in terms of what it potentially can do for exoplanet science and it could come with a second spacecraft that seems to be out of science fiction,  designed to block out starlight so exoplanets nearby can be observed. That 52-meter (or 170-foot) petal-rimmed, light-blocking disc is called a starshade or an occulter, and it would fly 76,600 kilometers (or 47,000 miles) away from the HabEx spacecraft and would work in tandem with the telescope to make those close-in exoplanet observations possible.

While the capabilities of HabEx are fewer compared to LUVOIR and the potential harvest of habitable or inhabited planets is less, HabEx nonetheless would be cutting edge and significantly more capable than the Hubble Space Telescope in nearly every way, while also being less expensive than LUVOIR and requiring less of a technology reach.

Scott Gaudi, an Ohio State University astronomer, was co-chair of the NASA-created team that spent three years studying, engineering and then proposing the HabEx concept. He put the potential choice between HabEx and LUVOIR this way:  “Do you want to take a first step or a first leap?  HabEx is a major step; LUVOIR is a huge leap.”… Read more

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