Many Worlds

Category: The Search for Life Beyond Earth (page 1 of 10)

What the JWST is Learning About Exoplanet Atmospheres

April 5, 2023 / / 0 Comments

We are now well into the era of exoplanet atmospheres, of measurements made possible by the James Webb Space Telescope.  While prior observatories could detect some chemicals in exoplanet atmospheres,  the limits were substantial. This is an artist’s impression of a hot Jupiter with a thick atmosphere transiting its host star. (NASA, ESA, and G. Bacon (STScI)

The James Webb Space Telescope is beginning to reveal previously unknowable facts about the composition of exoplanets — about the presence or absence of atmospheres around the exoplanets and the makeup of any atmospheres that are detected.

The results have been coming in for some months and they are a delight to scientists.  And as with most things about exoplanets, the results are not always what were expected.

For instance, gas giant planets  orbiting our Sun show a clear pattern; the more massive the planet, the lower the percentage of “heavy” elements (anything other than hydrogen and helium) in the planet’s atmosphere.

The James Webb Space Telescope is returning insights into the atmospheres of exoplanets that scientists have long dreamed about obtaining. Some are predicting a new era in exoplanet research. (NASA)

But out in the galaxy, the atmospheric compositions of giant planets do not fit the solar system trend, an international team of astronomers has found.

Researchers discovered that the atmosphere of exoplanet HD149026b, a “hot jupiter” given the name “Smertrios” that orbits a Sun-like star, is super-abundant in the heavier elements carbon and oxygen – far above what scientists would expect for a planet of its mass.

In its “early release” program for exoplanet results, JWST also observed WASP-39 b, a “hot Saturn” (a planet about as massive as Saturn but in an orbit tighter than Mercury) orbiting a star some 700 light-years away.

The atmosphere around the planet provided the first detection in an exoplanet atmosphere of sulfur dioxide (SO2), a molecule produced from chemical reactions triggered by high-energy light from the planet’s parent star.

The Trappist-1 system –seven Earth-sized planets orbiting a red dwarf star only 40 light-years away — is another subject of great interest and JWST has provided some exciting results there too.

While the first Trappist-1 planet studied — the one nearest to the star — apparently has no atmosphere, JWST was able to in effect take the planet’s temperature.  The telescope captured thermal signatures from the planet, which is another first.

When starlight passes through a planet’s atmosphere, certain parts of the light are absorbed by the atmosphere’s elements.

… Read more

The JWST Discovers its First Earth-Sized Exoplanet

January 17, 2023 / / 0 Comments

Artist rendering of LHS 475 b, an Earth-sized exoplanet recently identified using the James Webb Space Telescope. This was the first planet of its size detected by the JWST. {NASA / ESA / CSA / Leah Hustak (STScI)}

In the search for life on distant planets, scientists generally focus on identifying Earth-sized, rocky planets, finding planets in their host star’s habitable zone, and having available the telescope power to read the chemical make-up of the atmospheres.

A relatively small number of Earth-sized exoplanets discovered by telescopes in space and on Earth have meet some of the key characteristics.  But now with the James Webb Space Telescope in operation, with its 21-foot high-precision mirror, scientists have been looking forward to finding small, rocky planets that meet all the key criteria.

And during its first year of operation, the JWST  has already found and studied one small planet that meets at least some or those criteria.  The planet identified, called LHS 475 b, is nearly the same size as Earth, having 99% of our planet’s diameter, scientists said, and is a relatively nearby 41-light-years away.

The research team that detected the small planet is led by Kevin Stevenson and Jacob Lustig-Yaeger, both of the Johns Hopkins University Applied Physics Laboratory.

The team chose to observe this target with Webb after reviewing targets of interest from NASA’s Transiting Exoplanet Survey Satellite (TESS), which hinted at the planet’s existence. Webb’s Near-Infrared Spectrograph (NIRSpec) captured the planet easily and clearly with only two transit observations.

“There is no question that the planet is there,” said Lustig-Yaeger. “Webb’s pristine data validate it.”

“With this telescope, rocky exoplanets are the new frontier.”

The TRAPPIST-1 system contains a total of seven known Earth-sized planets orbiting a weak red dwarf star. Three of the planets — TRAPPIST-1e, f and g — are located in the habitable zone of the star (shown in green in this artist’s impression), where temperatures are potentially moderate enough for liquid water to exist on the surface.  As a comparison to the TRAPPIST-1 system the inner part of the Solar System and its habitable zone is shown. (NASA)

Earth-sized exoplanets have been found earlier.  The Trappist-1 system, only 39 light-years away, is famously known to include seven small, rocky planets, and it was detected by a small, ground-based telescope.

The Kepler Space Telescope also detected a debated but significant number of Earth-sized planets during its nine-year survey of one small section of the distant sky last decade. … Read more

The World of Water Worlds

December 22, 2022 / / 1 Comment

Artist rendering of a water world exoplanet. NASA predicts that quite a few exist in the galaxies but none has been confirmed. Two new candidates have been put forward. (The Cosmic Companion)

Among the most intriguing types of exoplanet expected to be orbiting distant stars is the  “water world,” planets that are liquid to a far, far greater extent than on Earth.

Astronomers have theorized the existence of such planets and several candidates have been put forward, though not confirmed.  But the logic is strong enough for NASA scientists to conclude there are likely many of them in our galaxy.

Now two new potential water worlds have been proposed in a planetary system 218 light years away.

Using both the Hubble Space Telescope and data from the retired Spitzer Space Telescope, a team from Montreal has identified  the planets circling a red dwarf star.  Water, they propose, may well make up a significant portion of the planets.

Though the telescopes can’t directly observe the planets’ surfaces, other paths to identifying a water world are known.  By determining the planets’ densities through measurements of their weight and radii (and then volume), these planets — which would normally be described as “super-Earths because of their size — are lighter than rock worlds but heavier than gas-dominated ones.

… Read more

Many Complex Organic Compounds –Evolved Building Blocks of Life — Are Formed Where Stars Are Being Born

December 14, 2022 / / 0 Comments

The Taurus Molecular Cloud is an active site for star formation.  It is also filled with complex organic molecules, including the kind that are building blocks for life.  The Cloud is 450 light years away, but similar star-forming regions with complex organics are found thoughout the galaxy. (Adapted, ESA/Herschel/NASA/JPL-Caltech)

Recent reports about the detection of carbon-based organic molecules on Mars by the instruments of the Perseverance rover included suggestions that some of the organics may well have fallen from space over the eons, and were then preserved on the Martian surface.

Given the cruciality of organics as building blocks of life –or even as biosignatures of past life — it seems surely important to understand more about how and where the organics might form in interstellar space, and how they might get to Mars, Earth and elsewhere.

After all, “follow the organics” has replaced the NASA rallying cry to “follow the water” in the search for extraterrestrial life in the solar system and cosmos.

And it turns out that seeking out and identifying organics in space is a growing field of its own that has produced many surprising discoveries.  That was made clear during a recent NASA webinar featuring Samantha Scibelli of the University of Arizona, a doctoral student in astronomy and astrophysics who has spent long hours looking for these organics in space and finding them.

She and associate professor of astronomy Yancy Shirley have been studying the presence and nature of complex organics in particular in a rich star-forming region, the Taurus Molecular Cloud.

Using the nearby radio observatory at Kitt Peak outside of Tucson, she has found a range of complex organics in starless or pre-stellar cores with the Cloud.  The campaign is unique in that some 700 hours of observing time were given to them, allowing for perhaps the most thorough observations of its kind.

The results have been surprising and intriguing.

In this mosaic image stretching 340 light-years across, the James Webb’s Near-Infrared Camera (NIRCam) displays the Tarantula Nebula star-forming region in a new light, including tens of thousands of never-before-seen young stars that were previously shrouded in cosmic dust. The most active region appears to sparkle with massive young stars, appearing pale blue. (NASA/STScI)

A first take-away (surprising to those unfamiliar with the field) is that complex organics are often detected in these star-forming regions throughout the galaxy and cosmos — just as they were found in many regions of the Taurus cloud.… Read more

Tantalizing Organic Compounds Found on Mars

November 29, 2022 / / 1 Comment

The NASA/ESA Perseverance rover on xxx. New findings tell of the presence of organic material — the building blocks of life — in several locations at Jezero Crater — for the first time found in igneous rock.  The long-ago environment when the organics were deposited were deemed to have been “habitable.” (NASA/JPL-Caltech/MSSS)

When searching for signs of ancient life on Mars, NASA scientists increasingly focus on organic material — the carbon-based compounds that are the building blocks of life.  Organics were found by the Curiosity rover in Gale Crater, and now new papers report they have also been identified by the instruments of the Perseverance rover in very different kinds of rock in Jezero Crater.

Unlike the Gale Crater organics that were found in sedimentary rocks, these newly found specimens are in igneous rocks — formed when molten rock cools and crystallizes — and are mixed with other compounds known to preserve organics well.

These rock samples are part of the NASA and European Space Agency Mars Sample Return mission, and so they could be brought to Earth in the future for more intensive study. Scientists are excited about what might some day be found.

The new findings about organics and the geology of Jezero Crater are part of a trio of articles in the journal Science published Wednesday.

The lead author of one of the papers, Michael Tice of Texas A&M University, gave this overview of what the Perseverance team is reporting:

“These three papers show that samples collected in the floor of Jezero should be able to tell us a lot about whether living organisms ever inhabited rocks under the surface of the crater over the past several billion years,”  he wrote to me.

The paper he led, Tice said, shows that small amounts of water passed through those rocks at three different times, and that conditions at each of those times could have supported life. “Even more importantly, minerals were formed from the water that are known to be able to preserve organic matter and even fossils on Earth.”

Different kinds of carbon-based organic compounds were viewed within a rock called “Garde” by SHERLOC, one of the instruments on the end of the robotic arm aboard the Perseverance rover. The rover used its drill grind away a patch of rock so that SHERLOC (Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals) could analyze its interior.

… Read more

Where Might Plumes of Water Vapor Come From on Icy Moons?

October 12, 2022 / / 0 Comments

This illustration depicts a plume of water vapor that could potentially be emitted from the icy surface of Jupiter’s moon Europa. New research sheds light on what plumes, if they do exist, could reveal about lakes that may be inside the moon’s crust. (NASA/ESA/K. Retherford/SWRI)

It’s been some years since Europa scientists agreed that the Jovian moon has a large global ocean beneath miles of ice.  More recently, scientists have identified what they view as pockets of water surrounded by ice but much nearer the surface than the ocean below.  And there has been research as well into what may be salty, slushy pocket of water further down in the ice covering.

With NASA’s mission to Europa scheduled to launch in about two years, modeling of these all potential collections of liquid water has picked up to prepare for the Europa Clipper arrival to come.

The latest research into what the subsurface lakes on Europa may look like and how they may behave comes in a recently published paper in Planetary Science Journal.

A key finding supports the idea that water could potentially erupt above the surface of Europa either as plumes of vapor or as cryovolcanic activity —  flowing, slushy ice rather than molten lava.

Computer modeling in the paper goes further, showing that if there are eruptions on Europa, they likely come from shallow, wide lakes embedded in the ice and not from the global ocean far below.

“We demonstrated that plumes or cryolava flows could mean there are shallow liquid reservoirs below, which Europa Clipper would be able to detect,” said Elodie Lesage, Europa scientist at NASA’s Jet Propulsion Laboratory and lead author of the research.

“Our results give new insights into how deep the water might be that’s driving surface activity, including plumes. And the water should be shallow enough that it can be detected by multiple Europa Clipper instruments.”

A minimally processed version of this image was captured by JunoCam, the public engagement camera aboard NASA’s Juno spacecraft. It was taken during the mission’s close flyby earlier this fall, almost 950 miles above the moon’s surface. The raw image was processed by “citizen scientist” Navaneeth Krishnan to add enhanced color contrast that allow larger surface features to stand out more.

The question of whether or not Europa has plumes is not settled.  While the plumes coming from Saturn’s moon Enceladus have been well studied and even had a spacecraft fly through one, Europa has only some fuzzy Hubble Space Telescope, Galileo mission and ground-based telescope images that suggest a plume.… Read more

The Virtual Planetary Lab and Its Search for What Makes an Exoplanet Habitable, or Even Inhabited

September 14, 2022 / / 0 Comments

As presented by the Virtual Planetary Laboratory, exoplanet habitability is a function of the interplay of processes between the planet, the planetary system, and host star.  These interactions govern the planet’s evolutionary trajectory, and have a larger and more diverse impact on a planet’s habitability than its position in a habitable zone. (Meadows and Barnes)

For more than two decades now, the Virtual Planetary Laboratory (VPL) at the University of Washington in Seattle has been at the forefront of the crucial and ever-challenging effort to model how scientists can determine whether a particular exoplanet is capable of supporting life or perhaps even had life on it already.

To do this, VPL scientists have developed or combined models from many disciplines that characterize and predict a wide range of planetary, solar system and stellar attributes that could identify habitability, or could pretty conclusively say that a planet is not habitable.

These include the well known questions of whether water might be present and if so whether temperatures would allow it to be sometimes in a liquid state, but on to questions involving whether an atmosphere is present, what elements and compounds might be in the atmospheres, the possible orbital evolution of the planet, the composition of the host star and how it interacts with a particular orbiting planet and much, much more, as shown in the graphic above.

This is work that has played a significant role in advancing astrobiology — the search for life beyond Earth.

More specifically, the VPL approach played a considerable part in building a body of science that ultimately led the Astro2020 Decadal Study of the National Academy of Sciences to recommend last year that the NASA develop its  first Flagship astrobiology project — a mission that will feature a huge space telescope able to study exoplanets for signs of biology in entirely new detail.  That mission, approved but not really defined yet, is not expected to launch until the 2040s.

With that plan actually beginning to move forward, the 132 VPL affiliated researchers at 28 institutions find themselves at another more current-day inflection point:  The long-awaited James Webb Space Telescope has begun to collect and send back what will be a massive and unprecedented set of spectra  of chemicals from the atmospheres of distant planets.

The Virtual Planetary Laboratory has modeled the workings of exoplanets since 2001, looking for ways to predict planetary conditions based on a broad range of measurable factors.

… Read more

A Detailed New Mapping of Where Mars Once Had Plentiful Water

September 8, 2022 / / 0 Comments

Measurements from the OMEGA instrument of European Space Agency’s Mars Express and NASA’s Mars Reconnaissance Orbiter’s CRISM spectrometer were used to map where formed-in-water minerals can found across Mars. This is an especially concentrated spot at Jezero Crater, where the Perseverance rover is located. (ESA)

NASA’s long-time motto for exploring Mars has been “Follow the water.”  That has changed some in recent years, as the presence of long-ago H2O has been confirmed in many locales around the planet.   Moving on, the motto today is more “Follow the organics” — the carbon-based building blocks of life — in the search for habitable environments and maybe signs of ancient life.

But water remains crucial to any discussion of habitability on Mars, and so a new set of global water maps from the European Space Agency, ten years in the making, is both useful and intriguing.

Specifically, the map shows the locations and abundances of these aqueous minerals — rocks that have been chemically altered by the action of water in the past, and have typically been transformed into clays and salts.

And the message that the maps deliver, said planetary scientist John Carter, is that these hydrated minerals are common across many parts of the planet.

Ten years ago, planetary scientists knew of around 1, 000 water-altered outcrops on Mars, he said.  This made them interesting as geological oddities.

But the new map has reversed the situation, revealing hundreds of thousands of such areas in the oldest parts of the planet.

“This work has now established that when you are studying the ancient terrains in detail, not seeing these minerals is actually the oddity,” says Carter, an assistant professor at the Institut d’Astrophysique Spatiale (IAS) in  France.

Global map of hydrated minerals on Mars. (ESA)

Now, Carter said in a release, the big question is whether the water was persistent or confined to shorter, more intense episodes. While not yet providing a definitive answer, the new results certainly give researchers a better tool for pursuing the answer.

“I think we have collectively oversimplified Mars,” says Carter, who was lead author in a paper published in the journal Icarus.

He explained that planetary scientists have tended to think that only a few types of clay minerals on Mars were created during its wet period — roughly 3.5 billion to 4 billion years ago — then as the water gradually dried up salts were produced across the planet.

… Read more

The James Webb Space Telescope Begins Looking at Exoplanets

August 24, 2022 / / 0 Comments

 

Artist rendering of Gliese (GJ) 436 b  is a Neptune-sized planet that orbits a red dwarf  star.  Red dwarfs are cooler, smaller, and less luminous than the Sun. The planet completes one full orbit around its parent star in just a little over 2 days. It is made, scientists say, of extremely hot ice.  (NASA/JPL-Caltech/UCF)

The James Webb Space Telescope has begun the part of its mission to study the atmospheres of 70 exoplanets in ways, and at a depth, well beyond anything done so far.

The telescope is not likely to answer questions like whether there is life on distant planet — its infrared wavelengths will tell us about the presence of many chemicals in exoplanet atmospheres but little about the presence of the element most important to life on Earth, oxygen.

But it is nonetheless undertaking a broad study of many well-known exoplanets and is likely to produce many tantalizing results and suggest answers to central questions about exoplanets and their solar systems.

Many Worlds has earlier looked at the JWST “early release” program, under which groups are allocated user time on the telescope under the condition that they make their data public quickly.  That way other teams can understand better how JWST works and what might be possible.

Another program gives time to scientists who worked on the JWST mission and on its many instruments.  They are given guaranteed time as part of their work making JWST as innovative and capable as it is.

One of the scientist in this “guaranteed time observations program” is Thomas Greene, an astrophysicist at NASA Ames Research Center.  The groups he leads have been given 215 hours of observing time for this first year (or more) of Cycle 1 of JWST due to his many contributions to the JWST mission as well as his history of accomplishments.

In a conversation with Greene, I got a good sense of what he hopes to find and his delight at the opportunity.  After all, he said, he has worked on the JWST idea and then mission since 1997.

“We will be observing a diverse sample of exoplanets to understand more about them and their characteristics,” Greene said.  “Our goal is to get a better understanding of how exoplanets are similar to and different from those in our solar system.”

And the JWST spectra will tell them about the chemistry, the composition and the thermal conditions on those exoplanets, leading to insights into how they formed, diversified and evolved into planets often so unlike our own.… Read more

Icy Moons, And Exploring The Secrets They Hold

August 18, 2022 / / 0 Comments

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

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