Category: Exoplanets (page 1 of 13)

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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The James Webb Space Telescope And Its Exoplanet Mission (Part 1)

 

This artist’s conception of the James Webb Space Telescope in space shows all its major elements fully deployed. The telescope was folded to fit into its launch vehicle, and then was slowly unfolded over the course of two weeks after launch. (NASA GSFC/CIL/Adriana Manrique Gutierrez)

 

The last time Many Worlds wrote about the James Webb Space Telescope, it was in the process of going through a high-stakes, super-complicated unfurling.  About 50 autonomous deployments needed to occur after launch to set up the huge system,  with 344 potential single point failures to overcome–individual steps that had to work for the mission to be a success.

That process finished a while back and now the pioneering observatory is going through a series of alignment and calibration tests, working with the images coming in from the 18 telescope segments to produce one singular image.

According to the Space Telescope Science Institute,  working images from JWST will start to appear in late June, though there may be some integrated  “first light” images slightly earlier.

Exciting times for sure as the observatory begins its study of the earliest times in the universe, how the first stars and galaxies formed, and providing a whole new level of precision exploration of exoplanets.

Adding to the very good news that the JWST successfully performed all the 344 necessary steps to unfurl and that the mirror calibration is now going well is this:  The launch itself went off almost exactly according to plan.  This means that the observatory now has much more fuel on hand than it would have had if the launch was problematic. That extra fuel means a longer life for the observatory.

 

NASA announced late last month that it completed another major step in its alignment process of the new James Webb Space Telescope, bringing its test images more into focus. The space agency said it completed the second and third of a seven-phase process, and had accomplished “Image Stacking.” Having brought the telescope’s mirror and its 18 segmented parts into proper alignment, it will now begin making smaller adjustments to the mirrors to further improve focus in the images. (NASA/STScI)

Before launch, the telescope was expected to last for five years.  Now NASA has said fuel is available for a ten year mission and perhaps longer.  Quite a start.

(A NASA update on alignment and calibration will be given on Wednesday. … Read more

More On The Very Hot Science of Stellar Flares and Their Implications For Habitability

A solar flare, imaged by NASA’s Solar Dynamics Observatory.

Among the many scientific fields born, or reborn, by the rise of astrobiology and its search for life beyond Earth is the study of stars, including our own Sun.  Now that we know that planets — from the large and gaseous to the small and rocky — are common in our galaxy and number in the many, many billions, there is suddenly vast amount of real estate where life potentially could arise.

We already know that many of those planets large and small are not candidates for habitability for any number of reasons, and that makes the understanding of what general conditions are required for life all the more pressing.

And as the astrobiological effort speeds ahead, it has become clear that the make-up, behavior and location of the stars that host exoplanets is central to that understanding.

Many stellar issues are suddenly important, and perhaps none more so than the nature, frequency and consequences of the constant stellar eruption of  flares, superflares and coronal mass ejections.

Created as intense bursts of radiation coming from the release of magnetic energy following reconnections in stars’ coronas, flares and related coronal mass ejections are the largest explosive events in solar systems. The energy released by a major flare from our Sun is about a sixth of the total solar energy released each second and equal to 160,000,000,000 megatons of TNT

The current focus of study is flares coming off red dwarf stars — much smaller and less energetic than our Sun, but the most common stars in the galaxy, by a lot.  Many are already known to have multiple rocky planets within a distance from the star termed the “habitable zone,” where in theory water could sometimes be liquid.

But red dwarf stars universally experience intense flaring in their early periods, and the planets orbiting in the those red dwarf habitable zones can be 20 times closer to their stars than we are to the Sun.

The crucial question is whether those flares forever sterilize the planets in their systems, which is certainly a possibility.  But a related question is whether the flares might also deliver amounts of ultraviolet radiation that may be essential to the formation of the chemical building blocks of life.

Not surprisingly, this is a subject of not only intense study but of heated debate as well.

Violent stellar flares from young red dwarf stars, as illustrated here, could potentially evaporate the atmosphere of a planet.

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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

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

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

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

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