Category: Planetary Systems (page 1 of 13)

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

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

And Then There Were Three: ESA Follows NASA in Selecting a Mission to Venus

Artist illustration of the EnVision orbiter at Venus (ESA/VR2Planets/DamiaBouic)

It was quite a week for Venus scientists. Just seven days after NASA announced the selection of two Venus missions, DAVINCI+ and VERITAS, the European Space Agency (ESA) revealed that a third Venus mission had been chosen for the agency’s medium-class mission category.

(See last week’s post here on Many Worlds about DAVINCI+ and VERITAS)

The new mission is named EnVision, and will be ESA’s second Venus mission following Venus Express (2005 – 2014), which investigated the Venusian climate. While EnVision is an orbiter like Venus Express and VERITAS, its focus is the planet’s geological circulation system that links the atmosphere, surface and interior.

In case you are starting to get your Venus missions in a tangle, the set can be broadly divided up as follows:

Venus Express (ESA: 2005 – 2014) and Akatsuki (JAXA: 2015 – current) are both Venus orbiters focussed on the planet’s climate, returning information about the rapidly rotating upper atmosphere and acidic cloud deck of Venus.

DAVINCI+ (NASA: est. 2029 launch) is an orbiter and descending probe that will dive through the Venusian atmosphere to return top-to-bottom data on the planet’s stifling gases.

VERITAS (NASA: est. 2028 launch) is an orbiter focussed on Venus’s surface and the deep interior. VERITAS will bring us global maps in three-dimensions at a resolution of 30m. This will knock the socks off our current images from NASA’s Magellan orbiter (1989 – 1994), which had a resolution of around 200m.

EnVision (ESA: early 2030s) is the mission focused on how these environments are linked together. Equipped with an instrument suite that covers the top of the atmosphere through to below the planet surface, EnVision will probe how the different regions influence one another to create the planet’s internal systems.

“EnVision has a holistic approach,” explained Jörn Helbert who is a member of the EnVision team. “The larger and more complex payload studies Venus from the top of the atmosphere all the way to the subsurface, with a focus on understanding how the coupled system on Venus works.”

Artist illustration of the EnVision spacecraft, reflecting the goal of understanding why Venus and Earth are so different (NASA / JAXA / ISAS / DARTS / Damia Bouic / VR2Planets).

The coupled system is at the heart of how habitability can develop on rocky planets. A major player in the Earth’s environment is the ability to cycle carbon between the atmosphere, surface and planet mantle.… Read more

Return to Hell: NASA Selects Two Missions to Venus to Explore the Pathway to Habitability

Artists’ renderings show the VERITAS spacecraft (left) and DAVINCI+ probe (right) as they arrive at Venus (Lockheed Martin).

For NASA scientists, Venus missions must feel like buses. You wait thirty years for one, and then two come along at once.

Last week, NASA selected two Venus missions for the space agency’s Discovery Program; solar system exploration missions that can tuck under a lower cost cap than candidates for NASA’s New Horizons or Flagship categories. The first of these is DAVINCI+, which is an orbiter equipped with a descending probe that will take a big whiff of Venus’s stifling atmosphere. The second is the VERITAS orbiter that plans to peer through the clouds to scrutinise the Venusian surface.

While Europe and Japan have both visited Venus more recently than NASA (in fact, the Japanese orbiter is still there), there is little doubt that our inner neighbor is dramatically under-explored compared to Mars. But why the past neglect, and why go twice now?

The answer to the first question is perhaps the easiest.

Venus is hell.

The planet is wrapped in a thick atmosphere consisting of carbon dioxide and clouds of sulfuric acid that beat down on the Venusian surface with pressures nearly one hundred times higher than on Earth and create temperatures sufficient to melt lead.

These conditions have made it difficult to follow the usual pattern of planetary exploration from fly-bys and orbiters to landers and rovers. The Venusian surface is so inhospitable that a rover like NASA’s Mars Perseverance would become rover goop. Although recent engineering combined with high-temperature electronics means that the surface is no longer impossible, it does greatly add to the challenge (and therefore cost) of a lander mission.

Professor Stephen Kane, University of California, Riverside.

Hell-scape conditions have also resulted in Venus being overlooked for any astrobiological studies compared to (the still rather nasty but at least you can stand a rover on the surface) Mars. This makes the urgency to explore Venus now particularly surprising. The missions are a quest to understand habitability. The bottom line is that the hell world of Venus is essential to understanding how a planet becomes habitable and to discovering other habitable worlds outside our solar system.

“Imagine you live in a small town full of life,” explains Professor Stephen Kane from the DAVINCI+ team. “The nearest town is the same size and seems it was once identical. But now, it’s burned to the ground with no sign of life.… Read more

Sure UFOs Exist. But There’s No Reason To Conclude That Aliens Are Flying Them

An apparently unidentified object detected on a Navy plane’s infrared camera. (U.S. Department of Defense/Navy Times)

It seems to happen with some regularity.  Claims that Unidentified Flying Objects are visiting us have captured the public imagination once more and a big reveal is expected soon.

That will come, oddly, from a government report required to be released by the end of June that will supposedly detail the many sightings made by high-flying military pilots and unexplained detections by satellites.  The requirement was added to the Covid relief package that was passed by Congress in December and orders the Department of Defense and the Office of the DIrector of National Intelligence to release their unclassified findings on the subject, information that has been apparently collected for decades.

In terms of national defense, these reports could indeed be meaningful.  If other nations are sending

This well known poster was first introduced during an episode of the 1990s television show, “The X Files.” and featured in a subsequent movie.

drones or satellites of some sort (true UFOs) to get close to and study American assets, then that’s important news.

But, of course, the UFO drama is overwhelmingly about something else:  The claimed presence of intelligent aliens that are scoping out Earth for reasons ranging from awe-inspiring or extremely worrisome.

The report — which sources say concludes that there is insufficient evidence to confirm or conclusively rule out extraterrestrial UFO sightings —  will no doubt be widely consumed by a population with many “UFO believers.”  After all, a 2019 Gallup poll found that 33 percent of American adults said that alien spacecraft from distant planets and galaxies have been visiting us.

I find all this to be not only unfortunate but also misguided and potentially damaging.  The moment will pass with no intelligent aliens identified, and then will return again some time in the future for another round.

The potential damage is to the very real, very challenging, very cutting-edge science being conducted around the world that seeks to identify actual signs of actual extraterrestrial life in the cosmos, or at least to know what to look for when we have space telescopes and instruments with the necessary power.

And I’m concerned that a focus on UFOs imagined to be carrying intelligent alien life takes away from the hard-won seriousness of their enormous and so compelling scientific effort.  This is especially true now that the scientific search for extraterrestrial life is on the front burner for the National Academy of Sciences, which will soon make recommendations about a next grand observatory for the 2030s.… Read more

China’s Presence in Space Grows and So Do Its Accomplishments

The Chinese Mars lander, with photo taken by the Zhurong rover after it rolled down onto the surface of Mars. (Chinese National Space Administration)

These are heady days for the Chinese space program.

On the heels of a successful 2019 mission to the dark side of the moon and the launch of the core of an ambitious low Earth orbit space station,  the Chinese National Space Administration has done what only NASA has accomplished before — landing a rover on Mars and then setting it into motion on the surface of the planet.

The Zhurong rover, which is named after an ancient fire god in Chinese mythology, rolled off its lander on Saturday and has begun its planned three-month mission.

The rover carries instruments to study the planet’s surface rocks and atmosphere using radar, spectroscopy and a magnetic field detector. It will also look for signs of life, including any subsurface water or ice.

The solar-powered, 530-pound and  six-wheeled robot will be exploring Utopia Planitia in Mars’ northern hemisphere – the general area where NASA’s Viking 2 lander touched down in 1975.  Zhurong will join NASA’s much larger (more than 2,200 pound) Perseverance and Curiosity rovers now operating on Mars.

“We hope we can get a comprehensive covering of Martian topography, landform and environment, and the exploratory data of the radar detecting the Martian subsurface during one Martian year,” said deputy chief commander of the mission, Zhang Yuhua.

“By doing so, our country will have our own abundant and first-hand data about Martian resources,” she said.

The Chinese Mars lander is powered by solar panels and is expected to explore for at least three months.  (Rendering by the Chinese National Space Administration)

While the rover will itself not bring many new technologies and approaches to Mars science, the architecture of the mission is unprecedented.  The Tianwen-1 spacecraft that brought the rover to Mars orbited the planet for more than three months before deploying the lander and rover.  Part of the spacecraft will remain in orbit as a communications hub.

All NASA missions have flown directly to the surface without first going into orbit around Mars.

While the Utopia Planitia region was explored to some extent by Viking 2, much more is known about the region now then was known in the 1970s.

The plains are part of the northern lowlands of Mars, and some theorize that the region was once covered by a great “Northern Ocean.”  Read more

Breakthrough Listen Searches The Crowded Center of the Milky Way for Possible Signals From Intelligent Beings

The Galactic Center from radio to X-ray frequencies.  ( X-Ray: NASA, CXC, UMass, D. Wang et al.; Radio: NRF, SARAO, MeerKAT)

Searching for technologically advanced civilizations inhabiting distant exoplanets is the astrobiological equivalent of swinging for the fences.

While much of the search of extraterrestrial life is now focused on microbes and chemical biosignatures in exoplanet atmospheres that would likely be byproducts of life, the search for extraterrestrial intelligence (or SETI) takes a very different approach.

SETI practitioners scan the skies for radio signals, and now laser signals, that are irregular and different from what is naturally produced.  Were such a signal to be detected, then it would be studied as the potential work of extraterrestrial life that is highly advanced — perhaps far more so than we Earthlings.

This search has been going on since Cornell University astronomer Frank Drake began it 1960 and has advanced (in steps large and small) ever since.  The biggest financial boost to the search took place five years ago when techno-billionaire Yuri Milner, in partnership with Stephen Hawking and other prominent scientists,  set up the Breakthrough Listen project with $100 million to buy telescope time and to greatly expand the SETI search.

And as part of that expanded search, radio telescopes focused on the crowded galactic center of the Milky Way for 600 observing hours.  The thinking was that stars and likely exoplanets are most plentiful in that central region — some 60 million  stars in the line of sight into the galactic center at low astronomical frequencies; 500,000 at higher frequencies  — and so the chances of finding a signal were perhaps higher.

Some preliminary and partial results of that effort were recently released and, unfortunately, no signals were found.  That has been the fate of all SETI searches so far.

But as SETI scientists explain, the night sky is huge and the percentage of stars (and their exoplanets) that have been sampled remains quite small.

The Green Bank Radio Observatory in West Virginia is one of the two main sites for the Breakthrough Listen galactic center campaign.  The other is the Parkes Telescope in Australia . (NRAO)

This latest effort was unique in that it was the “most sensitive and deepest targeted SETI” survey ever done of the galactic center, as the SETI scientists write in a study set to be published in the Astronomical Journal (a preprint is currently available on the arXiv).… Read more

The Space Telescope That Could Find a Second Earth

This rare picture of an exoplanet (called 2M1207B) shows a red world several times Jupiter’s size orbiting a brown dwarf much smaller and dimmer than our sun. LUVOIR is after more elusive targets: small, rocky planets around bright stars. (ESO)

What will it take to capture images and spectra of a distant world capable of harboring life?
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For all the excitement surrounding the search for distant exoplanets in recent years, the 4,000-plus planets confirmed so far have been unseen actors on the cosmic stage. Except for a handful of very large bodies imaged by ground-based telescopes, virtually all exoplanets have been detected only when they briefly dim the light coming from their host stars or when their gravity causes the star to wobble in a distinctive way. Observing these patterns and using a few other methods, scientists can determine an exoplanet’s orbit, radius, mass, and sometimes density—but not much else. The planets remain, in the words of one researcher in the field, “small black shadows.”

Scientists want much more. They’d like to know in detail the chemical makeup of the planets’ atmospheres, whether liquid water might be present on their surfaces, and, ultimately, whether these worlds might be hospitable to life.

Answering those questions will require space telescopes that don’t yet exist. To determine what kinds of telescopes, NASA commissioned two major studies that have taken large teams of (mostly volunteer) scientists and engineers four years to complete. The results are now under review by the National Academy of Sciences, as part of its Decadal Survey for Astronomy and Astrophysics that will recommend government funding priorities for the 2030s. Past and current NASA mega-projects, from the Hubble Space Telescope launched in 1990 to the James Webb Space Telescope, which is scheduled for launch this year, have all gone through this same vetting process. Sometime this spring, the Decadal Survey is expected to wrap up its deliberations and make recommendations.

That puts four proposals in the running to become NASA’s next “Great Observatory” in space: an X-ray telescope called Lynx; the Origins Space Telescope for studying the early universe; and two telescopes devoted mostly, but not exclusively, to exoplanets. One is called HabEx, for Habitable Exoplanet Observatory. The other—the most ambitious, most complex, most expensive, and most revolutionary of all these concepts—is called LUVOIR, for Large UV/Optical/IR Surveyor.… Read more

A Close Exoplanet Found That May Have An Atmosphere Ideal For Study

Planet Gliese 486b is close to us (in a relative sense), rocky, on the small side and may have an atmosphere.  These conclusions come from studying the planet using both the transit and radial velocity techniques, which have been the primary methods used by astronomers to find and characterize exoplanets.  Charts showing the presence of the planet using both techniques are in the blue boxes. (Render Area, Max Planck Institute for Astronomy, MPIA)

Different methods of searching for and finding distant exoplanets give different information about the planets found.

The transit method — where an exoplanets passed in front of its sun and dims the bright sunlight ever so slightly — gives astronomers not only a detection but also its radius or size.

The radial velocity method — where an exoplanet’s gravity causes its host star to “wobble” in a way that can be measured — provides different information about mass and orbit.

If a planet can be measured by both the transit and radial velocity methods, an important added dimension can be determined — how dense the planet might be.  This tells us if the planet is rocky or gaseous, watery or even if it has a central core and might have an atmosphere.  So many things have to go right that this kind of dual detection has seldom been accomplished for a  relatively small and rocky planet, but such a new planet has now been found.

The planet, Gliese 486b, is a super-Earth orbiting its host star at only 24 light-years away.  That makes the planet the third closest transiting exoplanet to Earth that is known, and the closest with a measured mass that transits a red dwarf star.

The authors of the study in the journal Science say Gliese 486b is an ideal candidate for learning how to best search for and characterize an all-important atmosphere, and to study potential habitability, too.  Future telescopes will make this kind of work more of a reality.

“Gliese 486 b is not hot enough to be a lava world,” lead author Trifon Trifonov of the Max-Planck-Institut für Astronomie and colleagues write. “But its temperature of ~700 Kelvin (800 degrees Fahrenheit) makes it suitable for emission spectroscopy and …. studies in search of an atmosphere.”

Artist impression of the surface of the newly discovered hot super-Earth Gliese 486 b. With a temperature of about 700 Kelvin (almost 800 degrees Fahrenheit), 486b possibly has an atmosphere.

Read more

New Insights Into How Earth Got Its Nitrogen

An artist’s conception shows a protoplanetary disk of dust and gas around a young star. New research by Rice University shows that Earth’s nitrogen came from both inner and outer regions of the disk that formed our solar system, contrary to earlier theory.  (NASA/JPL-Caltech)

Scientists have long held that many of the important compounds and elements that make life possible on Earth arrived here after the planet was formed and was orbiting the sun.  These molecules came via meteorites and comets, it was thought,  from the colder regions beyond Jupiter.

But in a challenge to that long-accepted view, a team from Rice University has found isotopic signatures of nitrogen from both the inner and the outer disk in iron meteorites that fell to Earth.  What this strongly suggests is that the seeds of rocky, inner solar system planets such as Earth were bathed in  dust that contained nitrogen and other volatiles, and the growing planet kept some of that “local” material.

“Our work completely changes the current narrative,” said Rice University graduate student and lead author Damanveer Grewal. “We show that the volatile elements were present in the inner disk dust, probably in the form of refractory (non-gaseous) organics, from the very beginning. This means that contrary to current understanding, the seeds of the present-day rocky planets — including Earth — were not volatile-free.”

The solar protoplanetary disk was separated into two reservoirs, with the inner solar system material having a lower concentration of nitrogen-15 and the outer solar system material being nitrogen-15 rich. The nitrogen isotope composition of present-day Earth lies in between, according to a new Rice University study that shows it came from both reservoirs. (Credit: Illustration by Amrita P. Vyas)

This work helped settle a prolonged debate over the origin of life-essential volatile elements — such as hydrogen, water, carbon dioxide, methane, nitrogen, ammonia — on Earth and other rocky bodies in the solar system.

“Researchers have always thought that the inner part of the solar system, within Jupiter’s orbit, was too hot for nitrogen and other volatile elements to condense as solids, meaning that volatile elements in the inner disk were only in the gas phase,” Grewal said.

Because the seeds of present-day rocky planets, also known as protoplanets, grew in the inner disk by accreting locally sourced dust, he said it appeared they did not contain nitrogen or other volatiles because of the high temperatures, necessitating their delivery from the outer solar system.… Read more

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