Astrobiology

Category: Astrobiology (page 1 of 14)

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?

June 28, 2021 / Marc Kaufman / 0 Comments

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

UFOs, Redux

June 26, 2021 / Marc Kaufman / 0 Comments

A U.S. government report found that there was no evidence to conclude that the more than 140 unidentified flying object sightings in recent years involved extraterrestrial beings.

The government was unable to determine whether the flying mysteries were atmospheric events distorting readings from sensors, confusions in judging objects in motion, spacecraft from other potential hostile or whether the objects were extraterrestrial in origin.

But the long-anticipated report released Friday by the nation’s top intelligence official made clear that although the presence of aliens couldn’t be 100 percent ruled out, there was no evidence at all that they were commanding the UFOs.

Here is a link to the full report.

And here is the Many Worlds take of on the UFO issue from earlier this month:

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

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

June 3, 2021 / Marc Kaufman / 1 Comment

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

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

May 10, 2021 / Marc Kaufman / 0 Comments

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

Novel Sights and Sounds on Mars

April 28, 2021 / Marc Kaufman / 1 Comment

The helicopter Ingenuity has now flown three times on Mars and has proven itself to be a dependable (for now) and potentially ground-breaking addition to Mars science.

Ingenuity, brought to Mars as part of the Perseverance rover landing, took off early Sunday morning on its third and most ambitious Martian mission yet. The 4-pound helicopter traveled a total of 330 feet laterally, stayed aloft for 80 seconds and reached a maximum speed of about 4.5 mph, handily breaking marks set on its previous two flights.

In the video above, you can see the helicopter taking off on the bottom left, crossing the screen, and then coming back a bit later to land in the same spot.

The “flight was what we planned for, and yet it was nothing short of amazing,” said Dave Lavery, the Ingenuity program executive at NASA Headquarters. “With this flight, we are demonstrating critical capabilities that will enable the addition of an aerial dimension to future Mars missions.”

If this capacity proves to be robust it will clearly have many positive implications for Mars science with successor rotorcraft — allowing scientists to quickly study areas surrounding a rover and to put their discoveries into larger geological contexts.

Ingenuity rover preparing to go airborne. The wings, legs and more were folded up for its long ride to Mars and then robotically unfurled on the Martian surface. (NASA)

The Mastcam-Z imager aboard NASA’s Perseverance Mars rover, which is parked at “Van Zyl Overlook” and serving as a communications base station, captured video of Ingenuity.

The Ingenuity team has been pushing the helicopter’s limits by adding instructions to capture more photos of its own – including from the color camera, which captured its first images on the second flight. As with everything else about these flights, the additional steps are meant to provide insights that could be used by future aerial missions.

The helicopter’s black-and-white navigation camera, meanwhile, tracks surface features below, and this flight put the onboard processing of these images to the test. Ingenuity’s flight computer, which autonomously flies the craft based on instructions sent up hours before data is received back on Earth, utilizes the same resources as the cameras.

If Ingenuity flies too fast, the flight algorithm can’t track surface features.

On Earth, NASA sought to simulate those conditions in NASA’s Jet Propulsion Lab vacuum chambers, which were filled with wispy air consisting primarily of carbon dioxide. … Read more

The Hows and Whys of Mars Sample Return

April 14, 2021 / Marc Kaufman / 0 Comments

Combining two images, this mosaic shows a close-up view of the rock target named “Yeehgo” taken by the SuperCam instrument on NASA’s Perseverance rover on Mars. To be compatible with the rover’s software, “Yeehgo” is an alternative spelling of “Yéigo,” the Navajo word for diligent.
(NASA/JPL-Caltech/LANL/CNES/CNRS/ASU/MSSS)

One of the fondest dreams and top priorities of space science for years has been to bring a piece of Mars back to Earth to study in the kind of depth possible only in a cutting-edge laboratory.

While the instruments on Mars rovers can tell us a lot, returning a sample to study here on Earth is seen as the way to ultimately tease out the deepest secrets of the composition of Mars, its geological and geochemical history and possibly the presence of life, life fossils or of the precursor molecules of life.

But bringing such a sample to Earth is extraordinarily difficult. Unlike solar system bodies that have been sampled back on Earth — the moon, a comet and some asteroids — Mars has the remains of an atmosphere. That means any samples would have to lift off in a rocket brought to Mars and with some significant propulsive power, a task that so far has been a technical bridge too far.

That is changing now and the Mars Sample Return mission has begun. The landing of the Perseverance rover in Jezero Crater on Mars signaled that commencement and the rover will be used to identify, drill into and collect intriguing bits of Mars. This is a long-term project, with the best case scenario seeing those Mars samples arriving on Earth in a decade. So this entirely unprecedented, high-stakes campaign will be playing out for a long time.

“I think that Mars scientists would like to return as much sample as possible,” said Lindsay Hays, NASA Mars Sample Return deputy program scientist. “Being able to return samples that we collected with purpose is how we take the next step in our exploration of Mars.”

“And it seems that there are still so many unknowns, even in our solar system, even with the planets right next door, that every time we do something new, we answer a couple of questions that we hoped to and but also find a whole bunch of new things that we never expected.”

“I am so excited to see what comes of this adventure. And I think that is a feeling shared by Mars scientists and planetary scientists broadly.”… Read more

The Space Telescope That Could Find a Second Earth

March 25, 2021 / Marc Kaufman / 0 Comments

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?

By Marc Kaufman

Air & Space Magazine |
April 2021

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

What Happened to All That Water on Ancient Mars? A New Theory With a Surprising Answer

March 16, 2021 / Marc Kaufman / 1 Comment

How did Mars lose the surface water that was plentiful on its surface 3 to 4 billion years ago? New research says it did not leave the planet but rather was incorporated on a molecular level into Martian minerals. (NASA)

Once it became clear in the past decade that the surface of ancient Mars, the inevitable question arose regarding what happened to it all since the planet is today so very dry. And the widely-accepted answer has been that the water escaped into space, especially after the once thicker atmosphere of Mars was stripped away.

But NASA-funded research just made public has a new and bold and very different answer: Much of the water that formed rivers, lakes and deep oceans on Mars, the research concludes, sank below the planet’s surface and is trapped inside minerals in the planet’s rocky crust.

Since early Mars is now thought to have had as much surface water as half of the the Earth’s Atlantic Ocean — enough to cover most of Mars in at least 100 meters of water — that means huge volumes of water became incorporated into the molecular structure of clays, sulfates, carbonates, opals and other hydrated minerals.

While some of the early water surely disappeared from Mars via atmospheric escape, the new findings, published in the latest issue of Science, conclude that atmospheric loss can not account for much or most of its water loss — especially now that estimates of how much water once existed on the surface of the planet have increased substantially.

“Atmospheric escape doesn’t fully explain the data that we have for how much water actually once existed on Mars,” said Eva Scheller, lead author and a doctoral candidate at the California Institute of Technology. The rate of water loss was found to be too slow to explain what happened.

Scheller and others at Caltech set out to find other explanations. Based on modeling and data collected by Mars orbiters, rovers and from meteorites, they concluded that between 30 and 99 percent of that very early Martian surface water can now be found trapped in the minerals of the planet’s crust.

Mars mudstone, as imaged by the Curiosity rover. (NASA/JPL-Caltech)

As described in a release for NASA’s Jet Propulsion Laboratory, the team studied the quantity of water on Mars over time in all its forms (vapor, liquid, and ice) and the chemical composition of the planet’s current atmosphere and crust through the analysis of meteorites as well as using data provided by Mars rovers and orbiters. … Read more

NASA’s Perseverance Rover Lands on Mars — The Third Martian Arrival in a Week

February 16, 2021 / Marc Kaufman / 0 Comments

This true-color Mars globe includes Terra Meridiani, the region where NASA’s Opportunity rover explored from 2004 to 2018. Two more Mars rovers — one from NASA and the other from China — are scheduled to land this week and then later in the year. (NASA/Greg Shirah)

Mars is receiving visitors these days. Quite a few of them.

The most prominent visitor is NASA’s Perseverance rover, which made a difficult but smooth precision landing at 3.55 ET this afternoon.

The rover now sits in Jezero Crater, in an area that clearly once had lots of water flowing. The site was selected, in part, because the Perseverance rover’s official mission includes — for the first time since the mid 1970s — an effort to find signs of long ago life.

Perseverance will join the Curiosity rover on Mars, that pioneering machine that has revolutionized our understanding of the planet since it landed in 2012 The Curiosity and Perseverance rovers are similar in design but carry different instruments with different goals.

A key difference: Curiosity was tasked with determining whether Mars had once been habitable and found that it definitely had been, with flowing rivers, large lakes and necessary-for-life organic compounds. Perseverance will take another scientific step forward and search for signs that Mars actually was once inhabited.

Perseverance also joins China’s Tianwen-1 (“heavenly questions”) probe, which went into orbit around Mars last week. It is the first Chinese spacecraft to arrive at Mars, and later this spring or summer the Chinese space agency will attempt to land a rover as well on the planet’s northern plains..

And then there’s the Hope spacecraft which entered into Mars orbit last week as well. Launched by the United Arab Emirates, it was placed in a wide orbit so it could study the planet’s weather and climate systems, which means it also can see the full planet in one view.

These spacecraft will join several others on or orbiting Mars, making this by far the busiest time ever for exploration of Mars — a real milestone.

NASA’s Perseverance rover will land in Jezero Crater. This image was produced using instruments on NASA’s Mars Reconnaissance Orbiter, which helps identify potential landing sites for future missions. On ancient Mars, water carved channels and transported sediments to form fans and deltas within lake basins, as is clearly visible at here at Jezaro Crater (NASA/JPL-Caltech/ASU)

That the Perseverance mission has a formal goal of searching for ancient signs of life is a big deal, and involves a lot of history.… Read more

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