Tag: exoplanets (page 1 of 3)

Our Ever-Growing Menagerie of Exoplanets

While we have never seen an exoplanet with anything near this kind of detail, scientists and artists now do know enough to represent them with characteristics that are plausible, given what is known about them..  (NASA)

With so many exoplanets already detected, with the pace of discovery continuing to be so fast, and with efforts to find more distant worlds so constant and global,  it’s easy to become somewhat blase´ about new discoveries.  After so many “firsts,” and so many different kinds of planets found in very different ways, it certainly seems that some of the thrill may be gone.

Surely the detection of a clearly “Earth-like planet” would cause new excitement — one that is not only orbiting in the habitable zone of its host star but also has signs of a potentially nurturing atmosphere in a generally supportive cosmic neighborhood.

But while many an exoplanet has been described as somewhat “Earth-like” and potentially habitable, further observation has consistently reduced the possibility of the planets actually hosting some form of biology.  The technology and knowledge base needed to find distant life is surely advancing, but it may well still have a long way to go.

In just the last few days, however, a slew of discoveries have been reported that highlight the allure and science of our new Exoplanet Era.  They may not be blockbusters by themselves, but they are together part of an immense scientific exploration under way, one that is re-shaping our understanding of the cosmos and preparing us for bigger discoveries and insights to come.

 

Already 3,940 exoplanets have been identified (as of April 17) with an additional 3,504 candidates waiting to be confirmed or discarded.  this is but the start since it is widely held now that virtually every star out there has a planet, or planets, orbiting it.   That’s billions of billions of planets.  This image is a collection of NASA exoplanet renderings.

What I have in mind are these discoveries:

  • The first Earth-sized planet detected by NASA’s year-old orbiting telescope TESS (Transiting Exoplanet Survey Satellite.)  TESS is designed to find planets orbiting massive stars in our near neighborhood, and it has already made 10 confirmed discoveries.  But finding a small exoplanet — 85 percent the size of Earth — is a promising result for a mission designed to not only locate as many as 20,000 new exoplanets, but to find 500 to 1,000 the rough size of Earth or SuperEarth. 
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Does Proxima Centauri Create an Environment Too Horrifying for Life?

Artist’s impression of the exoplanet Proxima Centauri b. (ESO/M. Kornmesser)

 

In 2016, the La Silla Observatory in Chile spotted evidence of possibly the most eagerly anticipated exoplanet in the Galaxy. It was a world orbiting the nearest star to the sun, Proxima Centauri, making this our closest possible exoplanet neighbour. Moreover, the planet might even be rocky and temperate.

Proxima Centauri b had been discovered by discerning a periodic wobble in the motion of the star. This revealed a planet with a minimum mass 30% larger than the Earth and an orbital period of 11.2 days. Around our sun, this would be a baking hot world.

But Proxima Centauri is a dim red dwarf star and bathes its closely orbiting planet in a level of radiation similar to that received by the Earth. If the true mass of the planet was close to the measured minimum mass, this meant Proxima Centauri b would likely be a rocky world orbiting within the habitable zone.

 

Comparison of the orbit of Proxima Centauri  b with the same region of the solar system. Proxima Centauri is smaller and cooler than the sun and the planet orbits much closer to its star than Mercury. As a result it lies well within the habitable zone. (ESO/M. Kornmesser/G. Coleman.)

Sitting 4.2 light years from our sun, a journey to Proxima Centauri b is still prohibitively long.

But as our nearest neighbor, the exoplanet is a prime target for the upcoming generation of telescopes that will attempt to directly image small worlds. Its existence was also inspiration for privately funded projects to develop faster space travel for interstellar distances.

Yet observations taken around the same time as the La Silla Observatory discovery were painting a very different picture of Proxima Centauri. It was a star with issues.

This set of observations were taken with Evryscope; an array of small telescopes that was watching stars in the southern hemisphere. What Evryscope spotted was a flare from Proxima Centauri that was so bright that the dim red dwarf star became briefly visible to the naked eye.

Flares are the sudden brightening in the atmosphere of a star that release a strong burst of energy. They are often accompanied by a large expulsion of plasma from the star known as a “coronal mass ejection”. Flares from the sun are typically between 1027 – 1032 erg of energy, released in a few tens of minutes.… Read more

A National Strategy for Finding and Understanding Exoplanets (and Possibly Extraterrestrial Life)

The National Academies of Science, Engineering and Medicine took an in-depth look at what NASA, the astronomy community and the nation need to grow the burgeoning science of exoplanets — planets outside our solar system that orbit a star. (NAS)

 

An extensive, congressionally-directed study of what NASA needs to effectively learn how exoplanets form and whether some may support life was released today, and it calls for major investments in next-generation space and ground telescopes.  It also calls for the adoption of an increasingly multidisciplinary approach for addressing the innumerable questions that remain unanswered.

While the recommendations were many, the top line calls were for a sophisticated new space-based telescope for the 2030s that could directly image exoplanets, for approval and funding of the long-delayed and debated WFIRST space telescope, and for the National Science Foundation and to help fund two of the very large ground-based telescopes now under development.

The study of exoplanets has seen remarkable discoveries in the past two decades.  But the in-depth study from the private, non-profit National Academies of Sciences, Engineering and Medicine concludes that there is much more that we don’t understand than that we do, that our understandings are “substantially incomplete.”

So the two overarching goals for future exoplanet science are described as these:

 

  • To understand the formation and evolution of planetary systems as products of star formation and characterize the diversity of their architectures, composition, and environments.
  • To learn enough about exoplanets to identify potentially habitable environments and search for scientific evidence of life on worlds orbiting other stars.

 

Given the challenge, significance and complexity of these science goals, it’s no wonder that young researchers are flocking to the many fields included in exoplanet science.  And reflecting that, it is perhaps no surprise that the NAS survey of key scientific questions, goals, techniques, instruments and opportunities runs over 200 pages. (A webcast of a 1:00 pm NAS talk on the report can be accessed here.)

 


Artist’s concept showing a young sun-like star surrounded by a planet-forming disk of gas and dust.
(NASA/JPL-Caltech/T. Pyle)

These ambitious goals and recommendations will now be forwarded to the arm of the National Academies putting together 2020 Astronomy and Astrophysics Decadal Survey — a community-informed blueprint of priorities that NASA usually follows.

This priority-setting is probably most crucial for the two exoplanet direct imaging missions now being studied as possible Great Observatories for the 2030s — the paradigm-changing space telescopes NASA has launched almost every decade since the 1970s.

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The Architecture of Solar Systems

The architecture of planetary systems is an increasingly important factor to exoplanet scientists.  This illustration shows the Kepler-11 system where the planets are all roughly the same size and their orbits spaced at roughly the same distances from each other.  The the planets are, in the view of scientists involved with the study, “peas in a pod.” (NASA)

Before the discovery of the first exoplanet that orbits a star like ours, 51 Pegasi b, the assumption of solar system scientists was that others planetary systems that might exist were likely to be like ours.  Small rocky planets in the inner solar system, big gas giants like Jupiter, Saturn and Neptune beyond and, back then, Pluto bringing up the rear

But 51 Peg b broke every solar system rule imaginable.  It was a giant and hot Jupiter-size planet, and it was so close to its star that it orbited in a little over four days.  Our Jupiter takes twelve years to complete an orbit.

This was the “everything we knew about solar systems is wrong” period, and twenty years later thinking about the nature and logic of solar system architecture remains very much in flux.

But progress is being made, even if the results are sometimes quite confounding. The umbrella idea is no longer that solar, or planetary, systems are pretty much like ours, but rather that the galaxy is filled with a wild diversity of both planets and planetary systems.

Detecting and trying to understand planetary systems is today an important focus 0f  exoplanet study, especially now that the Kepler Space Telescope mission has made clear that multi-planet systems are common.

As of early July, 632 multi planet systems have been detected and 2,841 stars are known to have at least one exoplanets.  Many of those stars with a singular planet may well have others yet to be found.

An intriguing newcomer to the diversity story came recently from University of Montreal astronomer Lauren Weiss, who with colleagues expanded on and studied some collected Kepler data.

What she found has been deemed the “peas in a pod” addition to the solar system menagerie.

Weiss was working with the California-Kepler Survey, which included a team of scientists pouring over, elaborating on and looking for patterns in, among other things, solar system architectures.

Weiss is part of the California-Kepler Survey team, which used the Keck Observatory to obtain high-resolution spectra of 1305 stars hosting 2025 transiting planets originally discovered by Kepler.… Read more

Exoplanet Science Flying High

An 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, as of February 2018. Credit: NASA/JPL-Caltech

 

Early this spring, the organizers of an exoplanet science gathering at Cambridge University put out the word that they would host a major meeting this summer.  Within a week, the 300 allotted slots had been filled by scientists aspiring and veteran, and within a short time the waiting list was up to 150 more.

Not the kind of reaction you might expect for a hardcore, topic-specific meeting, but exoplanet science is now in a phase of enormous growth and excitement.  With so many discoveries already made and waiting to be made, so many new (and long-standing) questions to be worked on, so much data coming in to be analyzed and turned into findings,  the field has something of a golden shine.

What’s more, it has more than a little of the feel of the Wild West.

Planet hunters Didier Queloz and Michel Mayor at the European Southern Observatory’s La Silla site. (L. Weinstein/Ciel et Espace Photos)

Didier Queloz, a professor now at Cambridge but in the mid 1990s half of the team that identified the first exoplanet, is the organizer of the conference.

“It sometimes seems like there’s not much exploration to be done on Earth, and the opposite is the case with exoplanets,” he told me outside the Cambridge gathering.

“I think a lot of young scientists are attracted to the excitement of exoplanets, to a field where there’s so much that isn’t known or understood.”

Michel Mayor of the Observatory of Geneva — and the senior half of the team that detected the first exoplanet orbiting a star like our sun, 51 Pegasi b– had opened the gathering with a history of the search for extra-solar planets.

That search had some conceptual success prior to the actual 1995 announcement of an exoplanet discovery, but several claims of having actually found an exoplanet had been made and shown to be wanting.  Except for the relative handful of scientists personally involved, the field was something of a sideshow.

“At the time we made our first discovery, I basically knew everyone in the field.  We were on our own.”

Now there are thousands of people, many of them young people, studying exoplanets.  And the young people, they have to be smarter, more clever, because the questions are harder.”

And enormous progress is being made.… Read more

Joining the Microscope and the Telescope in the Search for Life Beyond Earth

 

Niki Parenteau of NASA’s Ames Research Center is a microbiologist working in the field of exoplanet and Mars biosignatures. She adds a laboratory biology approach to a field generally known for its astronomers, astrophysicists and planetary scientists. (Marisa Mayer, Stanford University.)

 

The world of biology is filled with labs where living creatures are cultured and studied, where the dynamics of life are explored and analyzed to learn about behavior, reproduction, structure, growth and so much more.

In the field of astrobiology, however, you don’t see much lab biology — especially when it comes to the search for life beyond Earth.  The field is now largely focused on understanding the conditions under which life could exist elsewhere, modeling what chemicals would be present in the atmosphere of an exoplanet with life, or how life might begin as an organized organism from a theoretical perspective.

Yes, astrobiology includes and learns from the study of extreme forms of life on Earth, from evolutionary biology, from the research into the origins of life.

But the actual bread and butter of biologists — working with lifeforms in a lab or in the environment — plays a back seat to modeling and simulations that rely on computers rather than actual life.

Niki Parenteau with her custom-designed LED array, can reproduce the spectral features of different simulated stellar and atmospheric conditions to test on primitive microbes. (Marc Kaufman)

There are certainly exceptions, and one of the most interesting is the work of Mary “Niki” Parenteau at NASA’s Ames Research Center in the San Francisco Bay area.

A microbiologist by training, she has been active for over five years now in the field of exoplanet biosignatures — trying to determine what astronomers could and should look for in the search for extraterrestrial life.

Working in her lab with actual live bacteria in laboratory flasks, test tubes and tanks, she is conducting traditional biological experiments that have everything to do with astrobiology.

She takes primitive bacteria known to have existed in some form on the early Earth, and she blasts them with the radiation that would have hit the planet at the time to see under what conditions the organisms can survive.  She has designed ingenious experiments using different forms of ultraviolet light and a LED array that simulate the broad range of radiations that would come from different types of stars as well.

What makes this all so intriguing is that her work uses, and then moves forward, cutting edge modeling from astronomers and astrobiologists regarding thick photochemical hazes understood to have engulfed the early Earth — making the planet significantly colder but also possibly providing some protection from deadly ultraviolet radiation.… Read more

NASA’s Planet-Hunter TESS Has Just Been Launched to Check Out the Near Exoplanet Neighborhood

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A SpaceX Falcon 9 rocket transporting the TESS satellite lifts off from launch complex 40 at the Cape Canaveral Air Force Station in Cape Canaveral, Fla., Wednesday, April 18, 2018. The space telescope will survey almost the entire sky, staring at the brightest, closest stars in an effort to find any planets that might be encircling them. (AP Photo/John Raoux)

On January 5, 2010, NASA issued  landmark press release : the Kepler Space Telescope had discovered its first five new extra-solar planets.

The previous twenty years had seen the discovery of just over 400 planets beyond the solar system. The majority of these new worlds were Jupiter-mass gas giants, many bunched up against their star on orbits far shorter than that of Mercury. We had learnt that our planetary system was not alone in the Galaxy, but small rocky worlds on temperate orbits might still have been rare.

Based on just six weeks of data, these first discoveries from Kepler were also hot Jupiters; the easiest planets to find due to their large size and swiftly repeating signature as they zipped around the star. But expectations were high that this would be just the beginning.

“We expected Jupiter-size planets in short orbits to be the first planets Kepler could detect,” said Jon Morse, director of the Astrophysics Division at NASA Headquarters at the time the discovery was announced. “It’s only a matter of time before more Kepler observations lead to smaller planets with longer period orbits, coming closer and closer to the discovery of the first Earth analog.”

Morse’s prediction was to prove absolutely right. Now at the end of its life, the Kepler Space Telescope has found 2,343 confirmed planets, 30 of which are smaller than twice the size of the Earth and in the so-called “Habitable Zone”, meaning they receive similar levels of insolation –the amount of solar radiation reaching a given area–to our own planet.

Yet, the question remains: were any of these indeed Earth analogs?

In just a few decades, thanks to Kepler, the Hubble Space Telescope and scores of astronomers at ground-based observatories, we have gone from suspecting the presence of exoplanets to knowing there are more exoplanets than stars in our galaxy. (NASA/Ames Research Station; Jessie Dotson and Wendy Stenzel)

It was a question that Kepler was not equipped to answer. Kepler identifies the presence of a planet by looking for the periodic dip in starlight as a planet passes across the star’s surface.… Read more

Nobel Laureate Jack Szostak: Exoplanets Gave The Origin of Life Field a Huge Boost

Jack Szostak, Nobel laureate and pioneering researcher in the origin-of-life field, was the featured speaker at a workshop this week at the Earth-Life Science Institute (ELSI) in Tokyo.  One goal of his Harvard lab is to answer this once seemingly impossible question:  was the origin of life on Earth essentially straight-forward and “easy,” or was it enormously “hard” and consequently rare in the universe. (Nerissa Escanlar)

Sometimes tectonic shifts in scientific disciplines occur because of discoveries and advances in the field.  But sometimes they occur for reasons entirely outside the field itself.  Such appears to be case with origins-of-life studies.

Nobel laureate Jack Szostak was recently in Tokyo to participate in a workshop at the Earth-Life Science Institute (ELSI) at the Tokyo Institute of Technology on “Reconstructing the Phenomenon of Life To Retrace the Emergence of Life.”

The talks were technical and often cutting-edge, but the backstory that Szostak tells of why he and so many other top scientists are now in the origins of life field was especially intriguing and illuminating in terms of how science progresses.

Those ground-shifting discoveries did not involve traditional origin-of-life questions of chemical transformations and pathways.  They involved exoplanets.

“Because of the discovery of all those exoplanets, astronomy has been transformed along with many other fields,” Szostak said after the workshop.

“We now know there’s a large range of planetary environments out there, and that has stimulated a huge amount of interest in where else in the universe might there be life.  Is it just here?  We know for sure that lots of environments could support life and we also would like to know:  do they?

“This has stimulated much more laboratory-based work to try to address the origins question.  What’s really important is for us to know whether the transition from chemistry to biology is easy and can happen frequently and anywhere, or are there one or many difficult steps that make life potentially very rare?”

In other words, the explosion in exoplanet science has led directly to an invigorated scientific effort to better understand that road from a pre-biotic Earth to a biological Earth — with chemistry that allows compounds to replicate, to change, to surround themselves in cell walls, and to grow ever more complex.

With today’s increased pace of research, Szostak said, the chances of finding some solid answers have been growing.  In fact, he’s quite optimistic that an answer will ultimately be forthcoming to the question of how life began on Earth.… Read more

The Very Influential Natalie Batalha

Natalie Batalha, project scientist for the Kepler mission and a leader of NASA’s NExSS initiative on exoplanets, was just selected as one of Time Magazine’s 100 most influential people in the world. (NASA, TIME Magazine.)

I’d like to make a slight detour and talk not about the science of exoplanets and astrobiology, but rather a particular exoplanet scientist who I’ve had the pleasure to work with.

The scientist is Natalie Batalha, who has been lead scientist for NASA’s landmark Kepler Space Telescope mission since soon after it launched in 2009, has serves on numerous top NASA panels and boards, and who is one of the scientists who guides the direction of this Many Worlds column.

Last week, Batalha was named by TIME Magazine as one of the 100 most influential people in the world. This is a subjective (non-scientific) calculation for sure, but it nonetheless seems appropriate to me and to doubtless many others.

Batalha and the Kepler team have identified more than 2500 exoplanets in one small section of the distant sky, with several thousand more candidates awaiting confirmation.  Their work has once and for all nailed the fact that there are billions and billions of exoplanets out there.

“NASA is incredibly proud of Natalie,” said Paul Hertz, astrophysics division director at NASA headquarters, after the Time selection was announced.

“Her leadership on the Kepler mission and the study of exoplanets is helping to shape the quest to discover habitable exoplanets and search for life beyond the solar system. It’s wonderful to see her recognized for the influence she has had on the world – and on the way we see ourselves in the universe.”

And William Borucki, who had the initial idea for the Kepler mission and worked for decades to get it approved and then to manage it, had this to say about Batalha:

“She has made major contributions to the Kepler Mission throughout its development and operation. Natalie’s collaborative leadership style, and expert knowledge of the population of exoplanets in the galaxy, will provide guidance for the development of successor missions that will tell us more about the habitability of the planets orbiting nearby stars.”

Batalha has led the science mission of the Kepler Space Telescope since it launched in 2009. (NASA)

As a sign of the perceived importance of exoplanet research, two of the other TIME influential 100 are discoverers of specific new worlds.  They are Guillem Anglada-Escudé (who led a team that detected a planet orbiting Proxima Centauri) and Michael Gillon (whose team identified the potentially habitable planets around the Trappist-1 system.)

But Batalha, and no doubt the other two scientists, stress that they are part of a team and that the work they do is inherently collaborative.… Read more

A Vision That Could Supercharge NASA

An artist rendering of an approximately 16-meter telescope in space.  This image was created for an earlier large space telescope feasibility project called ATLAST, but it is similar to what is being discussed inside and outside of NASA as a possible great observatory after the James Webb Space Telescope and the Wide-Field Infrared Survey Telescope.  Advocates say such a large space telescope would revolutionize the search for life on exoplanets, as well as providing the greatest observing ever for general astrophysics. (NASA)

Let your mind wander for a moment and let it land on the most exciting and meaningful NASA mission that you can imagine.  An undertaking, perhaps, that would send astronauts into deep space, that would require enormous technological innovation, and that would have ever-lasting science returns.

Many will no doubt think of Mars and the dream of sending astronauts there to explore.  Others might imagine setting up a colony on that planet, or perhaps in the nearer term establishing a human colony on the moon.  And now that we know there’s a rocky exoplanet orbiting Proxima Centauri — the star closest to our sun — it’s tempting to wish for a major robotic or, someday, human mission headed there to search for life.

All are dream-worthy space projects for sure.  But some visionary scientists (and most especially one well-known former astronaut) have been working for some time on another potential grand endeavor — one that you probably have not heard or thought about, yet might be the most compelling and achievable of them all.

It would return astronauts to deep space and it would have them doing the kind of very difficult but essential work needed for space exploration in the far future. It would use the very costly and very powerful Space Launch System (SLS) rocket and Orion capsule being built now by NASA and Lockheed Martin respectively.  Most important, it would almost certainly revolutionize our understanding of the cosmos near and far.

At a recent meeting of the House Science Committee, chairman Lamar Smith, said of the hearing’s purpose that, “Presidential transitions offer the opportunities to reinvigorate national goals. They bring fresh perspectives and new ideas that energize our efforts.”

That said, here’s the seemingly feasible project that fires my imagination the most.

It has been quietly but with persistence promoted most visibly by John Grunsfeld, the former astronaut who flew to the Hubble Space Telescope three times to fix and upgrade it, who has spent 58 hours on spacewalks outside the Shuttle, and towards the end of his 40 years with the agency ultimately became an associate administrator and head of the agency’s Science Mission Directorate.… Read more

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