Category Archives: News

Exoplanets: Headlines from the Future

The field of exoplanet is exploding: on a typical day about a dozen new peer-reviewed exoplanet studies are published and most weeks see announcements of multiple discoveries: new results range from the compositions and structures of exoplanet atmospheres through new findings on exoplanet formation and exoplanet population to exciting discoveries of the smallest, coolest, or lowest-mass planets. Exoplanets all over the headlines. But what discoveries will be in the headlines ten and twenty years from now?

Surprisingly, this question is very important now. It is important because most discoveries today are made by telescopes that were designed and built ten to twenty years ago – and what discoveries we may make in the future depends on what telescopes, instruments, and space missions we are building now. Different telescopes and observational techniques are great for answering different questions: no telescope can do it all.

Karl Stapelfeldt, NASA Exoplanet Exploration Program Chief Scientist, with a possible cover from a future New York Times.

So, what questions we will be able to answer in the future depends on what telescopes we build now, which in turn depends on the questions we think are going to be important.

I posted yesterday on the preprint server arXiv a report we worked on with a dedicated group of exoplanet experts and which we recently delivered it to the NASA EXOPAG Executive Committee and to the NASA Astrophysics Advisory Committee (more on the abbreviations at the bottom of the page)*. The study builds on input from the exoplanet community to identify the most interesting science questions that we may be able to study in the future with direct imaging missions – that is, space telescopes that can directly image exoplanets (separating their light from that of their host stars).

To be clear, our report does not determine or advise NASA on which missions we should build – that will be done by multiple other committees – but reports on what science questions the community thinks are the most important and potentially solvable questions. Our study informs and guides the community and NASA (and various observatories and organizations) when deciding on future exoplanet strategies.

So, what do astronomers think about the future of exoplanet research?

Even though we have learned a lot about exoplanets in the past decade, it is clear that we are just scratching the surface of the universe of amazing, exotic, and surprising worlds. Reflecting this our group started with a huge list of questions – close to a hundred of them, everything we wanted to know about exoplanets. Too many questions to be useful, but through discussions and analysis we weeded out questions that seemed to be intractable even in the best foreseeable future. This cut down our list, but still left us with too many questions. After lengthy discussions we were able to combine many of the questions into more general or fundamental questions, which again led to a shorter list.

Then the work really started: we needed to understand which of our questions will be answered in the next decade or so by telescopes already being built (such as NASA’s JWST, TESS, or the 30m-class ground-based telescopes) — none of those questions were interesting for our report. With the truly amazing work being done on exoplanets now, many of the obvious questions on our list will, in fact, be answered by 2030.

This process left us with high-level, important, but often very tough questions that will not be answered with any of the telescopes currently existing or being built. They will be the big questions in   a few decades. These are the questions that require truly powerful new telescope(s).

Many of the questions have to do with habitable worlds, which is not surprising. Still, some focus on gas exoplanets and some on ice giants (think cold or hot exo-neptunes) or super-earths. (In our report we did not focus on directly searching for and characterizing extrasolar life, because it was being addressed in a parallel report, SAG16 – but we covered how habitable worlds can be characterized).

The nine questions we identified naturally fell in three categories: Questions in Category A  aimed at exploring planetary systems: what are their structures, components, how do they form and evolve, what combinations of planets and planetesimal belts are common, etc. Although much progress will be made on these questions over the next two decades by telescopes being built now, we found that no telescope will be able to give us the complete picture: some will detect only close-in planets, others only dust disks, yet others only planets far out.

Questions in Category B are questions about individual planets: what are their atmospheres made of, do they have clouds and hazes and if so, where do those come from? Which of the (small) planets are truly habitable, i.e., that they have liquid water on their surfaces?

Finally, Questions in Category C aim to understand how planets work. These were some of the toughest questions, especially those about rocky planets. These worlds are the most difficult to detect, yet they can be so diverse (we think): just consider how different Mercury, Mars, Venus, and Earth are! In the future we will want to know not only how these planets look now, but why — how did they evolve to be the worlds they are. Unlike massive gas giant planets, whose strong gravity will hold on to pretty much all the stuff they formed with, puny rocky planets often lose their atmospheres (Earth and Mars definitely did).

This study has been fun: over one and a half year we held virtual and physical meetings to explore ideas and methods for exoplanet characterization; I found the list of questions we converged to to be really exciting.

Perhaps the most important questions are, however, those that directly aid our search for life on other planets. It is clear that the search for life around other stars is going to be with one of the most fundamentally important experiments ever conducted; but it is also clear that it is going to be extremely difficult. Not only is it technically difficult to detect the gases in the atmospheres of earth-like planets that could reveal life, but it is similarly difficult to interpret them. In fact, none of the atmospheric signatures we think we could detect in exoplanets would allow us to conclude that we found life unless we have a pretty good understanding of the planet. This is because all biosignature gases we could possibly detect could also be produced by some odd geological or atmospheric processes — all without life. To exclude those “false positives”, we must know the worlds in detail.

Questions in Category C aim exactly at this: Is there a geological activity on a planet? How did it evolve? What processes set is atmospheric circulation?

Many of the tough, but also very exciting questions go beyond astrophysics and connect to planetary sciences, geophysics, geochemistry, and atmospheric sciences: fortunately, we could draw on multi-disciplinary expertise from the NASA NExSS group to explore these questions.

Our report was a community effort – we received input from a large number of exoplanet scientists who volunteered their time and expertise to explore what the future should bring. For me, it has been a thrilling experience to work with such a great team and to try to figure out if and how we could in explore oceans, volcanism, climate, and other exotic properties of exoplanets in the future – for all the exciting discoveries we are making today, I am sure that the future will be even cooler.

Of course, we can be sure of one thing: With all the exciting questions we can identify, there will be many surprises and unexpected discoveries.

So, even though our report helps us to guess some of the topics in which future exoplanet discoveries will be made – I, for one, will surely follow closely the exoplanet news even twenty years from now.

The Future of Exoplanet Research

By Daniel Apai
Includes interview with Nick Siegler and Shawn Domagal-Goldman

Over the weekend, at the Hilton on the San Diego Bay, a small group met to speak about the present and future of NASA’s Exoplanet Exploration program. To someone not in the field of exoplanets the talks and debates may have resembled science fiction: giant space telescopes, rockets and spacewalks, hyper-precise measurements of stellar motion, search for alien life, exploration of volcanism on exoplanets, laser-combs, starshades, and other Earths across the Galaxy were just a few of the topics that were debated. The memorable images included cows illuminated by lasers in a Nevada desert. It was a fun meeting and a timely one, too.

EXOPAG Meeting San Diego

The field of exoplanets is hotter than ever: we learned that planets are literally everywhere and that planets with sizes similar to Earth are the most common among the known planets. Many of the stars (probably 1 in 4) harbor about-earth-sized planets with stellar heating similar to Earth. Not only did we learn about the frequency of the planets, but also about their properties. New missions and instruments are being built and planned, conferences and school galore, and amazing discoveries are made almost weakly. The enthusiasm is palpable in the field; yet. we know that reaching our grand goal of finding extraterrestrial life is going to be anything but easy.

We can only find life if it produces a signature that is detectable from vast – literally astronomical – distances. Seen from space humans, trees, elephants, or even whales are undetectable and unremarkable, yet Earth would reveal its secret to an outside observer through the surprising abundance of a highly reactive gas, molecular oxygen. Oxygen is and has been produced by  advanced photosynthetic organisms, first in the ocean and then on land. About 2.3 billion years ago oxygen has saturated the planet’s surface and rapidly accumulated in vast amounts in our atmosphere, From that point on Earth’s atmosphere became a glowing indicator of life for the entire Galaxy – at least, for civilizations that are slightly better in building telescopes than we are.

So, starting from the only example we have, NASA’s Exoplanet Exploration program is aiming to build a telescope that will look for oxygen or other similarly odd gases in other earth-like planets atmospheres as possible signatures of life.

In a perhaps unusual consensus, the exoplanet community is united behind the most important goal, surveying nearby exo-earths for biosignatures. Few other approaches to detecting extraterrestrial life seem feasible. Although the goal is clear, possible approaches and ideas are plenty: the abundance of proposed approaches stems from the fact that no telescope that exists today (or at least, accessible to astronomers) is capable enough to directly search for biosignatures in known exo-earths. Building one that will be up for the job is not going to be easy: in fact, right now, we do not know how good exactly that telescope would need to be, what capabilities it would have to have — and we don’t know how we would build it.

Guided by the vision of finding extraterrestrial life, astronomers, astrobiologists, technologists, engineers, project managers are all working together to come up with concrete plans for such telescopes. Our goal is to create at least two different designs for life-finding telescopes by 2019. The year is important, because in 2020 the astronomical community will issue a major report, the Decadal Survey. This study will set the strategy for NASA for 2020s and beyond and will determine whether planning and construction of such a telescope can begin in a few years or we need to wait another decade.

What the best telescope design is will depend on what questions we want to answer and on the properties of planets, too: our meeting in San Diego explored these issues as well as the technology development needed to build a telescope more ambitious than anything very built. For example, one possible telescope design would use a “starshade” – a giant (think fifty meters or hundred and fifty feet) flower-petal-shaped mask. The strange mask would fly tens of thousands of miles in front of the telescope and could, if positioned precisely, cancel out the light of the host star completely, revealing the faint planets. However, nothing like this has ever been flown in space or used in ground – so a Northrop-Grumman team of engineers is testing this idea in the night in a dark Nevada desert, shining bright a light to a telescope from miles away and covering the light with a small starshade mask in between. One night however, a cow, perhaps intrigued by the strange glowing flower in the desert, wandered into the light beam and photo-bombed the experiment, thus becoming part of the history of space exploration.

The San Diego meeting was exciting and fun: a lot of progress has been made recently, but much more needs to be done in the next three years to finalize plans for a space telescope that can look for life on other Earths

At the meeting I also grabbed the opportunity to interview two experts who approach this question from different angles: Dr. Nick Siegler, who is the Chief Technology of NASA’s Exoplanet Exploration Program; and Dr. Shawn Domagal-Goldman, astrobiologist and biosignature-expert at the NASA Goddard Space Flight Center.

Several important studies of space telescope design and science questions will be carried out over the next year or two, pushing our technology and understanding toward the long-term goal. It will be exciting to see how this group of smart people figures out solutions to problems that were thought to be impossible to solve, and how it will overcome unexpected barriers, such as curious cows.

NExSS Kick-off Meeting at NASA HQ

Two weeks ago NASA has announced its new Nexus for Exoplanet System Science, which may prove to be a major change in the way NASA will fund exoplanet science in the future. Our UA-led team was part of the first selection and I, the principal investigator of our project, joined the program’s two-day kick-off meeting at NASA HQ. The meeting was exciting, inspiring, and challenging at the same time. There have been several press releases and articles about the program in various online and printed media; what follows is my own personal perspective on the meeting.
Introduction to VPL by Victoria MeadowsView from 17th Floor in Crystal City

Questions, Problems, & Puzzles

NASA has invited the principal investigators and key members of 16 NASA-funded teams working on topics related to exoplanet habitability, as well as the directors of the new initiative to discuss and debate the best format and goals for the new program. The teams were selected from regular proposal  submissions to different NASA programs through the usual peer-review process, but invited to NExSS in addition to their selection to carry out the research they proposed.

The motivation for launching NExSS, as I understand, comes from the rapidly growing importance of extrasolar planet habitability research within many different NASA programs. The recent restructuring of NASA research grant programs (XRP, Habitable Worlds, etc.) further emphasized planetary habitability studies across many programs, which led to different aspects of habitability funded through different channels, without a good way to coordinate research between the programs. In addition, planetary  habitability-related proposals accounted for a very large fraction of the major proposals that responded to the latest opportunity to join the NASA Astrobiology Institute.

NExSS is a new approach to study extrasolar planets: the program’s idea is to combine various studies of planetary habitability funded through existing NASA programs into a new framework – one in which the teams collaborate and have influence over the broader, longer-term research directions.

Although many people at NASA have been involved in and contributed to launching NExSS, Mary Voytek, senior scientist for astrobiology, is the chief architect of the new program and program officers Christina Richey and Doug Hudgins, among others, also played important roles. Shawn Domagal-Goldman has also provided important input and advice for the new program.

Our meeting began with short talks at a NASA HQ auditorium, which included welcomes by Jim Green and Paul Hertz, the directors of the NASA Planetary Sciences and Astrophysics divisions. They expressed excitement about exoplanet research, emphasized the need for studying planets as “systems” and they strongly endorsed connecting research projects in different disciplines that address exoplanet habitability. Their enthusiastic support of NExSS was a clear demonstration of how strongly NASA is supporting the new interdisciplinary research coordination network.

We were also welcome by the three new co-directors of NExSS, Dawn Gelino, Natalie Batalha, and Anthony Del Genio, who work on various aspects of exoplanet research.

Next, lightning talks by the leads of each of the 16 teams introduced the scope of the teams; the single-slide presentations gave the first insights into the surprising breadth of NExSS. The NExSS teams have been selected from a set of projects submitted and selected for regular NASA programs (e.g., XRP, Habitable Worlds, Astrobiology, Heliophysics), so the sixteen teams brought very different expertise and perspectives to the table.

The projects also covered a broad spectrum in size, ranging from a few 1-2 investigator grants through a number of medium-sized teams to a few really large teams with multi-million dollar grants. These latter programs are our University of Arizona-led Earths in Other Solar Systems team (PI: Apai), the Arizona State University-led team (PI: Desch), a team led by NASA Goddard Institute for Space Sciences (PI: Del Genio), a team led by Berkeley (PI: Graham), and the one at Hammond University (PI: Moore). NASA’s press release and the team websites provide more information about the teams; I will instead focus on the kick-off meeting.

DistantEarths-1027

Working hard on putting the puzzle pieces together at the NASA NExSS Kick-Off meeting.

In contrast to the more usual top-down approach, our group’s first task is to brainstorm on its own purpose and definition. This has been an unusual responsibility; most committees are tasked to chart a course to reach a specific goal on a well-defined timescale. Defining our own goals and purpose is much more challenging; however, it also gave us the valuable opportunity to brainstorm and debate on the importance and achievability of different science goals over various timescales.

NASA has contracted a small company, KnowInnovate, to facilitate the creative process; this small team — two brothers — helped us move forward in the complex debate. Indeed, it has proven challenging for our team to converge on a set of well-defined goals in its first meeting; but by the end of the meeting we did identify our next steps and, I believe, made progress forward in surveying the questions, problems, and goals for the field.

Questions, Questions, Questions

Questions, Questions, Questions

The 2-day discussion resulted in covering most vertical surfaces of the meeting room with neon-colored sticky post-it notes, each with a question, problem, goal, or idea relevant for exoplanet studies. Arranged thematically, by importance, or by timescale, these stickies captured well the complexity and the heavily connected nature of next decade’s exoplanet research.

There discussion was productive and interesting; the number of questions and problems identified, and their complexity, is daunting, to say the least. Questions ranged from the impact of stellar hosts on the habitable planets through the importance of the formation and evolution of planetary systems to the unknowns of planetary interiors and life’s impact on the planet.DistantEarths-1029

Nevertheless, in a process that built on large quantities of coffee, snacks, and post-it notes, we identified some short-term steps and topics of immediate interests. These included establishing working groups on topics relevant for many questions (missing experimental data, cloud physics and chemistry), plans for workshops/conferences to connect to the community, blog-type snippets on new exoplanet research papers, just to name a few.DistantEarths-1028

It has been exciting to see a launch of a new program and one the exoplanet community can so actively shape. From my perspective, the NExSS group’s most important goal is interfacing and connecting: both within the group – in which we had a great start – and also with the broader community. The NExSS Executive Council will gradually change as PIs rotate in and out of the group over the next years, but I am very hopeful that the group will maintain its collaborative spirit as we put together the pieces of this exciting, but complex extrasolar puzzle.

You can follow our team’s work and results on Twitter (@EOSNExSS) or by subscribing to email announcements on our website ( http://otherearths.org ).

On to A New Year and New Exoplanets!

Grand Canyon Panorama

The 2014 year has brought much excitement in the field of extrasolar planets and 2015 is set to be at least as exciting as the past year: new powerful adaptive optics systems are searching the northern and southern skies for new exoplanets and Kepler2 should start bringing a large number of new planet candidates!

Just after Christmas my family took a break and visited the Grand Canyon, just a few hours drive from Tucson. I took the pictures from the South Rim’s Mather Point. Amazing to think how, in just about 5-10 million years, the apparently small Colorado river eroded away one vertical mile of rocks deposited over 1.8 billion years!

Back to the field, the first week of January also brings along the largest US meeting of professional astronomers, the winter meeting of the American Astronomical Society. This year astronomers are gathering in Seattle and we can take for certain that during the course of the next week there will be exciting announcements every day.

The large AAS meeting will be preceded by the open meeting of the NASA Exoplanet Analysis Group, where many in our field gather to review progress in exoplanet research and plan the next steps. The meeting will be broadcasted live, so you can watch it even if you are not in Seattle!

I wish everyone an exciting new year!

In just 5-10 million year the Colorado river eroded one vertical mile of mostly sedimentary rocks deposited over nearly two billion years.

In just 5-10 million year the Colorado river eroded one vertical mile of mostly sedimentary rocks deposited over nearly two billion years.