Leading scientists seek to guide this process every 10 years with a comprehensive survey, sponsored by the National Research Council, that sets priorities and recommends federal budget outlays for the projects deemed most promising.
The latest such document, Astro2010, draws on insights from throughout the U.S. astronomical and astrophysics community and offers a list of large, medium-sized and small projects recommended for federal funding over the next 10 years. Leading the effort was Roger Blandford, a professor of astrophysics at Stanford University and head of the Kavli Institute for Particle Astrophysics and Cosmology.
The Kavli Foundation Newsletter recently talked with Blandford and fellow survey committee member Michael Turner, director of the Kavli Institute for Cosmological Physics at the University of Chicago, about the new decadal survey, the thinking behind it and its role in the future of astronomy and astrophysics.
An Interview with Roger Blandford and Michael Turner
Quite a bit has changed in science and in the outlook for federal spending since the last decadal survey was done. How does the Astro2010, the newly released survey charting astronomy and astrophysics spending in the coming decade, reflect those changes?
RB: Obviously the most important thing is the science itself. It has been a decade of explosive discovery. Dark energy, dark matter, exoplanets, making precise cosmological measurements .... These are all enduring developments in science and we’ve clearly got a lot to exploit in this decade. You are also looking at bigger science, epitomized on the ground by ALMA [Atacama Large Millimeter Array] and in space by JWST [James Webb Space Telescope], and also a much more global program with lots of collaboration, not just with foreign agencies but also with public and private partners. This has been a feature of astronomy for a long time, but I think the importance of it has been growing every decade. This is certainly something that we’ve seen in this survey.
Hovering over all of this is a rather somber view that was communicated to us by the [federal] agencies of the likely budgets as they saw them over the coming decade, which were really quite restrictive. To drive home the point, the NSF budget permitted almost nothing new this decade, while the NASA budget is forecast to decline at 3% or 4% a year in purchasing power, depending on inflation So we were under a lot of pressure to optimize the science return on a very restricted potential budget. Michael, you were a committee member on both surveys, What do you see as the big changes?
MT: There were three major changes. Astro2010 began by identifying the most important science opportunities so that we could make sure -- particularly in the constrained budget scenario that we have -- that the highest-priority science gets done. At the time of the last survey, the nation’s biggest problem was how to wisely spend a looming surplus, and there was a sense that we’d better get a lot on the table because science should get its share of the surplus. This time, we had a much better idea of likely budgets, and we tried to put forward a program that is executable -- i.e., doable with realistic budgets. That also included schedule realism. Not only have projects gotten more expensive and bigger, they take longer and have technical challenges to address. So one of the things we looked at very carefully was schedule and technical risk, and when projects would start and be complete. One of the biggest disappointments with the last Survey was GSMT [the Giant Segmented Mirror Telescope project]. GSMT has still not started construction; however, that is not because of lack of funds. This is such an ambitious project that its schedule was not commensurate with the decade. It was recommended again by Astro2010 and this time we are confident that it will get started and will begin doing great science in the early part of the 2020s. Finally, Astro2010 did not “grandfather in” projects that had been previously recommended but had not been started: That is, previously recommended projects that had not begun, were re-prioritized; and some of them were not recommended.
Astro2010 gives a high priority to small-scale work, especially the Explorer Program. What is the thinking behind that?
MT: The astronomy community has always appreciated that the optimal program to advance the field requires texture, by which I mean a few big missions, more medium-size projects and lots of small things. Previous surveys said good words about small and medium-sized projects in the text, but the reality is that if they’re not in “The Table” [of recommended activities], no one really notices them. Astro2010 put its money where its mouth is; the number two priority for both space and ground are medium-sized: Explorers at NASA and a mid-scale program at NSF. Flagship missions are necessary, but that these smaller, more nimble projects get a lot of bang for the buck, maintain the vitality of the field and help train the next generation of scientists.
Could you give an example of what one of these smaller-scale or medium-scale enterprises has produced in recent years?
MT: There are two easy examples in cosmology. One is the Cosmic Background Explorer, COBE, which discovered the anisotropy of the cosmic microwave background, began the era of precision cosmology and won a Nobel Prize. Another Explorer was WMAP [Wilkinson Microwave Anisotropy Probe]. WMAP helped to realize the promise of precision cosmology and has produced the most cited papers in all of the physical sciences. You can’t get much more bang for the buck than that!
RB: The Explorer Program actually goes all the way back to James Van Allen in 1958, with the discovery of the Van Allen belts. So it has a long heritage. But I think it was given a big boost two decadal surveys ago by the Decade of Discovery that was led by John Bahcall. You only have to look at all of the Explorers we’ve had over that period of time -- one had a launch failure, but otherwise they’ve been conspicuously successful. There are a huge number of outstanding applicants whenever there’s a solicitation for Explorers, so we felt confident that this was a good way of getting more science per dollar.
RB: I’m going to mention two general areas. They were both acknowledged but were a little understated in the last decadal survey. One was the transformation of cosmology. This was more than just confirming that the universe is accelerating, it was using microwave background and other observations to make measurements with high precision in a way that nobody expected. Maybe Michael, who is a leader here, expected it, but even he will admit to some surprise about how fast this happened. The other is the exoplanet [extra-solar planet] revolution. We’re sitting on nearly 500 exoplanets confirmed and another 300 waiting to be confirmed; I don’t think there are many people who really expected I’d be making this statement today.
MT: I would agree with Roger and say it just slightly differently. Ten years ago we had developed a model of the Universe deeply rooted in particle physics: particle dark matter, dark energy and an early burst of inflation that produced the seed perturbations for all cosmic structure from quantum fluctuations. That this amazing picture would hold together so well as the precision of the measurements increased is astonishing. I think the smart money would have said, OK, you’ve got a lot of the basic elements, but once you start making the precision measurements that Roger mentioned, it’s not going to hold up – there will be surprises. So far there haven’t been – this “stranger than fiction” picture is now firmly established. On exoplanets, which I know much less about, I would have said even more surprising than the number of exoplanets is the fact that they are in all the wrong places and have all the wrong characteristics. I think many had naively believed that our own solar system would be typical. Instead, we are finding lots of planets with highly eccentric orbits and Jupiters very close to their stars as well as evidence for planets that move around in their planetary systems. It just completely changed our view of planetary systems in general, and now, our solar system looks like the oddball. In the long run, exoplanets will teach us a great deal about how our solar system came to be, in addition to addressing the question of life elsewhere in the Universe.
Would you say that the 2000 decadal survey pretty well anticipated the science of the following decade or did it misfire in some ways?
RB: Modesty will prevent Michael from answering that question first, because he was more responsible than I was, but I think it does really rather well, and I think it does even better if you actually read what was written in the report. We just said we were surprised by the huge developments in cosmology and exoscience, but they’re both in there. It got that right, and I think it got much else right besides. Of course there are discoveries; astronomy is very much a discovery science. I’d be disappointed if, in ten years’ time, people don’t look back at what we have tried to do and say, “How could they have missed that? The signs were all there and there’s not even a comment about it.” I hope that happens.
MT: I think that in broad strokes the last survey did get it right, not because the survey members were smart, but because the survey engaged the entire community and benefitted from their collective wisdom. If I had to say where it missed the boat, it would be in the importance of survey science – and only a little bit. I think the survey committee had the sense, based upon the tremendous success of the Sloan Digital Sky Survey, that survey science was going to be big, but the committee didn’t appreciate how big it would be. We now realize the importance of survey science, which explains why, this time around, LSST [the Large Synoptic Survey Telescope] is Number One.
You seem to be saying that a conscious effort was made this time to build some element of flexibility into the planning so that, if you find surprising things, the survey won’t hold you back from pursuing them.
MT: That’s right. Astro2010 heeded the words of Pasteur – fortune favors the prepared mind. While you can’t anticipate surprises, you can prepare yourself for them.
RB: The white papers were quite emphatic on this unscripted nature of scientific progress, and I think this did have an influence on the committee as we made our choices. We were looking for program elements that would both facilitate discovery and the capability for follow up.
MT: I would add that the field of astrophysics and astronomy is still relatively young and we're still asking big questions – not just filling in the details. Major discoveries most certainly lie ahead, and an important element of planning is realizing that we won’t be able to identify all the important questions.
RB: I would not just say the “field;” Present company excepted, it’s also the practitioners. It’s a field that is still very much attracting young people who are very passionate about doing research. That’s a very healthy sign.
And of course it’s also a very international field, and always has been in the area of collaboration and partnerships. Has the planning for international cooperation, both in terms of money and in terms of execution, changed this time around?
RB: Every year, international collaboration is becoming more important. If you look at the major projects as they’re going on around the world or being proposed, they are all international in one way or another. They involve very complicated partnerships, and this means they are that much harder to manage. But nonetheless the benefits are clearly there. The obvious benefit is that for very expensive projects, you’ve got more than one agency to contribute. And that’s certainly important. But I think increasingly one is finding complementary expertise in different communities. The Europeans might be better at making X-ray mirrors, Americans might be better at making the detectors, and so on. So you could make the best facility by combining these different investments in technology or scientific expertise. It’s very much a challenge for this committee to make recommendations basically to three agencies in the U.S. government when we are in a much larger pool.
"If we’re going to answer the big questions and undertake the bold projects needed to address them, we’re going to have to get better at coordinating and cooperating on an international level." —Michael Turner
MT: An important contextual difference between this survey and previous surveys was the realization that roughly speaking parity has been reached in astronomy. If you compare Europe, the United States and Asia and if you look at almost any measure – number of papers, money spent, capability – they’re very comparable. 50 years of American dominance of astronomy is over. Among other things, that means coordination and collaboration are essential to future progress. There are excellent examples of both – Hubble, Gemini, Chandra and XMM, and the first truly global science project, ALMA. That being said, we still have much to learn about collaborating and coordinating. If you look at the recommended projects, two of them, LISA [the Laser Interferometer Space Antenna] and IXO [the International X-Ray Observatory], would not be possible without NASA collaborating with ESA (and JAXA for IXO). But we’re still in the very early stage of being able to do this in an efficient and highly predictive manner. Each country has its own budget peculiarities and its own way of setting priorities. If we’re going to answer the big questions and undertake the bold projects needed to address them, we’re going to have to get better at coordinating and cooperating on an international level.
How does the new U.S. survey interface with plans that the Europeans have recently released for 2015 to 2025?
MT: They have put out three planning documents recently –Astronet, the European vision for ground based astronomy, Cosmic Visions, ESA’s vision for space based astronomy, and a smaller one called Aspera, which is a strategy for particle astrophysics. The committee members read all three carefully, and what’s stunning – but maybe not so surprising – is that everyone has identified much the same science questions. And everyone understands that international cooperation and coordination are absolutely essential. However, on the issue of how we shake hands internationally and how we coordinate internationally -- we are really taking baby steps there. ALMA is the trailblazer, the first global science project. All three regions involved -- Europe, the Americas and Asia. ALMA has been a struggle -- different budget cycles, the different styles of running and managing projects, the different models for cost accounting, and so on -- but I believe the tremendous science ahead will make people forget the struggle.
Do you think the new decadal survey is going to have as much influence over global astronomy as past surveys have had?
MT: Yes. The U.S. was the first to do this type of prioritized, community-based strategic planning. Because it has been so effective, it’s catching on around the world. We still have the strongest astronomy program, both on the ground and in space. Last but not least, because there will be so much partnering and coordination, our priorities will be taken very seriously. For all of these reasons, I believe that Astro2010 will have at least as much global influence as in the past.
"What scientists are seeing is an opportunity... to set the science agenda and not just to let this happen by political default. It’s very hard to make the choices, to say 'Do this and not that,' but it’s worse to say, 'We can’t make up our minds' ..." —Roger Blandford
RB: Obviously, time will tell what the impact will be, not only of the specific recommendations -- whether they will be considered wise or foolish-- but also of the methodology, in which there is no question that we have changed the game. I’m sure that in retrospect we’ll say we’ve made some mistakes, but at least we’ve tried to create a report in a way we think is necessary in this day and age. What scientists are seeing is an opportunity for them to make the tough choices to set the science agenda and not just to let this happen by political default. It’s very hard to make the choices, to say “Do this and not that,” but it’s worse to say, “We can’t make up our minds; let the most powerful politicians decide.”
RB: I think there’s a several-layer answer to that. [First, there’s] the popular appeal of extra-terrestrial intelligence, of life on other planets, Avatar, all the science-fiction novels and so on. And I don’t mean this in a denigrating or patronizing way; quite the opposite, I think it’s an atavistic trait we all share. It’s the curiosity that captured the imaginations of the great explorers of the 15th, 16th and ƒ17th centuries. But I also think there’s much more. I really saw it starting about 20 years ago. I was then working at Caltech and I would teach undergraduate courses. I taught some outstanding and very interesting young people, and a subset of them went off to do research in astronomy. What I found was that more and more of the ones I remembered went off to work in this area of exoplanets. They were attracted by the science. It’s a different sort of science; it’s a very different type of research methodology that you have to master from, say, what you would do to be a cosmologist. There’s a lot of chemistry and increasingly astrobiology, the way you do the observing is quite different, and so on. And people have developed different scientific tools. You’ve seen this in the mere discovery of the exoplanets. There’s been an explosion of techniques, not just of discoveries. It isn’t just one breakthrough, it’s many. It’s the young people who have voted, and they find this science very attractive, as indeed vicariously, I would say, do I.
MT: I would say it even more simply. The question, “Are we alone; is there life elsewhere?”, is a question that humankind has always been keenly interested in. With the discovery of exoplanets, it’s finally become timely to answer, which has raised the interest level greatly. I hope within my lifetime – in fact, I’d be willing to bet that within my lifetime – we’ll find life elsewhere in the universe.
Another focus for Astro2010 is the period in the fairly early years of the Universe when the first stars formed. What is the fascination with that time?
RB: We talked earlier about this transformation of cosmology from, as Mike put it, a series of elements that we didn’t quite expect would fit together and would lead to more puzzles than solutions, to be something that we can call a standard model. Any scientist when confronting a standard model will say, “What are the bits that we really don’t know enough about, or what parts don’t quite fit together,” and so on. One of the larger areas of cosmological ignorance is what we sometimes call the end of the dark ages, or, more positively, the cosmic dawn. This is when the lights turn on in the Universe – the creating of stars and galaxies and black holes and all of that. This happened when the Universe was roughly half a billion years old. We know that, but we know relatively few of the details. And there’s a very strong sense that the time is ripe to fill in our understanding of that epoch. Getting a really good physical description of what actually happened is now, I think, within our grasp.
MT: Astronomers love to tell stories, and we’re putting together the biggest story of all time -- the Big Bang to us. A big missing piece of that story is this part when the first stars light up and when the first galaxies formed. It is remarkable that we know more about some events in the very early Universe than about this critical phase. We are now ready to finish, or at least write a very good first draft of this story. Even to someone more interested in dark matter and dark energy, this just jumped right out as a fantastic opportunity.
RB: We’re proposing a program that has a lot of technology development this decade, with a view to being ready to mount major flagship-class missions in space and large facilities on the ground that would attack some of the really big problems that we can identify but not specify now. So I hope very much that by the end of this decade we will have the scientific preparation and the technical development that will enable the submissions to the next decadal survey to put forward some very mature proposals and missions, and there will be such enthusiasm for them that they will then go forward.
MT: Let me just give three examples of where we hope to lay the groundwork. The first involves imaging an earth-like planet in its star’s habitable zone and searching for signs of life. We aren’t ready to do it in this decade, but we recommended the technology investment that if successful, will enable the next Decadal Committee to say, “Look, we’re ready to go, and here’s what the mission would look like.” The second example is what might be called the successor to Hubble – the next optical/UV space telescope, but much bigger and grander and not in low-earth orbit. Again, what Astro2010 found out is that the technology is not quite there yet to build a 4- or 8-meter optical/UV at an affordable cost. The hope is, that with the investment that will be made over the decade, we will be ready to go in 2020. The third example comes form the area that’s near and dear to my heart -- cosmology and the microwave background. It’s involving the search for the smoking-gun signature of inflation -- the gravity waves that produced by inflation and their polarization signature on the cosmic microwave background (so-called B modes). We’re not quite ready to design a space mission to do that; maybe we don’t even need one if the B-mode signature is discovered by ground based experiments. But here too, the committee recommended the technology investment so that we would be ready to go in 2020.
RB: I’d like to add one more example on the ground, and that is the square-kilometer array, which almost by definition is the future of radio astronomy. Again, despite the strong international enthusiasm for this, which is shared by radio astronomers in the United States, it was felt that it was not time to go for the full square kilometer array. Instead, we put the resources that we had into developing what might be seen as precursor instruments that would take us along the road to it.
What about the large ground-based telescope -- either 30-meter or GSMT – that is supposed to be built in this decade? You have recommended that 25% of its budget should come from NSF, but do you think it will be achieved? Do you think the project is important for the future?
MT: I think it is very important. And I hope that by the end of this decade we see three giant telescopes being constructed, with one of them having a very significant federal investment, 25% or greater.
RB: Just to underscore what Michael said, this is a very strong recommendation, and it is one that, again, is driven by the science. These are discovery engines that will transform a whole range of fields, and we are very excited about that prospect. Although our process recommendation is that the federal government choose one of the two projects as a partner. I believe that both will be built and be great telescopes.
MT: One of the things a foundation like The Kavli Foundation could do is help bring the international community together to begin the process of planning and setting priorities. This is crucial for the future of astronomy. One of our recommendations is having the international community meet every five years to compare science agendas and plans, and possibly even agree on science priorities and collaboration on big projects. A private foundation could well be the best facilitator for a meeting that brings the international science community together.
In the process of going through this survey and hearing from other scientists and so forth – what did you yourselves learn? And how did your thinking change?
RB: For me, the question is simple. What I’ve always most appreciated in these exercises is that one learns new things. You learn to think about science that you had some passing acquaintance with in a completely different way, because you’re forced to come to terms with recent discoveries and hearing from experts and having to read papers, and so on. And Michael and I have both said that we are not exoplanet guys. I think we both enjoyed hearing from our colleagues who are.
MT: I would say two things. First of all, I hadn’t quite appreciated that, across the board in astronomy, this is a very special and exciting time. I knew the opportunities in cosmology were breathtaking, but there are equally stunning opportunities involving exoplanets, black holes, the first stars and on and on. Just as gratifying was the personal experience of working with twenty-three astronomers with different outlooks and backgrounds, and how well this group worked together. Roger was a great leader in bringing out the best in all of us to create a program that is worthy of this great time of discovery.