My purpose in writing about this is to stimulate interest in the program among that part of the U. S. public that pays attention to basic science, especially advanced studies of the universe at large. Because, you see, as a result of last week's elections, the character of the U. S. Congress is going to change significantly next year. There's reason to hope priorities can change. When NASA's science budgets are discussed in future years, we can advocate that Congress reinstate funds for the missions that make up the Beyond Einstein program.
The main purpose of this post is to present background information on the program. But of course, a few words need to be said first about what the Beyond Einstein program is. Fortunately, NASA's home page of the project does a really great job of providing both an overview and detailed background information. See especially the science page, the mission descriptions, and additional resources.
In a nutshell, the various missions together and separately will investigate four of the most mysterious phenomena that we know of in the universe: black holes, gravitational waves, dark energy, and cosmic inflation. These phenomena are grounded in Einstein's general theory of relativity. Yet there's a great deal we don't understand about each one – hence the name "Beyond Einstein".
This graphic from the project site sums it up (click for full-size image):
If you go to this page, you'll be able to click on individual parts of the graphic for more information. The items at the far left are space missions that have already been launched (except for GLAST, whose launch is scheduled for late 2007) or ground-based facilities (LIGO) that are currently working on different parts of the puzzle. Immediately to the right of those are two missions (LISA and Constellation-X) that are well-along in planning – but not yet approved and funded. They (as well as everything else to their right) are missions that were ditched, at least for the present, in NASA's 2007 budget.
LISA will use interferometry techniques, as does LIGO, to search for gravitational waves. But because the separation of the three observation points will be millions of kilometers, instead of a few thousand in LIGO, it will be vastly more sensitive. LISA should be able to detect gravitational waves resulting from supernovae or black hole collisions.
Constellation-X is to consist of four X-ray telescopes on a single spacecraft. It is a successor to previous space-based X-ray observatories, such as Chandra. Constellation-X will be able to study phenomena that are energetic in the X-ray part of the spectrum, such as physics in the vicinity of black holes and very hot gas found in large galaxy clusters.
The missions in the center of the chart are less far along in planning. Of the three, the dark energy probe appears to be farthest along. In fact, there are actually three possible designs in competition. In August, NASA authorized a comparative analysis of the three designs in order to identify the "best". Each of them will measure the effects of dark energy over the history of the universe by locating and studying 1000 or more Type 1a supernovae. They differ in the additional kinds of measurements they can make. However, the status of this mission (as well as the others discussed here) has recently been thrown into further uncertainty, as we'll explain in a minute.
The purpose of the inflation probe is to gather stronger evidence for the process of inflation that appears to have occurred beginning a mere 10-35 seconds after the big bang. (As discussed here and here, back in March NASA announced that an analysis of WMAP data in fact gave preliminary evidence for inflation.) In addition, the probe will seek data that can discriminate among the many possible models which can describe inflation. There are different ways that the probe can study the problem, including a more detailed analysis of polarization in the cosmic microwave background, and a study of the evolution of large-scale structure in the universe.
The black hole finder, as the name implies, will be designed to locate and study black holes (both stellar-mass supernova remnants and supermassive black holes) in order to learn more about how they form and grow. As such, it will build upon work done by Constellation-X.
As for the two "vision missions", it's really too early for scientists and engineers to define them in any detail. Much will depend on phenomena that are better understood from the results of earlier missions, and most likely phenomena we don't even know of yet. Understandably, these missions (and certainly others like them) are decades in the future.
And this brings us to the latest news. It should be clear enough that there are plenty of overlaps and interdependencies among the various missions. The capabilities of later missions will depend critically on what we learn from earlier ones. After all, until 1997, no one seriously suspected that dark energy even existed. (And some experts still doubt its existence.)
Because of this, as well as because of the severe present constraints on NASA's science budget, The National Research Council (NRC) of the National Academies has formed a committee – at the request of NASA and the U. S. Department of Energy – to conduct an assessment of the Beyond Einstein program. The first meeting of the committee was held last week (November 6-8). The agenda is here. Further information on the committee, including its membership and staff, is here.
This is the committee's task statement:
1. Assess the five proposed Beyond Einstein missions (Constellation-X, Laser Interferometer Space Antenna, Joint Dark Energy Mission, Inflation Probe, and Black Hole Finder probe) and recommend which of these five should be developed and launched first, using a funding wedge that is expected to begin in FY 2009. The criteria for these assessments include:
a. Potential scientific impact within the context of other existing and planned space-based and ground-based missions; and
b. Realism of preliminary technology and management plans, and cost estimates.
2. Assess the Beyond Einstein missions sufficiently so that they can act as input for any future decisions by NASA or the next Astronomy and Astrophysics Decadal Survey on the ordering of the remaining missions. This second task element will assist NASA in its investment strategy for future technology development within the Beyond Einstein Program prior to the results of the Decadal Survey.
As of right now, I haven't seen any accounts of what happened at the meeting last week. If anyone out there has some actual information about the meeting, or has seen reports of it, please let me know.
What I do know is that some people are pretty worried that the real purpose of this committee is to narrow down the Beyond Einstein program to just one mission, or possibly two, because of NASA's budget problems. This might entail not merely postponing other missions, but essentially killing them altogether. The problem is that, if some level of misson activity cannot be funded on an ongoing basis, then many researchers and their institutions will have to find other things to do, and it could be very difficult to bring teams back together when, or if, funding becomes available. See two posts here and here, from Steinn Sigurðsson for examples of the kind of speculation going around.
Oh yes, there is one other thing. Along with the announcement on October 31 (before the NRC committee meeting), that a final service mission will be flown for the Hubble Space Telescope, there were strong hints that other astronomy missions are on hold. The report on this printed in Science: Hubble Gets a Green Light, With Other Missions on Hold is available only to subscribers, but says at the end:
Griffin's decision means that NASA will spend most of its astronomy budget on three major missions--the Hubble servicing flight, construction of the James Webb Space Telescope, and the Stratospheric Observatory for Infrared Astronomy (SOFIA). Technical troubles, schedule delays, and cost overruns plague the latter two. But Weiler [director of NASA's Goddard facility] says that the Webb is back on track after a rough couple of years, while SOFIA--which Griffin initially canceled only to revive in July--is slated to begin operations in 2009. Those large projects leave little room for smaller or future missions. For example, NASA halted work earlier this year on the extrasolar planet-seeking Space Interferometry Mission (SIM) in order to cover SOFIA's cost overruns. Those pressures worry some astronomers, who fear that the three missions will limit new efforts.
"Is the astronomy program with just [Webb], Hubble, and SOFIA a good astronomy program? You betcha," says Weiler. Although he acknowledges that there is a gap in smaller missions for the next few years, he notes that the cost of building the Webb will peak in 2008 and then decline over the next 5 years. "The big issue now is what to do with that wedge."
The four leading contenders appear to be the Joint Dark Energy Mission with the Energy Department, a mission called Constellation-X that features a bevy of x-ray telescopes, the Laser Interferometer Space Antenna to study black holes and the early universe, and SIM. NASA had intended to fund all in this decade and the next, but budget constraints likely will make for a competitive race.
Make of that what you will, but it certainly doesn't sound too good.
On the other hand, it certainly looks like the task of the NRC committee is to select at least one of the Beyond Einstein missions. Further, NASA is going ahead with other new astronomy projects. In addition to GLAST (launches late 2007), on October 13 there was an announcement that the Wide-field Infrared Survey Explorer will be launched in 2009 to do infrared sky maps, which would capture both nearby planetary systems undergoing formation as well as very distant galaxies – news report, further information.
So here's the bottom line I see for now: The NRC committee will take a year or so to ponder the situation. They may pick one project to go forward with initially. (Betting seems to be on the dark energy probe, because of the involvement of the Department of Energy.) Other missions in the advanced planning stage (LISA and Constellation-X) may wind up on hold, or one may be slotted as well.
The important point: there is plenty of time to make the argument before the appropriate Congressional committees that the NASA science budget should be increased enough so that the Beyond Einstein program can go forward, without having to sacrifice planning that has already been done and disrupting teams that are already in place.
Fortunately, as a result of last week's elections, Congress will have new people in charge who should be inclined to place a higher value on basic science than those they are replacing.
Update 1 (11/13/06): According to a comment by Steinn, LISA and Con-X have been "approved", but only minimally funded.
Update 2 (11/14/06): Now Steinn says funding was cut off. In any case, they're going noplace fast at this point.
- Beyond Einstein: From the Big Bang to Black Holes
- This is a 110 page document you can download in PDF format, and it's very much worth the effort. It's profusely illustrated (full color) and describes all of the missions and gives a good overview of the underlying science. Only problem is it was published in January 2003. But the additional science that has been learned in the last four years mostly confirms the premises of the program.
Tags: astrophysics, cosmology, Beyond Einstein, black holes, dark energy, cosmic inflation, gravitational waves, NASA
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