The Next Decade of US Space Astronomy

By Julianne Dalcanton | August 13, 2010 11:38 am

So, the Decadal Survey (“Astro2010″) results are out. I missed the webcast (which I heard was of pretty sketchy quality), but read Roger Blandford’s slides, and have skimmed or read a reasonable fraction of the preliminary report. Here’s my summary and first reactions, broken down by regime. Steinn has also been blogging a running commentary of his reactions here.

Space Missions:

The top recommendation for a space mission is “WFIRST” — basically a 1.5m wide-field IR imager in space, with low-resolution spectroscopy capabilities. This concept is the latest realization of what was previously known as “JDEM” (for “Joint Dark Energy Mission”, which itself was an expanded and reconstructed version of “SNAP”, the Supernova (SN) Acceleration Probe). The goal would be to use some combination of high redshift SNe, baryon acoustic oscillations (BAO), and weak lensing to constrain the parameters of dark energy. The committee recommended that the mission allow for a general observer (GO) program (thank goodness) and have a component dedicated to exoplanet discovery through microlensing (really? not really something I follow, but this isn’t something I’ve heard much about. UPDATE: from the comments, Andy Gould has a white paper pointing out that the weak lensing requirements are essentially identical to what’s needed for a microlensing-based planet search. Basically, you get it for free if you decide to pursue weak lensing. However, they did not take Andy’s recommendation that the dark energy mission not pursue 3 independent techniques in one satellite.).

The next recommendation is for a mixed portfolio of smaller satellite missions. These “Explorer”-class missions have historically been hugely successful — WMAP, GALEX, etc — but have been squeezed out recently by funding limitations and pressure from flagship mission development (JWST) and operations.

The third recommendation is for continued development of LISA, an orbiting interferometric gravitational wave detector. LISA is a really nifty project — one that I was not inately that interested in, but that became more and more compelling the more I learned about it. Co-blogger Daniel has thought a lot about LISA, and maybe we can get him to talk some more about it.

Reactions to the Space Recommendations:

Overall: These were hard choices, and reading the report, it’s clear that a huge amount of weight was given to cost, feasibility, and competitiveness. IXO, the next generation flagship X-ray mission, dropped compared to its previous ranking, largely because the committee found it to be technologically and financially risky (“The Survey Committee also found IXO technologies to be too immature at present for accurate cost and risk assessment”). They instead flagged IXO as ripe for money for “technological development”, so that it’s ready to go for the next report. The Space Interferometry Mission (SIM, or SIMlite) dropped completely out, in large part due to cost vs scientific return.

The real bummer about these recommendations is that entire subfields of US astronomy are pretty much shut out of the only environment where they can operate. X-ray, UV, and high-resolution astronomy (outside of IR and radio) are fundamentally space-based enterprises, and when Chandra and HST shut down, there will be nothing left, and nothing in the pipeline for a decade or more. The good times are continuing to role if you’re an infrared astronomer — (considering the series of Spitzer, WISE, JWST, and now WFIRST), but entire communities are going to be gutted. I do think that IXO will eventually get a start, because it’s a strong mission, but are there going to be any X-ray astronomers left when it starts getting data?

WFIRST: It will be interesting to see how this plays out, because two of the three dark energy techniques are going to making a fair bit of progress over the next decade, even without this mission — two of the three new gigundo Hubble Multicycle Treasury programs will have a significant high-redshift SN component, and ground-based BAO surveys like BigBOSS are viable candidates for completion within a 10yr timescale. I’m sure discovery space will be left, but it will be interesting to see where we are in 10 years. There is also a highly ranked ESA mission with very similar capabilities. The only way it makes sense to go forward with WFIRST is if the projects somehow merge.

Explorer Missions: There will definitely be broad community support for this recommendation. For certain wavelength regimes, this will be the only game in town. UV astronomers can probably make some real progress here, because there are huge gains that can be made by increases in detector efficiency, rather than by larger apertures, which are expensive to build and launch. High-resolution questions can’t be addressed through the Explorer program, since you really need large baselines that are inaccessible at this cost limit (large baseline = big mirrors or interferometry = expensive). Not sure what can be done in the X-ray, but hard to go from Chandra or XMM down to what’s available through this approach.

LISA: I think LISA is pretty cool. I would have thought that the technological challenges for LISA are comparable to those that IXO faces, but I’ll sensibly assume that the committee spent infinitely more time evaluating this issue than I have. Of the two, LISA probably has more pure discovery space potential. We at least know something about x-rays from space, but we know close to nothing about gravitational radiation from space.

Ok, I gotta try to do some actually science today before I tackle the rest of the recommendations…more later

CATEGORIZED UNDER: Science, Space
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  • East coast astronomer

    One of the first things that stroke me is as you mentioned that entire fields can nearly shut down. Even in the IR, what is there left beyond near-IR? Spitzer is dead in the mid/far-IR, Herschel will be gone in 2-3 years, the JWST will not last forever and SPICA is subject to deprioritization if funding is not at the expected level (and i guess it won’t be). So there could be nothing left after the JWST. Why would universities hire young faculties working in the UV and/or mid-/far-IR in this context? I fear dire consequences for me and my collegues. I am trying not to panic but it is hard.

  • Michele

    Indeed, LISA is recommended for more than “continued development”. With WFIRST, it’s one of the two large space missions that, according to the panel, should get a start in this decade (pending a successful technology demonstration by LISA Pathfinder, and ESA’s final commitment to its 50% share).

    LISA will contribute to both the “Cosmic Dawn” and “Physics of the Universe” key science objectives outlined by the report (by observing mergers of the lighter massive black holes, and by allowing precise tests of general relativity, respectively). The report directly emphasizes LISA’s great discovery potential (“It would be unprecedented in the history of astronomy if the gravitational radiation window being opened up by LISA does not reveal new, enigmatic sources”).

  • Eugene

    Nobody is going to kill LISA : it is just too sexy, but all this “let’s push it to next decade” thing is beginning to annoy me. I mean, somebody gotta throw the dice here.

  • Sam Gralla

    I don’t understand. JDEM is always tops in these types of rankings, but everybody I talk to (or read blog posts of) is lukewarm about it. What is going on?

  • Andrew

    The report’s conception of WFIRST recalls Andy Gould’s memorable “lemming stampede” white paper: http://arxiv.org/abs/0902.2211.

  • Magoo

    What I don’t understand is the title of the report. “New Worlds”? Really? I do not connect that with the emphasis of the high priority programs and the funding allocations. New Worlds Technology is recommended as a medium scale program, however if you read the details in the report the Board specifies a funding level of $4M/year over the next 5 years. That is not enough to build a credible program, let alone sustain a community. What a shame.

  • Ben

    WFIRST/JDEM in the more or less current version is a near-infrared survey mission. It would produce data on galaxies that is interesting for studying galaxy formation and evolution, not just a dark energy measurement. It would have to retain that as a design goal, of course.

    I hesitate to disagree with Andy Gould about this, but I think his white paper doesn’t explain why putting microlensing and weak-lensing dark energy into a single large DE mission is suicidally worse than trying to do it in a smaller version – presumably smaller because it leaves out the other DE methods. Larger projects are bigger and take longer, but the paper doesn’t actually lay out a reason why it would fail, other than that he thinks it will not get built. In my biased opinion weak-lensing DE will always eventually have to be supplemented by redshift surveys due to astrophysical systematics (redshift distributions in particular) and that points toward doing redshift-survey DE as well.

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  • Doug A

    Soft X-ray astronomy, at least for galaxy cluster science, isn’t completely dead in the near term, thanks to ongoing European efforts like E-rosita. Hard X-ray science seemed to get a strong endorsement through the explorer program as well.

    I’m a little surprised that JWST wasn’t under review, considering how much more time and money they need before launch. There would probably be more room for these other interesting projects if that was shelved.

  • Julianne

    Doug — I wasn’t involved in astro politics at the time, but I’m told that there were many calls to cancel Hubble at the exact same stage the JWST is at now. And frankly, I’m not sure if it’s a zero sum game. If JWST in cancelled, and thus the community shows no ability to manage a large project, I don’t know that we get to assume level funding. JWST is really close to the finish line, in terms of fraction of work completed.

  • TRL

    Julianne – Having been involved with HST in the 80’s, I’m aware of no serious calls for its cancellation at the time. The primary was finished in 82, and the telescope/spacecraft was essentially complete by 1985. It was slated to launch in ’86, which was reset by the Challenger disaster. As it happens, HST was not ready to go in ’86, so we don’t know what would have happened if the issue had been forced then. The issue probably with both HST and JWST is that there were no “show stoppers.” They were harder to do than was realized at the time, but progress was always being made, and at no time did you say, OK now we should stop. HST also had considerable buy-in from the community.

    After the discovery of spherical aberration, however, there were a few astronomers who did advocate shutting it off, rather than fixing it, at the level of writing letters to NASA. 1990 was really the time when we really had to push to find a path to success.

  • Dave

    I remember all the grumbling about canceling HST in the 80’s, and I think that it is similar to the JWST situation. Lot’s of complaining about it but no serious cancelation threat (until after launch).

    There isn’t any serious thought of canceling JWST because it was our top priority in 2000 and a great deal of money has already been spent. If Astro2010 were to recommend canceling it now, it would be a sign that the recommendations of the decadal surveys are not to be relied upon. This is not the signal that they want to send.

  • DrAstro

    Further delaying the development of IXO is disappointing since the X-ray astrophysics community is brimming with talent on the science and technology sides. When the time arrives for IXO to enter full development, where does the manpower come from? Many of the best X-ray people will be retired, or worse, dead. The best way to capitalize on this talent is to dovetail the era of Chandra into the era of IXO, but a decade hiatus might make that more difficult. In my opinion, what Astro2010 has done is gamble that the decline in capable X-ray researchers does not result in an inflated IXO (or whatever mission takes its place) budget. In addition, the report’s claim that the microcalorimeter technology proposed for IXO is too immature is a gross overstatement.

  • Bruce

    “One of the first things that stroke me is as you mentioned that entire fields can nearly shut down.”

    One shouldn’t necessarily think of it as fields (like UV/Vis) shutting down; the important way to classify astronomy and astronomers is not so much by wavelength as by subject-of-interest, and people will study the objects they’re interested in with new techniques.

    That being said, this does represent a substantial shift away from a whole kind of astronomy – the kind where individual astronomers do targeted observations of interesting topics. The highest space recommendation (WFIRST) and ground (LSST) are survey instruments producing huge datasets, mostly designed around key projects but with the data open to everyone. This is perhaps even more striking in space than on the ground – no new pointed-observation GO-type facility was recommended for a next decade start (given that IXO isn’t really a next-decade start) and after JWST shuts down, it’ll be a long time before there’s a GO space facility. The astronomer of 2025 isn’t going to be someone plans a program and goes to a telescope, or even someone who selects targets and plans a HST program and gets their personal data to analyze, but instead someone who is part of a collaboration mining archives of the giant data-making machines that are carrying out a master plan put together by their consortia. Whether this scientifically better or worse can be argued either way, but it’s definitely a change.

  • http://blogs.discovermagazine.com/cosmicvariance/julianne Julianne

    DrAstro — I agree completely with your analysis of the situation for x-ray astronomy (though I have no information to add about microcalorimeters). However, there is absolutely no way the community can get more than one flagship-class start into the NASA pipeline. Once the committee identified dark energy and extrasolar planets as two of the key science questions, they can’t really have IXO being the only large mission.

    Doug A. above seems more optimistic about there being ways that X-ray astronomers can keep busy in the interim, so maybe not _everything_ will go dormant. It’ll just go more international for a bit.

    Sucks though.

  • http://blogs.discovermagazine.com/cosmicvariance/julianne Julianne

    Bruce — The report strongly endorses a GO program for WFIRST, but it will certainly be a smaller fraction of the time than the current generation of flagship missions.

    I also agree that scientists should be more focussed on the topic than the tool. However, it does take years to develop the expertise to really use one’s tools well. (Take the VLA — no matter how many summer schools NRAO offers, pretty much no one goes after VLA data without a very knowledgeable collaborator.) Moreover, there are just some questions you can’t really get at without a particular wavelength regime.

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  • Bruce

    Certainly for exoplanets (which I would argue is an area the report is somewhat weak on), there aren’t likely to be meaningful GO programs with WFIRST – just a single staring project. For other science programs, my guess is that WFIRST GO programs will trend towards big surveys (since that’s what it’ll be good at), with small projects only around the margins. Again, not necessarily a bad thing scientifically, but it’s a shift.

    The other significant change of balance – even more so than uv/vis/ir/xray balance – is away from spectroscopy towards imaging.

  • Tony

    Found it hard to argue with the committee’s recommendations. Disappointments abound — having only a 30-m class telescope in one hemisphere, SKA axed etc — but the committee really seems to be emphasizing in investing in the most bang-for-the-buck projects.

    Also, it was wise for them to put the explorer programs near the forefront, and make sure they don’t get sidetracked when big projects go over budget, which is what happened this past decade. We need to stay nimble for new discoveries.

  • Shantanu

    Btw I didn’t see any discussion of successor to satellite based missions such as AMS, PAMELA(the latter of which has produced great science). Is it that no one in astro community is interested in this
    or it does not fall under purview of astro 2010?

  • Thomas

    Frustrated by the relative lip-service paid towards exoplanets — microlensing is a great technique and can do a nice job of statistical distributions of planet sizes I believe, but nothing (and I mean nothing — a few $M of tech funding is almost equal to nothing) towards really allowing a mission for breakthroughs in the areas where most exoplanet research is heading: nearby earth-like planets, and combined light spectroscopy of exoplanet atmospheres — or even better, direct imaging.

    As for WFIRST, excited about the prioritization of the science, frustrated that the committee didn’t explicitly recommend a direct partnership with ESA’s Euclid and save the money for additional programs. Especially considering NASA has been explicit that they don’t have $1.6B for a dark energy mission (ref: BEPAC report and outcomes, ISWG studies of $600M version of JDEM, etc..)

    Great about Explorers.

    we’ll see how NASA is able implement it all…
    It’s still cool stuff in the end.

  • Dave

    Thomas:
    I don’t think that it is lip-service about exoplanets. They clearly are a top priority. However, the selection of large missions. like JDEM or SIM depends on many other factors besides science priority, and once they picked JDEM over SIM there wasn’t much they could do beyond adding microlensing to JDEM. You may have a point about the tech funding for the future advanced exoplanet missions, though.

    However, I think that it is good that the committee did not try to adjust the science priorities to match the program they are recommending, as there is a temptation to do in order to make the report seem more consistent. This should give exoplanet missions an edge in the explorer competition, I think.

  • Fermi-Walker Public Transport

    If the US pulls out of the SKA project, does anyone know how that would affect its financial viability ? That is, is it likely that the remaining SKA partners will make up the shortfall ?

  • Martin E.

    The real story coming out of the Decadal is that astronomy has hit the Funding Wall. Like particle physics and the SSC, we just can’t afford a next generation of Great Observatories spanning IR-Gamma-rays. We can no longer just extrapolate from the last generation to something bigger. The WFIRST flagship is put at $1.5B. If this number sticks (and it really has to), the scale of a flagship just came down a factor 2-3.
    Yet astronomical objects don’t stick to our technology-defined wavelength bands. The absence of new MeV-GeV gamma-ray, hard & soft X-ray, UV, mid-IR, far-IR, and radio facilities in the next decade will slow down the response time from a discovery in one band to follow-up in another from a year to more than a decade. The paucity of spectroscopy will hurt similarly.
    The committee could not have satisfied this thirst. The funds just aren’t there. They did the best they could by beefing up the Explorer program (which I was a vocal advocate for), which gives everyone a shot. Instead of just going for more, we must now be clever. Luckily I’m sure we can be.

  • Kris

    You hit on a major concern of mine regarding WFIRST, Julianne. What happens if launch rolls around and ground-based surveys have found that w=-1 +/- epsilon? At what point is epsilon small enough as to be uninteresting? We could see the main science driver of our highly-specialized flagship mission essentially solved before the telescope ever collects a photon.

    I would argue that the true legacy of HST and Chandra will not be the projects for which they were designed (H0, resolving the X-ray background, etc), but discoveries made along the way. This is where not having a true GO observatory like IXO is really going to hurt.

    NuStar is a great example of what can (will, I guess) be done at the Explorer level in X-rays, but the lack of effective area hurts. An AGN-studying friend of mine calculated that the necessary exposure time for NuStar to achieve “interesting” depth for her particular science in the deep fields is something like 6 months. Any bets on that observation getting done?

    This question isn’t rhetorical (I just don’t know the answer): is there really a factor of 10 in UV sensitivity left in the detectors? Isn’t that the normal metric by which new missions are adjudicated?

  • Dispirited astronomer

    Not only will Erosita be launching in Europe soon, in the next few years there will be the new X-ray missions Astro-H, GEMs, and NuSTAR to add to the current fleet of active orbiting instruments including Chandra, XMM, Suzaku, RXTE. But the loss of IXO to beyond the event-horizon for most current X-ray astrophysicists is indeed a major set-back, that will most obviously become apparent around the end of the decade. IXO was pretty much the only observatory class mission being proposed in the traditional sense of astronomy, in which there would have been numerous different types of objects and science to study, an enormous discovery space opened up by the orders of magnitude improvement in effective area and high resolution spectroscopy, and the chance for the sort of traditional targeted studies by individuals/small groups that Bruce described. WFIRST and LISA will not support similar broad communities – their available science that can be achieved is way more focused to answer much smaller number of questions.

    I would like to correct DrAstro who claimed the report said that microcalorimeter technology is too immature. Microcalorimeters were mentioned twice, and this was not said on either occasion. The issue is with the optics, and the potential cost of their development. The cost of microcalorimeter development is almost insignificant by comparison.

    The sad truth behind the downfall of IXO is that a couple of years ago the decision was made to develop a mission concept that was beyond the capabilities of modern large area x-ray optics (ie. an angular resolution of 5″). The Decadal panel review is right to be skeptical of the estimated cost of this technology development – it could be very expensive indeed. This decision was made when Constellation-X had just been beaten up by the BEPAC review, which followed a similar beating-up by the Trip review panel that compared Con-X to LISA. After BEPAC there existed feelings by some that Con-X was not “sexy” enough to compete with LISA, and that by extending its capabilities towards a mission like the European XEUS concept, it could become more appealing.
    The additional cost might also be less to NASA if costs were shared with the International partners. At this time the mission concept went from being one that could be estimated as costing $1.5-$2B to a compromise with the European XEUS concept (a completely unrealistic concept that could well have cost $10B), that was ultimately estimated to cost $4-5B. (The Xmas tree of supporting instruments demanded by the European community did not help). Given that Europe and Japan contributions would amount to around $1.5B, this was simply too high for the maximum palatable cost to the NASA astrophysics program, which is around $2B for a large mission.

    Julianne, I can tell you that I do not believe that this Decadal review panel carried out their own research to assess risk and potential costs, and neither did the “experienced and competitively selected contractor” company that was hired to make the estimates. My guess is that this was a blind statistical analysis done based upon the self-assigned, highly subjective, TRL-levels (technical readiness level) to the various component technologies. I know that the contractor did not have sufficient information to do anything else. I suspect that some judgements were given to certain technologies where individuals had some personal knowledge, but not that much. So this means that WFIRST and LISA claimed to have higher TRL levels than IXO. This is fair for WFIRST, as the necessary technologies are not very new. This is not true for LISA. I can tell you, that if nothing changes by the next review, the community will cotton on to the fact that it is simply necessary to claim that they are at a high TRL level, to avoid being costed too highly or assigned as too risky.

    It should be noted that LISA funding is now completely dependent on the success of the European gravitational wave technology probe – that is doing very badly right now. So badly, LISA is quite likely not to do well in the European Cosmic vision assessment (analogous to the US Decadal survey).

    Reading the comments, it should also be emphasized that this review is a set of recommendations based upon information given to a panel over a year go now, not the decided road-map. NASA decides what it will do for itself, but certainly the review is of paramount importance. Already there is much less money for the decade than the panel assumed as JWST is over-running its costs again by quite a large amount – of the large scale options, only the top priority will be supported strongly.

    My biggest criticism of this report (so far – there will be a much larger final version), is that it did not address the criticisms formerly directed towards the Dark Energy mission concept while choosing it to be the top priority. It is true that it was probably the only mission concept studied in detail that was cheap enough to be considered for the current astrophysics program budget.

  • Jim Graber

    @Dispirited astronomer
    So what are the problems with LISA Pathfinder?
    Jim Graber

  • Gary B.

    I don’t think it’s accurate to say that common-user facilities are being neglected in the Astro2010 proposal. The lions’ share of the NASA budget for the coming decade is already tied up in JWST, with SOFIA being an astonishingly large fraction as well. Extensions to the HST lifetime are inevitable but were not yet budgeted. So it will remain true that common-user facilities will use most of the astrophysics budget at NASA.

    Regardless of your scientific or wavelength preferences, there is simply no way that a project as expensive as IXO would fit into the projected NASA budget, as I understand it. Even though I am a dark-energy fan, I was very surprised at the Decadal outcome, but in retrospect I can see the panel’s logic that the burden of JWST and other legacies of previous decades left them searching for something that could be squeezed into the remaining uncommitted budget while having a good chance of actually being accomplished interesting new science in this decade. I already have heard that more JWST delays (= cost) are on the way, leaving in doubt whether even one new mission can be started this decade.

    On the ground-based side, NSF’s biggest cost right now is ALMA, a traditional time-allocated facility. LSST is also a common-user facility, really – data for everyone, it’s just that you won’t get to request your own pointings, because it’s already pointing at everything every few nights!

  • Dave S

    @Dispirited Astronomer: Where did you get those costs for IXO from? They way higher than any the project itself ever said. And higher than the decadals rather dubious numbers too if i remember the presentation properly.

    The sad thing is this decadal was supposed to fix the last ones failure to address realistic costs for missions, yet we still seem to be at the mercy of jwst’s criminal overruns plus decadal ranking based on third party cost estimates of dubious accuracy.

  • Dave

    @Kris: I’m not a dark energy guru, but I think that the following is the argument for the WFIRST dark energy program. The main issue with all methods that try to measure w and w’ is that they have systematic errors that aren’t fully understood. In many cases, these systematic errors are likely to be more poorly understood with ground-based data. Thus, the w=-1 +/- epsilon measurement from the ground will come with hidden assumptions about the systematic errors and won’t be completely trustworthy. From space, you can do much better, particularly with 3 methods.

    You might recall that the final pre-COBE ground-based CMBR anisotropy upper limits were substantially below the current measured anisotropies. Certainly, there is some danger that the ground-based programs will steal WFIRST’s thunder if they get the correct result first. However, this isn’t what happened when Boomerang measured the CMBR Doppler peak prior to WMAP. WMAP did much better and is generally regarded as a great success, despite being scooped.

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  • Rich M

    Following ‘dispirited astronomer’- I have heard exactly the same rumors about the LISA pathfinder from a large number of European astronomers who tell me that they have heard it from the ‘ESA executive’- it is the same sort of problems presently bedevling JWST (lots of medium scale issues, no show stoppers, but no end to the problems.). Given the large cost increases for most of the recent ESA programs (Planck, Herschel, Beppi-Colombo) the ESA executive is, properly, gun shy.

    The other issue with LISA, which has not been discussed publically is the science risk. This has 2 aspects 1) there is no indication either theoretically or observationally that there is a problem with GR in the high energy limit. Thus it is not clear that there is something important to learn about GR from LISA 2) the estimated rates for massive black hole mergers are extremely uncertain- they are the convolution of 3 unknown functions (the fraction of proto-galaxies that host Black holes, the relationship of the black hole to the mass of the galaxy and the physics by which the black holes get close enough to merge (which depends greatly on the unknown physical conditions within the central pc of the merging systems.)
    I am amazed that this science risk has not been discussed and that virtually all the papers predicting LISA rates are extraordinarily optimistic.
    Finally there is the extraordinary optimism of this community. The NSF was assured 20 years ago that LIGO would definitively detect a signal. Then enhanced LIGO, now there will have been spent over $800M on advanced LIGO and LISA (ESA +NASA have spent of $350M on LISA pathfinder) with not even an indication of a signal.
    Another serious issue is the concept that one opens up a new field and immediately there are great discoveries. It took over 30 years for ground based gamma-ray astronomy to start having scientific success and to this day gamma-ray high resolution spectroscopy has only 3 results. Sometimes nature is not kind.

  • Bob

    To me, the potential for LISA is huge. The technology needs work, as the panel and others have said, but to me it is analogous to opening, for the first time, a new wavelength region. We can’t anticipate what we will learn from gravitational astronomy. The first satellites that opened up new wavelengths in the past have been hugely successful. I like that they hinged this on LISA Pathfinder, though, so they don’t end up spending a huge amount of money on unproven technologies.

    @Jim Graber, this probably isn’t the best place for LISA Pathfinder issues, but you can check out a Physics Today article is you subscribe:

    http://ptonline.aip.org/journals/doc/PHTOAD-ft/vol_63/iss_7/14_1.shtml

    The article discusses a problem and a proposed solution, but it’s always worrisome when you have to correct for a problem to a level of 0.1% or better (lower). We’ll see how they do!

  • Ryan M

    As a grad student stranded by this past year’s depressing job cycle, I am disappointed that little concern seems to have been giving to the frightening career prospects for young astronomers, despite the numerous white papers on the State of the Profession submitted to Astro2010 that addressed the problem that (1) there are too many post-docs relative to the number of permanent positions, thus effectively ensuring that about 75% of young astronomers will not be successful on the career path that we have been trained for, and the complimentary problem that (2) we are not be appropriately trained for the alternative career paths that many of us will have to take.

    There needs to be a paradigm shift in the way young astronomers are trained. And perhaps the profession needs to be allowed to contract back to sustainable levels. Even worse for those of us coming onto the job market during the current recession is that while we were always told that our skills were marketable outside of academia, at present, the door to other professions is effectively shut, because those markets are saturated with people who are actually experienced in those fields and are simply better-suited than we are.

    Astronomers of older generations might simply reply “stop complaining and pay your dues.” The problem is that for a majority of us, paying our dues seems at present to be a delusion that will prepare us for heartbreak rather than success.

  • zankaon

    Our multi-stellar system?

    Most stars form in multiples. Where are our sister stars? All of such sisters should be of somewhat similar mass, main sequence; but empirically perhaps 1 supernova. Such sisters must not be so far off. Hence might they be detectable by looking for ‘cold’ Jupiters? Use a dedicated infrared telescope to evaluate the luminosity and size of such gas giants, and through comparison, see if any are close. Such star(s) should be much less than 1 light year away, and hence within the common Oort Cloud. Thus if such sister stars are within our Oort Cloud, would it seem then to be a distorted cloud, common to such multiple star systems? However such set of sister stars would have a center of mass, and in accordance with a central force, a spherical distributed common Oort cloud of cometary material. Hence overlapping gravitational fields for such set of sister stars. Also if terrestrials are detected, then perhaps spectroscopically look for the atmospheric oxygen signature of photosynthesis. Also perhaps radio attention might be of interest for such near by sister star systems.

  • M. Muno

    In response to Rich M, who said, “there is no indication either theoretically or observationally that there is a problem with GR in the high energy limit”. . .

    There is in fact enormous evidence that GR needs to be examined carefully in the high-energy limit — GR can’t be reconciled theoretically with quantum mechanics! If any observations are to point the way to new theories for gravity, they will be found by studying high-energy interactions.

    In this regard, another answer to where X-ray astronomy might go in the next decade is to develop an Explorer-class successor to the Rossi X-ray Timing Explorer. By studying periodic variations in X-ray emission from near the event horizons of stellar-mass black holes and the surfaces of neutron stars, one might start to collect information about the space-time around these objects. I think similar science is important to pursue in the radio, by developing a sub-mm very long baseline interferometer to image the event horizon of the Milky Way’s supermassive black hole.

    Gravity — with quantum mechanics plaguing it at high energies, and possibly dark matter and energy at low energies — is not a solved problem!

    I was, until a couple years ago, very interested in pursuing this, but alas, I needed a steady job. Julianne’s reaction to the X-ray component of the Decadal Survey (“Not sure what can be done about X-ray”) is a small part of why I decided to leave astronomy. The X-ray community is concentrated at a handful of institutions. It seems to have a hard time explaining why their work is important, given that it has to compete for money with (arguably more inspiring) advances in cosmology and exoplanets. This definitely limits the perceived value of hiring X-ray astronomers to faculty.

    Thanks for the summary, and it is good to see the continuing and vigorous debate over the near future of astronomy.

  • Dr.M.A.Padmanabha Rao

    Regarding X-ray and UV Astronomy with reference to Solar X-rays, EUV:

    The phenomenon described in the following paper explains solar EUV

    Excerpts from the paper:
    Findings of the current experimental study have a direct bearing on solar emissions. There is a similarity in the γ-, X-, β, UV, VIS, and NIR radiation emissions from radioisotopes, XRF sources, and solar flares [14-19]. Therefore, the author has preliminarily reported [3] that solar γ-, X-, or β radiations cause EUV regardless of temperature by the atomic phenomenon described here. On the basis of the current study, it may be worthy of a review of interpretation of solar EUV lines to be of highly ionized atoms at high temperatures, and estimation of solar temperature from EUV line ratios [20-21]. An overall view of published reports suggesting presence of 235U, 238U, and radioisotopes in solar flare indicate that the phenomenon described here could be the most likely cause for Solar EUV emission. For example, as detection of γ, and neutron fission counts helps in finding the presence of uranium [22-23], simultaneous detection of X- rays, γ-rays, and neutrons reported in solar flares [24-27] suggests the presence of uranium in Sun. The hypothesis on likely presence of uranium in Sun derive further strength from the report on uranium content of solar salts [28] and traditional wisdom that 235U and 238U metals in the solar system are formed from previous supernovae. Moreover, presence of activation products such as 56Co, and 24Na in solar flare [29-32] and presence of7Be in open air after a strong solar wind [33] need to be critically examined to see whether any possibility exists for Uranium fission in Sun. If fission truly happens, the fission fragments left over at the site of fission might constitute dark matter [3].

    In the context of solar flare, the predicted Bharat radiation causing UV dominant optical radiation from radioisotopes and XRF sources by valence excitation seemed to be the familiar dark radiation from cosmic sources [3]. As Bharat energies produced internally within an excited atom cause non-thermal valence excitation resulting into UV emission from radioisotopes at room temperature, solar EUV may take place by valence excitation of dark energies from within excited atoms of radioisotopes present in solar flare regardless of temperature. As in the case of the current study, the γ-, X-, or β radiation emissions from radioisotopes formed by fission reaction in Sun cause two more generation of emissions: the predicted dark radiation, which is the same as Bharat radiation followed by EUV. Any how the current experimental study may prompt to examine all these possibilities.

    Brazilian Journal of Physics

    version ISSN 0103-9733

    Braz. J. Phys. vol.40 no.1 São Paulo Mar. 2010

    doi: 10.1590/S0103-97332010000100007
    http://www.scielo.br/scielo.php?pid=S0103-97332010000100007

    UV dominant optical emission newly detected from radioisotopes and XRF sources

    M. A. Padmanabha Rao

    Charak Sadan, Vikaspuri, New Delhi 110018, India

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