Get back on the gravitational-wave hunting horse. That鈥檚 part of the message of a new report from the US National Academies of Sciences, Engineering and Medicine, designed to check how well the US is meeting key scientific goals in astronomy and astrophysics.
The report follows up on the 2010 decadal survey, a wish list from the astronomical community released every 10 years to identify the top research priorities.
鈥淭he progress in the first five years has been incredible,鈥� says of the Massachusetts Institute of Technology, who was chair of the assessment committee. 鈥淭he government is getting its money鈥檚 worth in terms of the resources it鈥檚 been investing in support for scientists.鈥�
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Hewitt highlighted research into exoplanets, planets that orbit stars other than the sun, which has been booming since the launch of the Kepler Space Telescope in 2009.
The committee also praised the US-based LIGO experiment for its ground-breaking detection of gravitational waves, ripples in space-time shaken off when massive objects accelerate, earlier this year.
鈥淚t鈥檚 a technical coup, but it鈥檚 not only that,鈥� Hewitt says. 鈥淚t鈥檚 a new tool to study the universe. There鈥檚 a whole relativistic universe out there that we haven鈥檛 studied yet.鈥�
Friends reunited?
That success prompted the committee to recommend that NASA finish what it started: the Laser Interferometer Space Antenna. This space-based experiment was meant to hunt gravitational waves from even bigger black holes than LIGO can detect by sending lasers between three spacecraft arranged in a triangle. It was originally a collaboration between NASA and the European Space Agency, but NASA pulled out in 2011 citing funding limitations.
鈥淭hat鈥檚 been put on hold, even dissolved,鈥� Hewitt says. ESA has plans to launch 鈥渆volved LISA鈥� or eLISA on its own, and its test bed LISA Pathfinder spacecraft has been performing beautifully. Given that success 鈥� and the fact that we now know that gravitational waves exist 鈥� the National Academies committee urged NASA to renew its partnership with ESA.
The committee identified two reasons for the shortfall in money that led to the withdrawal. One was shrinking budgets, especially for the National Science Foundation 鈥� NASA鈥檚 budget has remained mostly stable over the past five years.
鈥淭here鈥檚 a lot that鈥檚 not happening because the budgets were not what the decadal survey predicted,鈥� Hewitt says.
The other culprit was the ballooning cost of the James Webb Space Telescope, the successor to the Hubble Space Telescope, which has been overbudget and delayed for years. Once targeted for launch in June 2014, the telescope is now expected to launch in October 2018.
Limit the features
鈥淲e did not expect JWST to cost as much as it did and to take as long to launch,鈥� Hewitt says. 鈥淭hat means things have been delayed.鈥�
It also means that the original 2010 report鈥檚 highest space-based mission priority, a 鈥淪wiss-army knife鈥� telescope called WFIRST, has still not launched. The current plan for that mission is to use one of two telescopes donated to NASA by the US Department of Defense to help understand dark energy, scrutinise Earth-like planets, and seek the universe鈥檚 first stars.
While the committee is glad that plans are still proceeding to launch the telescope, it also warns that adding too many features to the mission could lead to similar cost overruns to those plaguing JWST.
鈥淚t鈥檚 important to control growth in the cost of WFIRST, that is something the committee is concerned about,鈥� Hewitt says. 鈥淭here鈥檚 a tendency to increase scope. Right now the WFIRST plan is very good, it鈥檚 an exciting mission and NASA has been managing it carefully. But given the history, the committee is asking NASA please to continue managing it carefully.鈥�
