Get back on the gravitational-wave hunting horse. That’s 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.
“The progress in the first five years has been incredible,” says Jacqueline Hewitt of the Massachusetts Institute of Technology, who was chair of the assessment committee. “The government is getting its money’s worth in terms of the resources it’s been investing in support for scientists.”
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.
“It’s a technical coup, but it’s not only that,” Hewitt says. “It’s a new tool to study the universe. There’s a whole relativistic universe out there that we haven’t studied yet.”
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.
“That’s been put on hold, even dissolved,” Hewitt says. ESA has plans to launch “evolved LISA” or eLISA on its own, and its test bed LISA Pathfinder spacecraft has been performing beautifully. Given that success – and the fact that we now know that gravitational waves exist – 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 – NASA’s budget has remained mostly stable over the past five years.
“There’s a lot that’s not happening because the budgets were not what the decadal survey predicted,” 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
“We did not expect JWST to cost as much as it did and to take as long to launch,” Hewitt says. “That means things have been delayed.”
It also means that the original 2010 report’s highest space-based mission priority, a “Swiss-army knife” 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’s 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.
“It’s important to control growth in the cost of WFIRST, that is something the committee is concerned about,” Hewitt says. “There’s a tendency to increase scope. Right now the WFIRST plan is very good, it’s 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.”