SAN FRANCISCO — Frustrated by a lack of support for the work they deem critical to preparing the next NASA mission to search for Earth-like planets orbiting nearby stars, a group of scientists is drafting a proposal for a new, multistep plan to demonstrate promising technologies.
A preliminary draft of the plan, which is scheduled to be delivered in October to the astrophysics subcommittee of the NASA Advisory Council, recommends investing roughly $10 million a year for four years to enable scientists to build, test and demonstrate technologies that may enable space-based instruments to gather images of exoplanets and to analyze the chemical composition of their atmospheres in a search for the tell-tale signs of life.
The group of astrophysicists and planetary scientists, led by professor Webster Cash of the University of Colorado, is drafting plans to develop coronagraphs and star shades, technologies that were identified specifically in the National Research Council’s 10-year plan for astronomy published in August 2010. That report, “New Worlds, New Horizons in Astronomy and Astrophysics,” called work to identify and study exoplanets in the habitable zone of nearby stars “the single greatest area for unusual discovery potential in the coming decade, as it can be carried out with current methods provided that the necessary resources are made available.”
Scientists eager to begin building and testing those devices said the necessary resources either are not available or are not reaching them. John Trauger, an expert on coronagraphs at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., said the space agency has set aside $5.2 million a year for the entire exoplanet program. That money must be spread throughout a large community of scientists eager to investigate new ways of identifying planets.
In its most recent competition concluded in late August, the exoplanet office received 21 proposals and provided funding for six of them. “If you have to cut the funding up that way, the progress you can make is very limited,” Trauger said.
If the progress does not improve dramatically, the astrophysics community is likely to fail to produce a promising mission plan in 2020, scientists said. “If we don’t get funding for flight demonstrations of critical technology, there is little chance of success,” Cash said.
Doug Hudgins, Kepler program scientist at NASA headquarters, disagreed with scientists who said the exoplanets program is on the wrong track.
Hudgins said NASA is conducting a robust effort to develop the technologies “that are ultimately going to lead us to an exoplanets mission capable of detecting an Earth-like, habitable planet around a nearby star and actually separating [the planet] out of the glare of its star to study its atmosphere and characteristics.”
Still, Hudgins is not surprised that scientists passionate about their work would be clamoring for additional funding to develop technology to study exoplanets. “The job of trying to see a tiny, little planet orbiting next to a really bright star is tough,” Hudgins said. While the current budget allocates about $5 million to develop that technology, a much larger amount of money could be devoted to the effort. “This is difficult technology development,” Hudgins said. “Could we spend $200 million or $300 million? Yes. Sure.”
The budget plan drafted by NASA officials would increase funding for that technology development from year to year. The plan calls for the $5 million budget “to grow steadily by a few million dollars a year until the middle of the decade,” Hudgins said. After that, exoplanet scientists hope their work will be recognized by the National Research Council’s mid-decade review. “We hope they say, ‘You are doing a great job of moving these technologies forward and we think you ought to ramp up your technology effort,’” Hudgins said. If that happens, the budget could jump significantly, he added.
National Research Council support for a program is critical to its success in obtaining NASA funding. The Space Interferometry Mission, an astrophysics program conceived in the early 1990s to make precise measurements of the position of stars and detect planets in orbit around them, was halted in 2010 after the decadal review panel recommended that it be canceled in light of “competing compelling scientific opportunities” and a “highly constrained budget.”
The group of approximately 20 space scientists and engineers contributing to the report for the NASA Advisory Council’s astrophysics subcommittee is eager to help the next exoplanet mission avoid a similar fate. Although the group has not yet approved a final report, the group is expected to recommend a plan to develop star shades and coronagraphs. “It’s never a good idea to go after an important problem with just one tool,” Cash said.
The plan is designed to prepare scientists to make an informed decision in 2015 on the technologies to be included in the next major exoplanet exploration mission. The proposed astrophysics plan is expected to cost roughly $11 million a year, not including any expenses associated with conducting suborbital flight tests of promising technology.
That funding also is needed to help researchers develop the skills they need to carry out a successful mission. “In space science, you’ve got to have a chance to try things out and find out what works,” Cash said. “If you fail, fail cheaply before you go on and commit large sums of money to a project.”
Cash is using that technique to test his plan to employ star shades in the search for exoplanets. In 2007, Cash used the facilities at the University of Colorado’s Laboratory for Atmospheric and Space Physics in Boulder to test whether a star shade could block out the bright light from a star, making it easier for a telescope to detect faint objects near the star.
During the first test, Cash placed a tiny star shade 100 meters from a telescope to demonstrate the concept. Once that test proved the concept was valid, Cash began submitting proposals for NASA funding to conduct additional demonstrations, including a plan to use a star shade to obtain imagery of planets orbiting Alpha Centauri. Those proposals have been rejected.
