By Eugenie Samuel Reich

NASA will play a leading part in protecting the United States and the world from the threat of a dangerous asteroid strike, according to letters sent by John Holdren, director of the White House Office of Science and Technology Policy (OSTP), to Congressional committee leaders on Friday.

Holdren's letters to the Senate Committee on Commerce, Science, and Transportation and the House Committee on Science and Technology assign responsibilities to the US space agency that go beyond its 2005 Congressional mandate to detect and track 90% of potentially hazardous asteroids with a diameter greater than 140 metres. To date the agency has found 903 of the estimated 1,050 asteroids with diameters of a kilometre or more passing within about 50 million kilometres of the Earth.

NASA will be mandated to notify other organizations, including the US Federal Emergency Management Agency (FEMA), if a dangerous asteroid is found, and to drive research and development on the capability needed to deflect the rock.

In assigning NASA's new asteroid defence role by 15 October, Holdren was meeting a requirement of the 2008 NASA Authorization Act. Under the act NASA is also required to choose an agency or agencies that would protect the United States and implement a deflection, if one were necessary.

Ramping up funds

So far, NASA's mandate to track near-Earth objects has been largely unfunded.

Former US astronaut Russell 'Rusty' Schweickart, who has advocated for the United States and other countries to be more active in planetary defence against asteroids, says that NASA's amplified responsibilities give it a platform for asking Congress for extra funds. "This is a major step forward," he says. Schweickart co-chairs NASA's Ad-Hoc Task Force on Planetary Defense, set up by the agency in March with the expectation that it would be assigned a leading role in coordinating asteroid defence (see 'NASA panel weighs asteroid danger').

Holdren also envisions a key role for FEMA in passing along news of the impending strike to states and territories that could be affected. "The essence of the planned notification approach is to utilize existing communications resources and mechanisms resident at FEMA," he wrote in the letters.

The letters add that NASA would make additional notifications through the US State Department and diplomatic channels to other countries that could be affected, and to the United Nations. Those notifications would be updated by NASA as more information became available about the threat, up until one day in advance of the projected impact, Holdren says.

Strategic defense

The ad-hoc task force released a report on 6 October listing actions NASA should take on planetary defence. It recommended the establishment of a Planetary Defense Coordination Office, with an annual budget of around $250 million, and the initiation of a mission to prove capability to deflect an asteroid.

Holdren notes in his letters that the President's budget for the 2011 fiscal year asks for a three-fold increase in funds for near-Earth object detection activities, from $5.8 million to $20.3 million. It remains to be seen whether next year's budget request will cater for the agency's additional responsibilities. "It's especially important that those activities discussed by the OSTP be supported by a proposed budget to cover those modest costs required," says Tom Jones, another former astronaut and co-chair of the ad-hoc task force.

Despite being fairly specific about notification procedures, Holdren's letters were much vaguer about the methods for deflecting an asteroid on a collision course with Earth. He says that the US government's assessment of deflection options is still at an early stage.

"As NASA tests in space the techniques and technologies needed for deflection, the OSTP should re-examine this question and identify the lead agency--or agencies--to actually execute a deflection demonstration," says Jones.