The Act directs the NASA Administrator to plan, develop, and implement a Near-Earth Object Survey program to detect, track, catalogue, and characterize the physical characteristics of near-Earth objects (NEOs) equal to or greater than 460 feet (140 meters) in diameter in order to assess the threat of such near-Earth objects to the Earth.

Engaging the experts

NASA's call for papers and selection of best ideas will lead to a NEO Detection, Characterization and Threat Mitigation workshop, to be held in a few months time. This workshop is being organized in support of NASA's Office of Program Analysis & Evaluation study in response to the congressional direction.

The four-day workshop is to engage experts from the NEO scientific and technical communities to identify the fullest possible set of alternatives for meeting congressional direction. Three focus areas of the workshop are:

* Detection, Tracking and Cataloging NEOs
* Characterization of NEOs, and
* Deflection or other forms of NEO Threat Mitigation

An objective of the workshop is to wrestle with a number of issues, such as what are current U.S. and international capabilities to discover and track NEOs? How does warning time vary with object size for an object on a likely collision course?

Additionally, the workshop would delve into possible need for space-based systems-do they provide advantages over ground-based detection and tracking systems? Furthermore, can amateur or other astronomers assist with discovery and tracking? How can they be encouraged to do so...perhaps using cash awards for spotting new objects?

Deflection options

In the area of deflection and threat Mitigation of NEOs, the workshop would scope out key options.

For one, what is the ability of a proposed concept to characterize, either remotely or on-the-spot, a NEO for factors related to mitigation, including the size, composition and structure? Also, how best to mitigate the impact effects of a Near-Earth Object found to be on a likely collision course with Earth during a determined time period in the future?

NASA's call for ideas in abstract submission form is open until May 26. Those selected will be required to submit a full white paper by June 25. The workshop location and dates are yet to be determined, but penciled in for the late June-July time frame.

"It disappeared behind a ridge and I immediately drove out over the ridge without stopping so I was there in a few minutes.

"When I turned the lights off the car I saw a glowing green ball up on the ridge three-quarters of a mile away and a smaller piece was rolling down the side of the ridge. They were both glowing green," he said.

Mr Vernon, who is in his seventies, said the object landed on a steep section of land that was covered in undergrowth and was not easily accessible.

"It was a brilliant light before it landed," he says. "A bit like a green sun. I rang a neighbour and asked if he had found superman."

Astronomers are uncertain whether the object was a piece of space junk or a meteorite, however Jim Barclay from the Maidenwell Observatory suspects it was part of a satellite or some rocket casing.

"The description that I received from phone calls was that it was of a greeny blue colour which typically suggests something metallic," Mr Barclay said.

"Over 20,000 pieces of space junk are currently hurtling around the earth and they have to come back down. If this had landed on someone's house though it could have killed someone," he said.

The object, which looked like a comet, was spotted by hundreds of people and airport control towers across south-east Queensland at around 6:30pm last night.