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NASA Proposes to Search for Smaller Asteroids.
Five years ago NASA began a program to discover 90% of potential Earth-crossing asteroids larger than 1 km. 60% of the 1,000 to 1,200 large Near Earth asteroids have already been found, and the search should be complete by 2008. But objects below 1 km can still be devastating, so NASA is proposing a new survey to track hundreds of thousands of these smaller objects. The new report proposes that NASA spend $236 million over the course of 20 years to find 90% of these smaller, but still devastating, objects. Another option would be to build a space-based tracking system which would increase the cost to $397 million but cut the search time down to just seven years.
NASA has released a technical report on potential future search efforts for near-Earth objects after a year of analysis by scientists working on this issue. This Science Definition Team was chartered to study what should be done to find near-Earth objects less than 1 kilometer in size. While impacts by these smaller objects would not be expected to cause global devastation, impacts on land and the tsunamis resulting from ocean impacts could still cause massive regional damage and still pose a significant long-term hazard.
In 1998 NASA commenced its part of the "Spaceguard" effort, with the goal of discovering and tracking over 90% of the near-Earth objects larger than one kilometer by the end of 2008. An Earth impact by one of these relatively large objects would be expected to have global consequences and, over time scales of a few million years, they present the greatest impact hazard to Earth. Approximately 60% of the estimated 1,000 to 1,200 large near-Earth objects have already been discovered, about 45% since NASA efforts started, and each of the five NASA-supported search facilities continue to improve their performance, so there has been good progress toward eliminating the risk of any large, undetected impactor.
To understand the next steps to discovering the population of potentially hazardous asteroids and comets whose orbits can bring them into the Earth's neighborhood, NASA turned to this Science Definition Team of 12 scientists. The Team, chaired by Dr. Grant Stokes of the MIT Lincoln Laboratory, was asked to study the feasibility of extending the search effort to the far more numerous, perhaps hundreds of thousands, of near-Earth objects whose diameters are less than one kilometer.
NASA considers the Science Definition Team's findings to be preliminary, and a much more in-depth program definition, refining objectives and estimating costs, would need to be conducted prior to any decision to continue Spaceguard projects beyond the current effort to 2008.
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