Panel: NEO search efforts need more support
BY JEFF FOUST
Posted: July 12, 2002
"The Asteroid Threat" roundtable meeting, held Wednesday in a U.S. Senate office building, was organized by the space lobbying group ProSpace to bring together policymakers and experts to discuss the threat that NEOs pose to the Earth and the best ways to deal with that threat.
NASA currently funds several efforts to search for NEOs, noted Colleen Hartmann, director of NASA's solar system exploration system. Foremost among those programs is the Lincoln Near Earth Asteroid Research (LINEAR) program. LINEAR, operated by MIT's Lincoln Laboratories, uses two 0.9-meter telescopes in New Mexico with sensitive CCD cameras to scan the skies; LINEAR has discovered about 1,000 NEOs since 1998. LINEAR and the other programs cost NASA about $4 million a year, Hartmann said.
Those efforts are doing a good job of finding relatively large NEOs. A total of 603 NEOs one kilometer in diameter or larger have been found to date, and astronomers estimate that there are approximately 1,000 NEOs of that size overall. At current discovery rates Hartmann said that NASA should achieve its goal of discovering 90% of NEOs that size by 2008.
However, of growing concern are smaller NEOs. One example is 2002 MN, which was discovered by LINEAR on June 17. The asteroid, estimated to be between 50 and 120 meters across, passed within 120,000 kilometers of the Earth on June 14 - three days before its discovery. Had it struck the Earth it would have had enough destructive power to wipe out a large city.
While small NEOs like 2002 MN are discovered on a regular basis by search programs like LINEAR, they are not the focus of these efforts. "NASA and these programs are not concentrating on these small objects," said Brian Marsden, director of the Minor Planet Center at the Harvard-Smithsonian Center for Astrophysics. "It would be impossible with current facilities."
Even if search efforts concentrated on these smaller bodies, it could overwhelm those who catalog NEOs. Marsden estimates that there are about one million NEOs 50 meters across or larger; only 2000 NEOs of any size have been discovered. However, the Minor Planet Center has only 2.5 full-time employees, Marsden noted, who work 16-hour days seven days a week just to keep up with the current rate of asteroid and comet discoveries.
Hartmann said that NASA is currently concentrating on large NEOs because objects one kilometers or larger have the potential to cause global devastation. However, she acknowledged that smaller objects "can still make for a bad day" if they collide with the Earth, and said that NASA is initiating a feasibility study for conducting searches for smaller objects.
Disseminating data of NEO discoveries and related phenomena may turn out to be more important than searching for NEOs themselves. U.S. Air Force Brigadier General Simon "Pete" Worden of U.S. Space Command, speaking as an expert and not representing the Air Force, said that a bright flash was observed by U.S. early warning satellites over the Mediterranean Sea on June 6. The flash, the equivalent of a 20-kiloton nuclear explosion, was quickly determined to be a meteor. However, Worden noted, had the explosion took pace a few hours earlier at the same latitude, it would have occurred over India or Pakistan at a time when tensions between the nation were extremely high. Without access to the U.S. satellite data, the flash could have been mistaken for a nuclear attack, Worden believes. "It's quite possible it could have triggered a nuclear war," he said.
To prevent something like this from happening in the future, Worden advocates creating a coordinating body that could collect and disseminate data like satellite observations to both track NEOs and alert governments when events like those on June 6 take place. He said it could be handed by the U.S. Space Command using existing facilities and no more than five to ten personnel.
Proposals like Worden's, as well as efforts to expand current NEO searches, would require additional funding or approval by Congress, and the purpose of the roundtable session was to educate Congressional staffers on the issue. Increased support for NEO efforts already has the support of some members of Congress. Small NEOs are "a grave threat we should be investing in," said Rep. Dana Rohrabacher (R-CA), chairman of the House Science Committee's space subcommittee. "The potential danger of global warming is nothing compared to the potential danger of near-Earth objects."
Studying NEOs also has a benefit, Rohrabacher noted. The same NEOs that pose a threat to the Earth could also be rich in minerals and ice that would be beneficial to future exploration and development of space. By exploiting the resources of NEOs, he said, "we can turn these lemons into lemonade."
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