Wednesday, October 19, 2005

Former And Current Astronauts Speak Out On Impact Hazards

The Association of Space Explorers have posted a letter from their recent congress concerning the urgency needed for nations to act now to mitigate future impacts while we still have time. This issue needs to be continually raised whenever the discussion concerning funding for space exploration is brought up. As is stated repeatedly on this blog, THERE IS NO REASON WHATSOEVER TO SPEND A SINGLE DIME ON ANYTHING ELSE RELATED TO SPACE EXPLORATION UNTIL WE HAVE ADDRESSED THE MITIGATION ISSUE IN A TRULY SERIOUS AND PRO-ACTIVE SENSE.
Open Letter of the Association of Space Explorers 19th Annual Congress, Salt Lake City, UT 14 October 2005

The Association of Space Explorers (ASE), meeting in its annual congress in Salt Lake City, Utah from October 10 - 16, 2005, has taken special note of the series of unusually devastating natural disasters that have occurred around the world during the past year. While natural disasters of many types cause death, destruction and disruption of society around the world every year, the Indian Ocean tsunami in December 2004, hurricanes Katrina and Rita in September 2005 and the Pakistan earthquake in October 2005 have been unusually devastating. These unusually large events have, in our opinion, spotlighted the inadequacy of societal preparation for and response to these large natural disasters. In most cases it is clear in retrospect that the mitigation measures were inadequate not due to lack of understanding, but due to failure to effectively act based on well understood fore-knowledge of the disaster potential.

Yet we astronauts and cosmonauts are particularly concerned by a far more threatening natural disaster for which the world is totally unprepared; namely the future impact of a near-Earth object (NEO) with the Earth. While such cosmic impacts between NEOs and the Earth are infrequent their magnitude is often far greater than any other natural disaster, with an upper bound resulting in global, rather than local or regional devastation. Historically the largest of such cosmic impacts have lead to the virtually instantaneous extinction of a majority of the species alive on the planet at the time of impact.

In other NEO News, Russell L. Schweickart and Clark R. Chapman of the B612 Foundation have published an article in The American Scientist concerning another problem with Asteroids- ones that are less than 1 KM in diameter but still pose a very large threat.

NASA has been spending about $4 million a year to meet a 1998 Congressional mandate to chart (by 2008) at least 90 percent of the near-Earth asteroids that are more than 1 kilometer in diameter. NASA's Jet Propulsion Laboratory has been overseeing the effort, called the Spaceguard Survey, which has to date discovered more than 790 of an estimated 1,100 or so of these huge, rocky objects. The impact of a 1-kilometer asteroid would release the same amount of energy as 70,000 megatons of TNT or, equivalently, as 1,400 of the largest thermonuclear weapons ever detonated. The subsequent Sun-dimming pall of debris lofted high into the atmosphere would envelop our planet for months, threatening all of human civilization.

The need to be on the lookout for such an immense catastrophe is clear enough, as more than one Hollywood blockbuster has made widely known. The capability of the current search effort, however, is inadequate to address the danger posed by the far more populous cohort of smaller near-Earth asteroids, those down to about 100 meters in diameter. Such objects can cause serious local or even regional destruction. The impact of a 100-meter-diameter body would release the equivalent of an 80-megaton bomb and thus could devastate an area the size of a large city, for example. And a several-hundred-meter body could cause a tsunami rivaling or exceeding last year's horrific Indian Ocean event.

Objects in this range of diameters are discovered only incidentally today by the modest equipment that has been dedicated to finding their larger siblings. A recent addition to the list of small asteroids that have a small but real chance of striking the Earth is a 330-meter-diameter asteroid named 99942 Apophis (formerly known as 2004 MN4). It has a 1-in-32,000 chance of impacting in April 2035 and a 1-in-12,000 chance of striking in April 2036. So there's no need to become alarmed at this stage. Yet one of these smaller asteroids is far more likely than their larger counterparts to constitute a danger in the foreseeable future. They are also easier to deflect away from Earth using space technology. The problem is that today astronomers have discovered such a low percentage of the smaller near-Earth asteroids that a strike with no warning whatsoever is far and away more likely than our having enough time to undertake an effort at deflection.

The authors go on to further discuss the shelving by NASA of the technology that will be needed to help possibly mitigate asteroids in the future.

First, consider the technology-development front. It happens that NASA was, at least until recently, headed in just the right direction for building hardware that could deflect an object away from a collision with Earth. Prometheus is a NASA program to develop cost-effective deep-space propulsion capability by utilizing high-performance ion or plasma engines powered by a small nuclear reactor—just what would be needed to give a menacing asteroid the necessary shove. The nuclear-electric propulsion portion of the program now seems to be on hold with priority shifted toward developing a small reactor for future work on the lunar surface.

Just prior to the arrival of Michael Griffin as the new NASA Administrator, an asteroid-deflection mission was in the final throes of consideration as the first operational test of the Prometheus technology. This mission would have demonstrated the use of an "asteroid tugboat" to deflect near-Earth asteroids, a concept that we and two other members of our group spelled out in Scientific American in November 2003. However, this proposal, along with the Prometheus program, was put into limbo in a reshuffling of NASA priorities.

We need to demand a reshuffling of priorities for NASA until this issue is resolved.

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