Asteroid-watchers worry about cosmic Katrina

By Leonard David

Senior space writer

updated 8:47 p.m. ET May 6, 2006

LOS ANGELES - Natural events such as hurricanes, tsunamis and earthquakes rock this planet from time to time. But when Earth gets stoned by an asteroid, consider it akin to a Katrina from outer space.

When Hurricane Katrina slammed into the United States in August of last year, it became a deadly, destructive, and costly episode — one that has also become a metaphor for lack of government action, both pre- and post-strike.

At the current time there is no agency of the U.S. government — or of any other government  in the world — that has the explicit responsibility to develop and demonstrate the technology necessary to protect the planet from collisions with near-Earth objects, or NEOs. 

The U.S. Congress needs to be encouraged to take a step in demonstrating the ability to deflect a menacing NEO, says former NASA astronaut Russell Schweickart, chairman of the B612 Foundation. On Saturday he presented an update on dealing with troublesome asteroids here at the 25th International Space Development Conference.

Key capabilities
The goal of B612, a confab of scientists, technologists, astronomers, astronauts and other specialists, is to significantly alter the orbit of an asteroid in a controlled manner by 2015.

In detailing today’s NEO situation, Schweickart said there are several givens:

• Earth is infrequently hit by asteroids that cross our orbit while circling the sun.
• The consequences of such impacts range from the equivalent of a 15-megaton explosion to a civilization-ending gigaton event.
• For the first time in the history of humankind, we have the technology to prevent such occurrences from happening in the future — if we are properly prepared.

“Remember, we’re dealing here with a less frequent, but far more devastating Katrina … a Katrina of the cosmos,” Schweickart reported.

“NEOs happen so infrequently that even though they are orders of magnitude more devastating, people don’t naturally make that match,” he told Space.com, “but you don’t want to be caught with your pants down.”

Schweickart said there are key capabilities that will enable humanity to avoid devastating cosmic collisions: early warning; a demonstrated deflection capability; and an established international decision making process.

While some progress is being made, there remains significant work ahead in all these areas, Schweickart emphasized.

Sky-sweeping surveys
If the current pace of sky-sweeping surveys is extrapolated into the future, on the order of 10,000 NEOs with some risk of impact over the next 100 years are likely to be cataloged by 2018, Schweickart forecast. The chances are better than even that none of these 10,000 will actually hit Earth in those 100 years. 

“The important fact, however, is that a substantial number of them will appear as though they may be headed for impact,” Schweickart advised. Today, of the 104 currently on impact listings, “two have an elevated risk, and we are watching them closely,” he said.

At present, the two asteroids on that “keep an eye on them” roster are 2004 VD17 and Apophis, formerly listed as 2004 MN4.

Russell Schweickart / B612 Foundation This graphic shows the "path of risk" for the asteroid Apophis during an encounter in 2036. The red line shows the range of potential impacts, based on current projections of Apophis' orbital path. However, the uncertainties surrounding Apophis' orbit are so great that the chance of collision is currently set at 1 out of 6,250. Further observations are required to refine the risk assessment.

“Extrapolating to 2018, we may have as many as 200 in a similarly elevated attention category and of growing concern to the general public,” Schweickart reported Saturday. “Therefore, it is certainly possible, if not likely, that in the time frame of the next 12 years we — the world — may well be in a position where we need to take action to ensure that we will be able to carry out a deflection mission if needed,” he said.

The U.S. Congress amended the Space Act in 2005 to charge NASA with responsibility to “detect, track, catalog and characterize” NEOs wider than 460 feet (140 meters) in diameter. However, thus far Congress has come up short on actually assigning the responsibility to take action, should one of these objects be discovered headed for a collision, Schweickart pointed out.

There is a bit of good news forthcoming, Schweickart explained. Congress did require NASA to provide by the end of 2006 an analysis of possible alternatives that could be employed to divert an object on a likely collision course with Earth. In response to this congressional directive, NASA is about to announce a process for carrying out this mandate.

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