Article: "Asteroid threat demands response, experts warn"

Selected highlights from the article follow below. The article indicates a 1 MT gravity tractor spacecraft arriving as late as 2027 could change the course of the asteroid. I think these mission designs need more analysis/publication before such statements can be made given the potential error in trajectory calculations, etc.

Highlights from the article...

Beginning in the next few months, Schweickart's group will host a series of meetings to provide the UN with a 'decision process' for assessing and acting on the hazard posed by Apophis and other near-Earth asteroids (NEAs). A draft document ready for consideration by the United Nations Committee on the Peaceful Uses of Outer Space is expected by 2009.

Lu's favoured option is called a gravitational tractor. It involves placing a relatively massive spacecraft near enough to an approaching asteroid to shift its trajectory using only the minuscule force of gravity between the two objects. Although the method requires significant lead time and will not work in all cases, it has the advantage of controlling a hazardous object "in one piece", say Lu.

According to Lu, Apophis is particularly amenable to this form of manoeuvring. Prior to its threatening approach in 2036, the asteroid will sweep past Earth in the spring of 2029. Any change in the asteroid's position before this will be greatly magnified by the 2029 encounter, which could, in turn, eliminate the chance of an impact in 2036.

Such a mission could succeed with a 1-metric-tonne spacecraft arriving at Apophis as late as 2027, says Schweickart, who envisions a protocol that would allow the UN to 'contract' the world's space agencies to remove the threat.

"Asteroid threat demands response, experts warn"
Ivan Semeniuk, San Francisco
NewScientist.com
17 February 2007

Link: Article