Asteroids: from science to exploitation

Genuine bricks left over from the formation of the solar system, asteroids are of interest to scientists whilst others would like to exploit their mining resources.

 

Asteroid Itokawa as photographed by the Japanese Hayabusa probe. This 500 m diameter object is no threat to the Earth at this present time, but scientists believe that its orbit could intersect that of our planet in several millions of years time. Credit: JAXA/ISAS

The recent flyby of asteroid 1994 CC in June 2009 (see this Enjoy Space Latest News) reminds us that we still know very little about these fascinating objects — some of which are potentially dangerous. Consequently, there is no lack of projects with plans that include putting manned missions on their surface and extracting precious ores!

Science and prevention
It has to be said that having a better understanding of asteroids — and therefore of their composition, distribution and orbital characteristics — comes back to having a better understanding of the evolution of the solar system. As genuine “rejects” of the planet formation mechanism, these unused bricks bear witness to the conditions that prevailed at that time. The purpose of several robotic missions has, therefore, been their close observation and, at the end of 2005, the Japanese Hayabusa probe successfully completed the first controlled landing on one of them, in this case the asteroid Itokawa. Unfortunately, even JAXA, the Japanese Space Agency, acknowledges that it cannot be sure that the sample collection device functioned correctly. And the answer will not be known for certain until June 2010 when the probe, returning to Earth will release a capsule supposedly containing the precious samples.

The gravity tractor envisaged by the B612 Foundation. The simple presence of an automatic spacecraft strategically placed close to an asteroid would result in the deviation of its trajectory. However, it has to be put into action very early on. Credit: B612

A better understanding of asteroids, and more especially near earth asteroids, will also make it possible to develop a suitable strategy should we one day realise that an impact with one of them is unavoidable. Without alarmist pessimism, but in all seriousness, several space agencies are thus giving thought to means for redirecting an NEA (the Near Earth Asteroid is an asteroid whose orbit comes close to, or crosses, that of the Earth) when its trajectory could involve a collision with our planet. Several years ago, NASA submitted a report to the American Congress listing the possible options, including recourse to nuclear explosions to divert the object! This report was contested by the B612 Foundation which believes the means presented by the agency to be unsuitable and vague. Headed by several scientists and astronauts Russell Schweickart (Apollo 9) and Ed Lu (STS-106 and Expedition 7), this Foundation is petitioning for the development of accurate deflexion methods so as to be certain of putting the threatening asteroid into a new orbit which will not intersect that of the Earth again. It puts forward the idea, for example, of using a gravity tractor. In this hypothesis, a robotic spaceship would be dispatched close to the NEA deemed dangerous. The simple presence of the spacecraft (more exactly its mass) is enough to disturb the orbit of an asteroid such that it would no longer be on a collision course with the Earth. This method has the advantage of resulting in an extremely accurate orbit modification. The drawback is that this method requires action to be taken several decades prior to the impact, as the small mass of the spaceship dispatched only leads to a very slight orbit disturbance which can only be successful after some years. The European Space Agency is also carrying out its own research into the subject with the Don Quijote mission project which aims to voluntarily crash into an asteroid under the close surveillance of a probe in order to measure the different resulting effects.

The Don Quijote probe is observing the effects of the Sancho Pancha impactor on an asteroid. This is an ESA, European Space Agency, study project. Credit: ESA/AEOS Medialab

Manned flights and exploitation
Manned flights are not to be excluded as some agencies even envisage sending astronauts to the surface of a near earth asteroid and forecast spectacular scientific progress with experiments that could be carried out on site, and above all due to significant sample return. NASA has considered this type of mission several times and has not failed to point out that the different spacecraft required for going back to the Moon (Ares I and V rockets, Orion spaceship, Altair module) could be adapted for the manned exploration of certain asteroids when they come close to our planet. Moreover, the subject has recently come back into the limelight: Barack Obama, the President of the United States, has asked a committee to make a report on the direction that NASA’s human space flight programme should take and the subject of mission projects to near earth asteroids has been raised more than once.

Astronauts for better studying asteroids? On more than one occasion, NASA has highlighted the fact that equipment developed for going back to the Moon could be adapted at relatively little cost to carry out such a mission with an object flying close to our planet as its destination. Credit: NASA

In the longer term, there are those who have no hesitation in defending the idea of exploiting asteroids and envisage bringing raw materials (iron for example or more precious elements such as platinum) taken from these roaming rocks back to Earth. The instigators of this line of reasoning also put forward the idea that such a step would put an end to the deterioration and pollution caused on our planet by the various mining operations. But for the moment, the idea, besides being an extremely complex technical operation to put into practice, has come up against an economic reality that cannot be ignored: given the current state of space technology, a raw material — even one that is extremely precious — coming from an asteroid would cost more than its equivalent mined from our planet.

Published on 10 August 2009