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by Morris Jones for SpaceDaily
Sydney, Australia (SPX) Apr 11, 2013
The recent announcement of a NASA plan to drag an asteroid into lunar orbit with a robot spacecraft, then stage a crewed astronaut expedition to explore it, has stunned many boffins. The plan is highly original, slightly strange, and probably quite feasible. It also seems to have struck a chord with the general public, judging by the reactions to my earlier article (More Treasures from Asteroids) on this subject.
While there are many potential scientific and technical benefits from such a mission, its appeal to the public is a major reason why NASA should support this plan more strongly.
This analyst counts himself as a big fan of the proposed mission, but also notes that there could be some potential problems. One potential issue is the amount of disturbance that the asteroid will receive as it is captured and nudged across deep space, then inserted into orbit around our nearest off-planet world. Sure, the asteroid can be delivered, but what state will it be in when it arrives?
While the asteroid in question will probably be a fairly solid, rocky object, there is bound to be some damage. The pristine surface of the asteroid, along with the distribution of rocks, gravel and dust in its outer layers, are likely to be scoured by the journey.
This could have implications for some scientific studies of the asteroid and possibly present some hazards to the astronauts who will eventually visit it.
It seems difficult to avoid causing some changes in the outer surface of the asteroid. No method of moving it, however cautious, can avoid this. Even the act of accelerating the asteroid is bound to affect some surface features that have formed in near-microgravity conditions.
Then there are the effects of the large collection bag that will surround the asteroid for its capture and transportation. This is a very gentle and technically practical way of containing the asteroid, and it seems very hard to come up with a better technique. Nevertheless, the sides of the bag will also disrupt the asteroid.
The moral of this story is that some scientific studies of the asteroid should be performed when it is still in a pristine state. That means carrying out investigations before it is moved or even extensively touched by another spacecraft.
There's one easy way to perform some of these studies. The asteroid should be thoroughly photographed and spectroscopically mapped by the tugboat spacecraft soon after it approaches the asteroid. This can be done with standard remote sensing instruments.
These images will supply a useful set of data for not only understanding the properties of the pristine surface, but also help with "before and after" studies of the asteroid, when the effects of moving and exploring have taken their toll. The tugboat spacecraft would be called upon to repeat its scans after the astronauts have gone home.
This analyst would also like to propose another method of examining the asteroid in its "virginal" state. Toss beer cans at the thing and see what happens.
No, not literally. By this, I mean that small remote sensing probes, with roughly the same size and shape as a beer can, should be launched at the surface of the asteroid. These probes would be compact, light, and easy to deploy. They could also be useful to the engineering component of the mission.
To make this article more accessible to a family audience, I will now label these probes as Small Surface Impactors, or SSIs. An SSI will carry a small suite of instruments and remotely transmit its data back to the tugboat spacecraft.
The SSI will carry a small accelerometer to measure its deceleration on hitting the surface of the asteroid. This will give clues to the surface density. It will also carry a small CCD camera to take some close photographs of the surface granules. Some minor spectroscopy of the surface could also be performed with this camera.
The SSI will also feature reflective surfaces or high-visibility panels. If a few SSIs manage to anchor themselves securely to the surface of the asteroid, they can be used like trigonometry markers.
Cameras on a distant spacecraft can spot the Impactors and use measurements of their positions to help determine the geometry of the asteroid as well as its rotation. This could be useful for scientific purposes, but it could also help a robot vision system attempting to navigate the capture approach.
Some surfaces of the SSIs could be engineering test panels, designed to see how the rough and dusty surface of an asteroid affects them.
They would be embedded in the surface of the asteroid for a few years while the asteroid awaits the arrival of astronauts. Later, astronauts could retrieve these panels from the exteriors of the SSIs and return them to Earth for analysis.
Let's keep supporting this mission. We would love to see these dreams become reality.
Dr Morris Jones is an Australian space analyst and writer. Email morrisjonesNOSPAMhotmail.com. Replace NOSPAM with @ to send email.
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