Capturing asteroids
I've always wondered what it would take to capture an asteroid into a parking orbit somewhere out beyond GEO (geosynchronous orbit). Such a body would be handy to have nearby in that it would allow us to go out and practice a little prospecting without getting too far away from home. My thoughts on this are often stymied by the fact that it would require a lot more effort than we would be able to muster any time soon to redirect such an asteroid into a friendly co-orbit with the Earth.
Then I noticed this article which seems to indicate that we get visited fairly often by asteroids which drift close enough and just fast enough to get caught in our gravity well for a short time. They suggest that these space rocks may be let in, and eventually let out again, through transient gravitational gateways. These low energy paths are thought to arise out of the chaotic relationships between the various gravitational bodies in the solar system and has been dubbed the interplanetary superhighway.
Incidently, there is an asteroid which is currently sharing a somewhat stable orbit with the Earth. This is the so-called second moon, Cruithne. Unfortunately, it does not remain in the proximity of Earth for very long. It spends most of it's orbit out of phase with the Earth (i.e. lagging or leading the Earth in its orbit).
So anyway, this got me to thinking about capturing asteroids again and I was curious about what would be required to nudge one of these visiting bodies into a more stable orbit. Obviously a lot of this would be dependent upon the characteristics of the asteroid and its orbit. If a favorable candidate could be identified in time, and the B612 foundation has developed a suitable technique for alerting the path of an asteroid, then could we actually capture a whole asteroid and have it conveniently at our disposal?
This sounds like an excellent simulation to run in Orbiter (Hi, Bruce!).
posted by Unknown at 11:35 AM
5 Comments:
Eric, I too have been thinking about some of the potentials of these low delta v trajectories that that both Shane Ross and Ed Belbruno have been doing their research on. Belbruno has published a textbook that I would love to lay my hands on:
http://www.amazon.com/gp/product/0691094802/qid=1150662451/sr=1-2/ref=sr_1_2/002-1904466-5288043?s=books&v=glance&n=283155
A good step beyond my last exposure to astrodynamics at State (in Astro II; J2 harmonics, etc). Since the B612 demonstration mission is to provide a delta-v of O(1 cm/s) to a NEA with no possibility of making it into an impactor, the question then becomes:
How many generations of technology separate the first demonstrator tug from something that could 'sink the 8 ball' and get an asteroid through one of the transient chaotic gates around Earth-Sun L1/L2? Is a gravitational tractor (or whatever B612 ends up choosing) going to cut it, or will we need to actually touch down and grapple it?
Another question; based on my limited understanding of the Orbiter SDK, how much work do you think it would be to write a chaotic trajectory plugin? It looks like Shane Ross' papers have provided enough information to sit down and code it up, given a nice framework to minimize wheel reinvention.
It's been my hope to model this and other useful asteroid interactions with Orbit@home (http://orbit.psi.edu/) but I've been very low on time.
See also the figures that NASA keeps for the amount of energy required for various NEO flyby and intercept missions: http://echo.jpl.nasa.gov/~lance/
Quite a few asteroid missions are plausible for less delta-v than the moon.
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The asteroid problem is no more complex than a mission to mars, which we have already done. The main problem is calculating which asteroids are easy to capture and which of those is actually worth it. Given a timeframe of 10-20 years, a small satellite can nudge the orbit of a 5-10 meter asteroid significantly enough to effect capture.
NASA has published articles specifically related to asteroid deflection and how they would attempt to accomplish this. They noted that for objects over 200m in diameter, this gravity tug was basically useless. But they never really thought for what object it would be useful!
A small asteroid in GEO would cause a scientific boom that I believe would last at least a generation.
Planetary bombardment is a natural process which we may be able to do artificially, as we have with so many other natural processes. Some comets & asteroids are considered chaotic, meaning their paths are indeterminate, in this state several ionic engines could take control and these masses could be steered to influence other comets & direct them usefully, bombardment of Mercury to force in into Venus path, burn off its atmosphere, add spin, a metallic core & a moon; speed the deorbit Mars' moon Phobos, bombard its poles, or as you say, park a useful satellite in near earth orbit. Cosmic bombardment created the planets we have now but can be continued artificially in this manner, just as we have harnessed every other natural process. Imagine the effect of looping a chaotic asteroid in the asteroid belt around one asteriod and smack dab into Vesta slowing its speed, forcing it into a slightly closer orbit to the sun, could it start flinging one asteriod after the other into Mars path? This is what Mars need to creste and hold atmosphere, and a teaming colony of atmosphere producing organisms...
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