Safety of a mass driver tug, or lack thereof

So, no matter how many millions of pellets we fire, this process remains safe, and furthermore you're quite sure of that? Doesn't seem obvious to me. Perhaps even less so in light of your comments that gravitational perturbations, solar wind pressure, and other effects would make the pellet orbits essentially unpredictable. Surely the probability of colliding with any one particular pellet is vanishingly small, but what if one continues to fire off millions of pellets into the void as part of a lunar mass driver operation or as part of some other space industrialization endeavor?

Mike Combs' reply seemed more reasonable and measured to me: Mass driver tugs using non-vaporizable pellets would be only a short-term measure until the capability to use vaporizable pellets were developed. At least under that scenario, the total number of non-vaporizable pellets would be limited.

Ron Menich

cfrjlr@...
07/11/2001 07:26 PM

> I have seen statements of the form "The pellets ejected from a mass driver tug would not measurably alter the number of debris objects in near-Earth space" or words to that effect. Maybe even you have made such a statement; I don't recall.
>
> Perhaps I just need to really understand more deeply, but those words are not very comforting to me. In my
>

Why not ? It is the heart of the issue, and if it is true then we have little to fear from the pelletts.

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mind, pellets ejected from a mass driver tug would go into various orbits around the Sun, more specifically, orbits that intersect with Earth orbit or with Luna's orbit. Furthermore, it is likely that the pellets would be coplanar with Earth's orbit or with the Earth-Luna Trojan points, because that's where the mass driver tugs would be. What goes around would eventually come around, I suspect. Our orbit and the pellet's orbit would have some common synodic period. Shall we just
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Ron, this not much of an issue. There are lots of disturbances in the solar system, e.g. for small particles solar radiaiton pressure disturbs the orbit a great deal, and they will not orbit in simple elipses. As time goes on they will drift further and further away, and will "never" intersect their point of origin, nor the Earth's orbit.

Some material might collect at the Trojan points over time. But should be only a fraction of the natural material which is already there.

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fire off thousands or millions of pellets and just hope that they and we do not occupy the same point in space several years down the road?
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If the mass of pellets is a lot less than the natural backgroud, it does not increase the risk of debris collision.

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weeks, or months. But firing off pellets of slag seems very risky to me because, unless we track the orbit of each such pellet, there would be some risk that we and the pellet might become accidentally re-acquainted at a later date, much to the detriment of both of us.
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Not credible. Too many perturbations. We will never see the pellets again.

All orbits precess at different rates because of various distrubance forces.
Every pellet will have an orbit with a different precesion rate. A tiny percentage of the population will have a precession rate which matches the Earth's orbit by sheer chance.

Debris in the solar system does not bother me at all.
The volume of space for them to spread into is vast, and they will either spread or collect at trojan points where there is already billions of years worth of accumulated debris.