# Getting Rid of a Body (in Space)

I came across a science fiction story I had read as a child. It was not nearly so good forty years later. In the story a prospector killed his partner in the Asteroid Belt. He has to get rid of it.

The author says that if he had attached a small rocket to the body and fired it at the sun, the body would have entered an asteroid-like orbit closer in that the place from which it was launched.

A better solution the author claims, would be to attach the rocket and fire it into the belt but going the other way. That is to say the rocket would reduce the speed of the body to below the velocity required to maintain an endless orbit. It would then fall into the sun, presumably over several years.

Sounds sensible. The body is presumably in orbit with the asteroid belt, so it already has significant velocity relative to the sun. If you fire a rocket straight towards the sun, you’re not doing anything to reduce that velocity – just adding more in a different direction – so you end up putting the body into a higher energy orbit than it was before. The only way that can work is if you make the orbit so elliptical that it intersects the sun’s surface, which would take some doing since at all times the tangential velocity is going to be consistent with an asteroid-belt orbit.

Making the rocket push “backwards” actually does bleed off that tangential velocity, which would force the body into successively smaller orbits unit, when the tangential velocity hits zero, its orbital radius is zero as well.

Although, I’d think an even better solution would be to attach a small rocket to impart some random delta-v to the body for a short time and then shut off and let it cool to ambient temperatur. Space is big compared to the size of a body, so it would be very unlikely for investigators to find it if they don’t have bright, hot, rocket exhaust to look for.

I don’t think a small rocket is going to have anywhere near the deltaV to significantly impact the orbit of an object in the asteroid belt.

I would be tempted to launch it at 90 degrees (ie, pointing in a solar north direction) so it ends up in an orbit at an angle to the orbital plane. However, it appears that this is not a good use of the available deltaV. Launching the body at 45 degrees to the direction of travel towards the sun may apply enough eccentricity to the orbit to keep the body a long way from the parent asteroid most of the time.

Anyhow, once the body has frozen and dessicated, a solid hit from another asteroid will pulverise it sufficiently.

Try playing with this orbital simulator (requires flash).

Si

The asteriod belt is what - 2 or 3 AU or more from earth?
This - http://en.wikipedia.org/wiki/4_Vesta - Vesta is travelling around the sun at 19.34km/sec.
To drop a body onto the sun, you would have to bleed off most of that tangential speed so it drops straight toward the sun. Not sure what size rocket you need, but I’m guessing pretty serious size, not just a large roman candle. Otherwise, you get a long narrow elliptical orbet where it drops down around the sun and comes back to where it starte.

A more useful strategy would be to plop the body onto a larger asteroid, with a grey paint covering to cammoflage the shiny bits; unless someone is doing a photographic/magnetic survey, how many centuries before they find the body? (Ideally, strip the body of its space suit so it is less detectable. You could probably also drop it into Earth’s atmosphere to burn up, but the meteor protection patrol might pick it up incoming. Let’s assume Mars is much less monitored than near-earth orbit, the closest and much less monitored convenient drop point. You still have a fairly substantial celestial body (sorry) travelling thorugh space, and without massive rockets, the transit time is measured in month or years (Like current planetary probes). Too much time to be discovered.

The simplest disposal - most craft designed to travel for more than a week in space probably will have waste recycling units rather than canned air and water; so just put your obnoxious partner down the garbage disposal. Just don’t be like one of Larry Niven’s protagonists, who sent someone down the sewer but forgot to check for a titanium hip joint.

Any jetpack is going to run out of fuel long before you can kill all of the orbital speed to fall into the Sun. Or before you can build up enough additional orbital speed to escape, which is actually significantly easier. So basically, all a jetpack is going to do will be to put the object in a somewhat different orbit.

Which is probably going to be enough, anyway, no matter what direction you aim. Space is deep. Just make sure you destroy any suit transponder or radar retroreflector or the like, and the body’s never going to be found.

Even without freezing, a “solid hit” (say, a relative velocity of 1/10 the orbital speed) will splash a human wonderfully. Problem is, collisions are extremely rare in the asteroid belt. Chances are, by the time an asteroid hits your victim, his great-great-great-grandchildren are already dead of old age.

As strange as it may seem, from Earth it takes about twice as much energy to send an object to the Sun as it does to send it completely out of the solar system. The farther out you are, the greater this ratio becomes (assuming you’re in a solar orbit).

To get to the sun, you have to counteract the orbital velocity, so the most efficient way would be to point it in the direction opposite the current motion.

However, you would need very powerful rocket to counteract your orbital velocity. Most likely you would end up with an elliptical orbit where the aphelion (farthest point from the Sun) is still in or near the asteroid belt, but the perihelion is somewhere closer. Unless you get close enough to the Sun for the body to burn up, it will remain in this orbit pretty much indefinitely.

If you’ve got a rocket in the first place, depending on what kind (ie, not something like a low acceleration/high efficiency ion drive) you’ve already got yourself a tool that can reduce a body to ashes. Scatter any ashes not already scattered by the exhaust and any investigators will be stuck looking for space dust.

“East takes you out, out takes you west, west takes you in, in takes you east.” You will need a goodly amount of delta-vee, though. Something on the order of 20 km/s.

I take it that sticking the body in a position to absorb the prospector ship’s rocket exhaust wasn’t an option? Any ship with the energy to get to and move within the asteroid belt, should have more than enough energy to utterly vaporize the corpse?

Edit: Or, what Der Trihs said, above.

I’m imagining that this is a standard sci-fi rocket that gives the same thrust forever without running out of fuel, and a standard sci-fi asteroid belt that has an average spacing of 10 metres between 100 metre boulders.

Just attach one end of a power extension cord to the body and allow the other end to dangle. Glue a remote to one of the hands. In the other hand attach a large sign that says, “Free! We bought a new one and don’t need the old one. Comes with working remote.”

Set it adrift and I guarantee in no time it will get scooped and disappear.

You mean the one that looks like dog kibble on a black cloth?

How would exposing a body to vacuum affect it? I am guessing the liquids would boil off so you would wind up with a freeze-dried corpse. Perhaps a couple of strategically placed incisions would help the process.

But a body without water would have a lot less mass to worry about. I would just chop the remains into bitsy pieces and scatter it amidst the asteroids. Space is an awfully big place to look for one dessicated corpse in a hundred pieces.

Regards,
Shodan

Actually, the ratio is independent of how far out you are, provided that your distance from the central object is large compared to its radius.