Re: Are we ruining the solar system?

From: Allen Thomson (thomsona_at_flash.net)
Date: 06/18/04 

Date: 18 Jun 2004 11:20:49 -0700

khatcat@hotmail.com (BigKhat) wrote

> Pardon my ignorance, but why would it be easier to get something to
> Jupiter than to get it to the sun? It thought all we had to do was
> get it travelling directly towrds the sun and it would just collide
> with the sun. What am I missing?

Because to get to Jupiter' orbit from Earth requires getting "only"
9ish km/sec from a rocket whereas dropping something directly from
Earth into the sun requires almost 30 km/sec, which is beyond
the capability of modern rockets.

Once the something gets to Jupiter a couple of things come into
play. 1) It requires less than an additional 9 km/sec to drop
into the sun, because you've been decelerated on the trip out
by the sun's gravity and 2) You can use the very same gravity-
assist maneuver that we've been talking about earlier in this
thread to use Jupiter to slow the payload. What you do is to
use a transfer orbit that is an ellipse with its outer end
at the orbit of Jupiter and just a bit ahead of the planet (and
with the sense of motion in the same direction as the planet's).
When the payload gets there, Jupiter will tug *back* on it,
slowing it down and thus causing the inner end of the new
elliptical orbit to be closer to the sun than it was before.
Repeat as necessary.

http://www.go.ednet.ns.ca/~larry/orbits/gravasst/E-Jprobe.html

http://www.fact-index.com/g/gr/gravitational_slingshot.html

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