BigKhat ) wrote:
: A while ago, I started a thread ...

: It struck me the other day that we might be ruining the solar system.
: Let me explain. Our use of gravity assist to speed up and sling
: probes such as Cassini doesn't come for free. It slows down the
: planet we are using to sling the probe (conservation of momentum).
: This, of course, brings the planet closer to the sun. If we do it
: once or twice, that might be okay, but continued use would ruin our
: solar system. Maybe we should have a moratorium on using gravity
: assist in the future. Thoughts?

: Most people said it no affect. For example....

: BigKhat wrote:
:
: Christopher James Huff wrote in message .. .
: In article ,
: (BigKhat) wrote:
:
: Didn't Cassini also use Venus twice and the Earth too which are
: *considerably* smaller than Jupiter. As for my math literacy, I'd be
: the first one to admit that I'm not very good at math. But heck,
: today, you don't need any math (or any technical ability) to become
: successful. I was quite a successful technology directory without
: really knowing anything about what the developers were actually doing.
:
: Jupiter is about 318 times as massive as Earth and 390 times the mass of
: Venus. Compared to the difference between the size of Jupiter and the
: probe, that's not very much.
:
: Venus, the lightest of the three, masses 2.26x10^21 times as much as
: Cassini. That's 2260,000,000,000,000,000,000 times as much.
:
: Okay, so how much does each gravity assist affect the orbit of Venus
: then? How much does it get closer to the Sun after each pass?
:
: (sigh) See that figure above? However much the velocity of a probe is
: changed, that of Venus will be changed by 1/that much, if I'm
: understanding it correctly.
:
: Suffice it to say that it's so tiny as to be unmeasurable, unles your
: space probes have the mass of small moons or greater, themselves. This
: is not guessing about unintended consequences, like certain Earth
: environmental effects, the numbers involve the ratio of the two massees
: involved, how closely they pass each other, how fast they initially
: approach each, ant the angles by which they do. Crunch those numbers,
: and you get the results. Period. Fly another probe by, and you get
: insignifigance times two.

: I found it rather ironic and amusing that the January 2005 Sky and
: Telescope page 24 has an article explaining that even mighty Jupiter
: has moved significantly because of flinging out tiny objects. Maybe
: gut feeling and intuition are better than math here!

Do the periodic comets that Jupiter has basically created have any ill
effect as you are citing? IOW, given that we have been at it for decades
and comets have been at it for millennia, why do you think our much fewer
and much later induced effects are worse than what mother nature has been
doing all these years?

This isn't like global warming which goes on 24/7/365 all over the globe.
You're talking about a few probes per decade.

May I suggest reading up on periodical comets specifically related to
Jupiter? "Jupiter" by Isaac Asimov is an oldy but goody.

Eric