Comet from another star?

On Dec 6, 2:38*am, "Martha Adams" wrote:
wrote in message

...



On a more serious note, devoid of any anime nonsense, it seems to me
that the energy requirements to intercept an extrasolar comet on a
hyperbolic trajectory would be too great.
Too much fuel would be needed to even catch up to it.

Not if the probe used an ion engine like the one used by DS2. Or maybe
this would a good mission use Dr. Franklin Chang-Diaz's VASIMR engine.

Link:
http://en.wikipedia.org/wiki/Variabl...Magnetoplasma_...

That's true but it's wrong. *You fire your rocket engine
to accomplish a vectored delta v. *That's how you get
around in space until someone comes up with something
better. *The orbit changes to catch the hyperbolic comet
and then to return are the same whether you use an ion
engine, a VASIMR, or that extra F2 engine you had along
with you, and its (massive) huge tanks of fuel.

I think if your probe has people aboard, your outgoing
and return firings would act too slowly for that. *I do
expect engines of greater thrust eventually, but then,
where do they get the electric energy which they then
make into thrust?

Titeotwawki -- mha *[sci.space.policy 2006 Dec 06]

Besides the engineering problems, you have to convince the politicians
that a mission would be worth the federal dollars to go there.