Interplanetary trajectory software?

There is plenty of software available for visualizing and calculating
satellite orbits around the Earth, but I can't seem to find any software for
calculation - and preferably also visualization - of interplanetary
trajectories. I'm looking for a program not too expensive (for private,
educational use - preferably free :-) no more than $100), which is able to
e.g. simulate a trip to Mars. I can calculate a simple Hohmann-transfer
myself, so I'm looking for a program that is able to take into account e.g.
the difference in inclinations and eccentricities of the departure and
arrival planets, relativistic effects, etc.

The more functions, the better. For instance, if you could input the
spacecraft mass, fuel type and engine thrust, it should be able to calculate
burn durations.

/steen

Timo K Suoranta wrote:
[...]
Then there are gravity-assist and aero-gravity assist trajectories which
I guess are harder to figure out, and windows are still involved. I
found out that there actually is a whole book written about this
subject, "Multiple Gravity Assist Interplanetary Trajectories".

One approach I'd investigate is using the terra-centric models, but
with the origin translated to Sol-centric coordinates. Drag is going
to disappear, of course, and I'm not sure how much of the accessible
software handles burns...

I would think that gravity-assist, to a first approximation, could be
handled by modelling each leg seperately, and pretending that the
planetary interaction was a funny "rocket burn". Each leg might be a
Hohmann based on the v-bar out of the last encounter, but I'm not
saying that under oath.

I would also look at the window issue by a "relaxation" or "Newton's
roots" method -- picking a starting value, calculating where you'd hit
the orbit of the other end, figuring the error (perhaps by using the
t2 of the first guess to find where body b2 is, and reversing the
calculation of t2).

Of course, I'm a pure-wannabe as an astrogator, so take what I say
with a Euclid-truck of salt (not just a grain, a whole bunch of
grains).

/dps

In article ,
dave schneider wrote:
I would think that gravity-assist, to a first approximation, could be
handled by modelling each leg seperately, and pretending that the
planetary interaction was a funny "rocket burn"...

It's easy enough to calculate the trajectories in between gravity assists,
and the effects of an individual gravity assist. The tricky part is
finding a series of gravity assists that work properly together.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |