Starting an interplanetary mission from Geostationary orbit?

[hypersonic]

Hi All,
What might be the pros (if any) & cons, of planning / lauching an interplanetary mission when starting from a geostationary orbit?

Firstly the pro's & cons for missions to the inner planets (Including Mars)
Secondly the pro's & cons of missions to any of the outer planets?

Look forward to your input.




---------- Post added at 02:56 PM ---------- Previous post was at 02:53 PM ----------

P.S. Apologies for the poorly worded thread title.. Didn't notice until after submitting. Alas 'edit' doesn't allow you to edit the thread title?

 

[2552]

I can't think of any pros, but a con would be the deltaV of burns from Earth would be higher, due to being farther away from the Earth during the burn, thus taking less advantage of the Oberth effect, which is the fact that a burn from a lower orbit results in you going faster than the same burn in a higher orbit, due to the fact that in a lower orbit, you're moving faster, and so applying the same deltaV to a faster speed.

Edit: You can edit the thread title, but you have to click the Go Advanced button first.

 

[hypersonic]

2552 - Thanks for the info on Oberth .. makes logical sense.

Granted it is not so good from an initial velocity perspective, but what about from an alignment perspective...
Would orbiting around the equator from a GEO position have any benefits for orbital alignment to any of the planets (minus Pluto)?

 

[garyw]

Alas 'edit' doesn't allow you to edit the thread title?

It does when you click on the advanced button in the edit dialogue screen.

 

[Mindblast]

One pro i could think of is when you're using a medium/low thrust high ISP engine where you need longer burn times to get the needed dV. You will have a bit more time in GEO to do the burn..

 

[hypersonic]

It does when you click on the advanced button in the edit dialogue screen.

Thanks Gary, found it & sorted it

 

[TJohns]

Did no-one think that a GEO orbit is over the equator, and therefore 23 deg offset from the plane of the ecliptic where the planets tend to orbit?

Trev

 

[Andy44]

Depends. Geostationary means it's over the equator, but you could have a geosynchronous orbit which is inclined 23 deg and more closely match the ecliptic.

Why? Well, if you're using GEO as a staging point for interplanetary flight, being stationary isn't that important, since your mission isn't communications.

In addition, 23 deg inclination is much easier to get to from the Cape (28 deg N) than zero is.