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# Transfer Between Co-planner Orbits

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## Transfer Between Co-planner Orbits

(OP)
Can a transfer between co-planner orbits be effected
by an elliptic orbit with perigee and apogee distances
equal to the radii of the respective circles ?

### RE: Transfer Between Co-planner Orbits

(OP)
IRstuff
Thank you....for the answer
Will the ratio of velocities be greater
for the inner orbit, (greater than 1/1)
thereby requiring additional thrust ?
Is this considered to be a minimum
energy transfer situation?
Which is greater thrust required to escape from the
inner orbit or thrust required to do the tranfer ?

### RE: Transfer Between Co-planner Orbits

The Hohmann transfer is supposedly the most efficient, but I've never done the math nor been directly involved in these things.

As the article states, you need to apply thrust to get to a higher orbit.  This is evident from the increase potential energy perspective as well as from the classical free-falling orbit perspective, since a lower orbital speed will cause the ballistic trajectory to intersect with the Earth, clearly a bad thing.

As for net energy expenditure, that depends on the amount of orbital change, but you can get some idea from the fact that the bulk of the total mission energy was consumed in getting into a low earth orbit to begin with and most geo-sync satellite boosters easily fit inside the Shuttle cargo hold.  You'd have to do an integral of m*g(r)*r to get a better idea.

TTFN

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