Re: Viability of volatile imports to Mars?

Erik Max Francis wrote:

Hop David wrote:

No, it isn't.

Applying a sudden 2.4 km/s periapsis burn to slow a mountain sized object is a lot harder than a 1 km/sec deceleration.


Sure, it takes more deltavee. But you weren't counting it at all since you were ignoring the need to circularize the orbit for final impact.

I had argued that capture to a long elliptic orbit was a sensible first
step. I then compared delta vee required for such capture between cargo
from Ceres and Ganymede.

And I wasn't ignoring the need to circularize the orbit. From an earlier
post:

"My plan has been to capture the asteroid to a very long elliptical
orbit about Mars. This takes far less delta vee than capture to, say, a
low Mars circular orbit.

"If the perigee of this eccentric ellipse is in the upper atmosphere,
aerobraking will reduce the velocity and slowly circularize the ellipse.
(You could also do circularizing burns at perigee to exploit the Oberth
effect)."




And when periapsis is in the upper atmosphere, most, if not all the remaining delta vee can be done with aerobraking.


As I pointed out, even relying on aerobraking doesn't reduce the deltavee budget to zero,

And as I pointed out, tweaking the perigee altitude takes relatively minute amounts of delta vee.

which is what you were doing by implication by
counting the deltavee required to capture in the maximally elliptical orbit but nothing after.

I said it takes a 1.02 km/sec perigee burn for capture to an elliptical orbit. That in no way implies the circularizing delta vee budget is zero.

Hop
.

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