Re: what is orbital speed around the moon?



thomsona@xxxxxxxxx wrote:
For an application as simple as the apogee kick motor we're talking
about, I'd think an end-burning solid grain would do. No elegance
required.

You might be able to do some sort of monopropellant liquid engine as well.
Here's a novel approach - strap a pressurized gas orientation system on the back of the orbiter projectile, the front of which has a short tube on it in which the payload proper rests in a folded condition (this would gas seal the projectile in the gun during firing). The cannon fires the whole works into a pre-orbital trajectory, the gas system gets it aligned in the right direction for the circulisation maneuver, and a small explosive charge goes off under the payload, firing it out of the front of the gas alignment stage like a low velocity shell. The orbit is now circular, and the decelerated gas alignment stage falls to the surface.
The principle would be similar to a "countershot" recoilless gun, where mass is shot rearwards to balance the recoil of the shell leaving the barrel.

Pat
.