Although an orbiting moon base makes for a quicker return to earth vicinity
No, actually it doesn't. transfer orbit for LLO to Earth takes just about as long as a transfer orbit from Luna surface to Earth.
The major problem of a moon base, or simply visiting the moon, is the problem of fuel expenditures for lift off. For all the Buck Rogers si-fi we've written, we still can't carry enough fuel to get out of sight. Any system we have for getting off of the surface amounts to a zero-backup, Hail Mary. There is no plan B.
Umm, no.
One possibility is to use that lunar water to manufacture LH2/LOX + O2 for use by the base (LH2/LOX mixtures typically don't include enough LOX to burn all the LH2). So, LH2/LOX fuel, Isp 450 more or less, depending on engine design. Assume 420 to allow for generous margin of error.
DeltaV required from Lunar surface to enter an orbit that'll drop you into the upper atmosphere is ~2.4 km/s.
Allow for 80% extra fuel, which should be sufficient for an abort anytime up till you actually enter lunar orbit - 4.4 km/s.
A 420 Isp for 4.4 km/s deltaV requires a mass ratio of less than 3.0. Two kg of fuel for every kg of spacecraft/cargo. Which is pretty easy to achieve, actually.
Alternately, you use Al/LOX. O2 is easier to come by on Luna than H2, since you can find oxygen in the compounds making up the rocks. Ditto Aluminum. Isp is crap, but fuel density is much greater, so you need much smaller fuel tanks. Higher mass ratio, of course.
Which would be the best course is a matter for professionals, of course. But either option is doable, and either vehicle could be developed before we could get a base on the moon to deliver it to.
Of course, if you're really looking for exotic solutions, there's always an escape speed mass driver on the moon. Gives the loonies something to bombard Earth with later, also...right, Mike?
yvette vickers yvette vickers ronald reagan sidney crosby nhl mph abraham lincoln
No comments:
Post a Comment
Note: Only a member of this blog may post a comment.