Re: Man-Rating Atlas V


Jonathan Goff wrote:
Will,

On the other hand, NASA was probably correct in believing that, all
other things being equal, the fewer launches the better.

But alas, all other things *aren't* equal. In fact they are unequal to
the
tune of $20B or more. That buys a lot of experience with on-orbit
assembly,
propellant transfer, and a boatload of commercial launches.


True. But the argument also goes the other way.

There are costs to going to the moon in only two launches. Clearly
that solution requires a rather large vehicle which does not yet exist.
And maintaining that vehicle has some ongoing fixed costs as well.

On the other side, there are costs to going to the moon in pieces small
enough to fit on existing launchers.

Let x be the probability that an attempt at automated rendezvous and
docking will fail.

Let y be the probabillity that so many payloads of a multipayload
mission will fail that propellant boiloff or other factors will require
restarting the mission and discarding payloads launched to date.

Let z be the probability that a rendezvous and docking will succeed if
humans are nearby.

If x and y and z are clearly identified, then it should be fairly easy
to decide how many launches are optimum.

Are they?

Will McLean

.

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