In article , "Greg D. Moore
\(Strider\)" wrote:

"Hop David" wrote in message
...


Joe Strout wrote:
In article ,
Hop David wrote:


If you achieve LEO with an empty fuel tank you're not halfway there.


Of course you are. You just don't have the fuel to go any farther. If
my car runs out of gas halfway to San Jose, is it not halfway to San
Jose?


Well, that's true enough.

So when we get to LEO all we need to do is stand by the road and stick
out our thumb.

Basically yes.

Imagine the shuttle bringing up a TLI for a lunar mission.

Let's give it 60,000 lbs mass (you can pick the fuels, payload, etc.) at
(we'll be generous) $300,000,000.

Someone else is quoting $640 million per launch.

http://www.theatlantic.com/issues/20...asterbrook.htm

So you're paying $5000/lb

Now, let's say something like Roton had succeeded.

I don't recall mass to orbit, but some of the schemes out there are already
talking $1000/lb or less.

Let's give it a payload of 2,000lbs, but a cost of $1000/lb.

You have to fly 30x missions, but it's still cheaper.

$1000 x 2000lbs == $2,000,000 per launch. That sounds too good to be true!

So, each of those 30 missions, you fill up your orbital depot and sell to
the highest bidder.

Wouldn't you have to build the orbital depot first?

If nothing else, you'd need somewhere to house those assembling the lunar
mission's ship. As a benchmark, the ISS will be over 350 metric tons when
finished. Even if your depot was only one-tenth it's size, that would
still be a lot of missions to fly (at 2000 lbs apiece) before you could
even begin flying the missions to take the pieces of the lunar ship into
orbit. Not to mention the missions for rotating crews while the lunar ship
is being constructed.

--
Stephen Souter

http://www.edfac.usyd.edu.au/staff/souters/