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Old May 26th 19, 05:09 PM posted to sci.space.policy
Fred J. McCall[_3_]
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Default NASA?s full Artemis plan revealed: 37 launches and a lunar outpost

JF Mezei wrote on Sat, 25 May 2019
19:39:13 -0400:

On 2019-05-25 18:13, Fred J. McCall wrote:

Well, there's that and there's the problem that if you combine
everything in LEO now you need an upper stage with enough grunt to get
the whole works to where it's going all at once. Sending little
pieces is easier.


So they are hoping to have pieces small enough to get to Gaweway with
standard Falcon 9 second stage?


No. Falcon 9 flown as expendable can get around 6 tonnes to TLI.
Lander Elements will likely mass more than that. Falcon Heavy flown
reusable has about the same capability, but if expended can manage
around 20 tonnes or so to TLI


If you need to build a new second stage to get the pieces to Gateway,
why not build 1 hefty one which you fuel from LEO and get everything in
one go?


Because that's more complicated and requires a tanker vehicle that's
capable of refueling it. In other words, YOUR way takes longer, costs
more, and is more expensive to operate. Perhaps NASA has a job for
you?


During ISS assembly, people here complained about the 53° inclination
"costing" many more Shuttle flights since cargo capacity was more
limited.


And rightly so, since the only reason to launch to that high an
inclination was because of Russian limitations.


If you need to ship separate stage II to Gateway to deliver
each component, don't you end up with same problem of extra mass being
carried and thus reducing payload?


No, you don't. What you get is the difference between "possible" and
"impossible". You don't ship "stage II" to Gateway. That stage gets
you to the point where you can insert into Gateway's orbit. When in
doubt, look at reality to check your logic. You could perhaps throw
it all direct once you have SLS Block 1B on a pair of launches at $850
million dollars or more per launch. Or you can launch pieces on
Falcon Heavy expendable at around $150 million per launch and use
three launches (less than half the cost of SLS) plus an SLS launch for
Orion. So by breaking things up you SAVE around half a billion
dollars.


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