JF Mezei wrote on Mon, 20 May 2019
15:30:31 -0400:

On 2019-05-20 12:56, wrote:
"In the nearly two months since Vice President Mike Pence directed NASA to return
to the Moon by 2024

Unless MASA is given unlimited budgets, could it do this by 2024?


First, nobody is asking for "unlimited budgets". Second, I'm not
convinced that THIS plan is executable even if they give them all the
money they think they need (around another $8 billion a year on top of
the $20 billion they currently get).


A while back, NASA signalled that it isn't opposed to commercial rockets
and mentioned Falcon Heavy. Could this be the perfect excuse to put SLS
out of its misery and redirect budgets towards building a moon lander
ASAP and launch using Falcon Heavy or some other commercial rocket?


Falcon Heavy just doesn't have the 'grunt' for the sort of mission
architecture that NASA has fixed on. In fact, SLS Block 1 is short by
around 10 tonnes of having enough power for these missions. Block 1B
is required and that's essentially under a 'stop work' until Block 1
is completed. Since SLS Block 1B was scheduled for 2024 BEFORE it was
stopped, I doubt it can be completed in time for a 2024 manned lunar
landing. Falcon Heavy comes in around another 10 tonnes under SLS
Block 1, so NASA's mission architecture requires something MUCH bigger
than Falcon Heavy (about twice the capability).

The only vehicles in any stage of development that could do the job
with NASA's architecture are SLS Block 1B and Block 2, Falcon Super
Heavy (BFR), New Armstrong, and Long March 9. The latter two are
still in the planning stages right now. Musk's plan with Falcon Super
Heavy and Starship doesn't need NASA's architecture, but does require
the completion of Starship Tanker as well as the crewed article. Super
Heavy as a booster in the NASA program could probably do the job, but
it's not really intended to ever be used that way.


Would NASA require a sequence of flights similar to those that
preeceeded Apollo 11? Or would it compress the testing into fewer
flighst? Combine 9 and 10 together and test the LEM in Earth orbit, and
eliminate 8 which was a sightseeing flight.


It's probably going to require something similar. And you're
mischaracterizing the purpose of Apollo 8.


If NASA insists on SLS, would it compress the testing to culminate onto
the pne flight to the moon on the last set of SSMEs they have left? Or
would this trigger the contract to actual build more of them instead of
just studying how to build new SSMEs ?


Where did you get that they only have a single set of SSMEs left? Last
I knew they had 16 engines and hadn't expended any, so they should
have four sets of engines on hand. As for building more, that's
already at least partially triggered, since they've procured all the
long lead time items to produce six engines.


In terms of a lunar lander, considering the time frame, is NASA's only
option to dust off the LEM plans and just update avionics? (Or even
build an emulator on an iPhone and have it run the original software).


No. Do you not follow any news at all? NASA just recently let
contracts to 11 different companies to study and, in some cases, build
prototypes of pieces of their lander architecture. Note that one of
those companies is Blue Origin, which says that its Blue Moon lander
will be ready to fly by 2024.


Or do current NASA safety rules eliminate the LEM due to lack of
shielding , lanck of redundancy etc etc ?


What eliminates the LEM is that you would have to totally rebuild an
industrial base to produce it. It's probably faster and cheaper to go
with a 'clean sheet' design that uses currently existing industry.


In terms of hypergolic engines, has efficiency changed much since the
last Apollo missions, (aka: mass of new lander would have to be as
limited as it was for Apollo missions) or have significant improvements
happened since then to allow far more mass (shielding etc) to be loaded
onto the lander?


It doesn't matter, since hypergolic engines aren't a requirement. Blue
Moon, for instance, uses LH2/LOX.


--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn