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Old May 23rd 19, 07:22 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 Thu, 23 May 2019
01:23:23 -0400:

On 2019-05-23 00:11, Fred J. McCall wrote:

Yes, they will, which means all the avionics (including heat
dissipation, which affects structure) will be a clean sheet design.


Consider when they upgraded the Shuttles to glass cockpit. They also
updated the flight computers with 386s with more RAM but the core
software was preserved. (they would have had to add the LCD screen
drivers to emulate the old analogue gauges).


OK, I've considered. What the hell is your point?


With the modest advances in computing since the 1960s, it would be
rather easy to host computing power needed to run the LEM software
unmodified im emulation with less weight, less heat dissipation, less
power.


Everything is always "rather easy" until you actually have to do it.


However if you remove the huge challenge of fitting all the logic onto
the limited LEM computer, is the actual logic of landing a craft on the
Moon very difficult to write?


That depends. LEM, for example, was always flown manually, so
'auto-landing' would be difficult because it wasn't built for that.
And don't think that writing the software is the difficult part.
Remember, SpaceX did away with powered landings for Crew Dragon
because CERTIFYING it was too difficult to be worth the trouble to
them, not because of concerns about difficulty writing the software.

Meanwhile, Blue Moon is designed for automated landings going in,
since it's supposed to be able to be used as an unmanned cargo lifter.


Just curious of what sort of challenge exists to write one from scratch
to be ready by 2024.


Depends on the vehicle. Certification will be anywhere from difficult
to impossible, since all the testing will be done in Earth orbit. It
wouldn't surprise me to see manual control required for the landing
unless you're going to run an unmanned test flight to landing.

Probably because they don't want the limitations of that design. Why
do you think Blue Origin didn't just do that for their Blue Moon
lander?


Have they landed on the moon?


Of course not. Don't be an idiot. Your 'new LEM' hasn't ever landed
on the Moon, either.


or is this just a proposal on paper?


No. It's well beyond that, unlike your 'new LEM'.


And
was that plan devised before there was a 2024 deadline imposed by a
politician?


Of course it was. Otherwise it would just be some napkin doodles.
However, the company says it can be ready to put humans on the Moon by
2024, so who cares that their development effort started years ago?


Of course if you are asked to get to the Moon or Mars, your initial
thoughts are to create a clean sheet design and take whatever time it
takes.


Yeah, because that's going to be faster and cheaper than trying to
update some half century old design to try to make it work.


But when one imposes a 2024 deadline, you have to wonder if a clean
sheet design can meet that deadline and if not, whether you could re-use
older proven designs.


You cannot use "older proven designs" BECAUSE YOU CANNOT GET THE
BLOODY PARTS AND HAVE TO RECERTIFY EVERYTHING. Which part of that
don't you get? Bezos says that the Blue Moon lander can be ready to
put people on the Moon by 2024. How long would it take to recruit and
recertify vendors for your 'new LEM'?

Not really, no. Whatever you build needs to interface with boosters
in a standard way and be of a size to fit inside the payload fairing


Would any commercial rockets be able to launch a LEM ?


To the Moon? No. Insufficient grunt. The baseline LEM (good for 48
hours on the lunar surface) weighs in at a bit over 15 tonnes. Falcon
Heavy can get around 20 tonnes to TLI if you fully expend the vehicle.
Nothing else can, so that's the only commercial launcher that could do
that job. Then you have the problem of the LEM being a dead hunk
until people board it and power it up.

Note that that mass doesn't get you any people out there. That
requires an SLS launch.


Saturn5 had 3rd stage width of about 6m. Falcon 9 has 5.2m (4.6 usable
by payload).

reading Wikipedia for the LEM, it appears it had 4.22m width with
landing gear retracted. So it would fit with the right adaptor.


But you cannot get it to anywhere because it's too heavy for anything
but Falcon Heavy expended or SLS. And if you could get it to anywhere
it would be just a big dumb rock until people could get to it and
power it up.

of whatever rockets you plan on using to get it out to Gateway. You'd
like to use modern alloys to build the thing.


Wouldn't modern version of aluminium just be lighter and stronger and
thus can be easuly meet requirements of the older aluminium used?


Of course, but that's all new design, new heat dissipation studies,
new structural studies, etc.

It needs to provide
power and heat dissipation for all the electronics you stuff in it.


Surely a modern version would need less power and dissipate less heat?


You don't know that until you do the studies. This is engineering.
You're not allowe to just reach into your ass and pull out a "surely"
or an "easy".


Its batteries might be much lighter than the ones used in Apollo era?


Maybe yes, maybe no. However, you're now also replacing the whole
power system in your 'new LEM'. More studies and more certifications.


Seems to me this is one area where meeting the needs of the LEM is much
easier today than it was back then, AND same on power and heat dissipation.


This is engineering. You cannot just reach into your ass and pull out
a "much easier" based on how things "seem to you".

You'd like to use modern, more efficient engines that use propellants
that you can make in situ out of water ice.


Yeah, as if fuel production on the moon will happen by 2024 so that the
first mission can land there with a ready-made fuel refinery that is
operating and they just have to use their credit card to buy the guas at
the pump.


You need to pull your head out of your TDS ass. Despite your inane
idiocy in insisting that it is, this is NOT supposed to be a 'one off'
mission after which you throw away all the hardware and start over.


If hypergolics are so "old" why is SpaceX using them for Dragon1 and 2?
Japan is using them for HTV, right?


Stop being so ****ing stupid. None of those vehicles are landing and
taking back off. None of those vehicles are using hypergolics to land
payloads, which is sort of the goal of the exercise. More efficient
engines and propellants means more mass up and down. It's really that
simple and even you ought to be able to wrap your head around it.


Has anyone gone to actual orbit with de-orbiting as part of mission
without hypergolics?

Super Heavy. It relies on a docking adapter that doesn't exist
anymore.


Should be pretty easy to fit the standard docking adaptor that is used
for station, Dragon2 and Orion. Is it much different in diametre than
the original Apollo one?


Again, this is engineering. You don't get to pull a "pretty easy" out
of your ass and claim you're done. There is a lot more to any docking
mechanism than 'diameter'. The more Rube Goldberg **** you have to
string together the heavier **** is.

It's battery powered and only has power for a 75 hour
duration.


Obviously, one would use different batteries today.


This is engineering. You can't just reach into your ass and pull out
an "obviously" and declare that you're done.


And would solar
panels be usable in flight considering whyat happens when you land? Or
just something you deploy once you have landed? Those would just be
cosmetic add-ons to the structure, and probably could have easily been
added by NASA on the LEMs if it had access to current solar panel tech.


This is engineering. You can't change the power system and claim it's
"just cosmetic add-ons". You can't just pull an "easily" out of your
ass and declare the problems solved.

Note that Blue Origin's plan for Blue Moon is to use boil off from the
LH2 tanks to run hydrogen fuel cells for power. This gives you weeks
(not days) of stay time on the surface.


But in the end, how much autonomy do you really expect the ship that
lands in 2024 to really have? not just power, but also ECLSS, food, water?


Contrary to your TDS delusions, this is not intended to be a 'one-off'
mission after which we throw all the hardware away. With your 'new
LEM' you get four days on the surface with two people. Or you could
do the 'extended' LEM, which gets you up to 75 hours but adds several
tonnes to the mass.

See what a poor fit that is for what we actually want to do?


Sicne they are trying to do the exact same thing, why is it a poor fit
for the 2024 mission ?


Because you're not "trying to do the exact same thing". "Flags and
footprints" is not the goal here. Blue Origin started developing
their lander some three years ago and says it will be ready for use in
2023. A year later their Ascent Element will be ready for manned
landings in 2024.

NASA has asked for crews of up to four people (twice your 'new LEM'
capability). The Blue Moon Ascent Element weighs in at around 6.5
tonnes, which is almost half again as heavy as the LEM Ascent Element.
Want to guess why?


--
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