2909: Moon Landing Mission Profiles

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Moon Landing Mission Profiles

Title text: If you pick a low enough orbit, it gives you a lot of freedom to use a lightweight launch vehicle such as a stepladder.

Explanation

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Transcript

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[Top left panel]

Lunar orbit rendezvous

Spacecraft orbits Moon, drops lander

Chosen by the Apollo program

[Top right panel]

Earth orbit rendezvous

Large lander assembled in Earth orbit via several lanches, travels to Moon

Rejected for requiring multiple Saturn Vs per landing and potentially taking longer

[Lower left panel]

Direct ascent

Lander launched from Earth directly to Moon

Rejected for requiring an unreasonable large rocket

[Lower right panel]

Lunar Earth rendervous

Moon transits to rendezvous with spacecraft in low Earth orbit

Rejected because I guess no one thought of it?!

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Discussion

Direct assent was a common method in many sci-fi movies. Including the classic From the Earth to the Moon Barmar (talk) 19:18, 20 March 2024 (UTC)

It feels like it needs an addition of more detail from the planned Artemis mission. In several ways it's going to be a "multiple rockets, assembled in orbit" plan (if not Earth orbit, then Lunar), with SLS and Orion scheduled to be cooperating with the Lunar-Starship launch (later, maybe, other independently craft)... which is itself almost a "one big rocket" solution, sticky-taped onto the plan. That's with or without the addition of the dedicated and semi-manned Lunar Gateway moon-orbiting element. I mean, most of the prototypical Apollo-era plans (DA, EOR, LSR and LOR) had their own crazy bits to them, and the full Artemis premise definitely seems crazy as well, if only because the LOR version got chosen for Apollo and pretty much got proven to work. (Or worked enough to even get 13 back home safely!) 172.70.85.254 21:04, 20 March 2024 (UTC)

Which mission profile will the artemis missions use? --162.158.202.135 06:58, 21 March 2024 (UTC)

From wikipedia:

Artemis 3 (2026) is planned to be the first crewed lunar landing. The mission depends on a support mission to place a Starship Human Landing System (HLS) in a near-rectilinear halo orbit (NRHO) of the Moon prior to the launch of SLS/Orion. After Starship HLS reaches NRHO, SLS/Orion will send the Orion spacecraft with a crew of four to rendezvous and dock with HLS. [...]

...so it's a kind of Lunar Orbit Rendezvous With Multiple Launches (not sure what its official name is, probably something as pithy as "Skycrane" was). Certainly not unambiguously any one of the main types considered for Apollo/in this comic. 172.69.194.225 09:17, 21 March 2024 (UTC)

So it's both an earth orbit rendezvous and a lunar orbit rendezvous? --162.158.94.201 07:15, 22 March 2024 (UTC)

Depends on how you define the SpaceX contribution (in the current plan.

• In Earth Orbit, there is due to be unmanned refuelling of the Lunar Starship from 'normal' Starships, which is a sort of EOR, I suppose.
  • But the Apollo EOR would have been basicically building up small bits, assembling 'a Moon rocket' in space that could avoid the LOR rendezvousing but was too big to launch in one go. The Saturn V helped there, in becoming good enough at lifting to not need the EOR stage, along with other mission refinements.
• Lunar Starship and Orion capsule (and, later, other items, including the Lunar Gateway) meet up in Lunar Orbit prior to any landing, fulfiling a "multiple rocket LOR" hybrid, one could say.
  • The equivalent phase for Apollo was the 'pointy bit' command module temporarily disconnecting from the lunar lander (stowed behind it in the same rocket) and reconnecting nose-to-nose (or nose to head?), but it wasn't really a full rendezvous, just a reconfiguration of bits already floating around together. And this happened on the way between Earth and Moon, anyway, so isn't in either Lunar or Earth orbit. Could have been either, but it just happens in a 'quiet' bit of the mission profile, and probably they also needed the TLI burn to happen before they started messing around 'unpacking' the LM from its shroud, etc.
• Lunar Starship then goes down to land on the Moon (hopefully) mirroring Apollo's LM separating from the CM
  • But none of the plans ever refer to any undocking stages, by name. Even the Direct Launch approach would probably require disconecting from bits of the rocket stack that they'd discard, at various points, rather than the Single-Stage-To-Moon-And-Back of the Tintin rocket and other popular SF versions of the era.
• LS then LORs with Orion (again, hopefully!), as that Starship model isn't going to be useful in getting back down to Earth. It'll perhaps be left for use by the next Orion to arrive (and maybe they'll get more fuel to it), if everything goes to plan.
  • This is the LOR bit that the used Apollo profile really refers to, because ascent-stage of the lander had to meet up again with the command module in order to return home. Again, this lander was not set up to get the crew back to Earth (no use carrying heat-shields/etc down to the Moon and back if you didn't have to...), though most bits of landers were either left on the Moon (descent stages) or crashed back into it (ascent stages, once the crew had transfered back), without any plans for re-use by later missions.
• Pretty much every plan (past and current) has whatever kind (and state) of vehicle that departs the Moon then coming straight back into the re-entry (though discarding the last bit of rocketry below the capsule might still be required).
  • It's possible that future missions will add a post-landing EOR (or similar), perhaps so that Orion's successor can be a reusable ferry back and forth between Earth orbit (ISS/whatever) and Moon orbit (Lunar Gateway/etc) and not need the capsule heat-shield/parachutes, instead crews can hitch rides up/down on Crew Dragons or similar HLSs.

Perhaps let's call the Artemis plan something like Multiple Rocket Earth Orbit Refueling Lunar Orbit Rendezvous/Reusable Rockets (MREORLOR/RR, but only cats can pronounce that properly). 172.70.160.166 11:43, 22 March 2024 (UTC)

I see Lunar Earth Rendezvous will be bad for Earth's climate, tides, stock markets and ecosystems. Has anyone considered the impact this will have on the trout population? 172.70.111.48 00:02, 21 March 2024 (UTC)

What is the deal with trout? I’ve seen trout population mentioned in 2 places online. 172.68.3.44 17:42, 22 March 2024 (UTC)

from a quick google search on "Trout and the moon":

> Anglers often report that trout may be caught all night long on a bright moonlight night. It seems reasonable that when fish feed at night they may have a tendency to feed less than usual dur- ing the day, which in turn may affect the catch.

Also:

> The idea behind fishing by moon phases is that the bigger the tide, the more active the fish. The strongest tides happen twice a month: during a new moon, when the sun and moon are both pulling in the same direction, and during the full moon, they're pulling on either side of the planet. 162.158.154.170 (talk) 21:07, 15 April 2024 (please sign your comments with ~~~~)

The choice of Lunar Orbit Rendezvous wasn't easy for the Apollo planners. Thanks to John Houbolt, the "voice in the wilderness" as he called himself, NASA finally adopted LOR rather than Direct Ascent or Earth Orbit Rendezvous they were planning in the early 60's. Remembering John Houbolt, NASA’s Voice in the Wilderness Orion205 (talk) 01:09, 21 March 2024 (UTC)

When you think about it, the complex (re)docking procedures for happen entirely beyond Earth orbit (for all Moon-bound missions). The uncovering of the LM and crew-connection made from the CM early in TLI, and the return of the ascent stage to rendezvous with the CM in lunar orbit.

How tempting must it have been to just have a single, 'uncomplicated' lander that doesn't rely on potentially awkward coordination well beyond any conceivably timely 'rescue shot' from Earth (LEO construction variations might realistically be still somewhat inaccesable, at the time, but there might yet still have been a chance to do something with a handy 1B sitting on a pad just in case.)

But it turned out Ok. Maybe better than Ok, as Aquarius (13's LM) was an important temporary 'lifeboat', whereas any single-craft-to-Moon solution with the same engineering failure might have left the crew with nowhere near as survivable a situation.

As Eleven's initial landing maybe showed (had to choose another landing spot from the one initially aimed for), the Lunar Surface Rendezvous seems to me the trickiest 'rendezvous' variation. At best, the preparatory 'reception lander' might have needed to have been sent again, when the first one encountered the bad landing zone (either landed badly or landed okish but revealed awful conditions to send the manned expedition). At worst, the manned craft lands but not realistically close enough to perform the intended fuel transfer, and very little that they can do about it by then.

So, looked at one way, it was a crazy decision. In another, it was just workable enough to avoid all the problems that the various other schemes had? 172.69.43.225 09:01, 21 March 2024 (UTC)

Randall's been thinking a lot about space recently. No complaints from me. MrCandela (talk) 02:08, 21 March 2024 (UTC)

He's probably playing KSP2 :D Elektrizikekswerk (talk) 08:35, 21 March 2024 (UTC)

Getting astronauts to the moon isn't hard. Getting them there (and back) in one piece is.141.101.98.76 10:18, 21 March 2024 (UTC)

Yes, Carl... ;) 172.69.194.81 13:04, 21 March 2024 (UTC)