Was the Moon Lander or Space Shuttle harder to fly?

For the discussion of the sciences. Physics problems, chemistry equations, biology weirdness, it all goes here.

Moderators: gmalivuk, Moderators General, Prelates

jewish_scientist
Posts: 658
Joined: Fri Feb 07, 2014 3:15 pm UTC

Was the Moon Lander or Space Shuttle harder to fly?

Postby jewish_scientist » Sat Oct 14, 2017 9:43 pm UTC

I just got into an argument with someone. They thought that the astronauts on the mission to the Moon did not actually do that much, because computers were doing all the flying. He thinks that professional pilots were sent on the mission, because if they were going to send someone, why not just send the best. On the other hand, he also thought that the astronauts on the Space Shuttle did/ do the majority of the flying. How can I explain to him why this is wrong?

User avatar
Eebster the Great
Posts: 2750
Joined: Mon Nov 10, 2008 12:58 am UTC

Re: Was the Moon Lander or Space Shuttle harder to fly?

Postby Eebster the Great » Sun Oct 15, 2017 7:57 am UTC

Landing the lunar module was by far the most dangerous part of what was unambiguously an extremely (perhaps supremely) dangerous mission. No craft had ever been built before to move humans exclusively in a vacuum, and failure to any extent meant certain death. Even if the astronauts survived a poor landing, extraction would have been impossible.

I don't know much about the computer guidance capabilities of the lunar module, but I do know that there was a damn good reason to send expert pilots. If it was just ashoulder-shrugging "might as well" situation, there would have been many more important considerations.

Mutex
Posts: 1043
Joined: Wed Jan 09, 2008 10:32 pm UTC

Re: Was the Moon Lander or Space Shuttle harder to fly?

Postby Mutex » Sun Oct 15, 2017 11:21 am UTC

The pilots of the LEM had to manually fly along the surface until they found a suitable landing site, and land there. Armstrong's heart-rate was incredibly high by the time they finally managed it.

Re-entering the atmosphere in the Shuttle could be done entirely by computer as I understand it. The pilot might have manually done the S-swerves to bleed off speed high up in the atmosphere, I'm not sure. Nothing like as difficult as landing on an unknown, uneven rocky surface in a delicate lander though.

User avatar
Soupspoon
You have done something you shouldn't. Or are about to.
Posts: 2476
Joined: Thu Jan 28, 2016 7:00 pm UTC
Location: 53-1

Re: Was the Moon Lander or Space Shuttle harder to fly?

Postby Soupspoon » Sun Oct 15, 2017 12:11 pm UTC

On the face of it, I'd say that to a (fixed wing) pilot, the operation of thr LEM is more alien, during landing, than even for the flying-brick that is the Shuttle, but then Armstrong was retrained to the LEM. How do you quantify the difference, once you know you're not just plonking a relative amateur onto the flight controls and telling them they've got to master this before craft meets surface?

The lunar target (far from help, with no prepared ground) probably swings it as the most difficult part, for me. A good landing is one you can walk away from, they say, but a merely-that-good landing on the Moon doesn't have an outcome much dissimilar to a bad landing. Walking away from a belly-flopped Shuttle that over-ran the landing runway would be Ok, though.

On the flipside, the Shuttle is an unpowered 'glider' (or "brick with flaps") and abort-and-go-around procedures, close to the ground, are few and far between (not even any reasonable option to bail), whilst Apollo 11, in its attempt to find a suitable landing spot, still had ?almost 10 seconds? left before it needed to abort back to Lunar orbit and meet up with Collins again (again, a procedure they were as fully trained in as possible).


Still, back with Armstrong, he hadn't had any similar tries before. You can (and they do) adapt a plane to respond like a landing Shuttle, once captive simulators have been mastered, and you then experience everything pretty much as you might, as far as landing is concerned. Flying the LLRV, on Earth, has the issue of atmosphere and greater gravity to spoil the simulation accuracy prior to the real event. (The LLTV adressed these issues, apparently to the satisfaction of the post-Moon Armstrong, but if the sophistication involved had not been tuned quite accurately enough, nobody would have known before the unrecoverable-from first real attempt.)

User avatar
gmalivuk
GNU Terry Pratchett
Posts: 25789
Joined: Wed Feb 28, 2007 6:02 pm UTC
Location: Here and There
Contact:

Re: Was the Moon Lander or Space Shuttle harder to fly?

Postby gmalivuk » Sun Oct 15, 2017 1:44 pm UTC

jewish_scientist wrote:
because computers were doing all the flying
He does know it happened almost 50 years ago, right? Like, you can now wear more computing power on your wrist than existed in all of NASA at that time. How much does he think the computers were really capable of?
Unless stated otherwise, I do not care whether a statement, by itself, constitutes a persuasive political argument. I care whether it's true.
---
If this post has math that doesn't work for you, use TeX the World for Firefox or Chrome

(he/him/his)

morriswalters
Posts: 6902
Joined: Thu Jun 03, 2010 12:21 am UTC

Re: Was the Moon Lander or Space Shuttle harder to fly?

Postby morriswalters » Sun Oct 15, 2017 1:52 pm UTC

I just got into an argument with someone. They thought that the astronauts on the mission to the Moon did not actually do that much, because computers were doing all the flying. He thinks that professional pilots were sent on the mission, because if they were going to send someone, why not just send the best. On the other hand, he also thought that the astronauts on the Space Shuttle did/ do the majority of the flying. How can I explain to him why this is wrong?
The astronaut corps originally were all pilots and military officers with degrees. If you couldn't fly you didn't go. Otherwise it's an apples and oranges comparison. Two extremely different missions separated by 10 years of technology. Apollo lunar missions did two landings to the shuttle's one per mission. And the lunar trips never knew the precise point at which they would land on the moon. The shuttle didn't have to dodge boulders in the landing zone because they landed on runways.

User avatar
somitomi
Posts: 440
Joined: Fri Nov 06, 2015 11:21 pm UTC
Location: can be found in Hungary
Contact:

Re: Was the Moon Lander or Space Shuttle harder to fly?

Postby somitomi » Thu Oct 19, 2017 12:42 pm UTC

Mutex wrote:The pilots of the LEM had to manually fly along the surface until they found a suitable landing site, and land there. Armstrong's heart-rate was incredibly high by the time they finally managed it.

IIRC the LEM landing was automated to some degree, but astronauts could take control or make adjustments manually if necessary. At any rate, whatever computerised control a spacecraft had in the late sixties was probably like the commercially available self-driving cars of today: capable of performing some part of the job, but requiring a trained driver to do the rest and take control if things get hairy.
Image
they/them/theirs = he/him/his ❖ If you want to use something else out of dadaist spite, I won't mind.
✆ Hello? This is Forum Games Discord, what is your emergency?

User avatar
Soupspoon
You have done something you shouldn't. Or are about to.
Posts: 2476
Joined: Thu Jan 28, 2016 7:00 pm UTC
Location: 53-1

Re: Was the Moon Lander or Space Shuttle harder to fly?

Postby Soupspoon » Thu Oct 19, 2017 1:22 pm UTC

The actual Apollo missions were far from automated to that degree. And a good job, given the Executive Overload condition that happened in the guidance system due to altitude radar (for landing) and docking radar (left fixed on the CSM in case of abort) using up so much of the processing power at the same time that it got dangerously overloaded during that descent, on top of the cycles dedicated to other things.

Theoretically, the LM "Truck" (unmanned delivery lander module) would have come down fully automated, but that includes the landing site already being checked and prepared by the crew already down on the surface, being delivered to. I don't think it had the ability to deal with unexpected boulder-fields, or even awkwardly sloping terrain, the way the Mk I Eyeball helped for Armstrong, after also finding they were around four seconds "ahead" of where they had planned should have been, for whatever reasons.

(BTW, welcome to the fora... In response to your recent Intro post, regardless of the public and private conversations I know we've already had. :P )

commodorejohn
Posts: 958
Joined: Thu Dec 10, 2009 6:21 pm UTC
Location: Placerville, CA
Contact:

Re: Was the Moon Lander or Space Shuttle harder to fly?

Postby commodorejohn » Thu Oct 19, 2017 2:00 pm UTC

If you want a neat read about the computer systems in the LEM, here is a pretty extensive article on it.
"'Legacy code' often differs from its suggested alternative by actually working and scaling."
- Bjarne Stroustrup
www.commodorejohn.com - in case you were wondering, which you probably weren't.


Return to “Science”

Who is online

Users browsing this forum: No registered users and 16 guests