The crew of Apollo 10 did everything 11 did except land on the moon, get out, and take off from the surface. From a purely technical/difficulty point of view was the Apollo 11 mission significantly more impressive that 10? Or was the landing of the Eagle relatively easy compared to what it took to get there?
I wouldn’t call all that Neil Armstrong stuff, dodging boulders with limited fuel with a bunch of alarms going off, “easy”.
There were essentially two different feats, both of which were difficult; traveling to the moon and back and landing on the moon and taking off again. Apollo 10 was the first manned vehicle to go to the moon. Apollo 11 was the first manned vehicle to land on the moon.
I guess if I had to pick one, I’d go with Apollo 11 being more impressive. In addition to making the first lunar landing, they also made the second trip to the moon.
Apollo 8 went first. Apollo 10’s accomplishment was testing the LM with docking/undocking in lunar orbit. Apollo 9 had already demonstrated the LM in orbit around Earth.
I understand that to make certain the crew of Apollo 10 didn’t get carried away with the thought of making a first lunar landing, NASA loaded the dice. There was NOT enough fuel in the LM to make a soft landing on the moon and take off afterwards. Sandbags might have been used to simulate the weight of the missing fuel.
You’re right. I was thinking of Apollo 8.
It worked out that way, but it wasn’t intentional on NASA’s part. No sandbags or other dead mass was used. Grumman, the builders of the Lunar Module, were having a problem meeting the maximum mass specification for the LM. It was overweight. They were working frantically to get the mass down with each new build. Rather than let this delay the whole program, NASA went ahead and used an overweight LM on Apollo 10, and took out the balance in the fuel it carried. So not having enough fuel in the ascent stage was a side effect, not some deliberate method to keep the astronauts from going cowboy on them.
Some years ago I asked about this very same thing and was told the answer, but I can’t find that thread to link to it now.
Found it. Here’s my question, and see Claude Remains’s answer and my followup post further down the thread.
As with all things Apollo, Andrew Chaikin’s book “A Man on the Moon” is instructive. He pointed out that some within NASA advocated going for the landing on 10 from the standpoint of assumed risk. By sending them to lunar orbit, un-docking the LM, descending to where the landing procedure would be initiated (around 60,000’ IIRC) and then executing an escape maneuver which involved jettison of the descent stage, you’ve already exposed them to most of the risk associated with a full lunar landing mission. Why not go all the way? It’s a fair point.
Bu cooler heads prevailed, and I think they were right. The powered descent and approach phases certainly had their interesting moments during the six flights that eventually landed. A rehearsal flight was warranted.
Been awhile since I read his book but at what point in the mission planning did they settle on definitely no landing attempt to be made? It must have been fairly early because Tom Stafford & Gene Cernan never got any LLRV/LLTV training for Apollo 10 and of course, neither did the back-up crew.
The mission profiles seem to date from October 1967, with the letter designations of missions. Apollo 10 was an F mission, and Apollo 11 a G. What is interesting is that there was an E mission that basically was a mission rehearsal but in a high Earth orbit - and that was cancelled. It is possible that had that one gone ahead, it could have been set up as an alternative to the F mission. But Apollo 8 and 9’s success meant that going straight to the rehearsal round the moon was more sense, and not much was to be gained from an E mission. The mapping from mission type to Apollo mission number was done late in the game, being predicated on availability of hardware and the success of previous missions. Famously Apollo 8 jumped the queue and did an otherwise un-lettered mission, when initially it was slated to be a D mission with a LM (a mission that was flown as Apollo 9) - but the LM wasn’t ready.
The basic outline was worked out before they knew the LM was behind as much as it was, and they still wanted an F mission, so overall, one suspects that no matter what happened, Apollo 10’s mission was going to be flown as designed.
The LM used in A10, Snoopy, was too heavy to land, or more accurately it was too heavy to land without using up more fuel than mission safety margins permitted.
Considering how much of a close run thing the actual landing was, probably a wise decision.
The A11 LM, Eagle was ready before A10 launched. In fact the A11 stack was already at its launch pad when A10 lifted off.
The NASA leadership, especially Gulwrith, and I think maybe Kraft, suggested that they simply land using the hardware earmarked for A11, using the A10 crew. Tom Stafford, the CDR considered it and decided against it. Stafford had a lot of pull, amongst astronauts only less than Slayton and Shepard, certainly more than Armstrong did, so it’s significant that he refused a landing chance. He would be the only Apollo 10 astronaut, never to walk on the moon. And the only one alive today.
On the actual mission Snoopy’s decent stage was under-fuelled, making a landing actually impossible. Cernan always maintained that it was since NASA didn’t fully trust him and Stafford not to land. However, nothing has come out officially.
Whether or not Apollo 10 could have landed if they wanted isn’t what I’m looking for. Was actually landing on the Moon and then taking off again one of the hardest problems NASA had to solve as part of the Apollo program, or was it one of the easier (or somewhere in between)?
Well, my opinion is that the most technically difficult part of landing on the moon was building a large enough rocket to get the necessary payload into LEO for the TLI burn. Of the approximately 400,000 people involved with the Apollo program, roughly 300,000 were needed designing and building the Saturn family of rockets plus all the logistics required to prep them for launch. Prior to the Apollo program, the USA experienced up to about a 40% failure rate with its various rocket launches which were pretty small and relatively uncomplicated. Of the 32 rockets in the Saturn program, all 32 of them were successfully launched. These were some of the most complex machines built at that time culminating in the Saturn V with its 13 successful launches. A big reason for such a turn-around success story is the fact that all the components built for these rockets had to be rated for a 99.99992% reliability requirement. By contrast, the Russians had a 100% failure rate with their version of the Saturn V, the N1 blowing up spectacularly 4 out of 4 times and the cancellation of their moon landing program shortly after despite accomplishing many of the other goals for a manned landing on the moon such as testing their version of the LM in Earth orbit and soft landing probes on the moon. Others may disagree with what I’ve said but the Russians inability to successfully launch the N1 speaks volumes as far as I’m concerned.
As for the actual landing on the moon, I would rate that in the medium difficulty level. Certainly helped that they chose naval aviators/air force pilots who all became test pilots and the best of those that applied and became astronauts were eventually selected for the extensive training with the LLRV’s & LLTV’s.
The most? I don’t know. One of the most? Probably. Not only from an engineering standpoint, but also from piloting standpoint. The flight characteristics of the LM were completely novel and not easily emulated on Earth, because unlike other spacecraft, it actually would have to be operated in gravity, but not earth gravity, and in a way (particularly landing with a rocket-controlled descent) that conventional (air)craft didn’t operate. Armstrong famously narrowly escaped a fiery crash trying to gain experience in the Earth-based trainer, and they pretty much just decided to shrug and keep their fingers crossed after that. It was just too dangerous to keep risking astronauts lives practicing on a free-flying craft in Earth’s atmosphere.
Did Apollo 10 even have EVA suits on board? There wasn’t any need for them.
EVA was a back-up contingency for if they were not able to dock properly again, and needed to transfer back to the CSM in vacuum. All three would need to be suited up to effect this transfer as the CSM would be open. However any of the actual lunar surface gear, that is another matter. Lunar surface suits were different, they had more rugged outer shells, as well as all the additional gear - such as overboots. Importantly they had attachment points for the backpack (PLSS) feeds and controls.
Inthis picture of the Apollo 10 crew, you can see that the LM crew’s suits had the needed bits to attach a PLSS, whereas the CM pilot’s suit didn’t. The CM pilots would only be able to use his suit when it was plumbed to the spacecraft’s support system. I suspect, given the lead time for suits, that once the nominal role was known, he suits for the LM pilot and mission commander were known, they got fully specified surface suits made. I wonder if they were able to reuse any of Cernan’s suit for Apollo 17.
Re Cernan, no. The suit had changed by the time A17 came around, the ones used on Apollo 10 was AL7, from Apollo 14 onwards they used AL7B version.
Here is a list of all the suits flown and used in training. or backup.
Cernan flew Suit SN 044 on Apollo 10
He worse SN 087 as backup CDR on Apollo 14
He flew with SN 328 on Apollo 17
Famously he had to use SN 315, David Scott’s suit from Apollo 15 during training.
Picture
“Landing on the moon and then taking off” involved several issues not adequately explored in the only previous lunar flight of Apollo 8. In general proceeding from a 50,000 ft lunar altitude to a landing was viewed as very difficult and involving numerous risks.
The LM landing radar was critical to this, yet there had been reliability and testing problems from the beginning. Only on Apollo 10 did a realistic flight test provide sufficient confidence it to try an actual landing on Apollo 11. (Source: Mindell, David A… Digital Apollo).
Lunar mascons (mass concentrations) beneath the surface would perturb descent and ascent trajectories. These were insufficiently mapped by Apollo 8. They also wanted a closer photographic reconnaissance of the tentatively selected first lunar landing site, only possible in Apollo 10. (Source: Kelly, Thomas J… Moon Lander).
Planners generally felt there were still too many unknowns to think about a lunar landing. There had been no flight testing to track and communicate with two spacecraft orbiting the moon. The delicate dance of lunar orbital mechanics and rendezvous and docking was untested. (Source: Donovan, Jim…Shoot for the Moon)
The LM was way behind schedule which resulted in only a single prior manned test (Apollo 9). There was a general feeling it needed more manned flight testing short of an actual lunar landing. Although descending to 50,000 feet seems almost the same as a landing, it was judged less risky overall than trying a landing.
Another unknown rarely discussed is the LM software called LUMINARY had never been flown before. The Apollo 9 test in earth orbit used a prior version called SUNDANCE. IOW trying for a landing on Apollo 10 would have been using version 1.0 software. (Source: Eyles, Don…Sunburst and Luminary).
An example of how simple things can cause problems is the RCS exhaust plume deflectors added for Apollo 11. The Apollo 9 test determined these were needed but there was no time to add them for 10 and it was safe to fly a non-landing mission without them. On Apollo 11 the deflectors distorted the radio beams at lunar distance, causing voice/data dropouts, almost causing a mission abort due to poor comm. On later missions this was worked around, I don’t remember the method.
RCS plume deflectors shown on Apollo 14: https://www.hq.nasa.gov/alsj/a14/AS14-66-9254HR.jpg
Nitpick: Not quite, although your point still stands. Apollo 10 lifted off on 18th May 1969, two days before Apollo 11 rolled out of the VAB.
I only point it out because after reading your post I went searching for photos of two Saturn Vs on the pads at LC-39 simultaneously, and obviously found none.