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126 votes
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Why did the Apollo 13 crew extend the LM landing gear?

According to LMA790-3-LM Apollo Operations Handbook: Lunar Module LM 10 and Subsequent Volume I, section 2.3.6: The landing gear must be deployed before descent engine firing. If not deployed, ...
DrSheldon's user avatar
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101 votes
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What was Apollo 13's "Little Jolt" after MECO?

The film gets this mostly right. Merely taking the thrust, and, therefore, the acceleration of the rocket down to zero wouldn't throw the astronauts forward; there are a couple of other effects at ...
Russell Borogove's user avatar
63 votes

Was not saving the Apollo 13 astronauts ever considered as an option?

Noone talked about continuing the mission and having them die on the Moon, or abandoning the mission and letting them die in space. There had already been two successful moon landings at this point, ...
Russell Borogove's user avatar
60 votes
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When did Jack Swigert realize that he forgot to file his taxes?

Jack Swigert realized that he forgot to pay his taxes around the first hour of the second day. Here's the dialogue from the Apollo 13 transcript: Note, Jack Swigert is the CMP (Command Module Pilot), ...
Star Man's user avatar
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54 votes
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Apollo 14-17 - Why didn't they keep the Lunar Module docked as a lifeboat for the way back to Earth?

Without the descent stage, you have a far less capable lifeboat. Looking at Wikipedia, the ascent stage had two batteries with a total capacity of 592 Amp-Hours (some of which would have been used in ...
Eugene Styer's user avatar
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52 votes

Was Apollo 13 radio blackout on reentry longer than expected?

Sort of, but not for the usual reasons. When you are low on batteries, parachutes are more important than radios. Remember that they were running off of batteries, everything non-essential was ...
DrSheldon's user avatar
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47 votes
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Did the crew lock themselves inside the LM on Apollo 13?

The hatch was left open for a number of reasons. The Lunar Module is crowded with two people in it; with three, there's barely room to move. For much of the time, the crew would be spread between the ...
Mark's user avatar
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46 votes

Did Apollo 13 produce any scientific results?

It did, with the third rocket stage. Instead of just becoming another object in solar orbit like the previous Apollo third stages, this time the third stage was sent into the Moon for a crash landing ...
Oscar Lanzi's user avatar
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43 votes
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Was the Apollo 13 CO2 problem a matter of capacity, or of rate?

From this NASA page about Apollo 13: There were four cartridges from the LM and four from the backpacks, counting backups. However, the LM was designed to support two men for two days and was being ...
Uwe's user avatar
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40 votes
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Why did Apollo 13 not use the electronics waste heat to raise the Lunar Module cabin temperature?

A means to transfer heat from the electronics to the cabin was simply not designed into the LM. It's worth noting that the LM had a very different approach to thermal management than the CSM. The ...
DrSheldon's user avatar
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37 votes

Without the accident, would Apollo 13 still have been the farthest crewed mission from the Earth?

You've hit on a really interesting question. To answer this, I'm going to look at JPL Horizons, using the center of the Earth and the center of the Moon as the distances provided. I'm going to look at ...
PearsonArtPhoto's user avatar
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37 votes
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Would replacing a damaged tank have prevented the Apollo 13 incident?

In short yes. But it would have just caused the problem to occur at another time. The drop just cause circumstance that aggravated an existing danger. The fundamental cause of the fire was due to the ...
CuteKItty_pleaseStopBArking's user avatar
36 votes

Apollo 13's plutonium RTG re-entry into the Tonga Trench: Good shootin' or good luck?

Good shooting. Chuck Deiterich, lead retrofire officer, was responsible for the impact point. From Henry S. F. Cooper's book Moonwreck aka Thirteen: The Flight That Failed: Deiterich, however, ...
Organic Marble's user avatar
35 votes
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Why would oxygen be stored as a super critical fluid?

The same system was used on Shuttle - allow me to discuss that, the design philosophy applies to Apollo as well (Shuttle deleted the fans though, and had a special Avoid-Apollo-13-circuit in the O2 ...
Organic Marble's user avatar
34 votes
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Who developed the mathematics used to correct the trajectory of Apollo 13?

The authors of the paper are Harold A. Hamer, Katherine G. Johnson, and W. Thomas Blackshear. Of these, the name Katherine Johnson might ring a bell with people, as she was one of the protagonists in ...
Ludo's user avatar
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32 votes

Was a one way trip to the moon considered by the crew of Apollo 13?

The stack of the SM (service module), CM (command module) and LM (lunar module) was on a free return trajectory to Earth. To get into an orbit around the Moon, the main engine of the SM was needed. ...
Uwe's user avatar
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30 votes
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What does "stirring tanks" mean?

There was no "slush" in the Apollo cryo tanks. The O2 and H2 in the tanks were stored at conditions that made them supercritical fluids. The critical pressure for O2 is ~ 730 psi, the Apollo tanks ...
Organic Marble's user avatar
30 votes

Did Apollo 13 produce any scientific results?

In addition to crashing the Saturn V's S-IVB into the moon to collect seismic data from sensors installed by the crews of Apollo 11 and 12, several life sciences experiments were performed on the crew ...
Justin Braun's user avatar
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29 votes
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Was a one way trip to the moon considered by the crew of Apollo 13?

They weren't actually considering it. It's just one of those wishful thinking moments, or a joke to lighten things up. Furthermore, there isn't anything said along those lines in the official ...
PearsonArtPhoto's user avatar
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28 votes
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Did USSR discontinue radio transmissions, relocate ships, to aid the US in response to Apollo 13?

According to NASA's Space Educator's Handbook: As the men in Apollo 13 experienced what no men had undergone before, millions followed the developing drama by radio and television in public squares, ...
called2voyage's user avatar
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28 votes

Apollo 14-17 - Why didn't they keep the Lunar Module docked as a lifeboat for the way back to Earth?

The primary purpose of every Apollo Moon landing mission was to land on the Moon. Once the vehicle had passed safety checks and had made the lunar orbit insertion burn, the next step was to separate ...
David Hammen's user avatar
27 votes

What happened to Apollo 13 LM descent stage?

Lets have a look into Apollo By The Numbers: There was a lot of unused fuel (Aerozin 50) and oxidizer (nitrogen tetroxide) remaining in the descent stage of the Apollo 13 LM, 55 %. No need to use the ...
Uwe's user avatar
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26 votes
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Why wasn't the Apollo 13 Service Module jettisoned until hours before reentry?

It appears that your speculation is correct. From the Lunar and Planetary Institute's Apollo 13 Mission Overview (emphasis mine): On the Apollo spacecraft, the Service Module (SM) was intended to ...
Organic Marble's user avatar
26 votes
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Did Apollo 13 "barbecue roll" under the propulsion of the lunar module?

Was the lunar module also used to perform a barbecue roll? Yes, although it took them a while to get there, according to the Apollo Flight Journal. Starting at about 7 and a half hours after the ...
Russell Borogove's user avatar
26 votes

What kept crosswinds from pushing Apollo rockets into their own gantry?

The clearances were calculated to be OK up to a 95th percentile wind. I assume there was a Launch Commit Criteria (LCC) for the ground wind, but I have not been able to find an Apollo LCC document. ...
Organic Marble's user avatar
26 votes
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What exactly makes the "bang-bang-bang-bang-bang-bang-bang!" sound just before "Houston, we have hard dock." in the Apollo 13 movie?

Around the perimeter of the docking system are a set of 12 spring-loaded latches that lock the two spacecraft together. I believe the latches trip as the retractable probe pulls the two spacecraft ...
Russell Borogove's user avatar
25 votes
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Why did NASA collect so much data about electrical phenomena at the Apollo 13 launch site?

According to an article from the Lunar and Planetary Institute (archive.org link): As a result of the electrical disturbances experienced during the Apollo 12 launch, several experiments were ...
Russell Borogove's user avatar
24 votes
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What is this unlikely-looking contraption ("plutonium battery and scientific equipment") they're making Jim Lovell carry around a parking lot?

The black thing on the right is a SNAP-27 RTG. and the box on the left is an ALSEP (Apollo Lunar Surface Experiment Package) that it powers. Here's a picture of the ALSEP for Apollo 12: And here is ...
Starfish Prime's user avatar
23 votes

What was Apollo 13's "Little Jolt" after MECO?

If so, what was stopping this ~750Ton vehicle (launch mass minus first stage fuel)? I can't speak to the severity of the "jolt" but there would certainly be one at MECO - not because the vehicle had "...
motosubatsu's user avatar
22 votes

Without the accident, would Apollo 13 still have been the farthest crewed mission from the Earth?

I believe the answer is yes, but just barely. The distance from the Earth to the moon varies significantly over time, from 356,400 to 406,700 km. I plugged the dates of orbital entry and departure ...
Russell Borogove's user avatar

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