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Questions tagged [apollo-program]

NASA's Apollo program was a 17-mission program that focused on landing a human on the lunar surface. The program was the third human spaceflight by NASA, after Mercury and Gemini.

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Why did Apollo spacecraft use both AC and DC equipment? Still used in present and future designs?

Why did the Apollo spacecraft use both DC and AC power, requiring heavy inverters? Was it impractical to design everything to run on DC power only? Why? Are both AC and DC power still used in present ...
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What was the “sour milk smell” during the 1967 Apollo 1 testing?

In the first edition of Andrew Chaikin's 1994 book, "A Man on the Moon, there is a paragraph in chapter 1 which talks about troubles the Apollo 1 testing crew were going through. Chaikin states that ...
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Did the combined Command and Service Module and Lunar Module perform another 180° turn after transposition, docking and extraction?

After the transposition, docking and extraction maneuver, it seems that the Apollo spacecraft is "facing the wrong way": Was this "corrected" with another 180° turn after stage separation? Or was ...
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Was CNC milling used in the 1960's for making the Apollo/Saturn rocket engines?

As far as I know, CNC machining was being used in the aerospace industry in the 1960s. Were such machines use for the F1 engines?
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How did the Apollo Lunar Module ascent engine prevent gas bubbling through fuel?

As I understand it, in order to keep the lunar module ascent engine simple, instead of fuel and oxidant pumps, tanks of helium at pressure were used. This pressure was used to force the fuel and ...
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Could the Apollo LM abort mode be engaged after touchdown? What would have happened if it was?

The Lunar Module had an abort mode where the crew basically just had to push the ABORT button on the control panel, and the ascent stage would detach from the descent stage, followed by the ascent ...
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Could an Apollo LM land unmanned?

I believe that Apollo mission control had the ability to upload data and commands to the LM's guidance computer as long as they had an operational communications link. I'm wondering if, from the point ...
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If the astronauts on Apollo 11 had landed safely on the moon but could not take off, would there have been a rescue mission?

Say they landed on the moon but discovered the ship was damaged during the landing and they could not launch again. What would have been the plan? Would another crew have been sent to rescue them? ...
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Apollo re-entry guidance

I am referencing chapter 7 of the book "Spacecraft Navigation and Guidance" by Maxwell Noton. Can anyone tell me how to determine control gains C1 and C2 in equation 7.58 and 7.59 in respective ...
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Why Did Apollo Smoke Twist When Taking Off?

I've been looking at some references of rockets taking off. I came across the Apollo 14 Saturn V launch and noticed that when the rocket was taking off the smoke coming from around the rocket and from ...
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1answer
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What were the chances of failing the Apollo 11 mission? [duplicate]

What were the chances of the Apollo 11 mission failing? Consider the following scenarios: least one of the crewmembers dying, failing to land on the Moon, unable to return to Earth, the Soviets ...
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Lunar Module water supply

As weight was a problem from the beginning (launch) of an Apollo mission, was the LM water tank already filled, or were they filled during the trip to the moon from fuel-cell byproduct water?
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Apollo guidance

I am studying the Apollo Guidance, specifically the derivation of guidance equation. While laying the baseline, a Target-referenced time (T) is chosen as time variable for guidance calculation of the ...
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Why were the two Quindar tones so close in frequency and not apodized?

This and this answer explain the function of the Quindar_tones within Apollo mission comms. At 2525 and 2475 HZ they are only 50Hz or 2% apart in frequency, and the duration is 250 ms or 0.25 seconds....
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What purpose serve the audible “bip” on apollo radio communications? [duplicate]

When looking at moonwalk videos, we can hear bips. What are those bips? Why are there bips? Do this bips still exist in nowaday space missions?
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What was the purpose of an Apollo 10 test?

The point of Apollo 10 was to test the LM in Lunar Orbit, but without landing. Why bother? If the LM had any sort of bugs (say the upper stage wouldn't launch, or they couldn't re-dock), then the ...
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To what extent did Apollo payload mass drive Saturn capability?

Uwe wrote in an answer that The possible payload of Saturn V was carefully planed for the whole mission, but the difference of the payloads of the missions Apollo 11 and 17 was less than 3000 kg. ...
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Before the Apollo 1 fire, what was the plan for the missions leading up to a lunar landing?

The actual Apollo flights 2-6 were test launches of the Saturn rocket, the CM and LM (1 was retired due to the fire). What were the original plans? Did they intend to launch people on a Saturn ...
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S-I, S-II, S-IV; what happened to III?

Stages of the Apollo stack (at least the configuration that landed humans on the Moon) are identified as S-IC, S-II, and S-IVB for the first, second, and third stages. There's no S-III. Why the gap in ...
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Was the Apollo spacecraft always gravitationally bound to the Earth-Moon system?

When the Apollo spacecraft was en route to the Moon, was it an escape trajectory from the Earth-Moon system? If not for the burn(s) to enter lunar orbit, would it have continued in an independent ...
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Which Apollo “mystery” was said to be finally solved by a better rendering engine?

I remember reading several years ago about a mystery or puzzle about a photograph from an Apollo moon landing mission that had to do with why someone's suit was as bright as it was in the photo. There ...
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Was an elliptical orbit considered for the CSM when planning the Apollo moon landing missions?

The Apollo moon landing missions used a Lunar Orbit Rendezvous (LRO) approach where the Command Service Module would be in a low lunar orbit (LLO) while the Lunar Module would land on the moon. This ...
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Why did moon dust not cause problems on Apollo during the return flight from the Moon?

The Apollo Command Module and the LEM were built in clean rooms free of dust on earth and yet (knowing that they didn't have air locks on either module) the astronauts came in directly from the moon ...
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Is it possible to estimate the nozzle characteristics of the Rocketdyne HG3 engine?

Boeing and the Marshall Space Flight Centre brought to pass many studies of improved Saturn V launch vehicles. The rockets proposed under the MLV and ELV projects would feature longer stages for more ...
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How is the Rocketdyne J-2S area ratio larger than that of the J-2?

The standard J-2 engine measures 3.38 metres in total length, with a nozzle exit diameter of 2.03 metres, to support its 27.5:1 expansion ratio. However, these dimensions are apparently identical for ...
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How much power do missions to other planets use for radio transmissions?

How much power did the voice and data radios have on the Apollo missions? Additionally how much broadcast power is used on data transmissions from the surface of Mars?
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How does the efficiency of the Rocketdyne F-1A compare to the F-1?

The Rocketdyne F-1 was to be updated with a new turbopump and gas generator assembly, without other major component redesign. This was to result in a thrust increase from around 1,522,000 pounds force ...
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What was the maximum thrust of the Rocketdyne F-1 engine?

Reading through several old reports, I have come across studies conducted by MSFC on improved Saturn V designs with greater payload capacity, and with uprated engines. As a result of increasing launch ...
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What did Apollo need the crewed Command Module for?

Doubling the life support, almost doubling the crew space, carrying lots of extra mass - the recent question about direct ascent made me ponder this: the fundamental role of the Command Module was to ...
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What's considered the boundary for “earth orbit?” [closed]

According to this CNET article, The last time a human broke free from Earth's orbit was the Apollo 17 mission in 1972. I thought that the moon orbited the Earth, and that visits to it were still ...
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Why was Apollo 12 allowed to go up in such bad weather?

I'd always heard the story about how Apollo 12 was struck by lightning and wondered why they let it head up in a storm. They always check the weather before a launch, and if there is any chance of ...
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Lunar lander, apollo 11, start position

If i were to simulate a lunar module with: $x_0$, $\dot{x}_0$, $y_0$, $\dot{y}_0$. $x$ is horizontal position, and $y$ is vertical position. What would be appropriate values?
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Moment of inertia of apollo 11 lunar module

I'm currently modeling the lunar landing in 2D. When I set up the momentum balance: $\ddot{\theta} = \frac{dF_l}{J}$ where $d$ is the distance between the sidethruster and the center of mass. $F_l$ ...
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Why did the Apollo program become a MULTIPLE human landing program?

How did JFK's promise of landing one man on the Moon grow into a whole series of landings of 12 men on 7 missions, with even more planned? Given the motivation of the program, shouldn't Apollo have ...
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Using command module as a lander

Question: Why doesn't NASA or SpaceX use the command module as their lander, instead of having another spacecraft as the lander? I was playing Kerbal Space Program the other day, and noticed how many ...
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Combination of liquid hydrogen and liquid oxygen

For the Apollo missions in the 1960s, NASA used a combination of kerosene and liquid oxygen to get the rockets out of Earth's atmosphere. Why did they do that? If you look at the statistics, the ...
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Apollo CSM thruster quad orientations vs LM

Can anyone explain to me the reasoning behind the differences in the placement and orientation of the thruster quad packages on the CSM and LM? On the CSM a quad is a + shape and are located in a ...
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How did the USA cooperate with western allies during the Apollo program?

France launched its Diamant rocket to orbit between 1965 and 1975, and the UK its Black Arrow 1969-1972. Did they take advantage of NASA's rocket development experiences? Were any Apollo system ...
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Why does the side of the LEM look almost black in this photo? Did that cause problems?

After reading this answer about the RTGs used on the Lunar surface, I added some of the images from the Wikipdia article Apollo Lunar Surface Experiments Package into this answer, where I noted that ...
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What were the uses of the RTGs in the Apollo spacecrafts?

I was listening to the Plutonium episode of "the Elements" on the BBC, and between 07:00 and 08:30 they talked about uses of plutonium such as spacecraft power and heat. While the returning astronauts ...
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Did any of the Apollo lunar modules land significantly off level?

I'm pretty sure I recall some images of a lunar module sitting on a slope, although perhaps it just looked that way due to a tilt of the camera. Anyway, my question is: whether any of the lunar ...
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What does 'Switch SCE to AUX' mean?

During the launch of Apollo 12 a major malfunction was caused by 2 lightning strikes. See http://www.realclearscience.com/blog/2013/02/apollo-12-struck-by-lightning.html for more info. The solution ...
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What was the best late Nova rocket design among the request for proposals NASA received?

According to Wikipedia (https://en.wikipedia.org/wiki/Nova_%28rocket%29) the late Nova rocket was a "larger version" of the Saturn 5, meant to send manned missions to Mars. Some requests for proposals ...
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What is this on the craft from the Apollo 17 mission?

For me it looks like water droplets but, I doubt thats the case in space. Also I don't understand why this should be a crafts surface feature. wouldn't one aim to design a spacecraft as smooth as ...
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How was it possible for the Apollo 11 to film and take pictures with such radiation?

There's plenty of people who said it would have been impossible for the astronauts in the Apollo 11 to film or take pictures in the moon due to the high radiation there's in the moon because of the ...
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Apollo/Shuttle launch site fuel handling

I read somewhere that fuel was delivered to the Apollo launch site by tanker truck (for cryogenic propellants) and rail cars (for the kerosene). Were the fuels transferred directly from delivery ...
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How did Apollo 16 capture this full photograph of the Moon's far side?

Apollo 16 famously photographed the far side of the Moon, as seen below. This seems odd to me. Apollo 16 orbited the Moon at an orbit of only 100 km. It seems too close to get this kind of a ...
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Where can I find the amended/improvised checklists for Apollo 13 post-accident?

I have been trying to find this online without too much avail. For my own reference and cross checking, I wanted to know where I could find the emergency checklists and the "made up on the spot" CM ...
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How was time kept on board early manned spaceflights?

I have not been able to find a definitive answer to this. From Mercury to Gemini to Apollo, what was the mechanism for keeping time onboard the spacecraft? Did the Engineers spend energy (and maybe ...
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Software development for Apollo [closed]

How was software developed during apollo? From various sources, it can be gleaned that the computer was a ibm system 360, and the language was basically a fortran dialect or fortran. What I'd like ...