PDA

View Full Version : Q about Moon landing.



Mr.X
2006-Apr-05, 12:46 AM
Was the LM constantly re-pressurised?
I mean when they opened the hatch the air escaped and after each walk when astronauts went back to LM do they close hatch and then repressure the LM and took their helmets off?

ToSeek
2006-Apr-05, 01:24 AM
Yes. This actually turned out to be very helpful for Apollo 13, as oxygen was one of the few resources that was not an issue after the accident when the lunar module became the "lifeboat."

PhantomWolf
2006-Apr-05, 01:27 AM
Yes.

There was a valve in the door, which opened inwards, and they opened that to let out the air inside the LM. Once they returned they repressurized the craft. The Decent Module carried enough oxygen for numerous repressurisations, remember it was a small voloume and they on used a partial oxygen pressure, ie the amount of gas in the LM was what would have ben in there if you pressuried it at 1 atm with air, then removed everything but the oxygen from that air, so repressurising wasn't a major thing.

Jason Thompson
2006-Apr-05, 12:55 PM
Was the LM constantly re-pressurised?

Yes. The LM was a very small space to fill with gas at 5psi, so there would have been more than enough oxygen available to depressurise and repressurise a few times.

I mean when they opened the hatch the air escaped

Actually they had to use a depressurisation valve to allow the air to escape. The LM door opened inwards, and the astronauts were unable to open it with the LM pressurised. In fact, on Apollo 11 Aldrin was surprised at how low the pressure had to go inside the LM cabin before he could open the door, and even then he had to do it by pulling at one corner to break the seal rather than the latch which was located halfway down one side.

and after each walk when astronauts went back to LM do they close hatch and then repressure the LM and took their helmets off?

Yes. And then they did it once more prior to ascent to dump the excess weight, which included the spent PLSS backpacks, lunar overshoes and the white lunar surface helmet cover.

Nonkers
2006-Apr-05, 03:13 PM
When the LM astronauts redocked with the CM, were they still wearing their lunar dust covered space suits?

Jakenorrish
2006-Apr-05, 04:39 PM
When the LM astronauts redocked with the CM, were they still wearing their lunar dust covered space suits?

They were indeed. Harrison H. Schmitt of the Apollo 17 mission described the unusual 'burnt' smell of the lunar soil on the suits, probably due to the fact that the moon's rocks are bombarded by far more harmful rays and particles from the Sun than Earth gets due to our protective atmosphere.

Jason Thompson
2006-Apr-05, 09:13 PM
Thank you for a great info. Was there any health effect to the low pressure (lightheadness etc?)

No, mainly because the astronauts still got roughly the same amount of oxygen as they would had they been breathing normal air at sea level, or if anything more oxygen. The suits were only pressurised to about 3.5psi pure oxygen. When preparing for the first NASA spacewalk, Ed White and Jim McDivitt suited up and then reduced the pressure in the Gemini capsule to 2psi. The reason for this was had something been wrong with the suit seals and the suits leaked, both men could survive at 2psi pure oxygen long enough to repressurise the cabin without ill effects.

The physical effects of low pressure are negligible, as the human body is quite an excellent pressure vessel provided it is not subjected to sudden changes of pressure.

When the LM astronauts redocked with the CM, were they still wearing their lunar dust covered space suits?

They were indeed. On Apollo 12 Dick Gordon opened the hatch to the Command Module, took one look at Pete Conrad and Al Bean, and then closed the hatch again telling them they were not going to dirty up his nice clean spaceship and that they had better remove their spacesuits before even trying to transfer across.

Denis12
2006-Apr-05, 10:16 PM
What will be the lowest pressure that a man can survive before it is getting dangerous in PSI and milibars? And how much milibars was the pressure in the lunarmodule when it has landed on the Moon? And how much in the spacesuits when the astronauts are walking on the Moon?

antoniseb
2006-Apr-05, 10:48 PM
If the pressure is pure oxygen 3 PSI is the same as what we get at sea level. Some exceptional people can survive on the top of Mount Everest where the Oxygen is about 1 PSI, but no one is comfortable at that pressure, and most people die.

ToSeek
2006-Apr-06, 04:58 PM
When the LM astronauts redocked with the CM, were they still wearing their lunar dust covered space suits?

I forget which mission it was, but one of the command module pilots made the LM crew strip naked before he'd let them into his nice clean command module.

AGN Fuel
2006-Apr-06, 11:56 PM
I forget which mission it was, but one of the command module pilots made the LM crew strip naked before he'd let them into his nice clean command module.

Yep, that was 12.

I don't know if it was poetic licence, but 'From the Earth to the Moon' did this scene beautifully - after they had stripped off completely and safely ensconced in the CM waiting for the Ascent Stage jettison, Conrad looks at the naked Bean and then at his own naked self and comments something like, "If there's a catastrophic loss of pressure during this jettison, the recovery team is going to be real surprised when they find us!"