Apollo vs Gemini suits

[Dr_Orpheus]

Some of the Gemini astronauts got overheated during strenuous activities on EVAs (9 and 11) while I'm not aware of this being a problem during the Apollo missions.  I'm assuming that the Apollo suits had better cooling systems.

[Zakalwe]

They developed the Liquid Cooling garment as a direct result of the overheating problems encountered in the early spacewalks.

https://en.wikipedia.org/wiki/Liquid_Cooling_and_Ventilation_Garment

Cernan became dangerously overheated and exhausted during his Gemini spacewalk:
http://www.universetoday.com/99959/memorable-astronaut-spacewalks-show-danger-darin/

[bknight]

Gemini 9-11 had basically technical EVA failures, in that work designed was not completed as designed.  All the astronauts worked harder and got less accomplished.  Plus the astronaut was connected to the capsule with an umbilical circulating not the PLSS in Apollo missions. A lot of work and refinement between Gemini and Apollo.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19750007244.pdf

[Peter B]

Just to clarify - the Gemini spacesuits used air for cooling, and anything more than a moderate amount of physical activity simply overwhelmed the air's ability to carry heat away. The Apollo spacesuits used water for cooling. Now I'm no physicist or chemist, but I get the impression that a given volume of water can absorb a lot more heat in a given period of time than the same volume of air at the same temperature. Thus, I understand the Apollo Liquid Cooled Garments were so efficient at removing heat that the astronauts were guaranteed to collapse from fatigue before they'd overheat.

[ka9q]

Right, liquid cooling on Apollo was a direct result of the Gemini experience and analysis of the workloads that could be expected on the moon. The designers had originally planned to rely on gas (i.e., oxygen) cooling but adding water cooling reduced the electrical power requirements (it takes less power to pump water than the extra oxygen required for sufficient gas-only cooling).

[Ishkabibble]

Some years ago, I read a book regarding the development of the suits from the Navy high-altitude to the A7L, and one passage stuck in my head. David Jennings was the engineer at Hamilton Standard who came up with the idea for a water-cooled undergarment, after seeing something similar that the British used. They made up a test-bed undergarment with regular long-johns and rubber tubing, and the test-subject (Harland somethingorother) started complaining how cold it was. He said something along the lines of it being like jumping into the Arctic Ocean in January. Problem solved.

When I think of the incredible ingenuity and resourcefulness of those guys, at those times, in those places, and realize that the pimply-faced babies who are daring to deny these great achievements probably have to have velcro because they can't tie their shoes, it just fills me with disgust. If these kids only realized the wonder of the incredible achievements and amazing engineering that went into all of this....

[Obviousman]

If interested, read 'US Spacesuits' by Kenneth S Thomas & Harold J McMann (Springer Press / Praxis Publishing, 2006) pages 102 - 104.

[Dr_Orpheus]

Thanks for the answers.  I didn't know that liquid cooling wasn't used for the Gemini space suits.

[ka9q]

Liquid cooling does complicate things. You've got to put the cooling jacket on and hook up the water connectors. The PLSS (or spacecraft life support system) has to have a water pump and heat exchanger in addition to the fan and heat exchanger in the oxygen circuit. You need extra connectors on the suit and two extra lines in the umbilicals for the water.

The Apollo suits were designed to circulate oxygen throughout the suit, so in principle they could cool the entire body with gas alone if the flow is high enough. But that tends to rely on the evaporation of sweat, which could easily dehydrate you if you're not careful.

I know they had water bottles to drink from during long EVAs. Did they contain sodium to replace that lost by perspiration? I learned that lesson on my first trip to the desert here in California; having grown up on the east coast I'd never been in such a situation before. I knew to carry and drink lots of water, but I still felt bad. After consulting with my doctor, we brought salty potato chips and pickles on our next trip. Worked like a charm.

[ajv]

The infamous "orange drink" in the Apollo 16 EVA drink bags was potassium fortified as a reaction of the heart arrhythmias experienced by the Apollo 15 lunar surface crew.

[raven]

The Voskhod 2 EVA suit was also oxygen cooled. It didn't work so good. Leonov was apparently up to his knees in sweat by the end.

[Dr_Orpheus]

The Voskhod 2 EVA suit was also oxygen cooled. It didn't work so good. Leonov was apparently up to his knees in sweat by the end.

If it hadn't been for the extreme secrecy of the Soviet Space program at the time, NASA might have decided to develop liquid cooled suits sooner.   

[Dalhousie]

The Voskhod 2 EVA suit was also oxygen cooled. It didn't work so good. Leonov was apparently up to his knees in sweat by the end.

He wouldn't have been.  Zero gravity remember?

[Dalhousie]

The Voskhod 2 EVA suit was also oxygen cooled. It didn't work so good. Leonov was apparently up to his knees in sweat by the end.

If it hadn't been for the extreme secrecy of the Soviet Space program at the time, NASA might have decided to develop liquid cooled suits sooner.

Yes the default "blame the USSR" syndrome.  In reality the US rapidly gained far more experience very quickly.  They have only themselves to blame if they didn't develop liquid cooling sooner.

[Dalhousie]

The Voskhod 2 EVA suit was also oxygen cooled. It didn't work so good. Leonov was apparently up to his knees in sweat by the end.

It was Gordon Swann who experienced this, while testing modified Gemini suits on simulated lunar EVAs for the USGS astrogeology center in 1964-65.