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41 votes
Accepted

What sounds do astronauts hear inside their helmets during an EVA?

Tom Jones talks about it some in his memoir "Skywalking" when he describes an EVA carried out on shuttle mission STS-98: Inside the airlock when it is pressurized Through the helmet shell, from ...
Organic Marble's user avatar
20 votes
Accepted

Why don't astronaut helmets fog up? What's the chemistry and thermodynamics behind keeping the field of view clear even during heavy breathing?

Dry, incoming air is blown across the inner surface of the visor from a part called a "spray bar". Thin-film heaters and chemical agents have also been used, to less success. Although water ...
DrSheldon's user avatar
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17 votes
Accepted

What is Earth's apparent magnitude from geosynchronous orbit?

Interesting question! tl;dr mag -22 maximum, no particular danger except UV because it's still quite a large extended source (not concentrated to a point). Easy part first: Surface brightness for ...
uhoh's user avatar
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14 votes
Accepted

What spacesuit helmet is this?

It was an early helmet/visor prototype for the Shuttle EMU Challenges in the Development of the Shuttle Extravehicular Mobility Unit describes how the suit used for spacewalks on the Space Shuttle -- ...
DrSheldon's user avatar
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6 votes
Accepted

Does sunlight warm an astronaut's face during a spacewalk?

Does sunlight warm an astronaut's face during a spacewalk? Perhaps a little, but not much. Most About 40% of the power in the Sun's spectrum is in visible wavelengths (not a coincidence, in several ...
uhoh's user avatar
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5 votes

Have astronauts ever used the helmet-to-helmet technique to talk to one another in vacuum?

In space, (probably) no-one can hear you scream through glass (very well) This is an interesting "Have astronauts ever...?" question, and I can't answer it directly. I can't answer if it's ...
uhoh's user avatar
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4 votes
Accepted

How does the thin gold film in the glass of spacesuit helmets block thermal IR but transmit visible? What's the property?

@BlakeWalsh started to figure out the answer here and finished here but declined the invitation to post the answer, so I'll finish by posting it by proxy. Why is gold "gold-colored"? Several answers ...
uhoh's user avatar
  • 149k
4 votes

How does the thin gold film in the glass of spacesuit helmets block thermal IR but transmit visible? What's the property?

If I Recall Correctly, The gold (and silver) was an early version of dichroic optical filters. Thin films of gold and silver, when applied in a specific order, create "thin-film interference" which ...
Rbeal's user avatar
  • 189
4 votes
Accepted

How far are space-walking helmet faceplates from the eyes? How far will I have to hold my "space binoculars" from my eyes during a space walk?

Not much of an answer as others kind of cover it. I just wanted to add this though: https://www.alamy.com/stock-photo-nasa-astronaut-john-glenn-uses-binoculars-to-look-at-the-earth-through-138988965....
blobbymcblobby's user avatar
3 votes

Why don't astronaut helmets fog up? What's the chemistry and thermodynamics behind keeping the field of view clear even during heavy breathing?

They use anti-fogging agents. This is actually a pretty famous factoid because Chris Hadfield went blind during a spacewalk after some of the anti-fogging agent irritated his eye, and he has given a ...
Jörg W Mittag's user avatar
3 votes

How far are space-walking helmet faceplates from the eyes? How far will I have to hold my "space binoculars" from my eyes during a space walk?

To avoid this particular engineering problem I imagine space binoculars would just come with a screen so that you can hold it at your preferred viewing distance :P I'm imagining something akin to a ...
Taha Attari's user avatar
3 votes

Is there anything preventing an astronaut from opening their helmet and exposing themself to the vacuum of space?

All of the past NASA spacesuit helmets cannot be removed under pressure. However, many spacesuits have had visors (faceplates) which can be opened. Unless noted, the source below is Dressing for ...
DrSheldon's user avatar
  • 48k
3 votes

Is there anything preventing an astronaut from opening their helmet and exposing themself to the vacuum of space?

The closed helmet is under pressure of the air inside the suit if the outside is the vacuum of space. The helmet is opened easily when both pressures are equal. But when the inside pressure is higher, ...
Uwe's user avatar
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1 vote

How far are space-walking helmet faceplates from the eyes? How far will I have to hold my "space binoculars" from my eyes during a space walk?

It's certainly possible to build a telescope (binocs are just pairs of 'scopes properly boresighted) with a distant pupil plane, or to build a focussing system with a digital display, as answers and ...
Carl Witthoft's user avatar

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