Some clarifications:
The Ham radios are switched off during EVAs.

The ISS is always controlled to 14.7 PSI. The EVA prebreathe procedure on the shuttle reduced the cabin pressure to 10.2 PSI, but this is not possible on ISS. There was a campout procedure where the EVA crewmembers sleep in the ISS airlock at reduced pressure, but this method hasn't been used for years. The current protocol is ISLE (in-suit, light exercise) with a fallback to a 4-hour in-suit prebreathe.

(NASA Flight Surgeon)

Keith E Brandt, WD9GET

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On 19-Jul-21 15:49, GMM via AMSAT-BB wrote:
Hi Rick:

Its is possible that most of the optional radios are turned off during a space walk.

I am not sure if Ham radio is on the Turn-off list.

Originally the 4x Ham antennas all contained a Patch antenna that was going to be used for external spacesuit helmet cameras

transmitting in the GHZ band.  I am not sure if the ham GHZ antennas were actually used for video.

Each antenna is on a different side of Service module, providing good line of site access to the crew during a space walk.

Does anyone know if the existing Ham Patch antennas were ever use for helmet cameras inflight?

More trivia/details on the air pressure.

It is not possible to go from 14psi to 5psi  quickly, without suffering from the Bends.

The space suits run at 4.3 psi.

If the pressure was much higher the arms would inflate so much they would be impossible to bend your arms.

The station is gradually de-pressurized from 14 to 10 psi a day or so before a spacewalk.

This allows the whole crew to depressurize to 10 psi.

Then the space walk crew breath pure O2 for an hour or so to get more nitrogen out of their systems.

Next the airlock is closed and the space walk crew de-pressurize the room from 10 to 0, but the suite, only goes down to 4.3 and hopefully no  lower.

On 7/19/21 3:49 PM, Rick Walter wrote:
"And if the ISS Air pressure is turned down from 14 psi to 10 psi [Usually during space walks], the radio will also run hotter at 10 psi, than at 14 psi." - I thought if there was a spacewalk ALL amateur radio transmissions would be turned off.



Keith E. Brandt, MD, MPH
[email protected]

Christianity and science are opposed… but only in the same sense as my thumb
and forefinger are opposed- and between them I can grasp everything.
                              —Sir William Bragg (Nobel Prize for Physics- 1915)

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