"you have to push your lungs forward through the drag of the atmosphere."
That is a quote from Chris Hadfield's YouTube clip for his MasterClass.
Is there a list or description of what an astronaut has to do with their body during launch?
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3$\begingroup$ Max acceleration during Shuttle ascents was 3 gees. For those cases, it was mostly just a matter of waiting it out for 8 1/2 minutes...enduring nothing more than moderate discomfort. $\endgroup$– DiggerJul 1, 2019 at 16:03
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1$\begingroup$ "You have to push your lungs forward through the drag of the atmosphere" is nonsensical; that's two separate sound bites edited together for a trailer. $\endgroup$– Russell BorogoveJul 30, 2019 at 0:10
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$\begingroup$ @RussellBorogove I see that now, thanks. $\endgroup$– Bob516Jul 30, 2019 at 1:33
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A little expansion on what Digger commented. Assuming you weigh 200lbs, 3 gees will make it feel like you weigh 600lbs. You could imagine it as a 400lb person sitting on you. That's definitely uncomfortable, but it's only for 8-9 minutes. It's not dangerous if you're otherwise healthy.
Further, not only is it really not that many gees, but they're pulling in a different direction. Fighter pilots are sitting mostly upright, when they turn they feel the gees pull towards their feet, which also tries to pull all their blood away from their brain. Astronauts on the other hand, sit almost completely reclined. During launch they feel the gees pull towards their back; so their blood still stays distributed properly.
Edit: As Russell Borogove has pointed out, it's not even 3 gees for the whole flight. There's a brief window of about a minute near the end of the launch where the astronauts feel about 3 gees. Most of the flight is under 2 gees. Here's a NASA article on the subject; they use m/s^2, not gees in their data, but just divide their numbers by 9.81 to convert to gees. All of this just reinforces what I said above though; space launches aren't that strenuous.
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1$\begingroup$ Maybe worth noting that the acceleration isn't a continuous 3g. It's under 2g for all but 45 seconds near the end of the booster burn and the last 130 seconds, and only 3g for about one minute. The extra weight is also well-distributed over the body, unlike having someone sitting on you. $\endgroup$ Jul 1, 2019 at 21:38
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$\begingroup$ There's a plot of the acceleration profile in this doc: nasa.gov/pdf/522589main_AP_ST_Phys_ShuttleLaunch.pdf $\endgroup$ Jul 1, 2019 at 21:48
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$\begingroup$ I really like the way you explained G's, much better than my haphazard attempt to explain it to my nephew. $\endgroup$ Jul 2, 2019 at 18:38
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1$\begingroup$ @RussellBorogove Well done! Anecdotally, I can say that, "gee for gee," taking them in the astronaut-launch recumbent position is considerably easier than taking them in the fighter pilot position - no straining maneuver required to maintain consciousness... $\endgroup$– DiggerAug 1, 2019 at 16:49