I’ve got an uncle that constantly posts conspiracy theories all the time, latest one is
‘The shuttle heats up during reentry at speeds of 16,700 mph’
‘But while leaving earth at speeds of 25,000 mph there’s no heat?’
In: Physics
Ignoring that the numbers aren’t exactly right…the entire problem boils down to the shuttle traveling through air; the air exerts forces on the shuttle’s body that result in heating.
When the shuttle exits Earth’s atmosphere to get into orbit, it first takes straight up going relatively slowly. As soon as it gets high enough that the air is thin and the resultant forces (and thus, heat) from moving through the air goes down, then it basically tips over and throttles up to maximum power to get up to it’s top speed (you can typically hear this in the old shuttle launch videos as the “Go at Throttle Up” command, where the shuttle goes from 70% (iirc) throttle to full throttle). Note that there *is* heating during this, just not enough to matter.
When the shuttle reenters the atmosphere, it has to pass back through that air, but this time it can’t really avoid traveling through that thicker cushion of air at high speed (as it uses that same air to slow down). Thus, you get lots of heat generation.
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