Reply to post: Re: encountering just 1.5 times Earth gravity

Teensy weensy space shuttle flies and lands

Norman Nescio Silver badge

Re: encountering just 1.5 times Earth gravity

@David Nash (and others)

It is rather unclear and smacks of someone just repeating a number they've heard rather than trying to describe exactly what it means.

I interpreted it as the force of impact on landing. Perhaps I was wrong.

I think you may be wrong - I interpret it as a maximum deceleration of 1.5 times the (standard) force of gravity at the earth's surface - that is, about 14.7 m/s2, which is pretty good. Standard Soyuz descents follow a profile that hits a maximum of 4.5G - if something goes wrong and the Soyuz does a ballistic descent, it can hit 8G. Space Shuttle descents hit about 3G. For contrast, there are abort scenarios for Soyuz launches that regard 21G as 'survivable'.

You can work it out yourself: if you know the orbital velocity and the velocity of the point on the surface of the earth where you come to a relative standstill (remember, the earth is rotating), then the change in velocity divided by the time taken for the descent gives you the average deceleration. The actual maximum will depend on the descent profile.

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