when coming back from space, why do astronauts don’t just use a parachute all the way down?

Question

when coming back from space, why do astronauts don’t just use a parachute all the way down?

In: Engineering

Answer 1

The velocity of a stable low earth orbit is over 17,000 miles per hour. That’s way too fast for any kind of parachute system, even if there was enough atmosphere at such altitudes to allow parachutes to deploy effectively. So the initial re-entry requires slowing using other means. Instead a shallow re-entry begins at that speed and a very shallow angle, gradually exchanging speed energy for heat energy produced from slowly increasing atmospheric drag on the re-entry vehicle.