Why do spacecrafts like the decommissioned Space Shuttles re-enter the atmosphere at such high speeds?

Question

I was just reading an article on the Space Shuttle Columbia tragedy and I began to wonder, why do they need to re-enter the atmosphere at roughly 17,000mph? Why not slow down to a less “burn up on re-entry” speed?

In: 2

Answer 1

The Space Shuttle use up all the fuel in the big orange external fuel tank to accelerate up to their 17,000mph. In order to slow down they would have to use another full fuel tank as the energy requirements are the same. Getting the entire fuel tank into space would require an enormous rocket as the full fuel tank is extremely heavy. This is not practical to do. It is much easier to just install a heat shield and use the atmosphere to slow down. It is safer too as this eliminates any issues with the rocket, see the Challenger disaster.