Second shuttle readied in case Hubble repair ship needs rescue

Yikes

On top of the usual launch and landing dangers, the Atlantis crew faces an estimated 1-in-185 chance that a piece of space junk or a micrometeoroid will cause catastrophic damage to their ship. Those are greater odds than for a typical shuttle flight because of Hubble's extremely high and debris-littered orbit. Before reaching Hubble and again after leaving it, the Atlantis astronauts will inspect their spacecraft for signs of damage, just as crews always do while in orbit.

Second shuttle readied in case Hubble repair ship needs rescue