Astronaut Steve Smith works on Hubble during the second servicing mission in 1997 with a ratchet. NASA specially designed the power tool to withstand the harsh environment of space, making it an essential item during three different Hubble missions. Hubble was specifically built to be serviced in orbit with replaceable parts and instruments. Astronauts performed four days of spacewalks during the second servicing mission to replace instruments and repair the telescope.
