DANGEROUS MISSIONS

Brave explorers
Going into space can be dangerous.  There have been two tragic accidents in the shuttle program.
In 1986, the Challenger broke apart right after launch.  It killed all seven people onboard, including the Teacher in Space, Sharon Christa McAuliffe.
In 2003, the Columbia was destroyed after re-entering Earth's atmosphere, just minutes from landing on Earth.  All seven crew members were killed. 
Astronauts know they could be in danger.  But like other explorers, they think the gains are worth the risk.
Changing the mission
One of the first jobs of the shuttle was to carry satellites into space.
After the Challenger accident, NASA decided not to use the shuttle to launch satellites.
Private companies now launch satellites.  Except for special satellites, such as the Hubble Space Telescope, that were designed to be launched by the shuttle, the shuttle was then used only for trips to the Russian Mir space station and the ISS.
The Hubble and the shuttle
One of the most important shuttle missions was to launch the Hubble Space Telescope.  Shuttle crews also returned five times to service the Hubble and add new instruments.
Although the Hubble wasscheduled for launch in 1986, all shuttle missions were delayedafter the Challenger accident.
The space shuttle finally carried the Hubble into space in 1990.