Despite this heartbreaking setback, the space shuttle was flying regularly again by 2006. In February 2008 Atlantis delivered the European Space Agency's Columbus laboratory to the ISS. And in February 2010 Endeavour brought up the Cupola, a robotic control station with seven windows that provides the ISS crew with a 360-degree view.

End of an Era

In 2004, U.S. President George W. Bush announced that the space shuttles would be retired. The final flight came to a close when Atlantis touched down at Kennedy Space Center on July 21, 2011. The three remaining orbiters and the prototype shuttle, Enterprise, are now be housed in museums in California, Florida, New York, and Virginia.

For its next phase of manned space exploration, NASA is designing and building the spacecraft needed to send humans deeper into the solar system, working toward a goal of putting people on Mars. The Multi-Purpose Crew Vehicle, for example, is being developed to take four astronauts on 21-day missions. NASA is also developing the Space Launch System, an advanced heavy-lift launch vehicle designed for human exploration beyond Earth's orbit.

In addition, the space agency is partnering with private companies such as Space Exploration Technologies Corporation, or SpaceX, to launch commercial vehicles to the ISS-and perhaps beyond.