When Atlantis launched on Friday morning, it was the last of NASA's space shuttle flights.
The event marks the end of a 30-year program that has put 777 people in orbit.
But it is not the end of space exploration in the United States. Companies have been engaging in a private sector space race alongside and in partnership with NASA for quite some time.
In April, NASA awarded four of these companies $269 million to develop spacecraft, and companies in the private sector have also established expertise in other aspects of space travel, like space suits and climate control. Some are even famously selling tickets for consumer space flights.
Here are what some of them are working on.