Manned space travel, from Gagarin to SpaceX
The anniversaries this week of the first man in space and the launch of NASA's first space shuttle missions come at time when commercial spacecraft are ushering in a new era of space flight.
Thursday was the 51st anniversary of Yuri Gagarin's 108-minute orbit around the Earth, an event that shocked the world and ratcheted up the speed of the Cold War-fed space race.
And 31 years ago on April 12, the space shuttle Columbia lifted off, the inaugural flight of NASA's shuttle program which drew to a close last year.
Astronauts from different countries on the International Space Station commemorated the events by taking time out from their experiments to reflect on the anniversaries over a meal, according to an article on Space.com.
Even with the NASA shuttle program drawing to a close, manned space travel to shuttle astronauts to the ISS and back remains one of the agency's top priorities.
Meanwhile, commercial space travel is advancing quickly. Space startup SpaceX is currently preparing to launch its rocket and dock its spacecraft with the ISS. If the 21-day mission is successful, it could lead to regular trips into space and a milestone in commercial space travel and exploration.
Ultimately, the company wants to send people to Mars, SpaceX CEO Elon Musk said on "The Daily Show" this week. Meanwhile, different spacecraft designs, such as the one pursued by Stratolaunch, aim to make traveling into space as repeatable as air travel today.
For a quick journey through the past, present, and future of manned spacecraft, take a look at this slideshow, which has links to many more images of space travel.