Former NASA astronaut Scott Kelly speaks about his historic mission aboard the International Space Station during an event at the United States Capitol Visitor Center, Wednesday, May 25, 2016, in Washington.
Mars has bright polar caps of ice that are easily visible from telescopes on Earth. A seasonal cover of carbon-dioxide ice and snow is observed to advance and retreat over the poles during the Martian year. Scientists using radar data have found a record of the most recent Martian ice age recorded in the north polar ice cap.
NASA's OSIRIS-REx spacecraft is revealed after its protective cover is removed inside the Payload Hazardous Servicing Facility at Kennedy Space Center, on May 21, 2016. OSIRIS-REx, targeted for a Sept. 8 launch, will be the first U.S. mission to sample an asteroid, retrieve at least two ounces of surface material and return it to Earth for study.
On May 19, 2016, NASA's IceBridge, an airborne survey of polar ice, crossed Greenland to fly central glacier flowlines in the east-central region of the country. This photo captures the fjord of Violin Glacier, with Nord Glacier at the upper left corner. This is IceBridge's eighth spring campaign of science flights over Arctic sea and land.
Cassini orbited in Saturn's ring plane -- around the planet's equator -- for most of 2015.
CubeSats fly free after leaving the NanoRacks CubeSat Deployer on the International Space Station on May 17, 2016. Seen here are two Dove satellites. The satellites are part of a constellation designed, built and operated by Planet Labs Inc. to take images of Earth from space.
Flames from the solid rocket boosters lit up the clouds of smoke and steam trailing behind shuttle Atlantis on May 19, 2000, as it lifted off on mission STS-101. It was the shuttle program's third space station assembly flight, and first space flight for astronaut Jeff Williams, currently aboard the station as a member of the Expedition 47 crew.
Expedition 47 Flight Engineer Tim Kopra of NASA posted this May 15, 2016 photograph to social media, writing, "Water etchings in western @Mexico sands. @Space_Station #Explore"
Astronauts aboard the International Space Station (ISS) see the world at night on every orbit — that’s 16 times each crew day. An astronaut took this broad, short-lens photograph of Earth’s night lights while looking out over the remote reaches of the central equatorial Pacific Ocean.