One-time test pilot Neil Armstrong stood next to an X-15, an experimental rocket-powered aircraft. NASA/File
Astronaut Virgil I. Grissom climbs into 'Liberty Bell 7' spacecraft the morning of July 21, 1961. Backup Astronaut John Glenn assists in the operation. The Mercury-Redstone 4 (MR-4) successfully launched the Liberty Bell 7 at 7:20 am EST on July 21, 1961. MR-4 was the second in a series of successful US manned suborbital flights. NASA/File
Apollo 8 becomes the first manned spacecraft to orbit the moon in 1968. NASA/AP/File
On Feb. 7, 1984, Bruce McCandless performs man’s first untethered spacewalk from the Challenger space shuttle. NASA/AP/File
The Challenger crewmember remains are being transferred from 7 hearse vehicles to a MAC C-141 transport plane at the Kennedy Space Center's Shuttle Landing Facility for transport to Dover Air Force Base, Delaware. NASA/File
Astronaut Rick Linnehan works on the International Space Station during a spacewalk. NASA/File
A portion of the International Space Station photographed by a space walking astronaut during the STS-128 mission on Sept. 3, 2009. NASA/AP/File
Mission control workers at the Johnson Space Center in Houston monitor all human spaceflight for the US, including shuttle missions and activities aboard the space station. Melanie Stetson Freeman/Staff
Photographers take pictures of the space shuttle Endeavour, scheduled for its last launch on April 29, at the Kennedy Space Center in Florida. It will ferry six crew members to the International Space Station. Joe Skipper/Reuters
The last crew of space shuttle Endeavour, including mission commander Mark Kelly (front, waving), the husband of US Rep. Gabrielle Giffords, who was shot in Arizona in January. Ms. Giffords was expected to attend the launch. Terry Renna/AP
A private company unveils a drawing of a rocket it is building to lift cargo into space in the postshuttle era. SpaceX/Reuters
The decision means Egypt will remain the second-largest recipient of US foreign military financing worldwide.
ByNedra Pickler, Associated Press
President Obama on Tuesday released military aid to Egypt that was suspended after the 2013 overthrow of the government, in an effort to boost Cairo's ability to combat the extremist threat in the region.