NASA's Project Mercury was the first American human spaceflight program, running from 1959-63. After several unmanned flights and after successfully launching four primates into space (they returned safely), five flights were piloted by astronauts; including Mercury-Redstone 3 piloted by Alan Shepard, the first astronaut in space and Mercury-Atlas 6, pictured here, piloted by John Glenn, the first astronaut to orbit the Earth. NASA/Sipa Press/Newscom/FILE
The Mariner 2 space probe performed the world's first successful planetary encounter when it reached Venus in 1962. The probe's mission was to communicate with Earth from Venus's vicinity and to take temperature readings of the planet. NASA
The Gemini Program ran from 1965-66 with the goal of developing more sophisticated methods of space travel in preparation for the Apollo Program. In total, the Gemini Program made 12 flights, all launched by Titan II rockets. Shown here, Gemini IV astronaut Ed White made NASA's first space walk when he left the capsule for 22 minutes. NASA/Newscom/FILE
NASA's Apollo program, which ran from 1961-75, was primarily concerned with landing astronauts on the moon, following President Kennedy's announcement in 1961 that NASA would land a man on the moon by the end of the decade. The Apollo program's crowning achievement, the first successful moonwalk, came on July 20, 1969, by astronauts Neil Armstrong and Buzz Aldrin. In this photograph Buzz Aldrin is seen on the left and the lunar landing module in the background on the right. NASA/CNP/Newscom/FILE
Skylab was the first space station launched by NASA, and remained in orbit from 1973-1979. After a botched launch, in which damage was sustained to the station's solar power system and micrometeoroid shield, a repair crew was able to save the station from uninhabitability. Skylab was used for scientific experiments until 1974, when it was abandoned. In 1979 the station fell back to earth, large parts of it ending up near the town of Esperance, Australia. Local authorities fined the US government $400 for littering. To this day, the fine remains unpaid. NASA/Newscom/FILE
The Space Shuttle is the vehicle currently used by NASA for human spaceflight. The Shuttle made its maiden flight in 1981 and has since made 122 successful launches. Space Shuttles are partially reusable, unlike previous NASA spacecraft, and can land on airport runways after reentering the Earth's atmosphere. The program will be retired in 2010. NASA/Newscom/FILE
NASA uses two Shuttle Carrier Aircraft, modified Boeing 747s, to transport the Space Shuttle from landing sites to Kennedy Space Center, where the Shuttles are launched. NASA
The International Space Station is a joint project between the US, Russia, Japan, Canada, and the European Space Agency. Construction began in 1998, and the station has been staffed continually since 2000. It is the largest artificial satellite in orbit and can even be seen by the naked eye on earth. The ISS is used primarily for scientific research in zero-gravity. NASA/JSC/IPI/Newscom/FILE
NASA's Mars Exploration Rover Mission began in 2003 with the purpose of geological research and investigation of water or evidence of water on Mars. Pictured here is one of two rovers sent in 2003, Spirit. Since the rovers' arrival, NASA has also landed the Phoenix Mars Lander and placed in orbit the Mars Reconnaissance Orbiter. Artists Rendering NASA/JPL/Maas Digital LLC for Cornell University
For a panoramic perspective on the student-led democracy protests in Hong Kong, check out this high-flying drone video.
ByKelly Dickerson, Livescience.com
A high-flying drone swept over throngs of protesters lining the highways of Hong Kong's central business district Monday, Sept. 29, capturing sweeping panoramic shots of the thousands of pro-democracy demonstrators.