The group started constructing its first lab in 1941: The Aircraft Engine Research Laboratory (AERL) was built in Cleveland, Ohio, to research how to increase the power and efficiency of aircraft engines.Explorer 1's looping orbit brought it between 220 miles (354 kilometers) and 1,563 miles (2,515 kilometers) above the Earth's surface.The Mercury Seven was the group of seven astronauts selected to fly in Project Mercury. The men completed rigorous testing and training exercises.Shepard piloted a 15-minute flight that reached an altitude of 115 miles. He was the second person to travel to space, after Russian astronaut Yury Gagarin. Shepherd named his spacecraft Freedom 7 after the seven Mercury astronauts.But the women were not allowed to complete physical training or fly spacecraft when NASA launched space missions.A nearly 5-hour flight aboard the space capsule Friendship 7 made Glenn the third American in space and the first to orbit. He circled the globe three times, traveling at speeds of more than 17,000 miles per hour. The launch served as the first unmanned test flight of the Saturn V rocket. The Apollo 8 crew circled the moon but didn't land on its surface. The mission's famous Earthrise photo revealed the Earth rising above the lunar landscape.It was a giant leap for mankind, Neil Armstrong famously said. Buzz Aldrin followed him onto the moon while their crew mate Michael Collins remained in orbit.The Mariner 9 space probe mapped 85% of the red planet's surface and sent back more than 7,000 pictures. It captured shots of Mars' ancient volcano, Olympus Mons; the Valles Marineris canyon; and its two moons, Phobos and Deimos.Skylab was occupied for about six months, from May 1973 to February 1974.In the image above, Kerwin examines Charles Pete Conrad, Jr., the Skylab 2 mission commander, in the crew quarters of Skylab. A restraint around Conrad's left leg holds him in position.The Cornell astronomer helped select the landing sites for the Mars probes. The twin Voyager probes — one of which is under construction in the image above — were designed to explore the planets of the outer solar system, then leave it entirely. Voyager 2 exited our solar system in 2018, becoming the second spacecraft to ever enter interstellar space. It followed six years behind Voyager 1. Many scientists and engineers helped create the eight phonograph records, which contain sounds and images reflecting life and culture on Earth.Ride worked the robotic arm to help launch the satellites into space. Just last month, NASA astronaut Christina Koch set a new record, notching the longest single space flight any woman has ever completed. Koch, who's still on the International Space Station, has now spent over 300 consecutive days in space.