On July 26, 1971, Apollo 15 was launched, bringing the fourth American crew to the Moon’s surface. Apollo 15 would become the first of three extended missions to the moon, known as K missions. The mission was more focused on science than previous landings had been. It also marked the first use of the lunar rover.
On July 23, 1999, NASA launched the Chandra X-Ray Observatory to observe x-rays from outside the Earth’s radiation field. The mission was originally intended to last just five years, but Chandra is still orbiting the Earth and making discoveries today, more than 20 years after launch.
Apollo 16 launched from the Kennedy Space Center in Florida at 12:54 p.m. on April 16, 1972. It was the 10th crewed Apollo mission and the fifth and second to last to land on the Moon.
Biochemist Melvin Calvin was born on April 8, 1911, in St. Paul, Minnesota. He earned the 1961 Nobel Prize for Chemistry for his discover of the Calvin cycle – the conversion of carbon dioxide into organic molecules during photosynthesis.
On March 16, 1926, Robert H. Goddard launched his first liquid-fueled rocket in Auburn, Massachusetts. Though his work went largely unrecognized during his lifetime, today he’s known as the father modern rocketry.
On July 20, 1969, the US effectively won the Space Race when Neil Armstrong and Buzz Aldrin landed the Eagle lunar module on the Moon’s surface.
On April 5, 1973 (some sources cite April 6 UTC (Coordinated Universal Time), the Pioneer 11 space probe launched from Cape Canaveral, Florida.
On January 26, 1949, the Hale Telescope at Palomar Observatory first saw light. Still in use today, the Hale telescope is one of the world’s largest optical telescopes.
On October 4, 1957, the Soviet Union launched Sputnik I, the first man-made object in space, which sparked the start of the Space Race with the United States.