In the history of NASA’s space exploration, many missions have left Earth orbit and ventured far out into deep space. We have visited every planet in the solar system, but what was the very first spacecraft to leave Earth’s gravity?
NASA’s Pioneer 4 mission launched 58 years ago today from Cape Canaveral, Florida on March 3, 1959.
In just over a year after launching its very first satellite, the United States launched Pioneer 4, the first spacecraft to escape Earth’s gravity and fly by the moon. The mission flew within 37,000 miles of the lunar surface.
The mission before, Pioneer 3, did not achieve escape velocity and was therefore unable to escape Earth’s gravity.
Weighing just 13.2 pounds, Pioneer 4 was a spin-stabilized spacecraft that carried an experiment to learn about the lunar radiation environment. It also carried a camera trigger mechanism that was meant to be a test for future missions that would take photos. The camera sensor did not end up working as a trajectory error prevented the spacecraft from flying close enough to the moon to trigger the sensor.
Before contact was lost with the spacecraft a few days after launch, the spacecraft provided data about radiation around the Earth. Pioneer 4 traveled 655,000 miles before losing contact, making it the farthest tracked human-made object at the time. After flying by the moon, Pioneer 4 became the first U.S. spacecraft to orbit the sun.
Pioneer 4 was developed at the Jet Propulsion Laboratory (JPL) in Pasadena, CA, and gave deep space navigators at JPL experience in tracking space objects.
The Pioneer missions that followed included different spacecraft that went on to observe other planets. Some of the most notable successes of missions that followed were Pioneer 10 that took the first close-up images of Jupiter, Pioneer 11 that made the first direct observations of Saturn, the Pioneer Venus Orbiter spacecraft that orbited Venus for 14 years and the Pioneer Venus Multiprobe spacecraft that sent probes into the atmosphere of Venus.
Learn more about NASA’s Pioneer missions at NASA.gov.