STS-31 was one of the most consequential Space Shuttle missions ever flown. On April 24, 1990, Space Shuttle Discovery launched from Kennedy Space Center’s Launch Complex 39B carrying the Hubble Space Telescope — a 24,500-pound observatory that would fundamentally transform humanity’s understanding of the universe.

To deploy Hubble into its operational orbit, Discovery climbed to an altitude of approximately 380 statute miles (612 km) — the highest orbit ever achieved by the Space Shuttle at that time, roughly twice the typical Shuttle altitude of 184 miles. At this rarefied height, the crew used the Canadarm robotic arm, operated by Mission Specialist Steven Hawley, to lift Hubble from the payload bay and release it into orbit on April 25, 1990.

The deployment was not without drama. After release, Hubble’s solar arrays initially failed to deploy properly. The crew prepared for a contingency spacewalk by Mission Specialists Bruce McCandless and Kathryn Sullivan, but ground controllers were able to command the arrays to unfurl successfully, averting the need for EVA.

Commander Loren Shriver and Pilot Charles Bolden guided Discovery through the mission with precision. Bolden, who would later serve as NASA Administrator from 2009 to 2017, called STS-31 “the most significant mission I ever flew.”

Since its deployment, Hubble has made over 1.5 million observations, peered back to within 400 million years of the Big Bang, helped determine that the expansion of the universe is accelerating, and produced images that have become cultural icons. Five subsequent servicing missions by Space Shuttle crews kept Hubble operational far beyond its original 15-year design life. More than 35 years after STS-31, Hubble continues to make groundbreaking discoveries — a lasting testament to the crew that placed it among the stars.