Karol “Bo” Bobko, who was the only NASA astronaut to fly on the first launch of two space shuttle orbiters, has died at the age of 85.

Bobko’s death on Thursday (Aug. 17) was confirmed by the Association of Space Explorers, a professional organization for the world’s astronauts and cosmonauts. A distinguished member, Bobko previously served as president of the U.S. chapter of the association.

Bobko joined NASA in 1969 with the agency’s seventh group of astronauts. Unlike the classes that came before and after his selection, though, Bobko and his six fellow Group 7 members were transplants from another astronaut corps: the U.S. Air Force’s Manned Orbiting Laboratory (MOL) program.

When the MOL program was canceled in June 1969, NASA accepted the seven youngest members into its astronaut corps but did not have any immediate need for them.

“Perhaps the first year or so was rather, at times, rather frustrating,” said Bobko in a 2002 NASA oral history interview. “During the first year, we were told twice that we were fired.”

“And then that was rescinded,” Bobko said. “They said, ‘The program is not going anyplace. We don’t need you folks, and, so you’re going to be let go and go back to the Air Force.’ But that was rescinded, and we stayed and got involved in the programs that were going on here.”

Related: Manned Orbiting Laboratory declassified: Inside a US military space station

Still, it would be 14 years before Bobko flew to space for the first time. On April 4, 1983, the space shuttle Challenger lifted off on its first mission, STS-6, with Bobko as its pilot.

“First flight of Challenger. First lightweight [external fuel] tank. Okay, we launched the big first satellite, the TDRS [Tracking and Data Relay Satellite-1],” said Bobko, listing what set STS-6 apart from other missions. “It was also the first flight of the HUD, the heads-up display, which I had on my side [of the flight deck].”

The mission also included the first spacewalk (extravehicular activity, EVA), from the space shuttle.

“My responsibility was getting them [Story Musgrave and Don Peterson] into the suits, which is not a small responsibility. I mean, you’re putting them into their own little spacesuit or spacecraft. You know, it provides power and atmosphere and communications and meteoroid protection. It does everything. So it’s kind of like launching a small satellite, except it’s got a man in it,” Bobko said.

“But that went well. It was interesting to take photographs of them out there in the payload bay. It looks different when you’re up in space and have somebody, one of your friends, floating around back there,” he said.

Not everything went as well during the five-day mission. The orbiter’s guidance computer went offline.

“It failed, but we were on orbit, and the shuttle is — the shuttle, unlike the station on orbit, is very benign. It doesn’t take computers to keep it running,” said Bobko. “So it failed, and we were able to go through the whole procedure and bring it back up, change it to basically another position. When you fly the shuttle, you have four computers and a fifth which is a backup, and those four computers have what are called strings, so each computer has different things that are hooked to it that it commands and some of those strings are more important to it than others, so we took this computer and put it on one of the less important strings.”