ORLANDO, Fla., April 9 (UPI) -- The 40th anniversary Monday of the first orbital flight of a space shuttle -- Columbia -- evokes the accomplishments of the program, but also a grim reminder of tragedies during its existence.
The first shuttle orbital flight in April 1981 revolutionized space exploration because it proved a reusable, piloted space plane could succeed.
But that legacy also offered perilous lessons. Space shuttle flights were canceled in 2011 after 14 astronauts perished in two accidents.
"We had two terrible tragedies that shouldn't have happened," Bob Crippen, 83, who piloted Columbia, told UPI in a recent interview.
"But it was quite a vehicle that allowed us to do some great things in space, bring over 300 people to space -- a much more diverse group of people than ever before. And I'm proud of it."
NASA built six shuttles -- one flew tests, while the others flew 135 space missions from 1981 to 2011, all launched from Kennedy Space Center in Florida.
NASA first created the shuttle Enterprise as a test vehicle that flew only in Earth's atmosphere. Following that, Rockwell International turned out Columbia, Challenger, Discovery, Atlantis and Endeavour, in that order.
Shuttles carried the first American woman into space, Sally Ride, and the first Black American, Guion Bluford, in 1983. They also launched important spacecraft, such as the Hubble Space Telescope in 1990, and they transported large segments of the International Space Station.
Long before the space station existed, shuttle missions led to advances in understanding how the low gravity of space affected people and materials. The shuttle also carried a set of special radar instruments to map previously uncharted jungles and mountaintops.
Disaster first struck the program in 1986 when the Challenger exploded shortly after liftoff. NASA recovered and launched shuttles successfully for the next 15 years until Columbia exploded during re-entry over Texas. Each tragedy killed all seven astronauts on board.
The final flight, an Atlantis mission, came on July 8, 2011, with a four-astronaut crew. It delivered electronics equipment to the space station.
As the 40th anniversary of the first launch approached, Crippen recalled celebrating many previous anniversaries with his crewmate, the late John Young, commander of the first mission. Young died in 2018 at age 87.
"John Young was the natural, right pick for that initial flight because he was their most experienced astronaut. He had flown to space four times and walked on the moon on Apollo 16," said Crippen, who noted he was a rookie when selected for the mission.
"I was his friend, and I'm sorry he's not here to mark this anniversary with us," he said.
Young was aware of the age difference between the two, according to a quote attributed to him by the New Mexico Museum of Space History, where Young is a Hall of Fame inductee.
"My heart rate wasn't as high as his [Crippen] because I'm so dang old and it just wouldn't go any faster" during the first shuttle launch, Young said. He was 50 that day; Crippen was 43.
Crippen remembered the first shuttle launch as a boost for the country's morale, coming as President Ronald Reagan recovered from a gunshot wound after a March 30 assassination attempt. The nation also dealt with inflation and a rise in unemployment during a recession in 1980.
The first flight had few problems, with the shuttle performing almost exactly as planned, he said.
"John and I found that the space shuttle -- the fact that it did succeed on that first launch -- really did kind of bring the country together, so I think it had a lot of positive support once we got to that first flight," Crippen said.
He said he always regretted that the United States canceled the shuttle without a replacement vehicle for U.S. human spaceflight. A replacement finally arrived after nine years with the launch of a crewed SpaceX Dragon capsule aboard a Falcon 9 rocket.
"It was a sad day for me when the last flight occurred," Crippen said.
The first orbital launch of shuttle captured public attention as the first human space venture from U.S. soil since 1975's Apollo-Soyuz Test Project with the Soviet Union, said Piers Bizony, a space historian and author of space books that include Space Shuttle: 40th Anniversary.
The United States employed a Saturn 1B rocket for its portion of the mission, and it was the last flight of that kind of rocket. The focus then turned to developing a reusable spacecraft.
"There was huge public interest in this major new adventure, especially as it seemed to promise a new era of regular and routine access to orbit," Bizony said in an interview.
But getting funding for the shuttle from Congress and President Richard Nixon's administration in the 1970s was difficult, Bizony said.
"Many people assumed the space race [with the Soviet Union] had been won with Apollo 11, so there didn't seem to be any need for another grand astronaut program," he said. "President Nixon's advisers eventually persuaded him that the shuttle was important as a way of maintaining American leadership in space."
NASA described the average cost of a shuttle mission as $450 million, but the program consumed a total of over $190 billion in 2010 dollars, so the average cost actually was more than $1 billion per mission.
Ultimately, Bizony said, it was the regularity of shuttle missions that led to complacency regarding risks, particularly during re-entry. Columbia disintegrated when super-heated air entered a wing where foam falling off a fuel tank had damaged the spacecraft during launch, according to NASA.
Challenger, on the other hand, blew up moments after being launched on Jan. 28, 1986. NASA personnel had dismissed warnings from engineers that cold weather in Florida that morning could create problems with circular gaskets that sealed part of the rocket's boosters.
A failure in such a gasket, or O-ring, led to the deadly explosion.
"Unfortunately, in the shuttle era, by the time a few flights had gone off without too many problems, the agency began to believe that the system was safe to fly, but it never really was," Bizony said.
One of the biggest flaws, he said, was the lack of an escape system, which is one reason NASA returned to space capsules that can abort more easily during launch.
Former astronauts, like shuttle pilot Sid Gutierrez, are marking the anniversary of the first shuttle flight in their own way.
"The first shuttle launch definitely said to the world, we're back -- the U.S. is back in leadership for spaceflight," Gutierrez said in an interview. "But we mistakenly thought spaceflight was routine then, partly because NASA sold it that way. Spaceflight was never going to be routine."
Shuttle safety issues are why Gutierrez is trying to develop a safer rocket engine at his Florida company, Vaya Space, he said. The company is testing a solid rocket fuel core that could be easier to shut off after ignition than purely solid rockets, which is what the shuttle's boosters were.
The retired shuttles are on display around the country. Discovery, which flew the most missions, 39, is on display at the National Air and Space Museum's Steven F. Udvar-Hazy Center in Chantilly, Va., near Washington D.C. It's temporarily closed because of the pandemic.
Atlantis is at the visitor complex outside Kennedy Space Center. Endeavor is in the California Science Center in Los Angeles. And the original shuttle, the Enterprise, is on display at the Intrepid Sea, Air & Space Museum in New York City.