At a time when budget-conscious lawmakers consider the possibility of eliminating, or at least privatizing manned space flight, it is appropriate, perhaps, to pause and remember what is considered by some to be America's greatest achievement in space: the rescue of three astronauts from almost certain death.
Launched April 11, 1970, Apollo 13 was to have been the United States' third mission to the lunar surface. Two days later and 200,000 miles from the moon, an oxygen tank exploded aboard the command module, forcing an abort of the lunar landing.
What followed was four days of an intensive rescue mission, as millions on Earth prayed for the astronauts' safe return.
Because all systems on the spacecraft had to be shut down to conserve power, astronauts Lovell, Fred Haise and Jack Swigert were forced to use the mission's lunar landing module as a lifeboat, making a slingshot move around the moon and back to Earth.
"When the explosion occurred, and the first time we heard the bang, we didn't know what caused it," said Lovell, noting that at that moment, his spacecraft began yawing wildly out of control as thrusters in automatic mode began fighting to regain the proper course.
"It started to move, and I started to try to control it. And that was when I said, 'How do I control this thing?'"
Haise, in Chicago for a 40 year commemoration at the Adler Planetarium, said because oxygen levels were dropping at an alarming rate, it was obvious immediately that the moon landing was impossible.
"I knew we weren't even going into lunar orbit," he said. "With no plan B, certainly it was a question mark in my mind if all this would come together and work right."
Not only was there no plan B, there was no plan at all.
Within minutes, controllers on the ground made a decision to shut down the dying spacecraft and move the crew into the lunar module which was never intended to support three people for such an extended period. But flight director Gene Kranz said he never considered the possibility that the crew would not get back alive.
"The mentality of the mission controllers," Kranz said, "is one that says whatever happens to us during the course of the mission, we will bring our crew back, and we will accomplish the objectives of the mission. We had a team that was almost invincible in standing up to a challenge."
Those challenges were almost incalculable: not enough electricity, oxygen, or water; a dangerous buildup of carbon dioxide in the cabin from the crew members' own breath; a discovery during the return that the spacecraft was on course to re-enter the atmosphere at an alarmingly shallow rate; even a prediction of a typhoon at the primary landing site.
"You throw out everything else, and you say, how do I get out of this particular situation and get back alive?" Lovell said. "I was very disappointed when we first learned that we couldn't land on the moon, but then when we saw the seriousness of the loss of the oxygen, then it was strictly a matter of survival."
Each peril was resolved by controllers on the ground. The crew re-entered the command module and all systems restarted, despite the fact that no spacecraft had ever been shut down in flight. But in the final minutes, as the spacecraft plunged through the atmosphere, fingers were crossed in mission control that the craft's parachutes would function properly. Some feared the explosive charges needed for deployment would be hopelessly frozen. Without the parachutes, the spacecraft would hit the ocean traveling hundreds of miles an hour, killing the crew.
"My elation came when I saw the parachutes, looking out the window!" Haise recalls. On the ground, Kranz called the sight, "Probably the most marvelous feeling I think any of us have ever experienced."
Officially, Apollo 13 was a failure. But history has rebranded that failure a success. With no guidebook, facing almost certain disaster, ground crews improvised and brought the crew home alive.
"There is absolutely no question," beams Kranz. "This was our finest hour."