houston, we’ve had a problem --10/23/24

23 Oct 2024

houston, we’ve had a problem --10/23/24

0 COMMENTS

Today's selection-- from Wicked Problems by Guru Madhavan. For NASA, Apollo 13 was a "successful failure.”

“One man who deeply understood the indispensability of systems engineering—and the tragedy when it is ignored—was Frank Hughes, the former chief of NASA's spaceflight training division. Hughes joined NASA as an instructor in 1966. On the first day of his job at the Kennedy Space Center, the first box of the Link Apollo simulator was delivered. Hughes's career at NASA evolved with the Link simulators through the Mercury, Gemini, Apollo, Apollo-Soyuz, and space shuttle missions leading up to the International Space Station program.

"‘We were lucky all the time,’ Hughes told a reporter. ‘I used to joke that God spent about half of his time just with NASA on those early missions.’ The early stage of the Apollo program had ‘no training rhythm to it,’ Hughes recalled. ‘The crew walked in the door and set the stage of what they wanted to do. There was no such thing as a lesson plan or objectives or whatever. You trained until you flew, and it just filled up the time. If things delayed, then you trained more, and you just went on like that.’

“One of the most critical elements of the training was the ability to simulate potential problems that astronauts could encounter. During the Apollo program, the Link engineers updated the simulators with over 1,000 exercises for malfunction scenarios. ‘The fuel cells could fail, tanks could leak, all that sort of thing,’ Hughes remembered. Simulations could be sped up and slowed down with advanced visuals and many improved capabilities for every step of the mission rehearsal. The star fields were even more credible. And the simulators now contained the exact measurements of every spacecraft element rather than estimates.

“The value of such almost identical features became apparent on Monday, April 13, 1970. Apollo 13, the third lunar landing mission, was 55 hours into its mission and 200,000 miles from Earth. The spacecraft was under the command of Jim Lovell, with John Swigert as the command module pilot and Fred Haise operating the lunar module, all trained as engineers. Meanwhile, after an intense and exciting day, Frank Hughes was driving home from Kennedy Space Center, already thinking about the training regimen for Apollo 14.

Jim Lovell, Jack Swigert, Fred Haise

“Suddenly an oxygen tank exploded in the service module, creating a sequence of breakdowns on Apollo 13. Lovell, Swigert, and Haise couldn't identify the problem. Soon after, the crew heard several more explosions. In an emergency call to mission control, Lovell uttered the most famous, inauspicious words in space history: ‘Houston, we've had a problem.’ Hughes raced back to mission control. He and the rest of the team quickly got to work on the simulator, continuing the effort for five restless nights. In the first three hours after the oxygen tank explosion, the crew lost over one-half of the oxygen reserves. Returning the trio safely to Earth was now the mission.

“With the command and service module Odyssey crippled, Aquarius, the lunar module, became the ‘lifeboat’ for the astronauts to operate for 90 hours, double the number of hours the module was designed to work in an emergency. As the spacecraft hurtled away from Earth at 2,000 miles per hour, preserving the module's power was paramount. New procedures had to be researched, recorded, and revised. The Link simulator operated nonstop as the ground crew and standby astronauts rapidly reworked their ideas. They tested scenarios based on the remaining onboard resources.

“With oxygen reserves depleting, the astronauts' challenge was compounded by the fact that their simulator sessions didn't perfectly reflect their reality. Although high in fidelity, the simulations didn't have the cloud of particles or debris striking the spacecraft that the crew had to contend with onboard. And there were further problems that the simulator hadn't anticipated: maintaining uniform temperatures within the spacecraft. Apollo 13 needed passive thermal control. A tricky maneuver first attempted in the simulator, nicknamed the ‘barbecue mode,’ slowly spun the spacecraft lengthwise for even exposure to solar heat. With a disabled command and service-module computer and the lunar module lacking the essential software, the slow-motion roll had to be done manually. Lovell controlled the forward-backward movement, and Haise handled the left-right motion of the spacecraft, rotating the spaceship at three revolutions per hour. This technique saved the spacecraft from being heated on one side and frozen on the other. And finally, thanks to the ground simulator, the crew learned a method to abandon the disabled module, which enabled the astronauts to plummet safely through the Earth's atmosphere. As the astronauts commenced reentry, the procedures were anything but orthodox. With orange-and-white parachutes inflated over the Pacific, they splashed down near Samoa.”