50 years ago today, Apollo 13 had a problem
Posted April 13, 2020 11:15 a.m. EDT
Updated April 13, 2020 2:39 p.m. EDT
The first The first 55 hours and 55 minutes of the Apollo 13 mission went smoothly until, shortly after the one and only TV transmission of their journey, about 3/4 of the way to the Moon, Apollo 13 had a problem.
A liquid oxygen tank exploded, pushing the flight off course, robbing the capsule of breathable oxygen and fuel for power generation.
An accident investigation board later found that upgrades to the tank, designed by American Rockwell, had overlooked thermostatic switches while being made to work with higher voltage test equipment at the Kennedy Space Center. These switches were likely welded shut during preflight tests allowing temperatures in the tank to rise to over 12 times the original design's limits.
Systems, including guidance, were shut down to conserve power. Over the next 6 hours, the astronauts with assistance from flight controllers on the ground, manually calculated a free return trajectory to get them back home.
The crew used the onboard sextant, which required no power, to determine their position looking for two stars from a list of 37 known to the guidance computer. This a common task used many times during all Apollo missions to provide updates to the guidance, but was particularly complex for Apollo 13.
Applying lessons learned at Morehead Planetarium
Planetarium director Tony Jenzano and the staff at Morehead had developed simulations for that enabled them to locate those 37 stars plus the Moon, Earth and Sun as Mercury, Gemini and Apollo crews would see them from their spacecraft.
Jenzano would later day “Carolina is the only university in the country, in fact the world, that can claim all the astronauts as alumni.”
The Apollo 13 crew of Jack Swigert, Fred Haise, and Jim Lovell collectively spent two and a half weeks at Morehead learning these celestial navigation skills.
I spoke with Jim Lovell when he visited the the planetarium to kick off the 2017 North Carolina Science Festival. He remembered well his days in Chapel Hill and the training there, recalling apparatus created by Jenzano and his staff.
Back in the Apollo 13 Command Module Odyssey, Commander Jim Lovell recalled his experience correcting Apollo 8's course using the sextant. But there was another problem, a trail of debris was following the spacecaft, creating "false stars". They turned to the one star they could reliably see, the Sun.
Five hours after the explosion, their position well known and new course had been calculated.. After about 30 minutes of entering commands into the guidance computer and double checking everything, the engine intended to gently lower the still attached lunar module onto the Moon's surface, was burned for 34 seconds to send the crew around the Moon and on their way back to Earth.
You can experience Apollo 13 in Ron Howard’s 1995 film starring Tom Hanks, Kevin Bacon, Bill Paxton, Gary Sinise, and Ed Harris. Look for Lovell's uncredited cameo appearance near the end of the film as the captain of the USS Iwo Jima. Lovell also recalls teaching Tom Hanks to navigate by the stars while serving as advisor on the film
You can also follow the mission in real time at an interactive website that includes video from mission control and the capsule as well as all 48 mission control audio channels.
Lovell’s words during his return to Morehead three years ago are especially true today: “No matter how bad things are, have a positive attitude.”