Sometimes it IS rocket science Apr 1, 2016

Nasa Mission Control

IT ONLY TAKES A SPLIT SECOND to go from calm to crisis. On the evening of April 13th 1970, the Apollo 13 spacecraft was approximately 56 hours and 200,000 miles into its journey to the moon. Other than a smattering of people with a vital interest in the progress of this particular mission, no one was paying much attention. Manned lunar landings had become “old hat.” Even the specialists at the mission control center in Houston were more focused on the televised baseball game than they were on their control consoles. All was going as planned.

At about 9 p.m., the flight crew was instructed to perform a routine matter of maintenance involving the super-cooled liquid oxygen that provided air and fuel to the spacecraft. Astronaut Jim Swigert flipped the switch that would “stir” the oxygen in the onboard tanks. That simple maneuver was destined to be the last routine act aboard Apollo 13.

A catastrophic failure

Suddenly and without warning, an enormous explosion rocked the spacecraft. “Houston, we’ve had a problem,” flight commander Jim Lovell radioed to ground control in one of the most famous understatements in recorded history.

At that moment, no one knew that a faulty wire had triggered a catastrophic explosion in one of the ship’s two oxygen tanks. What they did know was that the data on mission control monitors was suddenly going haywire. And the astronauts could see gas venting from their damaged vehicle into space. Without understanding precisely what had gone wrong, it was clear to all involved that their carefully choreographed lunar landing mission had just become a desperate deep-space rescue mission with only the remotest possibility of success.

Crisis management

The Apollo 13 flight controllers swung into crisis mode. As the “front line” of a vast mission-support network, these highly trained specialists were tasked with making the life-or-death decisions that would determine the fate of the crippled craft and its imperiled crew.

The first priority was to deal with the fact that the command module was rapidly running out of oxygen. Racing against time, mission control directed the astronauts to power down the command module to save enough battery power to re-enter the Earth’s atmosphere; power up the lunar landing module (LEM), which had its own supply of air, water and battery power; and transfer critical data to the landing module’s computers as mission control double-checked the astronauts’ hastily calculated conversions.

The flight crew moved into the lunar landing module with only moments to spare. Temporarily secure in their fragile “lifeboat,” they awaited further instructions. On the ground, flight director Gene Kranz was weighing his team’s limited options. A decision had to be made whether to 1.) “direct abort” the mission, which would get the crew home quickly at the risk of firing up a potentially damaged engine and crashing the spacecraft into the moon or 2.) adapt the LEM’s rocket to sling-shot the spacecraft around the moon, which would require four to five days in a module designed to support only two men for two days.

Kranz decided to go with his gut feeling that the direct abort was too risky; he chose instead to trust his team to come up with the solutions the astronauts would need to survive the long days ahead.

An endurance test

Operating on bare-bones power, the temperature inside the lunar module dropped precipitously. Food and water froze, and the flight crew was too cold to sleep for more than a few minutes at a time. Fred Haise developed an infection and debilitating fever. The exhausted, dehydrated men faced one crisis after the other.

The air purifiers maxed out, threatening to poison the crew with carbon dioxide. After a frenzied inventory of everything in the spacecraft that might be used to design a fix, the ground crew built a mockup in Houston, and then conveyed instructions to the crew. The hastily rigged contraption – using parts of a flight manual, plastic bags and large quantities of duct tape – worked.

As the spacecraft neared Earth, it began inexplicably to drift off course. Without an emergency correction, it would come in at the wrong angle, bounce off the atmosphere and hurtle back into space. Engineers frantically devised a plan to regain the proper trajectory, but it was left to the flight crew to execute the perilous and unprecedented maneuver. They had to steer and stabilize the spacecraft by sighting the Earth and moon through the windows and then fire the rockets manually at precisely the right moment for precisely the right length of time. It is an enduring testament to the courage and skill of these former test pilots – and to their absolute trust in their team on the ground – that they were able to accomplish this extraordinary feat under such impossibly difficult conditions.

The home stretch

Six days after take-off, Apollo 13 was just hours from home. Since only the command module had the shields to withstand the intense heat of re-entry, the flight crew had no choice but to try to power the command module back up using just the remaining battery power. This had never been attempted before; engineers on the ground painstakingly developed a checklist hundreds of steps long to make it happen. Every command was radioed to the crew, written down on scraps of paper and executed flawlessly. The crew then jettisoned the damaged service module, catching a glimpse for the first time of the devastating damage from the explosion. They also jettisoned the spidery-looking little LEM that had saved their lives. Finally, there was nothing left for anyone to do but wait.

A 5,000 degree fireball enveloped Apollo 13 as it hurtled through the atmosphere. The world, galvanized by the drama that had been unfolding over the past days, watched anxiously as the four minute deadline for the expected reestablishment of radio contact with the crew came and went. Had the heat shields been damaged in the explosion? Had the command module burned up during re-entry? Another agonizing minute and a half passed – and then the radio crackled to life with Jim Swigert’s voice. At that moment, mission control in Houston erupted with pent-up emotion. They had achieved the impossible – they had guided their crew safely home.

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