b'Engineer Innovation | The Digital Twin70 amperes, however which would have exhausted the limited battery supplies. To conserve precious power supplies, mission control had shut-down non-essential systems (including crew heaters) to reduce the load to less than 12 amps (less than a domestic vacuum cleaner). But even still, as the time approached to power-up the command module less than two hours of power remained. Behind the scenes EECOM, John Aaron worked around the clock to define a minimal power-up sequence, which everyone hoped would awake the command module before re-entry with the trickle of power left in the batteries. The exhausted and frozen crew were understandably anxious about correctly working their way through a long and complicated procedure that involved operating hundreds of switches in the correct order. Any mistake, any omission, would likely prove fatal, as turning the wrong system on would instantly deplete the small amount of Apollo 13 flight directors celebrate the successful splashdown and recovery of the Apollo 13 crew.remaining power. Astronaut, Ken From the left are Gerry Griffin, giving thumbs up, Gene Kranz and Glynn Lunney. Mattingly (who was bumped from the Credits: NASA Apollo 13 crew a few days before launch), sealed himself in a dark error, the simulator team came up withcommand module simulator to rehearse the ad-hoc process to align the tinyand refine the switch on sequence window of the lunar module with abefore it was broadcast to the crew.quadrant of the sun. Before making the complicated alignment maneuverIs that really a digital twin?commander, Jim Lovell sought repeatedI dont think its much of a spoiler to tell assurance from mission control: Hadyou that, thanks to the round the clock the backup crew configured thework of hundreds of NASA engineers simulator properly with the lunarand controllers, the three astronauts module in docked configuration? Hadwere returned safely home. What could they had any trouble performing thehave been NASAs greatest disaster maneuver?. He neednt have worried.turned into its greatest triumph. Using the rapidly assembled procedureAlthough the Apollo 13 mission Lovell managed to align the spacecrafthappened 32 years before the coining with the one-degree margin of errorof the term digital twin, I do think that required to keep it on course. it remains one of the best real-life examples of a digital twin in action. I The final problem was that in order todont think the astronauts would have use the lunar module as a life-raft, themade it safely home without it.astronauts had to power down the command module, which they wouldHere are the characteristics of the ultimately return to for reentry.Apollo simulators that I think defines However, the command module wasthem as perfect examples of a digital only ever designed to be powered-uptwin in action:on the launch pad, a complex process that took over two days, and no Physical: Digital twins are most useful procedures existed for restarting inwhen they relate to physical assets deep space, with almost exhaustedthat are (at least temporarily) out of power supplies. Under normalreach of direct human intervention. operation the lunar module drew aboutEven though there were three 16'