Among the most dreaded people at NASA are the folks known as the simsups. Simsup is short for simulation supervisor and the people who hold that job are the ones who devise and conduct elaborate—and harrowing—flight simulations, putting both engineers in Mission Control and astronauts in simulators through make-believe breakdowns and emergencies to test their moxie and mettle and prepare them for crises during real missions. Simulations are no easy thing, and in his fine autobiography, Flight: My Life in Mission Control, Chris Kraft, the original Director of Flight Crew Operations during the earliest days of the space program, evocatively described controllers at their consoles sweating real sweat as they fought to save astronauts from a make-believe crisis that felt every bit the real deal.
AS NPR reports, yesterday, June 12, there was a lot more sweating going as space followers listening in to the air-to-ground traffic between Houston and the International Space Station (ISS) on NASA’s website heard the alarming call that an astronaut was suffering from “DCS,” or decompression sickness. DCS is a very real risk on the ISS, which is filled with air at a sea level pressure of 14.7 pounds per square inch, keeping astronauts safe from the vacuum outside. There is no shortage of seams and fittings aboard the station, any one of which could spring a leak and threaten the lives of the crew aboard. Since 2019, NASA and Roscosmos, the Russian space agency, have been monitoring a very slow leak aboard the Russian Zvezda module, which has never proved life-threatening, but has defied efforts at a fix nonetheless.
The announcement about a DCS emergency put the Zvezda leak front of mind for listeners on the NASA loop, but ISS officials quickly sounded the all-clear, announcing on X, formerly Twitter, that the call was just the work of the simsups, the controllers, and an astronaut crew training at the SpaceX headquarters in Hawthorne, Calif., who were running a simulation and inadvertently crossed their transmissions with the air-to-ground line.
“There is no emergency situation going on aboard the International Space Station,” the X post read. “At approximately 5:28 p.m. CDT, audio was aired on the NASA livestream from a simulation audio channel on the ground indicating a crew member was experiencing effects related to decompression sickness (DCS). This audio was inadvertently misrouted from an ongoing simulation where crew members and ground teams train for various scenarios in space and is not related to a real emergency. The International Space Station crew members were in their sleep period at the time. All remain healthy and safe, and tomorrow’s spacewalk will start at 8 a.m. EDT as planned.”
SpaceX also rushed up a post. “This was only a test,” it read. “The crew training in Hawthorne is safe and healthy as is the Dragon spacecraft docked to the @space_station.”
Space station activities are proceeding more or less as planned today, though the spacewalk, involving NASA astronauts Tracy C. Dyson and Matt Dominick, was postponed. As of 10:40 AM EDT, NASA had not announced the cause of the postponement, but the errant DCS “emergency” does not appear to have been the reason.
