GPS Glitch Limited Altitude of Exos SARGE Rocket

SARGE launch at Spaceport America. (Screenshot from Exos Aerospace webcast)

Space News reports that Exos Aerospace’s SARGE launch from Spaceport America last month failed to reach its intended altitude due to a glitch in its GPS system.

In a mission report provided by the company a week and a half after the launch, Exos said that a GPS receiver on the rocket stopped providing data during the rocket’s ascent. That triggered an automatic shutdown of the rocket’s engine 38 seconds after liftoff, versus a planned duration of 62 to 65 seconds, said John Quinn, chief operating officer of Exos, Sept. 5.

As a result of the early engine shutdown, the rocket reached a peak altitude of 28 kilometers, rather than the planned 80 kilometers. Quinn said an extrapolation of the rocket’s performance during that powered phase indicated the rocket might have been able to reach nearly 90 kilometers had the engine fired for the full duration.

The cause of the GPS unit malfunction in the rocket is still being studied. The unit started providing data again later in the flight, and an inspection turned up no obvious damage to the unit, cabling or antennas. There were separate dropouts of telemetry from the rocket during the flight, according to the mission report.

  • Mr Snarky Answer

    COTS non-aerospace grade GPS units have a thresholds for Gee limit and velocity so they are not used for building weapon systems. This would cause a “blackout” of the GPS under these conditions. I wonder if this issue could be that simple, although unlikely since these guys are well seasoned.

  • Kirk

    That would be embarrassing.

  • windbourne

    and yet…..

  • patb2009

    COTS Non-Military GPS units often have limits coded in.
    It’s also possible a connector shook loose or an unlucky cosmic ray.

    I’m sure a decent failure investigation will lock this in