According tomedia New Atlas, ESA engineers have identified the reason why the space agency’s Huygens probe suddenly began spinning in the wrong way when it crashed into Titan Titan, Saturn’s largest moon, 15 years ago. Uncovering the mystery of the wrong direction of rotation of the Huygens probe could have an impact on future space missions.
In many ways, the Huygens mission was a great success. Launched in 1997 as a companion to nasa/ESA/ASI Cassini-Huygens mission, it was tasked with landing in Titan’s methane layer by parachute and, if it survives, transmitting data back from the satellite’s surface. It did, but there was still a major failure, and that remains a mystery.
Three weeks before the Cassini probe entered Saturn’s orbit, Huygens was released alone for three weeks before rezing with Titan on January 14, 2005. It operates at a rate of 7.5 RPM – the standard practice of stabilizing spacecraft by effectively turning it into a large gyroscope.
ESA engineers thought that when the probe hit Titan’s outer atmosphere, the 36 angled blades on board would slow down and control rotation. However, as huygens began to decline, the spin slowed faster than expected and rotated in the opposite direction within 10 minutes. It continues to do this for the next two hours and fifteen minutes of descent, and although this affects the time of some observations, the rotation speed does not interfere with the task too much.
However, the problem persists. Mistakes in the direction of rotation of Huygens could have disastrous consequences, for example, because a mix of imperial and metric measurements could cause NASA’s Mars Climate Orbiter to burn in the Martian atmosphere.
According to ESA, a recent subsonic wind tunnel test at the PRISME laboratory at the University of Orleans in France found the culprits in the error, namely the Huygens Separation Subsystem (SEPS) and radar altimeter (RA) antennas. When they are deployed, they are like wings, pushing the probe in the opposite direction until they overcome the control blades and the direction of rotating flips.
The space agency is continuing to investigate the impact of this event, in particular the impact of the Huygens Atmospheric Structural Instrument (HASI) boom, which may not be fully deployed during the descent, to better understand exactly what happened and to use this knowledge to improve the possibilities of future planets.