science
Eight years after launch, Mercury probe and its Mercury Transfer Module consciously uncouple as orbit approaches
After nearly eight years, ESA and JAXA's BepiColombo spacecraft is finally nearing Mercury, as engineers begin the arrival sequence by jettisoning the power module that got it this far. The spacecraft stack separated from the Mercury Transfer Module (MTM) on September 3 at around 1400 CEST. After a tense few minutes, controllers confirmed that a preliminary Doppler signal had been detected, indicating that the MTM had separated successfully; by 1552 CEST, it was confirmed that signals had been picked up, indicating that all had gone to plan. The solar panels of the Mercury Planetary Orbiter (MPO) were charging the spacecraft's batteries.The next stage involves dropping into orbit around Mercury on November 21. Then the Mercury Magnetospheric Orbiter (MMO) – aka Mio – will be released between December 9 and 10, and a week later MPO will start moving to its final orbit over 480 x 1500 km, with science commencing in April 2027.
The arrival is a year later than planned. BepiColombo was supposed to have been orbiting Mercury in December 2025, but problems with the spacecraft's Solar Electric Power (SEP) system meant the trajectory had to be rethought, which extended the spacecraft's cruise.
