ESA's BepiColombo probe successfully "halfway" to Mercury
The ESA BepiColombo interplanetary probe launched to Mercury in October 2018, and the main research tasks are expected to take place only in December 2025, when it will "park" in orbit around this planet. The halfway to Mercury is only a matter of time, not distance, because the probe is already approaching the planet repeatedly, and its scientific equipment is bringing the first unique results.
The problem of why the probe does not yet know how to park near Mercury, is related to the laws of celestial mechanics and limited energy resources for interplanetary flights. Since the probe launched from Earth's orbit, which is further from the Sun than the orbit of Mercury, it is accelerated by the Sun's gravity on its way to this planet so that it essentially "falls" towards the Sun, and, if it were not continuously braked, it would gain too high a speed. Despite being braked by chemical and unique ion engines and assisted by gravity on close flybys of Earth, Venus and Mercury itself, the probe is still flying past it too fast to be gravitationally locked into its orbit. So far, the probe has used one gravitational assist from Earth, two from Venus and two from Mercury, from which it will need four more. The Italian scientist Giuseppe "Bepi" Colombo, in whose honour the probe is named, made the calculations according to which the probe, using the gravity assistance to Mercury, is currently flying optimally.
The BepiColombo probe, worth over €2 billion, consists of three parts: the European MPO planetary orbiter, the Japanese MMO (Mio) magnetospheric orbiter, and the MTM transfer module, which provides propulsion and maneouvers with chemical and ion engines. However, not all scientific equipment can work actively now, as the sensors of some are blocked by the transfer module. Among the "lucky ones" with a free field of view is the ion mass spectrometer PICAM (Planetary Ion CAMera). "PICAM was constructed within the framework of very broad international cooperation with the contribution of our Institute of Experimental Physics SAS as well as Slovak technology companies," said one of its engineers, Ján Baláž. The PICAM and MIPA (Miniature Ion Precipitation Analyser) sensors are part of the SERENA (Search for Exospheric Refilling and Emitted Natural Abundances) scientific complex and recorded unique scientific data in its southern inner magnetosphere during the first flyby of Mercury, which is also discussed in the prestigious scientific journal Nature Communications with the affiliation of the Institute of Experimental Physics SAS.
Text: ÚEF SAV
Photos: ESA and ÚEF SAV