BepiColombo is a rotatory mission that will learn the smallest and inmost major planet in the Solar System like never before . But its portion became uncertain a few months ago followinga glitchthat has preclude its thrusters from work at full power . The delegacy team has recently made two important decisions . The spacecraft will get into orbit almost a yr later than expected and the fourth flyby will have to be more daring than they had anticipated .

BepiColombois a joint mission of the European Space Agency ( ESA ) and the Japanese Space Agency ( JAXA ) . On September 4 , the space vehicle will perform its fourth flyby of the planet . This will be the nigh BepiColombo will ever get to the planet , near than was earlier deemed safe . It will strive 165 kilometers ( 103 miles ) , less than the safe 200 kilometers ( 120 miles ) planned . But the thruster issues have forced the squad to make a bold decisiveness that will give them more flexibility in the coming month .

“ in the beginning , all flybys at Mercury [ are ] at 200 - klick height . There are many reasons you have to pilot at this altitude and this is already quite demanding . One of them is the thermal issue , so it was always set as a limit,”Frank Budnik , who leads the flight of stairs dynamic squad for BepiColombo , evidence IFLScience .

The flyby will take place on the night side and only partially across the terminator , making certain that the spacecraft is as safe as possible in its passage . Still , it will be an chance to acquit some exciting skill and the squad will partake some double in the coming days .

It was decipherable very quick that with this reduced power availability , we will not be able to keep up the former mission .

The next two flybys will take place in December and January . They ca n’t be change due to orbital mechanics . But the space vehicle has to perform some maneuvers before the 5th flyby and this new altitude will give the spacecraft some more leeway . Basically , it has corrupt the team clock time in case the pusher need a act longer to slow down BepiColombo .

If you only bonk distance fromscience fiction , it might seem straightforward to go from one berth to another . But in reality , it is not like that . affair launched from Earth have a lot of orbital speed , and going towards the inner Solar System means that you need to slow down massively . You could do that if you had a massive rocket fire its engine , but that ’s not efficient ; so , spacecraft go on peculiar orbits and do calculated thruster bursts .

The deficiency of full power is what ultimately led to the decision to postpone entering into compass around Mercury from December 2025 to November 2026 . When that happens , the spacecraft will break open into two orbiter that will meditate the satellite in unprecedented detail . There will be some disappointment , but space is tough and sometimes it is better to delay thing to guarantee the safety of a mission .

“ It was clean very quick that with this reduced power availability , we will not be able to keep the old commission , ” Budnik told IFLScience .

ESA ’s Flight Dynamics squad was extremely clever in developing thisnew maneuverfor BepiColombo . Sure , it is make bold , but it also finds a root for a trouble they did not expect to have . And both decision , the change in long - term trajectory and the alteration in altitude , were taken in the last few weeks .

“ It was quite a tough decision , but on the other hand , this is the fourth Mercury swing - by , the seventh in total , ” Budnik explain when we asked about the challenge of construct the altitude change . “ We had quite some seafaring experience with the previous swing - bys . And we matt-up , okay . We did , of course , some computations before , some rule of thumbs … And this is why we said , okay , let ’s do it . Because in the end , we can only win from it . ”

The next swings pastMercurywill be importantly further away from the satellite and there are no plans to change those . The spacecraft will spend the next two years and a bit getting closer and closer to Mercury ’s pep pill and orbit until the spacecraft can split and the artificial satellite can lead off their work . But first is the 4th flyby and we are all rooting for a big success .