As previously reported, the Japanese Space Agency’s (JAXA) Akatsuki spacecraft, launched in May last year, failed to achieve orbit around Venus last month. A faulty valve caused fuel pressure to drop, killing the main thruster in the middle of a long braking maneuvre, so that it was travelling way too fast to be captured by Venus’s gravity. Although Akatsuki ended up in a slightly lower orbit around the Sun which would bring it near to Venus again in six years time, JAXA scientists had to consider the possibility that the engines had been damaged in the incident (Akatsuki lacks engineering cameras which would have allowed ground-based engineers to visually inspect the thruster nozzle) which would seriously reduce the maximum thrust available. If this were the case then the six year plan would not work, as Akatsuki would not be able to accelarate hard enough to complete the maneuvre.
But some new options have just presented itself. JAXA have had more time to monitor the little craft, and now have a more accurate picture of its situation. It seems Akatsuki slowed down more than they previously thought, changing the dynamics of the problem. Thanks to the engines cutting out so early in the maneuvre, the spacecraft still has most of its fuel. Mission controllers can now program in extremely long but gentle burns (similarly to what was need to limp Hayabusa home), to meet Venus from the opposide side. This would allow Akatsuki to meet Venus in only five years, meaning that it would have a chance to complete it’s mission before it reaches it’s expected lifespan.
They’re also talking about using the craft’s fully functional suite of cameras and scientific instruments to monitor asteroids in low solar orbit near Venus – bodies about which we know next to nothing. Of course, space is really big so Akatsuki would have to do a lot of travelling to get close enough to an asteroid to do any work, so there may be some tough decisions in the future: Burn the remaining fuel to study asteroids, gaining valuable new information but abandoning the original mission, or press on to finally answer long unsolved questions about Venus. Personally, I suspect that the incredible tenacity and ingenuity of JAXA’s engineers may yet find a way to do both!