Akatsuki has a long and interesting history. Japan’s first probe to the planet Venus, the spacecraft was launched in in 2010 with an aim of inserting into Venus orbit six months later to commence a two-year mission studying the unique weather of our planet’s twin. (Fraternal twin, definitely. Venus is an unbelievably hostile environment.)
So what happened? Five years ago, Akatsuki encountered Venus and fired its main engine for orbital capture, but something went badly wrong. The spacecraft began spinning, and the computer automatically shut down the engine to prevent catastrophe. Analysis of the flight data suggests that the ceramic nozzle of the hypergolic main engine had shattered, causing the engine plume to billow out in unpredictable directions, resulting in the spin. The computer righted the spacecraft, but by then it was too late; Venus was now far behind.
But Japanese flight controllers are astonishingly stubborn, and they did not give up. They knew that the spacecraft would get another chance, if only they could coax it to last way past its original design lifespan. For five years later, it would be in position to take a second crack at Venus orbit insertion.
That moment came yesterday. Using a carefully choreographed routine that uses its reaction control motors in ways never intended, the spacecraft was programmed to ease into Venus orbit with a twenty-minute burn. So far, we know the spacecraft carried out the burn, and is still alive. It won’t be until sometime tomorrow that we know what orbit it’s in — and crucially, whether it’s now orbiting the Sun or Venus. But the early indications are very good! And JAXA has posted some truly adorable graphics to celebrate. This one is my favorite, showing Akatsuki and Venus cuddling up together. 😉