Good news and bad news! NASA’s Dawn spacecraft was recently forced to enter safe mode after a high-energy particle event made life for the mission more interesting, but the spacecraft is OK and has now resumed operation.
On September 11, Dawn automatically entered safe mode after being hit by high-energy particles. The event forced the spacecraft’s ion drive to shutdown. Mission scientists think this was caused by a cosmic ray hitting the Dawn. Ironically, a similar event happened three years ago as Dawn approached Vesta, the asteroid belt’s largest asteroid and first object of interest for the mission. In addition to the ion drive, the cosmic ray also caused the main communication antenna to go offline, which made communicating with the spacecraft much more interesting. Mission scientists were forced to use the secondary and much lower bandwidth antenna to restore operations to the spacecraft. Robert Mase, the project manager for Dawn, tactfully said, “This anomaly presented the team with an intricate and elaborate puzzle to solve.”
While talking about fixing the problem, Marc Rayman, Dawn’s Mission Director and Chief Engineer, said, “We followed the same strategy that we implemented three years ago to recover from a similar radiation strike – to swap to one of the other ion engines and a different electronic controller so we could resume thrusting quickly. We have a plan in place to revive this disabled component later this year.”
Fortunately, Dawn’s crew was able to get the spacecraft back online on September 15, but damage has been done. While the mission was inoperable, it lost 4 days of thrusting, which means it’ll arrive at Ceres later than it originally planned. Currently, the mission is expected to arrive in orbit around the dwarf planet in April 2015, which is about a month later than the mission originally anticipated.