NASA Dawn back on course after briefly slipping into Safe Mode

NASA's Dawn spacecraft has resumed normal operations after a high-energy particle event forced the mission to enter safe mode, knocking its ion drive offline.

Although mission managers deduced the source of the problem and restarted its propulsion systems, the unexpected hiccup will likely delay Dawn’s arrival at dwarf planet Ceres.

Safe mode was triggered on Sept. 11 and it is thought the same phenomenon that triggered a safe mode three years agoduring Dawn's approach to giant asteroid Vesta is to blame for this incident.

A high-energy cosmic ray hit the spacecraft's ion drive electronics, disabling it.

In addition to the ion drive glitch, Dawn's main antennae that the spacecraft uses to communicate with Earth was also knocked offline, meaning engineers had to decipher the problem using Dawn’s secondary, lower bandwidth antennae.

"This anomaly presented the team with an intricate and elaborate puzzle to solve," said Robert Mase, Dawn project manager at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif.

"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," said Dawn Mission Director and Chief Engineer Marc Rayman also of JPL.

“We have a plan in place to revive this disabled component later this year.”