Dawn devoted most of the month to continuing to thrust with its ion propulsion system.
A planned coast period from May 12 to 14 let the operations team conduct periodic maintenance. Some computer memory locations were checked and verified to be healthy. One of the three powered reaction wheels was turned off and the fourth wheel was powered on. All gyroscopes were powered on and operated for two days.
To investigate the temperatures that would be experienced for future long-duration thrusting with thruster #1, the spacecraft spent a few hours in the orientations that would be required. The resulting temperature data will contribute to determining when to switch from thruster #3 to #1.It seems amazing to me to think that Dawn is currently accelerating under thrust via its ion propulsion system, heading towards its distant rendezvous with Mars in 2009.
Dawn's goal is to characterize the conditions and processes of the solar system's earliest epoch by investigating in detail two of the largest protoplanets remaining intact since their formations. Ceres and Vesta reside in the extensive zone between Mars and Jupiter together with many other smaller bodies, called the asteroid belt. Each has followed a very different evolutionary path constrained by the diversity of processes that operated during the first few million years of solar system evolution.
|Schedule of Key Events in the Dawn Mission |
|Mars gravity assist||March 2009|
|Vesta arrival||September 2011|
|Vesta departure||April 2012|
|Ceres arrival||February 2015|
|End of primary mission||July 2015|
There is something slightly personal about all this. Prior to launch, during a “Send Your Name to the Asteroid Belt” campaign, more than 360,000 people signed up to participate in a virtual voyage to the asteroid belt. A computer chip holding all the participants’ names was installed on the Dawn spacecraft, and it blasted off with those names on board. The chip included several names from my own circle of family and loved ones.