December 31, 2009 - Dawn Continues Thrusting and Completes Engineering Tests
Dawn thrust with its ion propulsion system for most of December and remains On course for Vesta. the spacecraft conducted a set of special activities during the week of November 30. The gamma-ray and neutron detector (GRaND), visible and infrared mapping spectrometer (VIR), and science camera all were operated and verified to be healthy. “A measurement of the relative alignment of VIR and the science camera did not yield the desired data because of a conflict between commands within VIR, but the instrument remained healthy. The VIR commands are easily corrected, and the calibration will be executed early in 2010. Upgraded software was installed in the primary and backup cameras. Other spacecraft engineering activities were completed successfully as well.
November 30, 2009 - Dawn Completes Another Month of Interplanetary Thrusting
Dawn thrust with its ion propulsion system for most of November, pausing for less than half a day each week to point its main antenna to Earth.
The mission control team completed preparations for some special activities the spacecraft will execute in December (so check back next month to learn more!).
October 31, 2009 - Nearly in the Main Asteroid Belt, Dawn Continues Thrusting to Vesta
Dawn devoted most of the month continuing to thrust with its ion propulsion system. The spacecraft is healthy and making steady progress reshaping its orbit to rendezvous with Vesta. As it continues to climb away from the Sun, Dawn will reenter the main asteroid belt on November 13.
September 30, 2009 - Dawn Completes Second Year of Flight
Dawn passed its second anniversary of being in space on September 27. It spent most of the month continuing to thrust with its ion propulsion system. It has expended about 104 kilograms (230 pounds) of xenon in its 392 days of thrusting since launch. The effective change in speed so far is more than 2.6 kilometers per second (5800 miles per hour), far more than most spacecraft ever achieve with their propulsion systems.
August 31, 2009 - Dawn Maintains Steady Thrust to Vesta
Dawn devoted most of August to ion thrusting, as it will for most of the next two years leading to the rendezvous with Vesta. Controllers conducted routine maintenance on an ion thruster gimbal, reaction wheels, and gyroscopes this month.
August 3, 2009 - Dawn Spacecraft is Thrusting Nominally with the Ion Propulsion System (IPS)
The first Vesta scenario test executed successfully in the testbed last week, and the flight team reviewed the results. This test of a flight-like Vesta orbit sequence is an important step forward towards validation of the design and operations processes that will be used at Vesta.
July 30, 2009 - Dawn Continues Thrusting to Vesta
Dawn spent the month thrusting with its ion propulsion system. No special activities were conducted, allowing the spacecraft to devote as much time as possible to thrusting and permitting the operations team to engage in long-range planning for Vesta.
June 30, 2009 - Dawn Resumes Extended Thrusting
Dawn resumed its routine of long-duration thrusting with its ion propulsion system on June 8. The spacecraft is now following the same pattern it used for most of 2008, with only a single weekly interruption in thrusting to point the main antenna to Earth. Dawn had spent most of the time since October 31, 2008 coasting. In contrast, most of the time from now until arrival at Vesta will be devoted to thrusting.
May 25, 2009 - More Coasting Activities Completed
To verify that the software loaded in April could accomplish ion thrusting, the spacecraft executed two short thrust tests. Upon establishing that the software was performing well, engineers installed two copies in the backup computer and another copy in the backup location of the primary computer. Also this month, the xenon in part of the system to feed the propellant from the main tank to the thrusters was vented to space to allow mission controllers to calibrate pressure sensors.
April 30, 2009 - New Software Loaded to Main Spacecraft Computer
Mission controllers upgraded the software in the spacecraft's main computer this month. This was the first complete software replacement since November 2007. Running the new software required rebooting the computer, which puts Dawn into safe mode. The process of preparing the spacecraft, transmitting the software, rebooting, and recovering from safe mode all went extremely smoothly. Although the software was tested extensively before being radioed to the spacecraft, a short test of ion thrusting proved that no bugs were introduced that might interfere with this crucial capability.
On April 16, Dawn was at its closest distance to the Sun since last year. Now its elliptical orbit will carry it deeper into the solar system.
March 30, 2009 - Dawn Continues in Quiet Cruise
Dawn coasted quietly in its new orbit around the Sun this month. Controllers conducted some routine maintenance but devoted most of March to preparing for future special activities.
February 28, 2009 - Dawn Receives Gravity Assist from Mars
Dawn flew by Mars on February 17, successfully achieving the gravity assist it needed to help it reach the asteroid belt. The spacecraft passed less than 550 kilometers (340 miles) from the surface of the planet.
As Dawn was leaving Mars, fault detection software put the spacecraft into safe mode and canceled the bonus instrument calibrations. The cause was determined to be an inappropriate software response to an expected temporary loss of valid data from the spacecraft's star tracker in the vicinity of Mars.
The operations team subsequently commanded the spacecraft back to its normal configuration. In addition, they returned the bonus calibration data that had been transferred from the instruments to the main spacecraft computer prior to going to safe mode.
January 31, 2009 - Dawn on Course for Mars Gravity Assist
Engineers determined early this month that Dawn's trajectory to Mars is so good that the planned maneuver to fine tune it was not necessary. When Dawn flies by Mars on February 17, the planet's gravity will give the spacecraft a boost, helping it reach its targets in the asteroid belt.
The spacecraft has spent the month coasting with few activities occurring onboard. On January 20, the Gamma Ray and Neutron Detector was powered on so the instrument team could assess its health. The data it returned confirmed the unit is in good condition and operating normally.