PI Update - September 2003
Mission Scenario Tests (MSTs)
On 21 August, the command sequence for the Launch MST was successfully executed on the flyby spacecraft. This sequence controls the spacecraft from the time of liftoff, through separation from the third stage rocket, to a stable configuration with the solar panels oriented for maximum power. Actual liftoff and deployment of the solar panels, of course, was inhibited in the test environment. This test verified the soundness and safety of the testing approach, with the spacecraft at BATC in Boulder and the test command sequence being sent from the Ground Support Equipment in the temporary Mission Operations Area at JPL in Pasadena. Thus future MSTs (for other portions of the mission) will be diagnostic of the actual software on the spacecraft and will be as close as we can get on the ground to "test as we will fly" conditions. The additional MSTs will take place over the next several months.
The Space Infrared Telescope Facility (SIRTF) was successfully launched on 25 August. We anticipate that this facility will play a key role for Deep Impact, both in characterizing comet Tempel 1 prior to impact to optimize our targeting scenarios and in observing the events associated with the impact. Team members corresponded with and met with representatives of the SIRTF Science Center to discuss how best to meet Deep Impact's mission-critical needs and how to get the best scientific return from SIRTF about the Deep Impact encounter.
Workshop on Earth-based Support
On September 1st, Labor Day, we conducted a workshop for Earth-based observers (ground-based and Earth orbital) as a lead-in to the annual meeting of the Division for Planetary Sciences of the AAS. This was attended by close to 40 astronomers. Presentations describing the current plans and progress by team members and discussion brought out various ways in which other astronomers could collaborate with the project in carrying out scientific programs associated with the impact. There was some discussion of the phenomenology expected, an expanding debris cone controlled by gravity, and the less likely phenomenology of the event propagating through the entire comet nucleus at the time of impact. There were presentations also on the mission-critical observing needs prior to the impact as well as discussions of our status in analyzing the currently available data to pin down the size, shape, and rotational state of the nucleus. The project will set up a web site for collaborating observers, for exchanging observing schedules and for ensuring that prior to the impact the data most critical for mission success are obtained. We anticipate that this program, like our Small Telescope Science Program for amateur astronomers, will greatly enhance the scientific return from Deep Impact.
Mike A'Hearn, University of Maryland