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Dawn Ready to Ship to Launch Site

Carol A. Raymond
Dawn Deputy Principal Investigator, JPL

The Dawn project successfully completed its Post-Environmental Test Review (PETR) on March 19th, and its Pre-Ship Review, held March 20-21, clearing the way for the Dawn spacecraft’s trip to Cape Canaveral for launch preparations. The PETR assessed the completeness and validity of the thermal vacuum (TVAC) testing which was performed Jan 23-Feb 18 at the Naval Research Laboratory in Washington, DC. The spacecraft and instruments were put through a comprehensive series of performance tests to validate the spacecraft thermal model and operate the flight system (including instruments) in a flight-like manner, culminating in a test-firing of two of the three ion thrusters. Some rework was needed to adjust heater circuit setpoints and correct wiring, and the High Voltage Electronics Assembly was returned to JPL after TVAC for rework of faults not related to the TVAC testing. The HVEA rework and retesting has completed, and the box has been re-integrated to the spacecraft. Following an acoustics test at NRL, the spacecraft will be packed and shipped to the Astrotech facility near Kennedy Space Center in Cape Canaveral.

Final assembly of the spacecraft at Astrotech involves attaching the 19.7-meter solar array, which folds up accordion-style against the spacecraft body for launch. The array deploys after third-stage separation when thermal knives cut the kevlar cords that holdback the pre-tensioned panels. The high-gain antenna will also be re-installed and a series of functional and scenario tests performed to verify system functionality in preparation for launch. The Dawn launch is scheduled for June 30th. This ten-day slip from the original June 20th launch date was dictated by launch vehicle readiness.