06.22.2006
The MESSENGER spacecraft performed its final "flip" maneuver on June 21, rotating 180° and pointing its sunshade toward the Sun.
The 16-minute maneuver, designed to keep MESSENGER operating at safe temperatures as it moves closer to the Sun, wrapped up at 9:34 a.m. EDT, with successful reacquisition of signal from the front-side antenna. The spacecraft was 122 million miles from Earth and 89 million miles from the Sun when the maneuver occurred.
MESSENGER had been flying with its back to the Sun since a March 8 "flop," allowing it to maintain temperatures within safe operating ranges at Sun distances greater than 0.95 astronomical units (1 AU is Earth's distance from the Sun). Mission plans call for the spacecraft to keep its sunshade facing the Sun for the remainder of its cruise and science orbital operations around Mercury.
"Initial indications look very good," said MESSENGER Mission Operations Manager Mark Holdridge, of APL. "Spacecraft temperatures are coming down as expected and all systems and instruments are nominal."
The team will now turn its attention to preparing for the first Venus flyby on October 24. "We have mission simulations and flight tests coming up to test particular operations that will have to occur during the Venus flyby," Holdridge said. "There will be a 57-minute solar eclipse during the October operation, so we will so be testing the flight systems in the flyby configuration to verify they will behave properly during the eclipse period."
On August 11 the team will conduct a flight test of the new autonomy that will power off components prior to the solar eclipse, allow the battery to discharge by approximately the same amount as during the real eclipse, and then power on components again once the battery is recharged, all in a more controlled setting with real-time visibility. This test will be combined with a battery reconditioning.
Later in August and through September, during the approach to Venus, MESSENGER's navigation team will use the Mercury Dual Imaging System cameras onboard the spacecraft to take a series of optical navigation pictures. These images are not required for the Venus flyby but will be used by the MESSENGER navigation team for calibration and as practice for the optical navigation imaging to be utilized at Mercury.
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