MESSENGER instruments take aim

"All spacecraft sub-systems and instruments reported nominal operations indicating that MESSENGER is ready for its second encounter with Mercury," said MESSENGER Systems Engineer Eric Finnegan of APL.

At 22:05 UTC the last bits of data from the spacecraft were received as it transitioned from high-gain downlink to beacon-only operations, and the spacecraft reoriented itself to begin science operations. Before turning away, however, the spacecraft returned a set of optical navigation images of the terrain not yet seen up-close by any spacecraft to whet our appetite regarding the discoveries to come.

For the next 10 hours or so, the spacecraft will take repetitive scans through Mercury's comet-like anti-sunward tail, pausing now and then to take a color image and a high-resolution mosaic of Mercury with the Mercury Dual Imaging System instrument.

"The operations team is now preparing for the period of time about an hour prior to closest approach [at 08:40:21 UTC], when we will be transitioning our support from the Canberra ground station to the Madrid ground station that will capture the flyby," Finnegan said. "High-gain communications with the spacecraft will be re-established on Tuesday at 05:14 UTC at approximately 52 kilobits per second, and playback of the data stored in the solid-state recorder will start approximately 30 minutes later."

"MESSENGER is now on its own. The MESSENGER team is confident that our probe will carry out the full flyby command sequence, which was developed and thoroughly tested by the many dedicated engineers and scientists on the MESSENGER flight team," said MESSENGER Principal Investigator Sean Solomon of the Carnegie Institution of Washington. "We all look forward with excitement to the flyby data set that we will start to glimpse Tuesday morning. We'll be seeing at close range, for the first time, a region of Mercury larger in area than South America. Discoveries are just hours away."

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington.
High resolution image

The countdown to MESSENGER's second Mercury flyby continues. This image is from the seventh set of optical navigation images and was taken about 20 hours before MESSENGER's upcoming closest approach to Mercury, which will occur on October 6, 2008, 08:40:22 UTC. Similar to the results from the six earlier image sets, everything looks as planned for the flyby. One more set of optical navigation images will be acquired before MESSENGER begins its planned Mercury science flyby observations.

Source: Johns Hopkins University Applied Physics Laboratory
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