MESSENGER Instruments Take Aim at Mercury

Status Report From: Johns Hopkins University
Posted: Sunday, October 5, 2008



MESSENGER's engineering and operations teams convened at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., this afternoon to confirm the health and readiness of the spacecraft. "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 6:05 p.m. EDT 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 (available online at 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 4:40:21 a.m. EDT], 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 1:14 a.m. EDT 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."

As the flyby continues toward closest approach, additional information and features will be available online at, so check back frequently. Following the flyby, be sure to check back to see the latest released images and science results!

MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a NASA-sponsored scientific investigation of the planet Mercury and the first space mission designed to orbit the planet closest to the Sun. The MESSENGER spacecraft launched on August 3, 2004, and after flybys of Earth, Venus, and Mercury will start a yearlong study of its target planet in March 2011. Dr. Sean C. Solomon, of the Carnegie Institution of Washington, leads the mission as Principal Investigator. The Johns Hopkins University Applied Physics Laboratory built and operates the MESSENGER spacecraft and manages this Discovery-class mission for NASA.

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