01.14.08
At 2:04 pm EST today, the MESSENGER spacecraft experienced its closest approach to Mercury, passing just 124 miles above the planet's surface. Initial indications from the radio signals indicate the spacecraft is still operating nominally. The first science data return from the flyby was received just minutes before the closest approach point with the planet, as planned.
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Photo Caption: Image acquired on January 13, 2008, 06:34 UTC.
Photo Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington. |
During the historic flyby encounter, extensive scientific data will be gathered. The Mercury Dual Imaging System (MDIS) instrument will acquire over 1200 images of Mercury, including images of portions of the surface never before viewed by a spacecraft. The MDIS instrument is just one member of suite of instruments that will be used to study Mercury during the flyby. The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) will observe Mercury's surface as well as its tenuous atmosphere. The MESSENGER Magnetometer (MAG) will accurately measure Mercury's magnetic field, and the Energetic Particle and Plasma Spectrometer (EPPS) will characterize Mercury's space environment and interactions with the solar wind. The Mercury Laser Altimeter (MLA) will sense surface topography along a narrow profile. The Gamma-Ray and Neutron Spectrometer (GRNS) and X-Ray Spectrometer (XRS) will make the first measurements of Mercury's surface elemental composition.
MESSENGER will begin to transmit the new data to Earth once all of the scientific measurements are completed, about 22 hours after the spacecraft's closest approach to Mercury. These flyby data will shed light on fundamental scientific questions related to the formation and evolution of the planet Mercury. As scientists analyze the data, the MESSENGER spacecraft will continue on its planned journey, which includes two more encounters of Mercury in October 2008 and September 2009, before entering an orbit around Mercury in March 2011.
"The engineers and operators at the Deep Space Network (DSN) in Goldstone, CA, in conjunction with engineers at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, MD, pulled off a tremendous feat, acquiring and locking onto the downlink signal from the spacecraft within seconds, providing the necessary Doppler measurements for the Radio Science team" said MESSENGER Mission Systems Engineer Eric Finnegan, of APL." The spacecraft is continuing to collect imagery and other scientific measurements from the planet as we now depart Mercury from the illuminated side, documenting for the first time the previously unseen surface of the planet."
On Jan. 15 at noon EST, the spacecraft will turn back towards the Earth to start down-linking the on-board stored data. Measurements of this Doppler signal from the spacecraft will provide improved knowledge of Mercury's gravity field.
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