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NASA sending MESSENGER to Mercury

July 16, 2004 10:27 IST

America's National Aeronautics and Space Administration is getting ready to send a spacecraft to Mercury, the planet closest to the Sun.

The MESSENGER spacecraft will be launched into space from Cape Canaveral Air Force Station, Florida aboard a Delta II launch vehicle on August 2, the first day of a 13-day launch period, a press release said.

It will conduct an in-depth study of the planet during its three flybys in 2008 and 2009 and a year-long orbit of the planet starting in March 2011.

Mercury's proximity to the Sun makes it both a fascinating subject and an unprecedented mission design challenge. The sun can be up to 11 times brighter than what we see on Earth and surface temperatures at Mercury's equator can reach 450 degrees Celsius, but MESSENGER will operate at room temperature behind a sunshade of heat-resistant ceramic fabric.

The 1.2-ton spacecraft also features a heat-radiation system and will pass only briefly over Mercury's hottest regions, limiting exposure to the intense heat bouncing back from the broiling surface.

Carrying seven scientific instruments, it will provide the first images of the entire planet. It will also collect detailed information on the composition and structure of Mercury's crust, its geologic history, the nature of its thin atmosphere and active magnetosphere, and the makeup of its core and polar materials.

Some questions it is expected to help answer:
Why is Mercury - the densest planet in the solar system - mostly made of iron?
Why is it the only inner planet, besides Earth, with a global magnetic field?
How can the planet closest to the Sun, with daytime temperatures near 450 degrees Celsius (840 F), have what appears to be ice in its polar craters?

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"We're doing something no one has ever tried before," said MESSENGER Project Manager David G Grant, of the Johns Hopkins University's Applied Physics Laboratory (APL), Laurel, Maryland.

On a 4.9-billion mile (7.9-billion kilometer) journey that includes 15 loops around the Sun, the solar-powered MESSENGER will fly past Earth once, Venus twice and Mercury three times before easing into orbit around its target planet.

The Earth flyby, a year after launch, and the Venus flybys, in October

2006 and June 2007, will use the pull of the planets' gravity to guide MESSENGER toward Mercury's orbit.

The Mercury flybys in January 2008, October 2008 and September 2009, will fine-tune and slow MESSENGER's track while allowing the spacecraft to gather data critical to planning the mission's orbit phase.

MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) will become only the second spacecraft to set sight on Mercury. NASA's Mariner 10 sailed past it three times in 1974 and 1975 and gathered data on less than half the surface.

Dr. Sean C Solomon, from the Carnegie Institution of Washington, leads the mission as principal investigator; Johns Hopkins University's Applied Physics Laboratory designed, built and will operate the MESSENGER spacecraft for NASA's Office of Space Science.

External Link: For additional information about MESSENGER

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