NASA Preparing Its Messenger Spacecraft for Mission to Mercury 2004-07-15 10:10 (New York) NASA Preparing Its Messenger Spacecraft for Mission to Mercury By Chris Dolmetsch July 15 (Bloomberg) -- NASA is preparing its Messenger spacecraft to take off on the first mission to the planet Mercury in 30 years. Messenger is scheduled to launch from Cape Canaveral Air Force Station in Florida at 2:16 a.m. local time Aug. 2. It will ride aboard a Boeing Co. Delta II rocket for a seven-year journey to the closest planet to the sun, the National Aeronautics and Space Administration said in a statement. Scientists hope the 2,442-pound (1,108-kilogram), $286 million Messenger's mission will help astronomers better understand how the Earth and the other terrestrial planets -- Venus and Mars -- formed and evolved and interact with the sun. ``The data we get at Mercury is really going to help us understand planetary formation and planetary interiors,'' said Deborah Dominique, a deputy project scientist for the mission, in a telephone interview. ``It all folds back into understanding our own world.'' NASA has been focusing on unmanned missions to planets in the Earth's solar system as its space shuttle program remains on hold following the destruction of Columbia last year. Its two Mars rovers have been scouring the Martian surface since January and the Cassini-Huygens satellite entered Saturn's orbit last month after a seven-year journey. Bush Strategy The mission comes as NASA is working to implement President George W. Bush's strategy for the U.S. space program laid out in January, which calls for human missions to the moon and Mars as stepping stones to further exploration of the solar system and beyond. Mercury is about 3,030 miles (4,875 kilometers) wide, or about 38 percent of the Earth's diameter, and about 36 million miles from the sun, orbiting the star every 88 days. Like each of the terrestrial planets, it has an iron-rich core surrounded by magnesium and iron silicates, or rock. Yet Mercury is the densest of the four terrestrial planets, and as much as 65 percent of its core could be metal -- almost twice as much as Earth's. Understanding why the planet is so much denser could help scientists explain how planets formed in different regions of the solar system. Temperatures on Mercury can range from 840 degrees Fahrenheit on its sunny side to minus 300 degrees on the dark side, yet Messenger's instruments will operate at room temperature behind a ceramic-cloth sunshade designed to protect it from solar extremes. Neglected Planet ``Mercury is a planet that's been neglected in a lot in solar system exploration because it's very difficult to fly a spacecraft from Earth and make it stop at Mercury without going splat, straight into the sun,'' said Paul Withers, a research associate in Boston University's astronomy department. Messenger is powered by two solar panels and a nickel- hydrogen battery. It has three main titanium fuel tanks that can hold as much as 53 gallons of hydrazine propellant, which is mixed with a nitrogen tetroxide oxidizer to start combustion. The spacecraft will fly by Earth in August 2005, then past Venus in October 2006 and June 2007, using the planets' gravitational pull to move closer to Mercury. It will move past Mercury three times between January 2008 and September 2009, mapping the surface as it prepares to enter orbit in March 2011 after a 4.9-billion-mile journey. Messenger will orbit about 124 miles above Mercury at its lowest point, using its seven scientific instruments to determine the makeup of surface rocks and the thickness of the planet's crust. NASA's Mariner 10 spacecraft mapped about 45 percent of the surface during its mission in 1974 and 1975, and Withers said astronomers are anxious to see what the other half holds. `No Idea' ``We don't know if there are little green men dancing around there and things like that,'' Withers said. ``We just have no idea what the surface of the planet looks like on that other 50 percent. So it's going to be very exciting to see that huge chunk of unknown real estate.'' It will also use its instruments to examine the planet's magnetic field and polar regions. Radar images of the poles have returned ``bright'' pictures that may show ice in craters, and scientists have theorized that there are areas that get cold enough for ice to form. Studying the magnetic field could help astronomers better understand how Earth's works. Messenger, which stands for MErcury Surface, Space ENvironment, GEochemistry and Ranging, was originally scheduled to launch in May. Takeoff was postponed in order for engineers to further test the spacecraft's fault-protection software. The spacecraft is operated and built by Johns Hopkins University's Applied Physics Laboratory in Laurel, Maryland. Its instruments were built by the laboratory, NASA's Goddard Space Flight Center, the University of Colorado and the University of Michigan. Seventh Mission Alliant Techsystems Inc.'s Composite Optics unit provided the structure, GenCorp Inc.'s Aerojet division built the propulsion system and closely held KinetX Inc. provided the navigation system. Messenger is the seventh mission in the agency's Discovery program, which includes the 1997 Mars Pathfinder mission and the Stardust spacecraft that collected a sample from a comet earlier this year. The European Space Agency and the Institute of Space and Astronautical Science in Japan plan to launch two spacecraft on a joint mission to study Mercury in 2011. ``The goal is to learn `how did the Earth form?' and `how did it get to the point to where it could support life?''' Dominique said. ``In order to understand that, we need to understand the other planets in our solar system and what evolutionary path they took, and that's why we explore these worlds.'' --Editor: Todd. Story illustration: For the Web site of NASA, see: {NASA }. For more on the Mercury Messenger mission, see: http://messenger.jhuapl.edu. To contact the reporter on this story: Chris Dolmetsch in Princeton at (1) (609) 750-4652 or cdolmetsch@bloomberg.net. To contact the editor responsible for this story: Aimee Sullivan at (1) (609) 750-4617 or asullivan@bloomberg.net. [TAGINFO] ATK US CN GY US CN NI US NI DC NI MD NI NASA NI SPACE NI SCIENCE NI GEN NI COS NI EDU NI CO NI MI NI MN NI TEC #<648901.52818># -0- Jul/15/2004 14:10 GMT