APL Awaits Launch Spacecraft To Fly Near Asteroid Steve Libowitz ----------------------- Editor It is said that a voyage of a thousand miles begins with one step. Such is the case for the Near Earth Asteroid Rendezvous spacecraft, the Applied Physics Laboratory-designed and -built orbiter, which is scheduled on Friday to begin its 1.3 billion mile journey to asteroid 433 Eros. It is expected to reach its destination in early 1999. The NEAR spacecraft--the first asteroid orbiter of the space age--will be the initial launch in NASA's Discovery program for "faster, better, cheaper" planetary exploration. NEAR is also the first spacecraft to orbit an asteroid, chunky pieces of rock--sometimes hundreds of miles wide--that litter space generally along a belt between Mars and Jupiter. They are interesting enough to study as remnants from the creation of the solar system. But they also are quite unpredictable, often leaving their orbit and crashing into planets. In some cases, these cosmic collisions demolish the planet hit or create havoc upon them. Smaller asteroid assaults created craters on Earth. It is theorized that such a collision was responsible for setting into motion the environmental crisis that led to the extinction of the dinosaurs 65 million years ago. Today, some asteroids pass dangerously close to Earth. NEAR's target is one of them. The 25-mile-long Eros asteroid--the smallest solar system body to be orbited by a spacecraft--is one of a type that exists relatively near Earth. Asteroids such as Eros are thought to be dead comets or fragments from Main Belt asteroids, which orbit the sun. Approximately 250 near-Earth asteroids are known, and scientists estimate that there are at least 1,000 with diameters of 0.6 mile or more. Some scientists predict that Eros may one day cross Earth's path. So astronomers and physicists want to get a better look at it in hopes of being able to better predict its future course as well as to better understand the origins and makeup of the universe. The mission's scientific goal is to determine Eros' size, shape, mass and magnetic field and to measure--for the first time--an asteroid's detailed composition and surface structure. NEAR may provide scientific clues to long-standing scientific mysteries, such as the origin of meteorites and the relationship between asteroids, meteorites and comets. As a bonus during its 35-month journey to Eros, NEAR could pass within 750 miles of the large Main Belt asteroid 253 Mathilde. The flyby of Mathilde is tentatively scheduled for June 27, 1997. In addition, the spacecraft returns to Earth's vicinity for a slingshot gravity assist on Jan. 22, 1998, a maneuver that bends the NEAR trajectory 11 degrees out of the ecliptic to match Eros' orbital plane. The spacecraft makes its initial closest approach to the asteroid before it glides into orbit at approximately 310 miles on Feb. 6, 1999. During the yearlong rendezvous, NEAR will probe the asteroid at altitudes as low as 9 miles. APL is the first space center outside NASA to conduct a planetary mission. Although the NEAR mission will be managed by NASA from its headquarters in Washington, APL will direct mission and science operations from its Rockville campus. The project marks a new way NASA will be doing business in an era of tightened purses. The Jupiter-bound Galileo mission cost the federal government $1.6 billion when it was launched six years ago. The Discovery mission guidelines called for a development ceiling of $150 million in fiscal year '92. APL built the NEAR spacecraft for less than $112 million (in fiscal year '92 dollars) and completed it in less than the three years allowed by NASA. "This is a revolution," NASA associate administrator for space science Wesley T. Huntress Jr. told The New York Times. "It's a whole new way of doing business." "We took a planetary mission and did it better, faster and cheaper," APL's Stamatios M. Krimigis told the Times. NEAR's instrument package includes an X-ray/gamma ray spectrometer, near-infrared spectrograph, laser rangefinder, magnetometer, radio science experiment and a multispectral imager fitted with a CCD imaging detector capable of photographing details on Eros' surface as small as 3 feet. Several of the instruments are derived from designs developed by JHU/ APL for Department of Defense spacecraft, an example of dual-use technology transferred to the civilian sector. ----------------------------------------------------------------- NEAR on the Net ----------------------------------------------------------------- You can follow the progress of the NEAR mission by turning to the following homepages on the World Wide Web: JHU/APL, http://www.jhuapl.edu JHU/APL Space Department, http://sd-www.jhuapl.edu/sdpublic.html JHU/APL NEAR, http://hurlbut.jhuapl.edu:80/NEAR/ NSSDC NEAR, http://nssdc.gsfc.nasa.gov/planetary/near.html NASA Headquarters Discovery Program, http://mercury.hq.nasa.gov/office/discovery/ NSSDC Asteroid, http://nssdc.gsfc.nasa.gov/planetary/planets/asteroidpage.html NSSDC Asteroid factsheet, http://nssdc.gsfc.nasa.gov/planetary/factsheet/asteroidfact.html NASA/Ames Asteroid and Comet Impact Hazard, http://ccf.arc.nasa.gov/sst/ The Near Earth Asteroid Rendezvous launch is scheduled for Friday, Feb. 16, at 3:53 p.m. EST. For up-to-date information about the launch, call (407)867-2314.
Go to Gazette Homepage