NEAR gets close up look at asteroid Eros
NASA NEWS RELEASE
Posted: Feb. 17, 2000
Since the NEAR spacecraft met up with and began its historic orbit of Eros on Feb. 14, NEAR team members at the Johns Hopkins University Applied Physics Laboratory in Laurel, MD, which manages the mission for NASA, have pored over images and other early scientific returns. It will take months to unravel the deeper mysteries of Eros, but data from NEAR's final approach and first days of orbit offer tantalizing glimpses of an ancient surface covered with craters, grooves, layers, house-sized boulders and other complex features.
"Work is just starting, but it's already clear that Eros is much more exciting and geologically diverse than we had expected," says Dr. Andrew Cheng, of the Applied Physics Laboratory, who serves as the NEAR mission's lead scientist.
Scientists now know that Eros' mass is 2.4 grams per cubic centimeter -- about the bulk density of Earth's crust and a near match of the estimates derived from NEAR's flyby of Eros in December 1998.
Even without in-depth analysis, pictures snapped with NEAR's Multispectral Imager offer several clues about Eros' age and geography. The large number and concentration of craters points to an older asteroid, uniform grooves across its craters and ridges hint at a global fabric and, perhaps, underground layers. In addition to numerous boulders, the digital camera has also captured brighter spots on the surface that NEAR scientists are anxious to study.
NEAR's Near-Infrared Spectrometer has picked up variations in the asteroid's mineral composition, possibly the proportions of pyroxene and olivine, iron-bearing minerals commonly found in meteorites.
A low-phase flyby during last weekend's final approach put NEAR directly between the sun and Eros, allowing the instrument to gather unique data on the asteroid's mineral makeup under optimal lighting. Combined with multispectral images, this information will help form the first mineral map ever made of an asteroid.
For the next year, NEAR's instruments will continue to examine the potato-shaped asteroid's chemistry, geology, and evolutionary history. The mission also includes a radio science experiment to more precisely calculate Eros' density and mass distribution -- clues critical to determining the asteroid's gravity and refining NEAR's orbit.
NEAR's scientific capabilities expand soon, when its X- ray/Gamma-Ray Spectrometer and Laser Rangefinder are turned on within the next two weeks. The spectrometer will measure important chemical elements such as silicon, magnesium, iron, uranium, thorium and potassium; the laser scans will determine Eros' precise shape.
Mission Status Center
For a detailed account of NEAR's orbit insertion see Spaceflight Now's Mission Status Center.
Animation shows the NEAR spacecraft encountering 433 Eros and firing its thrusters to begin orbiting the asteroid.
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The infrared spectrometer aboard NEAR will be used to determine the asteroid's mineral composition as seen in animation.
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Dr. Andrew Cheng, NEAR's project scientist, explains what experiments the spacecraft will conduct once it arrives at Eros.
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Dr. Naom Izenberg, NEAR's instrument scientist, describes how the spacecraft will explore the early history of our solar system.
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