NASA Sets a Date With Eros

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In just over a year, NASA will launch the first spacecraft designed to rendezvous with an asteroid.

The Near Earth Asteroid Rendezvous (NEAR) mission promises to answer fundamental questions about the nature of near-Earth objects such as asteroids and comets. These objects are believed to consist of debris from the earliest days of planetary formation 4.5 billion years ago and better knowledge of them should provide clues about the origin and evolution of the Solar System. Near-Earth objects are anticipated to be a very important source of resources for future space development.

Scheduled for launch in February 1996 aboard a Delta 2 rocket, the NEAR spacecraft should arrive in orbit around asteroid 433 Eros in early January 1999. It will then survey the rocky body for a minimum of one year, at altitudes as close as 24 kilometers (15 miles). Eros is one of the largest and best-observed asteroids whose orbits cross Earth's path. These asteroids are closely related to the more numerous "Main Belt" asteroids that orbit the Sun in a vast doughnut-shaped ring between Mars and Jupiter.

The goal of the NEAR project is to carry out a mission with high scientific return and wide participation at relatively modest cost. NEAR will make the first quantitative and comprehensive measurements of an asteroid's composition and structure. The measurements have been identified by the National Academy of Sciences as the most important scientific objectives in the exploration of primitive bodies.

Primary scientific goals of the NEAR mission are to measure:

Bulk Properties: Size, shape, volume, mass, gravity field, and spin state.

Surface Properties: Elemental and mineral composition, geology, morphology, and texture.

Internal properties: Mass distribution and magnetic field.

Science data and related products will be archived in near real-time making them available for access by the general science community, the public and educators via the Internet.

The NEAR Science Payload consists of six instruments: a multispectral imager system; a near-infrared spectrograph; an X-ray/Gamma-ray spectrometer; a magnetometer; a laser altimeter; and the spacecraft's radio, which is also used for gravity measurements.

The U of A is privileged to have a member of the NEAR science-instrument team. Professor William V. Boynton of the Lunar and Planetary Laboratory will be participating in the development and operation of the X-Ray/Gamma-Ray Spectrometer. Dr. Boynton was principal investigator of the ill-fated Mars Observer Gamma Ray Spectrometer.

The Johns Hopkins University Applied Physics Laboratory in Laurel, Md. will build and operate NEAR, making it the first NASA planetary mission to be conducted by a non-NASA space center.

The NEAR project began in late 1993 and it will be the first launch in NASA's Discovery program, an initiative based on small planetary science missions with short development cycles and stringent cost caps. It requires missions to proceed from development to flight in less than three years, with total spacecraft and instrument development costs limited to no more than $150 million (in 1992 dollars) and an acceptance of a greater level of technical risk than on typical NASA missions.

Compiled from NASA press releases by Chris Lewicki