Overview

JPG = 67 KB - - - - - - - - GIF = 170 KB

Mission Summary

The Near Earth Asteroid Rendezvous (NEAR) mission is the first launch in the Discovery Program, a NASA initiative for small planetary missions with a maximum 3-year development cycle and a cost capped at $150 million for construction, launch, and 30 days of operation. The NEAR mission is managed for NASA by the Johns Hopkins University Applied Physics Laboratory , Laurel, Maryland.

As the first spacecraft to orbit an asteroid, the NEAR mission promises to answer fundamental questions about the nature and origin of near-Earth objects, such as the numerous asteroids and comets in the vicinity of Earth's orbit.

These objects are of interest for several reasons. First, they are the primary source of large bodies that collide with Earth, greatly influencing the evolution of the atmosphere and life on Earth. An asteroid collision with Earth was likely responsible for the mass extinction at the end of the Cretaceous period, and another impact in 1908 destroyed thousands of square kilometers of forest near Tunguska, Siberia.

In addition, clues to the nature of early solar system processes and conditions are preserved in various forms on small bodies like asteroids, comets, and meteorites (so-called primitive bodies). These records have been altered or destroyed on large, planet-sized bodies by processes of planetary evolution.

The near-Earth population of asteroids, in particular, is believed to contain clues to the nature of the building blocks (planetesimals) from which the inner planets, including Earth, were formed.

The NEAR mission will provide our first comprehensive scientific survey of an important class of objects found close to Earth, the near-Earth asteroids, and promises to be an auspicious beginning for the NASA Discovery Program.

433 Eros

Approximate Dimensions: 	14 x 14 x 40 km
Rotation Period:		5.27 hr
Class: 				S (silicate rock)
Surface Regolith Present
Orbit Parameters:
  		Perihelion	1.13 AU
 		Aphelion	1.78 AU
  		Inclination	10.8 degrees

Mission Characteristics

Launch Period:		Feb 16-Mar 1 1996 (15-day window)
Launch Vehicle:		Delta II-7925-8
Trajectory:		2-year Delta VEGA
Primary Mission:	Rendezvous with 433 Eros in Jan 1999
End of Nominal Mission:	December 1999

Rendezvous Geometry

Mission Objectives

The NEAR mission 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 the following:


• 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 Payload

(select instrument name for more details)

Instrument			   Mass (kg)	   Power (W)
 Multispectral Imager System 		10		 7
 X-ray/Gamma-Ray Spectrometer		26		31
 Near-IR Spectrograph			18		 9
 Magnetometer				 1		 1
 Laser Rangefinder			 5		22
 Radio Science				 *		 *
Totals					60		70

*Part of engineering subsystems

Spacecraft Characteristics

Mass:			805 kg (includes propellant)
Basic Design:		Three-axis stabilized
			Fixed solar panels 
			Fixed 1.5-m high-gain antenna
			Fixed instruments
			Passive thermal design
			Redundant critical subsystems
Power:			Solar powered 1600 W @ 1 AU 
Telemetry:		X-band link to NASA Deep Space Network
Size:			1.7 square-meters at the base
Data Rate:		Selectable between 1 to 27 kb/s
Memory Capacity:	1.0-Gb solid-state 
Propulsion:		(1) 100-lb thruster, (4) 5-lb thrusters,
			(7) 1-lb thrusters; 
			total Delta V of 1420 m/s
Mission Control Center:	Applied Physics Laboratory
Navigation Support:	Jet Propulsion Laboratory



The NEAR Spacecraft

Mission Management

NASA Program Manager:	Elizabeth Beyer
NASA Program Scientist:	Jurgen Rahe
APL Project Manager:	Thomas Coughlin
APL Project Scientist:	Andrew Cheng
APL Mission Manager:	Robert Farquhar

Science Team Leaders

Multispectral Imager / Near-Infrared Spectrograph

Joseph Veverka Cornell University

X-Ray/Gamma-Ray Spectrometer

Jacob I. Trombka NASA/GSFC

Magnetometer

Mario H. Acuña NASA/GSFC

Laser Rangefinder

Maria T. Zuber JHU and GSFC

Radio Science

Donald K. Yeomans NASA/JPL

Go to NEAR Overview Page

Go to Small Bodies Page

Return to MSSS Home Page