Encyclopedia Astronautica
NEAR



near.jpg
NEAR
Credit: NASA
American asteroid probe. One launch, 1996.02.17. NEAR (Near Earth Asteroid Rendezvous) was the first spacecraft ever to orbit and then (improvisationally) land on an asteroid.

The vehicle went into orbit around the asteroid 433 Eros and performed up-close observations for one year.

The NEAR mission was the first launch in NASA's Discovery Program. The spacecraft's mission was to rendezvous with and achieve orbit around the asteroid Eros in January, 1999, and study the asteroid for one year. However as it flew by the Earth on 23 January 1998, a problem caused an abort of the first encounter burn. The mission had to be rescoped for a later encounter, but NEAR successfully entered orbit around Eros on Valentine's Day 2000 and ended the mission by gently landing on its surface on 12 February 2001.

The primary scientific goals were to measure the asteroid' bulk properties (size, shape, volume, mass, gravity field, and spin state); surface properties (elemental and mineral composition, geology, morphology, and texture); and internal properties (mass distribution and magnetic field).

The spacecraft was 3-axis stabilized and used passive thermal control. Four deployed, non-articulating fixed solar panels provided 1600 watts at 1 AU. A fixed 1.5 m diameter high gain antenna provided X-band communications via the Deep Space Network with selectable data rates between 1 and 27 kbps. 1 Gbit solid state data storage was provided. The hydrazine propulsion system had one 100 lbf, four 5 lbf, and seven 1 lbf thrusters provided a total delta-V of 1425 m/s. Mission control was by JHU APL with navigation support from JPL.

The instrument payload totaled 55 kg and 48 watts and consisted of:

  • MultiSpectral Imager (MSI) - a refractive telescope with passively cooled Si CCD array (244 x 537) that would determine the overall size, shape, and spin characteristics of the asteroid, map the morphology and composition of the surface, and search for satellites of Eros. It had a 2.25 x 2.9 deg field of view, 10-16 meter resolution from 100 km altitude, was sensitive between 400 and 1100 nm.
  • X-Ray/Gamma-Ray Spectrometer (XGRS) - contained two sensors (an X-ray fluorescence spectrometer and a gamma-ray spectrometer), XGRS was used to determining the surface/near-surface elemental composition of the asteroid.
  • Near-Infrared Spectrograph (NIS) - a spectrometer covering 800-2700 nm, NIS was designed to map the mineralogical composition of Eros.
  • Magnetometer - a three-axis fluxgate sensor that would be used to measure Eros' magnetic field. These measurements would help determine the internal composition of the asteroid.
  • NEAR Laser Rangefinder (NLR) - an altimeter that used a solid-state pulsed laser to measure the distance between the spacecraft and the surface of the asteroid. It would be used to make would make accurate measurements of the asteroid's shape and detailed surface structure. The Nd-YAG laser operated at 1.064 mm wavelength, 6 meter resolution, 50 km range.
  • Radio Science - used the satellite's telemetry system to map Eros' gravity field.

The $ 650 million original estimated cost in May 1992 was reduced to $ 210 million via massive project reformulation to fit within Discovery program low-cost guidelines. This included the Delta launch for $ 55 million plus $ 122 million for the satellite.

AKA: Near Earth Asteroid Rendezvous.
Gross mass: 818 kg (1,803 lb).
Height: 2.75 m (9.02 ft).
First Launch: 1996.02.17.
Number: 1 .

More... - Chronology...


Associated Countries
See also
  • Delta The Delta launch vehicle was America's longest-lived, most reliable, and lowest-cost space launch vehicle. Development began in 1955 and it continued in service in the 21st Century despite numerous candidate replacements. More...

Associated Launch Vehicles
  • Delta American orbital launch vehicle. The Delta launch vehicle was America's longest-lived, most reliable, and lowest-cost space launch vehicle. Delta began as Thor, a crash December 1955 program to produce an intermediate range ballistic missile using existing components, which flew thirteen months after go-ahead. Fifteen months after that, a space launch version flew, using an existing upper stage. The addition of solid rocket boosters allowed the Thor core and Able/Delta upper stages to be stretched. Costs were kept down by using first and second-stage rocket engines surplus to the Apollo program in the 1970's. Continuous introduction of new 'existing' technology over the years resulted in an incredible evolution - the payload into a geosynchronous transfer orbit increasing from 68 kg in 1962 to 3810 kg by 2002. Delta survived innumerable attempts to kill the program and replace it with 'more rationale' alternatives. By 2008 nearly 1,000 boosters had flown over a fifty-year career, and cancellation was again announced. More...
  • Delta 2 7000 American orbital launch vehicle. The Delta 7000 series used GEM-40 strap-ons with the Extra Extended Long Tank core, further upgraded with the RS-27A engine. More...
  • Delta 7925-8 American orbital launch vehicle. Four stage vehicle consisting of 9 x GEM-40 + 1 x EELT Thor/RS-27A + 1 x Delta K + 1 x Star 48B with 2.4 m (8 foot) diameter fairing) More...

Associated Manufacturers and Agencies
  • NASA American agency overseeing development of rockets and spacecraft. National Aeronautics and Space Administration, USA, USA. More...
  • APL American manufacturer of rockets and spacecraft. Applied Physics Laboratory, Johns Hopkins University, Laurel, MD, Laurel, Maryland, USA. More...

Associated Programs
  • Discovery The Discovery program was begun by NASA in the early 1990s as the planetary counterpart to the Explorer program. More...

Bibliography
  • McDowell, Jonathan, Jonathan's Space Home Page (launch records), Harvard University, 1997-present. Web Address when accessed: here.
  • McDowell, Jonathan, Jonathan's Space Report (Internet Newsletter), Harvard University, Weekly, 1989 to Present. Web Address when accessed: here.
  • JPL Mission and Spacecraft Library, Jet Propulsion Laboratory, 1997. Web Address when accessed: here.
  • National Space Science Center Planetary Page, As of 19 February 1999.. Web Address when accessed: here.

Associated Launch Sites
  • Cape Canaveral America's largest launch center, used for all manned launches. Today only six of the 40 launch complexes built here remain in use. Located at or near Cape Canaveral are the Kennedy Space Center on Merritt Island, used by NASA for Saturn V and Space Shuttle launches; Patrick AFB on Cape Canaveral itself, operated the US Department of Defense and handling most other launches; the commercial Spaceport Florida; the air-launched launch vehicle and missile Drop Zone off Mayport, Florida, located at 29.00 N 79.00 W, and an offshore submarine-launched ballistic missile launch area. All of these take advantage of the extensive down-range tracking facilities that once extended from the Cape, through the Caribbean, South Atlantic, and to South Africa and the Indian Ocean. More...
  • Cape Canaveral LC17B Delta launch complex. Part of a dual launch pad complex built for the Thor ballistic missile program in 1956. Upgraded over the decades for use with Thor, Delta, Delta II, and Delta III launch vehicles, it remained in use for over half a century. More...

NEAR Chronology


1996 February 17 - . 20:43 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC17B. LV Family: Delta. Launch Vehicle: Delta 7925-8. LV Configuration: Delta 7925-8 D232.
  • NEAR - . Payload: Discovery 1. Mass: 818 kg (1,803 lb). Nation: USA. Agency: NASA Greenbelt. Program: Discovery. Class: Asteroids. Type: Asteroid probe. Spacecraft: NEAR. Decay Date: 2001-02-12 . USAF Sat Cat: 23784 . COSPAR: 1996-008A. Near Earth Asteroid Rendezvous (NEAR) mission was the first of NASA's Discovery missions, a series of small-scale spacecraft designed to proceed from development to flight in under three years for a cost of less than $150 million. The spacecraft's mission was to rendezvous with and achieve orbit around the asteroid Eros in January 1999, and study the asteroid for one year. However as it flew by the Earth on 23 January 1998, a problem caused an abort of the first encounter burn. The mission had to be rescoped for a later encounter but successfully entered orbit around Eros on Valentine's Day 2000 and ended the mission by gently landing on its surface on 12 February 2001.

1997 June 27 - .
  • NEAR, Asteroid Mathilde Flyby - . Nation: USA. Spacecraft: NEAR. Summary: Prior to its first flyby of the Earth on the way to Eros, NEAR flew within 1200 km of the C-class asteroid Mathilde..

2000 February 14 - .
  • NEAR, Asteroid Eros Orbit Insertion - . Nation: USA. Spacecraft: NEAR. NEAR finally entered orbit around Eros on Valentine's Day, 2000. Orbit insertion was at 15:34 GMT into a 323 x 370 km initial orbit with a period of 27 days. The renamed NEAR-Shoemaker probe moved into a 100 x 200 km orbit around Eros on April 2 at 02:00 GMT. NEAR returned spectacular detailed pictures of the surface over the next several months. Studies were made of the asteroid's size, shape, mass, magnetic field, composition, and surface and internal structure.

2001 February 12 - .
  • NEAR, Asteroid Eros Landing - . Nation: USA. Spacecraft: NEAR. Periapsis of the orbit was as low as 24 km above the surface of the asteroid during its final days. At the end of its mission, NEAR touched down on the surface of Eros at 20:01:52 GMT on 12 February 2001. The spacecraft obtained 69 high-resolution images before touchdown, the final image showing an area 6 meters across. NEAR apparently came to rest with the camera and gamma-ray spectrometer pointing towards the ground and the solar panels and low gain antenna pointing generally towards the Earth and Sun. NEAR was not designed as a lander, but survived the low-velocity, low-gravity impact, a signal continued after the "landing" using the omni-directional low-gain antenna as a beacon.

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