Near Shoemaker

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NEAR Shoemaker was the first spacecraft to orbit around an asteroid, the first to land on an asteroid and the first solar powered spacecraft to travel beyond the orbit of Planet Mars. NEAR Shoemaker was the first of NASA’s “faster, better, cheaper” series of Discovery spacecraft. NEAR stands for Near Earth Asteroid Rendezvous.

Near Spacecraft Picture - Near Shoemaker

Johns Hopkins Applied Physics Laboratory built and managed the NEAR mission. The NEAR Shoemaker spacecraft was originally known as NEAR (Near Earth Asteroid Rendezvous) and was renamed by NASA on March 14, 2000 in honour of geologist Gene Shoemaker. The Near mission was roughly five years from launch (February 17, 1996) until the end of the extended mission on the surface of Eros (February 28, 2001).

The aim of the NEAR mission was to:

1.  Determine the physical and geological properties of a near-Earth asteroid. Eros was the target asteroid.

  1. To further our knowledge on the nature and origin of the many asteroids, meteorites and comets close to Earth’s orbit.
  2. Further our understanding of how and under what conditions the planets formed and evolved.

Near Shoemaker achieved all of its science goals during the year in orbit and conducted the first long-term close-up study of an asteroid. An additional bonus was despite being designed as an orbiter, it achieved the unbelievable by landing on asteroid Eros. Future human explorers might visit Eros and perhaps in the distant future space tourists will visit it.


Spacecraft Info

NEAR Shoemaker was about the size of a car. It resembled an eight-sided box made of aluminium honeycomb panels, each 1.7 metres square, to which four gallium arsenide solar arrays were attached to provide electrical power. At launch, NEAR weighted 805kg (1.1775 lb), of which 325 (717 lb) was propellant. The scientific payload was much lighter, weighing just 56kg (124 lb).

The spacecraft’s extensive scientific payload comprised: a Mutli-Spectral Imager, a Near-Infrared Spectrometer, an X-Ray/Gamma-Ray Spectrometer, a Laser Rangefinder, a Magnetometer and a Radio Science Experiment.

Information sent back by NEAR included some 160,000 images that covered the entire surface of Eros, and 11 million laser ranging measurements to provide topographical information.


History

* Johns Hopkins Applied Physics Laboratory designed and built NEAR Shoemaker in 26 months and shipped it to Kennedy Space Center in Florida a month ahead of schedule. It built it in just 26 months at a cost of $223 million – less than expected, Johns Hopkins returned $3million to NASA.

* NEAR Shoemaker was launched by a Boeing Delta 2 rocket from Cape Canaveral in Florida on February 17, 1996. NEAR mission was designed to swing the spacecraft around Earth for a gravity boost which allowed use of the smaller, more economical Delta rocket. A direct trip from Earth to Eros would have taken about a year.

* The five year space trek covered some 3.2 billion km (2 billion miles) and included an Earth swing-by, a flyby of the main-belt asteroid Mathilde and two encounters with Eros.

* NEAR Shoemaker was supposed to reach Eros two years and 327 days after launch. Its entry into orbit around Eros was delayed by a year and 23 days after a failed orbit insertion attempt on December 20, 1998.

* NEAR Shoemaker entered orbit around Eros on February 14, 2000 on Valentine’s Day date. It orbited Eros 230 times from various distances.

* Near Shoemaker landed on Eros on February 12, 2001. It transmitted 69 close-up images of the surface during its four and a half hours descent. It landed on Eros at a gentle 6.4km/hr (4 mph). The landing site of NEAR Shoemaker was at the edge of a saddle-shaped feature on the surface of Eros, known as Himeros.

* After two mission extensions and two weeks of operating on Eros, the NEAR Shoemaker mission end on February 28, 2001 when communications shut down.


Eros Asteroid

Eros Asteroid Image

Eros is one of the largest near-Earth asteroids, with a mass thousands of times greater than similar asteroids. Eros asteroid is named after the Greek god of love. Eros was the 433rd asteroid to have its orbit calculated. Eros has far fewer craters with diameters below 100 metres (330ft) than was expected from studies of the Moon, Mercury and Mars.

Eros is potato shaped and is 33 kilometres (21 miles) in length and 13 kilometres (8) miles wide. The gravity on Eros is very weak. A person weighing 90kg (200 lb) on Earth would weigh around 50 grams on Eros, and a cork popped from a champagne bottle would have no difficulty in entering orbit around the asteroid.

The temperature on Eros is estimated to vary between 100 degrees Celsius during the day and 150 degrees below zero during the night.


Did you know?

– Near Shoemaker was the first NASA planetary mission to be built and controlled by a non-NASA space center. Radio signals from NEAR Shoemaker took around 15 minutes to travel to Earth during the landing.

– Gene Shoemaker was a geologist and one of the founders of the fields of planetary science and is best known for co-discovering the Comet Shoemaker-Levy 9 with his wife Carolyn Shoemaker and David Levy. He helped to pioneer the field of astrogeology by founding the Astrogeology Research Program of the United States Geological Survey in 1961. He died in a car accident in 1997 while on an annual study of impact craters in the Australian outback. Shoemaker once said he would like to take a geologist’s hammer to Eros.

– Asteroids that come within 121 million miles (195 million kilometres) of the sun are known as near-Earth asteroids. Theory holds that most of these objects broke away from the main asteroid belt between Mars and Jupiter. Aside from the moon they’re our closest neighbours in the solar system.

– NASA used the Deep Space Network with its three antenna stations located in Goldstone (California), Canberra (Australia) and Madrid (Spain) for communications.


Related Space Books

The Near Earth Asteroid Rendezvous Mission by C. T. Russell
From Amazon.comAmazon.co.ukAmazon.ca

Deep Space: The NASA Mission Reports by Robert Godwin (April 2005)
From Amazon.comAmazon.co.ukAmazon.caecampus.com

Impact!: The Threat of Comets and Asteroids
by Gerrit L. Verschuur
From Amazon.comAmazon.co.uk

Asteroid Impact by Douglas Henderson (Illustrator), Toby Sherry (Editor), Doug Henderson
From Amazon.comAmazon.co.uk


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