NEAR tightens orbit, beams asteroid with laser

NEAR obtained this image mosaic of a portion of Eros' surface on February 29, 2000, from a range of 289 kilometers (180 miles). It shows features as small as 30 meters (100 feet) across. (Click image for large version)

By Richard Stenger
CNN Interactive Staff Writer

March 3, 2000
Web posted at: 5:17 p.m. EST (2217 GMT)

LAUREL, Maryland (CNN) -- The NEAR spacecraft tightened its orbit around Eros on Friday to an altitude of approximately 130 miles (208 km), slightly further than expected but well within the acceptable range, a mission scientist said.

The first artificial satellite around an asteroid, the NASA robot ship will chart the surface topography and gravitational field of Eros over the next month, using a variety of sophisticated instruments, including a laser range finder that it used for the first time this week.

The Near Earth Asteroid Rendezvous (NEAR) craft began a yearlong orbit on February 14. Scientists hope its detailed study of Eros will offer clues about the origins of the solar system.

NEAR had been circling Eros from about 200 miles (320 km). A 15-second engine burn Friday nudged it closer, but preliminary estimates suggest not enough to reach the target distance of 124 miles (200 km).

"It looks like the burn was a little short (but) it's good enough," said Bob Farquhar, mission director for the NEAR project.

Laser beam caresses surface

The spacecraft aimed its laser range finder earlier this week, firing a red beam at the space rock twice the size of Manhattan.

	MESSAGE BOARD
Stargazing
	IMAGE GALLERY
The best of Eros.

Scientists plan to use the laser more extensively when NEAR closes in even further on Eros, obtaining precise measurements about the surface features on the potato-shaped asteroid.

"We will get a good shape model from this. Probably more accurate than with the optical instruments," Farquhar said.

Moving 3 mph (5 km/h) in relation to Eros, NEAR will orbit the asteroid three times from its current distance.

Another engine burn on April 1 will nudge it into an orbit 60 miles (100 km) from Eros, now about 152 million miles (245 million km) from Earth.

Mission scientists have good reason to proceed cautiously each time they move NEAR closer to Eros, which tumbles in an eccentric manner as it circles the sun.

"We don't want to crash it into the asteroid, so we're going down slowly and carefully," Farquhar said.

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Near Earth Asteroid Rendezvous Mission
NASA Homepage
Asteroid Comet Impact Hazards
The Spacewatch Project
Smithsonian Astrophysical Observatory
Impact of an Asteroid off the New York Coast

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