LAUREL, MARYLAND - Jubilant space scientists waved a thumbs-up from behind their mission control computers today as NASA's Near Earth Asteroid Rendezvous (NEAR) spacecraft plopped itself into orbit around asteroid 433 Eros.
For NEAR engineers and scientists, it has been the best Valentine's Day gift of all -- and a gift that keeps on giving, they believe, throughout the year.
Following tense minutes of anticipation as signals from NEAR sped through space and finally reached ground stations in Goldstone, California -- part of the Jet Propulsion Laboratory's Deep Space Network -- Robert Farquhar, Applied Physics Laboratory (APL) mission manager for NEAR announced that the spacecraft had gone into orbit around Eros.
"This looks good...almost perfect. We're at Eros," he said.
NEAR fired its thrusters Monday morning at 10:33 a.m. Eastern Standard Time, just as the spacecraft was a little over 200 miles (322 kilometers) distant from the center of the asteroid. That burn of the spacecraft's small motors -- just under one-minute -- slowed NEAR enough to be caught in Eros' weak gravitational grip. Less than an hour later, ground operators here confirmed that the probe had entered Eros orbit.
"Be patient with us and you'll see a world revealed from a long, long time ago."
NEAR is more than 160 million miles (257 million kilometers) away from Earth. At that distance, one-way radio communications between the craft and mission controllers takes 15 minutes.
The plan now is for the probe to circuit Eros for a year, zipping over the asteroid's battered surface in a series of closer and closer flybys.
Equipment on the craft has been busy acquiring data on the rocky world's shape, mass and gravity field. Other NEAR instruments are geared to understand its chemistry and mineral makeup.
As the mission comes to an end in February 2001, NEAR scientists want to ease the craft into hover mode over specific areas on Eros. If given a go-ahead by NASA, the probe may attempt a controlled touchdown on the asteroid.
The Johns Hopkins University Applied Physics Laboratory, situated in Laurel, Maryland, is conducting the NEAR mission. A NASA Discovery-class probe, it is the first NASA planetary mission to be carried out by a non-NASA space center. APL engineering teams assembled the NEAR spacecraft over a fast-paced 26-month period, doing so at a cost of a little over $108 million.
NEAR is the first spacecraft to orbit a solar system small body -- that is, an asteroid or comet. It was launched on February 17, 1996 from Cape Canaveral Air Force Station, Florida.
In December 1998, the spacecraft was nearly lost while trying a first attempt to orbit Eros. The probe shut itself down, then proceeded to fire its thrusters wildly, using quantities of precious fuel. Fast-reacting ground teams placed the spacecraft on a yearlong trajectory that swung it back Eros' way for the February 14 target date.
"Everything looks rock solid," said Andrew Santo, APL's spacecraft team leader. "The burn went perfect, we're very close to nominal," he said.
NEAR was in autopilot mode as it executed a series of commands sent from Earth over the last few weeks, Santo said.
NEAR's successful end-of-the-line arrival at Eros produced smiles and a series of high-fives between project managers, NASA Administrator Daniel Goldin, and Senator Barbara Mikulski (D-Maryland), who was a strong champion for NEAR funding within Congress, as well as the NASA Discovery-class missions.
"The NEAR team has brought America a space valentine," Mikulski said, following confirmation that the probe had begun orbiting Eros.
Following the thruster firing, NEAR's orbital survey of the Eros starts today, with the spacecraft turning back into position to point its camera and other instruments at the asteroid. "Be patient with us and you'll see a world revealed from a long, long time ago," said Lucy-Ann McFadden a NEAR science team member from the University of Maryland.
"The camera is the star of the show for the rest of the day," said NEAR project scientist, Andrew Cheng, of the APL. The first close-up photos relayed by NEAR from its orbiting bird's-eye view are expected later today.
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