BY JUSTIN RAY

February 17, 2000 -- Follow the NEAR spacecraft's orbit insertion around asteroid 433 Eros. Reload this page for the very latest on the mission.

THURSDAY, FEBRUARY 17, 2000

Only a few days into the first close-up study of an asteroid, data from NASA's Near Earth Asteroid Rendezvous (NEAR) mission indicate that 433 Eros is no ordinary space rock. See our latest report for full details and pictures.

MONDAY, FEBRUARY 14, 2000
1940 GMT (2:40 p.m. EST)

Officials are elated with today's successful arrival of NEAR at asteroid 433 Eros. The asteroid's weak gravity pull was able to capture the passing space probe when NEAR fired its thrusters to slow down about 160 million miles from Earth. NEAR is the first robotic satellite to orbit any small body in space.

Preliminary data shows the capture orbit features a periapsis, or low point, of plus or minus 49 km to the expected 327 km, an apoapsis, or high point, of plus or minus 67 km to the expected 450 km and period of plus or minus a half-day of the expected 27.6 days. What appears to be a large uncertainty in these numbers is caused by the unknowns about Eros' mass. Researchers say the understanding of the mass will be improved over the next few days, allowing the precise orbit achieved around the space rock to be refined.

NEAR has returned the first batch of images of Eros since the orbit insertion. Also, data collected from the overnight observations asteroid's northern hemisphere using NEAR's infrared spectrometer has been transmitted to Earth.

See the first image of Eros taken after orbit insertion.

Overall, the NEAR spacecraft is in good health almost four years since it was launched into space.

NASA plans to hold an early science results news conference on Thursday at 1800 GMT (1 p.m. EST).

1600 GMT (11:00 a.m. EST)

"The NEAR spacecraft is in orbit around the asteroid Eros!" That is the word from Dr. Robert Farquhar, the NEAR mission director.

Accelerometer data from NEAR is now being received on Earth from the spacecraft. It appears there was a very small under-burn, but nothing of concern.

In about an hour, the spacecraft will begin taking additional observations of the asteroid to determine the precise orbit NEAR achieved around Eros.

A press conference is planned for 1900 GMT (2 p.m. EST) today.

1556 GMT (10:56 a.m. EST)

A frame of data from the spacecraft shows NEAR's fuel tanks No. 1 and 3 open during the burn. At this point, all indications are that the burn went as planned. However, officials are awaiting complete data from the spacecraft to verify everything was successful.

1551 GMT (10:51 a.m. EST)

All indications show the burn was very nominal, about 0.04 percent from perfect. Data from the NEAR spacecraft is expected in about five minutes.

1550 GMT (10:50 a.m. EST)

Earth is receiving data that indicates the NEAR spacecraft has completed its orbit insertion burn! Further information will be needed over the next few minutes from NEAR to verify overall satellite health.

1544 GMT (10:44 a.m. EST)

Data from the NEAR spacecraft travels the 15 minutes to Earth's Goldstone tracking station in California. From there, it is sent to the Jet Propulsion Laboratory in California, uplinked to a geostationary satellite, received by NASA's Goddard Space Flight Center in Maryland and finally obtained by NEAR's controllers at the Johns Hopkins University in Maryland.

1540 GMT (10:40 a.m. EST)

A pair of large dish antennas in Goldstone, California, will be used to verify the NEAR spacecraft completed the orbit insertion burn. Onboard the satellite, NEAR's two data recorders should have collected all the information on the burn.

1535 GMT (10:35 a.m. EST)

The Near Earth Asteroid Rendezvous spacecraft should have completed its critical thruster firing to enter an orbit around 433 Eros. However, Earth won't "see" this maneuver until 1547:27 GMT (10:47:27 a.m. EST).

1530 GMT (10:30 a.m. EST)

Now about three minutes away from ignition of the orbit insertion burn. The maneuver will start at 1533:06 (10:33:06 a.m. EST) and last until 1534:03 (10:34:03 a.m. EST). NEAR officials say they don't expect to data on the burn until 1547 GMT (10:47 a.m. EST).

1520 GMT (10:20 a.m. EST)

"We are almost there," says Dr. Robert Farquhar, NEAR mission director. The orbit insertion burn in upcoming at 1533 GMT (10:33 a.m. EST). The firing of NEAR's thrusters will last about 57 seconds, slowing the craft so asteroid 433 Eros' gravity can capture the probe. If a problem occurs today that delays the burn, officials say they have contingency plans that would allow for orbit insertion over the next couple of days.

NEAR had an engine abort in December 1998, causing the craft to miss Eros during the first encounter attempt. Controllers sent NEAR through a U-turn, setting up for today's historic event and saving the mission.

1510 GMT (10:10 a.m. EST)

The NEAR spacecraft was the first mission launched as part of NASA's Discovery program. This series of space probes are built with the motto "faster, better, cheaper" at heart. After NEAR's launch in February 1996, the highly successful Mars Pathfinder followed in December, bound for the Red Planet. Pathfinder arrived on July 4, 1997, landing on Mars and deploying a small rover. The third Discovery mission was Lunar Prospector that mapped the moon's gravity field, magnetic properties and chemical composition. Prospector completed its successful mission last July. The fourth mission was launched last February -- the Stardust probe designed to collect comet dust and return the samples to Earth. Stardust is a 7-year mission.

NASA has approved four additional missions for launch over the next few years.

1500 GMT (10:00 a.m. EST)

After its four-year journey, the Near Earth Asteroid Rendezvous space probe is approaching its destination -- the asteroid 433 Eros. This space rocket is commonly referred to as potato-shaped, and is known to be roughly 21 by 8 by 8 miles. That is twice the size of Manhattan Island in New York.

The NEAR spacecraft is currently operating through a computer sequence that was loaded aboard the satellite quite some time ago. At this point, controllers say they are just watching and don't have much to do.

1430 GMT (9:30 a.m. EST)

The Near Earth Asteroid Rendezvous spacecraft, called NEAR, is about one hour away from firing its hydrazine thrusters to enter orbit around the asteroid 433 Eros. In doing so, NEAR will become the first space mission to orbit a small body in our solar system.

Controllers at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, report NEAR is in the proper attitude for the one-minute maneuver expected to begin at 1533 GMT (10:33 a.m. EST).

The rendezvous sequence was started by NEAR at 0700 GMT (2 a.m. EST) on Sunday. This program includes a unique low-phase flyby of Eros. About five hours ago, the spacecraft flew directly between the sun and Eros, allowing NEAR's infrared spectrometer to obtain observations of the asteroid's northern hemisphere under near-perfect lighting conditions. These observations were aimed at studying Eros' mineral composition.

The upcoming orbit insertion will occur when NEAR is about 207 miles from the center of Eros. The engine firing will slow the craft to allow the asteroid's weak gravity field to capture NEAR.

Officials expect to confirm a succesful orbit around Eros no later than 1630 GMT (11:30 a.m. EST).