BY SPACEFLIGHT NOW

February 28, 2001 -- Follow the conclusion of NASA's NEAR Shoemaker exploration mission after the craft's unprecedented landing on an asteroid. Reload this page for the very latest.

WEDNESDAY, FEBRUARY 28, 2001

NASA's NEAR Shoemaker -- the intrepid space probe that provided the first intensive examination of an asteroid -- has finally reached the end of its five-year adventure. Read our full story.

FRIDAY, FEBRUARY 23, 2001

NASA granted an additional four-day extension for the Near Earth Asteroid Rendezvous (NEAR) Shoemaker mission on Friday so that the spacecraft can return additional data from the surface of the asteroid Eros through the end of the month. Read our full story.

WEDNESDAY, FEBRUARY 14, 2001

NASA granted the NEAR Shoemaker mission a last-minute reprieve Wednesday, extending the mission by up to ten days to give scientists time to capitalize on a surprisingly successful landing on the surface of the asteroid Eros. Read our full story.

2300 GMT (6:00 p.m. EST)

Ground controllers have sent commands to the NEAR Shoemaker spacecraft to resume its scientific work on the surface of Eros.

As announced earlier today, NEAR's mission has been extended for up to 10 days to gather data from the spacecraft's gamma-ray spectrometer, a scientific instrument that could provide unprecedented information about the surface and subsurface composition of Eros. Mission controllers at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., have configured the instrument to begin collecting and recording this information.

NEAR Mission Operations Manager Robert Nelson said the team is also sending commands to prevent the rest of the spacecraft from sending data to its onboard recorder, since the only reliable telemetry link is through NEAR Shoemaker's low-gain antenna.

"Now that we have landed, collection and recovery of critical gamma-ray data is our primary objective," he said.

2100 GMT (4:00 p.m. EST)

At today's news conference, senior NEAR Shoemaker project officials said the spacecraft would not relaunch from the surface of asteroid Eros because such an endeavor lacked purpose. Watch a video clip of the officials' statements.

1740 GMT (1:40 p.m. EST)

Today's statement from the Near Earth Asteroid Rendezvous mission project:

The NEAR Shoemaker spacecraft's historic soft landing on asteroid 433 Eros Feb. 12 turned out to be a mission planner's dream - providing NEAR team members with more scientific and engineering information than they ever expected from the carefully designed series of descent maneuvers.

"We put the first priority on getting high-resolution images of the surface and the second on putting the spacecraft down safely - and we got both," says NEAR Mission Director Dr. Robert Farquhar of the Johns Hopkins University Applied Physics Laboratory in Laurel, Md., which manages the Near Earth Asteroid Rendezvous (NEAR) mission for NASA. "This could not have worked out better."

Two days after a set of five de-orbit and braking maneuvers brought it to the surface of Eros, NEAR Shoemaker is still communicating with the NEAR team at the Applied Physics Lab. The spacecraft gently touched down at 3:01:52 p.m. EST on Monday, ending a journey of more than 2 billion miles (3.2 billion kilometers) and a full year in orbit around the large space rock.

Yesterday the NEAR mission operations team disabled a redundant engine firing that would have been activated had it been necessary to adjust the spacecraft's orientation in order to receive telemetry from it. But because NEAR Shoemaker landed with such a favorable orientation, and telemetry has already been received, it was no longer necessary to move the spacecraft from its resting place.

Mission operators say the touchdown speed of less than 4 miles per hour (between 1.5 and 1.8 meters per second) may have been one of the slowest planetary landings in history. They also have a better picture of what happened in the moments after the landing: What they originally thought was the spacecraft bouncing may have been little more than short hop or "jiggle" on the surface; the thrusters were still firing when the craft hit the surface, but cut off on impact; and NEAR Shoemaker came down only about 650 feet (200 meters) from the projected landing site.

"It essentially confirmed that all the mathematical models we proposed for a controlled descent would work," says Dr. Bobby Williams, NEAR navigation team leader at NASA's Jet Propulsion Laboratory. "You never know if they'll work until you test them, and this was like our laboratory. The spacecraft did what we expected it to do, and everyone's real happy about that."

NEAR Shoemaker snapped 69 detailed pictures during the final three miles (five kilometers) of its descent, the highest resolution images ever obtained of an asteroid. The camera delivered clear pictures from as close as 394 feet (120 meters) showing features as small as one centimeter across. The images also included several things that piqued the curiosity of NEAR scientists, such as fractured boulders, a football-field sized crater filled with dust, and a mysterious area where the surface appears to have collapsed.

"These spectacular images have started to answer the many questions we had about Eros," says Dr. Joseph Veverka, NEAR imaging team leader from Cornell University in Ithaca, N.Y., "but they also revealed new mysteries that we will explore for years to come."

NEAR Shoemaker launched on Feb. 17, 1996 - the first in NASA's Discovery Program of low-cost, scientifically focused planetary missions - and became the first spacecraft to orbit an asteroid on Feb. 14, 2000. The car-sized spacecraft gathered 10 times more data during its orbit than originally planned, and completed all the mission's science goals before Monday's controlled descent.

"NEAR has raised the bar," says Dr. Stamatios M. Krimigis, head of the Applied Physics Laboratory's Space Department. "The Laboratory is very proud to manage such a successful mission and work with such a strong team of partners from industry, government and other universities. This team had no weak links - not only did we deliver a spacecraft in 26 months, we were ready to launch a month early, and that efficiency continued through five years of operations. This is what the Discovery Program is designed to do."

1702 GMT (1:02 p.m. EST)

NASA has formally announced the decision to extend NEAR Shoemaker's mission by up to 10 days to gather more data from the craft's gamma ray spectrometer instrument. The data would significantly improve scientists knowledge of elements in the asteroid's surface. NEAR's mission had been scheduled to end today.

1620 GMT (11:20 a.m. EST)

NEAR Shoemaker's five-year mission might not end today after all, sources suggest. Managers are considering an option to continue receiving information from the probe for the next week. Officials have not publicly announced anything yet. That will come at the 1 p.m. EST news conference today.

TUESDAY, FEBRUARY 13, 2001

Officials will hold a news conference on Wednesday at 1 p.m. EST (1800 GMT) to discuss NEAR Shoemaker's landing and status of the spacecraft. Rumors continue to swirl about the potential of relaunching the craft, but the project says it is unlikely.

We will provide a live streaming video broadcast of the briefing and provide updates on this page as details become available.

Meanwhile, a statement released from Johns Hopkins University Applied Physics Laboratory on Tuesday said the NEAR Shoemaker mission operations team had disabled a redundant engine firing command that would have been activated if it became necessary to adjust the spacecraft's orientation in order to receive telemetry from the ground.

But because NEAR Shoemaker landed with a favorable orientation, and telemetry has already been received, it is no longer necessary to move the spacecraft from its resting-place on the surface of Eros.s

1945 GMT (2:45 p.m. EST)

The Johns Hopkins University Applied Physics Laboratory issued the following status report today:

A day after its gentle touchdown on the surface of an asteroid - a deep-space first - the NEAR Shoemaker spacecraft is still communicating with the NEAR team at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md.

Mission operators picked up a single frame of telemetry from NEAR Shoemaker's low-gain antenna about 6 hours after the spacecraft's near-perfect landing on Eros, the 21-mile-long asteroid the craft had orbited for the past year. This information is helping the team assess the overall health and performance of the spacecraft, as team members evaluate ways they could gather additional telemetry and data from the craft. A decision on how to do that could be reached as early as later today.

NEAR Shoemaker touched town on Eros yesterday at 3:02:10 EST, cruising to the asteroid's surface at less than 4 mph. Cheers and congratulations filled the Mission Operations Center at APL, which built the spacecraft and manages the mission for NASA, when NEAR Mission Director Robert Farquhar announced, "I'm happy to say the spacecraft is safely on the surface of Eros."

The last image snapped by NEAR Shoemaker was only 394 feet (120 meters) from the asteroid's surface and covered a 20-foot (6-meter) area. NEAR Shoemaker continued to send a signal to Earth, assuring the team that it had landed gently. The signal was identified by radar science data, and about an hour later was locked onto by NASA's Deep Space Network antennas, which continue to monitor the spacecraft 196 million miles from Earth.

MONDAY, FEBRUARY 12, 2001

A review of data by NEAR Shoemaker ground controllers has pin-pointed the most likely time of landing as 3:02:10 p.m. EST (2002:10 GMT). The information also indicates the touchdown speed was 4 mph (1.9 meters per second). The final picture was taken by the probe at 394 feet (120 meters) above the asteroid's surface and covered a 20-foot (6-meter) area.

NASA's Deep Space Network -- a collection of powerful communications antennas around the world -- have been able to successfully "lock on" to NEAR Shoemaker. This is an improvement over the simple beacon signal that was heard at the time of landing. There has not been any telemetry transmission from the craft's systems, however. The DSN plans to continue monitoring the spacecraft until Wednesday when NEAR Shoemaker's remarkable mission officially ends.

There was speculation earlier today about NEAR Shoemaker performing one final feat -- launching from the surface of Eros. But there are currently no plans to do so. "We are down and happy and expect to stay that way," project spokeswoman Helen Worth says.

Also on Wednesday there will be a wrap-up news conference with project officials and scientists. We will cover it live!

2200 GMT (5:00 p.m. EST)

The voyage of the NEAR Shoemaker science probe came to an abrupt and most unexpected ending on Monday, surviving a four-hour descent to touch down on the surface of the asteroid Eros and live to relay a beacon signal to its home planet. Read our full wrap-up story.

2125 GMT (4:25 p.m. EST)

A spokeswoman at Johns Hopkins University Applied Physics Laboratory, which controls the NEAR Shoemaker mission for NASA, says a signal is still being received from the spacecraft and there is evidence of telemetry coming from the probe, too. However, the ground controllers but haven't been able to "lock on" to the telemetry transmission to fully gauge NEAR Shoemaker's health on the surface of Eros.

The mission has two days remaining on the Deep Space Network tracking system to receive data from the probe before the 5-year voyage of NEAR Shoemaker officially concludes.

2030 GMT (3:30 p.m. EST)

The celebrations continue in the NEAR Shoemaker mission control center after the craft miraculously survived its landing on the surface of asteroid Eros 196 million miles from Earth today. The controlled descent was a complete success, marking the first time a robotic probe has touched down on a small body in our solar system.

We will pause our coverage now, and will provide further information as it becomes available.

2028 GMT (3:28 p.m. EST)

Calculations show the spacecraft impacted the surface at a speed of 1.5 to 1.8 m/sec, or about 3 1/2 mph.

2026 GMT (3:26 p.m. EST)

Controllers report they are trying to set up two-way communications between Earth and NEAR Shoemaker to obtain real telemetry data from the satellite to determine its health. There is still a signal, although relatively weak, from the craft that means its internal systems have survived the landing.

2024 GMT (3:24 p.m. EST)

The final images taken by NEAR Shoemaker before touchdown show extraordinary detail of Eros' surface and boulders, which is why this crash landing idea was devised -- to get higher resolution images never before seen.

2019 GMT (3:19 p.m. EST)

Low-date rate (40-bps) telemetry could begin flowing from the spacecraft in about two minutes after reconfiguration of equipment. Officials report the signal being received has actually gotten stronger since the landing!

2017 GMT (3:17 p.m. EST)

More than 10 minutes after the landing, Earth is still receiving a beacon signal from NEAR Shoemaker. Controllers are now working to reconfigure the RF communications system in an effort to receive actual telemetry data from the craft on the asteroid's surface. This landing has gone better than anyone could have believed!

2010 GMT (3:10 p.m. EST)

The $223 million probe has completed its five-year odyssey to explore the asteroid Eros with an impact on the space rock's surface. Controllers will need some time to look through the data and determine the exact state of the situation, but officials did report receiving signals from the craft after it had landed. We will pass along further information as it becomes available.

And on Wednesday, officials will hold a post-landing news conference, which we will cover live.

2006 GMT (3:06 p.m. EST)

TOUCHDOWN WITH SIGNALS! NEAR Shoemaker has become the first spacecraft to land on the surface of an asteroid, and officials report they are continuing to detect signals that indicate the car-sized craft is still alive!

NASA had said there was less a one-percent chance of contacting the probe upon landing.

2005 GMT (3:05 p.m. EST)

NEAR Shoemaker should be on the surface -- one or more pieces.

2004 GMT (3:04 p.m. EST)

Controllers are listening for a beacon signal that would indicate NEAR Shoemaker has survived the descent and is operating on the surface. Officials say they are willing to listen for two days in hopes have hearing something from the car-sized craft on the surface.

2003 GMT (3:03 p.m. EST)

The tracking carrier signal still being received on Earth from NEAR Shoemaker.

2001 GMT (3:01 p.m. EST)

Latest images from NEAR are showing details in boulders on the surface of Eros with a resolution of inches. Scientists are giddy!

2000 GMT (3:00 p.m. EST)

The final burn is underway. Altitude is 350 meters.

1958 GMT (2:58 p.m. EST)

The last clear pictures from NEAR Shoemaker's telescopic camera should have been taken at this point. They are expected to show surface features as small as four inches (10 centimeters) across.

The camera will now provide blurring photos, along with the craft's laser ranging instrument giving range measurements and Doppler tracking to determine when NEAR Shoemaker touches down.

1956 GMT (2:56 p.m. EST)

The descent continues to go as planned. Landing is less than 10 minutes away.

1955 GMT (2:55 p.m. EST)

The third slowing burn has been completed. The final one will begin in four minutes and last four minutes in duration.

1953 GMT (2:53 p.m. EST)

NEAR Shoemaker is flying on its side, its outward-facing camera pointed down, snapping about two photos a minute. The spacecraft is headed for an area outside Himeros, the asteroid's distinctive six-mile (10-kilometer)-wide, saddle-shaped depression.

1952 GMT (2:52 p.m. EST)

Altitude now one kilometer.

1950 GMT (2:50 p.m. EST)

Confirmation of ignition of the third manuever. Altitude is currently 1.25 km. NEAR remains on the proper glide path as it switches to the final onboard commanding sequence as designed.

1947 GMT (2:47 p.m. EST)

A flood of pictures continues to flow from NEAR Shoemaker. The craft is snapping images twice a minute.

1947 GMT (2:47 p.m. EST)

The third braking burn should be in progress.

1945 GMT (2:45 p.m. EST)

About 20 minutes until impact.

1943 GMT (2:43 p.m. EST)

This is the fastest succession of maneuvers NEAR Shoemaker has ever attempted in its five-year, 2.3 billion mile (3.7 billion kilometer) mission.

1941 GMT (2:41 p.m. EST)

The next braking burn is about six minutes away. It will last for six minutes.

1939 GMT (2:39 p.m. EST)

The second of four braking maneuvers has been completed normally. Mission officials report the spacecraft is coming in "a little bit high" but the descent continues as planned.

1932 GMT (2:32 p.m. EST)

The pictures show a large variety of boulders, but the surface of Eros lacks any fresh craters.

1930 GMT (2:30 p.m. EST)

The newest views of Eros are showing details never seen before by NEAR Shoemaker with a resolution of only two-feet across, officials report. The pictures promise to get even better over the next half-hour or so.

1929 GMT (2:29 p.m. EST)

The first image of Eros after the first braking burn has been received on Earth.

1927 GMT (2:27 p.m. EST)

The altimeter on NEAR Shoemaker indicates the probe is currently 5.4 km above the asteroid's surface and following the planned descent profile.

1925 GMT (2:25 p.m. EST)

The first data is in from the spacecraft to determine its exact altitude.

1923 GMT (2:23 p.m. EST)

The next braking burn is scheduled for eight minutes from now and will last about five minutes.

1921 GMT (2:21 p.m. EST)

Officials report the first braking maneuver may have been a slight under-burn by a few fractions of a percent. But overall things are proceeding well for NEAR Shoemaker's impact with history today.

1919 GMT (2:19 p.m. EST)

The burn should be completed now. Standing by for controllers to determine the success of the burn.

1917 GMT (2:17 p.m. EST)

"So far so good" is the report from ground controllers as this near-three-minute slowing maneuver continues.

1916 GMT (2:16 p.m. EST)

There is confirmation that the first braking maneuver has begun!

1914 GMT (2:14 p.m. EST)

Now about two minutes away from ignition of the first braking burn, which will last for 151 seconds. These brakings are most crucial to slow NEAR Shoemaker's descent. If they don't occur, the craft would slam into the asteroid with no chance of hearing from it. The slowing is also important so the "bonus science" of capturing lots of high-resolution pictures of Eros' surface can be taken.

1908 GMT (2:08 p.m. EST)

Ground controllers are reviewing what clues to look for in the Doppler shift and telemetry today to verify the upcoming braking maneuvers are performed. These maneuvers that will slow the spacecraft from 20 mph to around 5 mph for the landing, which is expected at about 3:05 p.m. EST if all goes well.

1901 GMT (2:01 p.m. EST)

The timing update has been transmitted to the NEAR Shoemaker spacecraft, shifting its onboard timing sequence for today's descent burns by 17 seconds. This shift was done to optimize the craft's trajectory to landing.

Mission controllers also report the probe has been oriented for the upcoming braking burn now 15 minutes away. There are no problems being reported as NEAR heads for its impact on Eros.

1840 GMT (1:40 p.m. EST)

NEAR Shoemaker's free-fall descent to the asteroid Eros' surface continues. The first braking maneuver to slow the descent is about 35 minutes away. Three more will follow to prepare the spacecraft for a soft impact on the asteroid.

1830 GMT (1:30 p.m. EST)

Deep Space Network antenna stations in Madrid, Spain, and Goldstone, Calif., continue to simultaneously communication with the NEAR Shoemaker spacecraft located 196 million miles (316 million kilometers) away. Data from the spacecraft takes between 17-18 minutes to reach the tracking stations on Earth.

1809 GMT (1:09 p.m. EST)

In the next few minutes, NEAR Shoemaker will reorient itself for the first braking maneuver. The burn is scheduled for 2:16 p.m. EST (1916 GMT) and should last for three minutes.

Meanwhile, the navigation team is converging on a 16-minute timing update that will be uplinked to the craft. This will shift the spacecraft's onboard timing sequence for the upcoming maneuvers based upon imagery showing NEAR's position following the de-orbit burn this morning.

1757 GMT (12:57 p.m. EST)

Scientists say the images from NEAR Shoemaker captured following the de-orbit burn show the probe is on the proper course. The pictures are just two pixels off the predications, meaning the craft is just very slightly off the anticipated track.

1756 GMT (12:56 p.m. EST)

We have posted another image taken by NEAR Shoemaker today.

1750 GMT (12:50 p.m. EST)

Officials report the imagery data from NEAR Shoemaker indicates that an update to the craft's onboard timing for the upcoming maneuvers is not yet needed. The timing tells NEAR Shoemaker when to perform the four braking thruster firings and the maneuvers' duration.

The difference between the craft's location as predicated vs. the actual status following the de-orbit burn is currently just 6 seconds, which is reported as "good" by controllers.

Further pictures will examined before mission control decides to adjust the timing.

MONDAY, FEBRUARY 12, 2001
1731 GMT (12:31 p.m. EST)

With the optical images reviewed, the navigation team will compute timing updates that will be uplinked to NEAR Shoemaker to adjust the forthcoming four braking maneuvers.

1728 GMT (12:28 p.m. EST)

We have posted one of the first images of Eros following the de-orbit burn.

1723 GMT (12:23 p.m. EST)

The navigation team reports the de-orbit burn was right on -- there was not an over-burn or under-burn. The spacecraft is exactly where it was supposed to be following the 20-second thruster firing earlier today. This is all according to images from the camera on NEAR taken after the burn, which matched up to the predicted views expected.

1715 GMT (12:15 p.m. EST)

Controllers at the NEAR Shoemaker operations center in Maryland report the de-orbit burn data recorded aboard the spacecraft has been beamed back to Earth. Engineers say all systems look ready for the descent, and navigation images taken by NEAR are now being examined by scientists to determine the craft's location and altitude after the burn.

1605 GMT (11:05 a.m. EST)

Mission officials confirm the 20-second de-orbit burn has been performed by the NEAR Shoemaker spacecraft, which commences the craft's journey to the surface of Eros.

The next thruster firing is expected around 2:16 p.m. EST (1916 GMT) when the first of four braking maneuvers will occur to slow NEAR's descent.

Our continuous live coverage of the landing will begin at 1:30 p.m. EST (1830 GMT).

1532 GMT (10:32 a.m. EST)

The critical engine firing to begin NEAR Shoemaker's descent from orbit around the asteroid Eros should have been completed by now. The de-orbit maneuver was supposed to last 20 seconds, dropping the spacecraft out of a circular orbit 22 miles (35 kilometers) from the center of Eros, and starting the 4.5-hour descent to the surface of the space rock.

It will be a little while yet before mission controllers can confirm the burn occurred and was performed correctly.

Mission navigators plan to examine images taken by NEAR Shoemaker after this maneuver to calculate the spacecraft's location and altitude, and set the timing on the satellite for the final thruster firings upcoming in the next couple of hours.

0501 GMT (12:01 a.m. EST)

NASA's $223 million mission to get up-close and personal with an asteroid goes out with what could very well amount to a bang as the NEAR Shoemaker spacecraft heads for an unprecedented landing on Eros Monday.

Launched on February 17, 1996 and orbiting Eros since February 14, 2000, the 5-year, 2-billion mile voyage of NEAR Shoemaker is wrapping up because the project is out of money and the probe's fuel reserve is almost gone.

"We've been having a lot of fun over the last few years and we've fulfilled all the primary science goals of the mission. But all good things must come to an end, and the mission is scheduled to end (today)," said Dr. Robert Farquhar, the NEAR mission director at Johns Hopkins University Applied Physics Laboratory.

Officials decided to attempt the first-ever asteroid landing in an effort to collect "bonus" science by capturing pictures of the ancient space rock with more detail than NEAR Shoemaker has been able to see from its higher orbital perch. And the hoped-for "controlled descent" will give ground controllers a challenging opportunity to see if they can land the satellite -- even though it wasn't designed to do so -- now that it has finished its useful life.

"We're trying to find some way that we can end the mission on a high note, and we've come up with a way to do some bonus science, and also do some things with the spacecraft that have never been done before," Farquhar said.

"Of course, when you try to do something like this there is always a little risk involved. But since we're trying to get bonus science and the primary goals have been satisfied, in my view, the only risk is not taking one at this point in the mission."

Scientists hope the close-up pictures will be 5 to 10 times better than those collected so far, with the craft snapping about two images every minute during the descent and beaming them back to Earth in almost real time.

"The secondary goal is to try to impact on the surface in a relatively soft way -- a soft landing -- about somewhere between 1 to 3 meters per second, which is about 2 to 7 miles per hour," Farquhar explained.

"Now 7 miles per hour may not sound very fast, but I have personal experience with this kind of velocity. When I was in the paratroopers and we were jumping with World War 2 parachutes you would hit the ground at about 7 miles per hour if after swinging back and forth, so I know it's a fairly hard landing."

Farquhar describes today's descent: "We are going to de-orbit with the first engine burn about 4 1/2 hours before we would impact on the surface. As it comes down there is a kink in the orbit close to the surface; it takes about 4 hours to get there and not too much is happening, we're just drifting down. At that point, about 5 kilometers above the surface, is where we do our final controlled descent.

"That first burn, which I call brake number one, lasts about 3 minutes and is followed a bit later by another engine burn, brake two, which takes about 5 minutes, then another one that lasts 6 minutes, then a final one at about 4 minutes.

"You can see we're doing a whole series of these engine burns and we've never done this before on the mission. So this is rather complicated, but I have full confidence that we have very experienced teams both at the Applied Physics Laboratory and the Jet Propulsion Laboratory that will be in charge of planning and implementing this.

"The engines will fire and we come out of orbit; the sun is facing the right side of the solar panels and we're getting power. The thrusters fire as it gets closer; we do a roll to position ourselves properly for the final engine firing.

"All the way down we stay on the high-gain antenna; it points toward Earth, and about 20 degrees off of that is the sun, so were getting full solar power on the panels on the way down, and the imager is pointing down.

"When the spacecraft actually hits it could roll, or we could go into what we call the ostrich mode (tipped over on its top). We don't want to do that because it's hard to communicate with it. We are going to try to communicate with the low-gain antenna, but the chances of contacting it are probably less than one percent."

The satellite was never meant to land and the odds of successfully receiving communications from the craft once on Eros are extremely remote.

"The unknown nature of the surface makes it hard to predict what will happen to the spacecraft, especially since it wasn't designed to land. The most we can hope for is a beacon from NEAR Shoemaker that says it's still operating (on the surface)," Farquhar said.

NEAR Shoemaker descent is scheduled to start at 10:31 a.m. EST (1531 GMT) with a maneuver moving it out of its current orbit 22 miles (35 kilometers). Touchdown is expected at 3:04 p.m. EST (2004 GMT) on the surface of Eros more than 196 million miles (316 million kilometers) from Earth. The planned landing site is the outer edge of the saddle-shaped depression called Himeros.

The last clear pictures from the telescopic camera, taken in the final minutes before landing from approximately 1,650 feet (500 meters), could show surface features as small as four inches (10 centimeters) across.

"NEAR Shoemaker has set a high standard for low-cost planetary exploration," said Dr. Edward Weiler, Associate Administrator for Space Science at NASA Headquarters, Washington, D.C. "This mission has provided answers to a range of fundamental science questions, and it has excited the public with its exploration and great images. The team at Johns Hopkins University Applied Physics Laboratory and its many partner institutions are to be congratulated for achieving this historic first in space exploration."

"If you're not thrilled by the science and the basic exploration we accomplished, and you ask why we spent $223 million on this program, which is about a dollar per American over the life of the mission, let me tell you why it might be important," Weiler told reporters at a recent news conference.

"This marks the first time we really began the in-depth reconnaissance of the so-called class of asteroids, near-Earth objects. These are objects that in the past have caused some bad days for species on the Earth, namely the dinosaurs.

"We are not the agency that has the responsibility for protecting the Earth, but we do consider it a responsibility to learn as much as we can about these objects, and what you're going to hear today is the beginning of that process.

During its mission, according to NASA, NEAR Shoemaker gathered 10 times more data than originally planned. The data include a detailed shape model culled from more than 11 million laser pulses; radar and laser data on Eros' weak gravity and solid but cracked interior; X-ray, gamma-ray and infrared readings on its composition and spectral properties; and about 160,000 images covering all of the 21-mile-long asteroid's bouldered, cratered, dusty terrain.

Spaceflight Now will have continuing live updates throughout the day on Monday during the historic descent on this page. We will also provide a streaming video Webcast of the mission control room.