NEAR Orbit Around Asteroid 433 Eros

Early Orbit Images of Eros

The Near Earth Asteroid Rendezvous (NEAR) spacecraft snapped the image on the left (Image of the day Feb. 13, 2000 B) during its approach to on Feb. 11, 2000, from 2590 km (1,609 miles) away. This image shows a heart-shaped depression about 5 km (3 miles) long. The image mosaic on the right was taken from 204 km (127 miles) on March 3, 2000 and reveals that the mysterious heart shaped feature is actually 3 separate craters. The oblique lighting conditions and low resolution of the earlier image created the illusion of a heart shape. (This is a product of images 0125693155, 0127521294, 0127521356)

This image mosaic, showing Eros' saddle and a shadowed feature to its left, was taken from a distance of 204 km (127 miles). In this picture features as small as 20 meters (65 feet) are visible. This is the best view to date of this area. The sun is coming from the northeast illuminating a shadowed feature that consists of three large craters situated adjacent to each other. The two largest are each about 4-5 km (2-3 miles) across. Because the sun is very low with respect to these craters, even small topographic features cast long shadows, making them easier to see. As a result, several boulders can be distinguished, ranging from about 50 to 100 meters in diameter, on the crater walls. The saddle, on the right of the mosaic, is relatively smooth, with few impact craters, and has several grooves running across it. At the top of the saddle are several curved grooves that are brighter than the surrounding surface. Unusual brightness patterns are also visible in the crater at the top left of the mosaic. The walls of the crater appear to be more reflective and its floor less reflective than nearby parts of the asteroid. (Mosaic of 6 images 0127504836, 0127504898, 0127505146, 0127505208,0127505394, 0127505456)

This image of the northeast rim of the saddle region on Eros was taken after NEAR entered into its 200 kilometer orbit on March 3, 2000. The resolution of this image is 20 meters (65 feet) per pixel. On the right are bright sinuous features associated with a ridge seen in previous images of the day. Parallel, close ly spaced grooves are seen in the floor of the saddle. A cluster of boulders, ubiquitous on Eros, is seen in a small crater on the rim. (image 012733083)

This image, showing an oblique view of Eros' large central crater, was taken at a resolution of about 20 meters (65 feet) per pixel. The brightness or albedo patterns on the walls of this crater are clearly visible, with the brighter materials near the tops of the walls and darker materials on the lower walls. Boulders are seen inside this crater and the smaller nearby craters. The higher density of craters to the left of the large crater implies that this region is older than the smoother area seen associated with the saddle region on the opposite side of the asteroid. (image 0127591846)

This mosaic of 2 images, showing a cratered region of Eros located at the elongated end of the asteroid, was taken at a resolution of about 21 meters per pixel. A few of the craters show brightness (albedo) patterns on their walls, where the top portion of the walls are brighter than the surrounding terrain. The floor and lower portion of the walls of these craters have patches that appear darker than the surrounding terrain. A few boulders are also visible in this region. Some shallow, subdued troughs can also be seen trending vertically down the lower part of the asteroid. (Mosaic of : 0127470894 and 0127470956)

This image of the interior of Eros' saddle area, taken at a range of 204 km (127 miles), displays a paucity of craters compared to the surface on the right hand side of the image. The saddle displays many interesting structural features. Visible on the left wall are a series of closely spaced grooves that follow the terrain downslope. Opposite, on the upper right wall, trending towards the back of the saddle is a prominent ridge. Boulders are visible throughout this image. Features as small as 20 meters (65 feet) are discernable in this image. (Image: 0127521108)

This mosaic image of the large crater at Eros' center was taken during an optical navigation imaging sequence from a range of 127 miles (204 km). This same area was imaged following orbit insertion at a range of approximately 210 miles (330 km) on February 14th (Feb 14 G). This picture resolves features as small as 65 feet (20 meters) compared to the resolution of 100 feet (30 meter) in the earlier image. The shadow cast by the boulder near the floor of the crater (the sun is from the northeast) is now visible. The walls of the crater display some distinctive variations in their albedo or reflectivity. The upper part of the walls tend to be bright, while the lower portions of the walls and the crater floor show patches of darker or less reflective materials. These albedo patterns are also visible on other crater walls. To the right of the large crater two sets of closely spaced orthogonal grooves are visible. (Mosaic of 4 images 0127531846, 0127531908, 0127532094, 0127532156.)

NEAR takes several images mosaics of Eros daily for purposes of navigating the spacecraft. The one shown here was taken February 29, 2000, from a range of 289 kilometers (180 miles). It shows features as small as 30 meters (100 feet) across. All of the mosaics show the same territory over and over, but changes in lighting plus the gradual decrease in the spacecraft's range to the surface are both constantly bringing out new details.

The very oblique illumination in this mosaic is ideal for bringing out small landforms. Many parts of the asteroid have "grooves," linear troughs about 100 meters (330 feet) wide and several kilometers long. Similar features have also been observed on other asteroids such as Gaspra, and they are especially numerous on Mars' moon Phobos. Their origin isn't completely understood, but formation of the grooves probably involves fracturing of the asteroid's subsurface in some way. (Mosaic of images 0127210446, 0127210510, 0127210574, 0127210656)

On February 23, 2000, the NEAR spacecraft obtained a sequence of image mosaics showing Eros' surface as the asteroid rotated under the spacecraft. At that time the range to the surface was approximately 355 kilometers (220 miles). These two mosaics, part of that sequence, show the stark beauty of the two opposite hemispheres. The smallest detail visible is 35 meters (120 feet) across. The top mosaic shows wavy brightness banding exposed in the interior walls of the saddle. In the bottom mosaic, similar banding is visible in one of the craters near the limb at left. To the right, the angle of the illumination accentuates the quasi-linear troughs near the terminator.

Successful firing of NEAR's thrusters yesterday, February 24, placed the spacecraft on course for insertion into the next lower orbit, at a 200 kilometer (120 mile) altitude. Images from that orbit, commencing in early March, will have nearly twice the spatial resolution of data returned so far.

(Product compiled from images 0126712790, 0126713054, 0126713230, 0126723526, 0126723790, 0126723878)

This image mosaic of Eros was taken by the NEAR spacecraft on Feb. 18, 2000 from a range of 224 miles (361 kilometers). The smallest detail visible on the surface is about 115 feet (35 meters) across. At the time the spacecraft was over the shadowed southern hemisphere, looking north at a crescent Eros. Although this view of Eros is similar to others that have been returned, the coverage at different illumination and viewing geometries provides important information on the shapes of landforms.

(Mosaic of images 0126286145, 0126286419, 0126286483)

Over Eros' horizon

This incredible picture of Eros, taken on February 14, 2000, shows the view looking from one end of the asteroid across the gouge on its underside and toward the opposite end. In this mosaic, constructed from two images taken after the NEAR spacecraft was inserted into orbit, features as small as 120 feet (35 meters) across can be seen. House-sized boulders are present in several places; one lies on the edge of the giant crater separating the two ends of the asteroid. A bright patch is visible on the asteroid in the top left-hand part of this image, and shallow troughs can be see just below this patch. The troughs run parallel to the asteroid's long dimension. (Mosaic of images 0125971425, 0125971487)

NEAR's first whole-Eros mosaic from orbit

This picture of Eros, the first of an asteroid taken from an orbiting spacecraft, is a mosaic of four images obtained by NEAR on February 14, 2000, immediately after the spacecraft's insertion into orbit. We are looking down over the north pole of Eros at one of the largest craters on the surface, which measures 4 miles (6 kilometers) across. Inside the crater walls are subtle variations in brightness that hint at some layering of the rock in which the crater formed. Narrow grooves that run parallel to the long axis of Eros cut through the southeastern part of the crater rim. A house-sized boulder is present near the floor of the crater; it appears to have rolled down the bowl-shaped crater wall. A large number of boulders is also present on other parts of the asteroid's surface. The surface of the asteroid is heavily cratered, indicating that Eros is relatively old. (Mosaic of images 0125956839, 0125957025, 0125957087, 0125957273.)

Inside Eros' giant gouge

This picture was taken from NEAR on February 15, 2000, while the spacecraft was passing directly over the large gouge that creates Eros's characteristic peanut shape. It is a mosaic of individual images showing features as small as 120 feet (35 meters) across. Although most of the asteroid is in shadow, we are able to see inside the gouge. Many narrow parallel troughs closely follow the shape of the gouge. Although they appear curvilinear from this view, they are most likely oriented parallel to the length of the asteroid. The strong lighting contrast along the terminator (the line separating day from night on Eros) makes it easy to see that most of the surface is saturated with impact craters. Inside the gouge, however, only smaller craters are present, indicating that the area within the gouge is younger than the surface along the terminator. This implies that the event that caused the gouge must have happened more recently than the formation of the rest of the surface of Eros. (Mosaic of images 0126023473, 0126023535, 0126023721, 0126023783, 0126023845, 0126023907, 0126024093, 0126024155)

Eros: The first look from orbit

In the first hours after NEAR's insertion into Eros orbit, the spacecraft's camera took these images from a range of 210 miles (330 km) above the surface. The many craters visible serve as landmarks for navigating the spacecraft. Mission operators observe such features from different angles, and use triangulation to calculate NEAR's position relative to the surface of Eros. The changes in position over time help to plot NEAR's course in orbit.

(Images 0125957273, 0125956839, 0125971425 and 0125971487)

NEAR's historic first image from Eros orbit

Today at 10:33 AM EST the NEAR spacecraft was successfully inserted into orbit around 433 Eros, becoming the first artificial satellite of an asteroid. Just over an hour later, NEAR pointed its camera at the asteroid and took this picture from a range of 210 miles (330 km) above the surface. Mission navigators and operators will use this image and others to be taken later to triangulate on landmarks on the asteroid's surface, precisely measuring position of the spacecraft to plot NEAR's course.

Features as small as a 100 feet (30 meters) across can be seen. This view shows the 3-mile (5-kilometer) impact crater which the spacecraft has spied for over a week during its approach. The two smaller craters superimposed on its rim are each about 1.2 miles (2 kilometers) across. An enormous boulder a full 170 feet (50 meters) in size sits on the large crater's floor. Other key features of the surface are shallow subsurface layering exposed near the tops of crater walls, and shallow grooves crossing the surface and cutting the crater's rim. (Mosaic of images 0125957025 and 0125957087)

NEAR Eros recent orbit images
NEAR Eros animations (large files)
NEAR Eros approach images and animations
NEAR Eros Science Returns

More information on asteroid 433 Eros
Asteroid Fact Sheet
NSSDCA Asteroid Home Page

Information on the Multispectral Imager
Information on the NEAR Mission Profile and Trajectory

Images from the Eros and Mathilde Flybys
NEAR Eros Images - Applied Physics Lab, JHU

NSSDCA NEAR Home Page
Detailed information on NEAR from the NSSDCA Master Catalog
NSSDCA Planetary Home Page

NASA Official: Dr. Ed Grayzeck, edwin.j.grayzeck@nasa.gov
Last Updated: 18 December 2001, DRW