Discoverer

Johann Palisa - 1885.

Diameter (km)

66 x 48 x 46

Mass (kg)

1.033*10^{^17}

Rotation period (hrs)

417.7

Orbital period (yrs)

4.31

Semimajor axis (AU)

2.64724

Orbital eccentricity

0.26522

Orbital Inclination (deg)

6.70777

Albedo

0.04

Type

C

Images of Mathilde

This distant image of asteroid 253 Mathilde was returned by the NEAR spacecraft just before 11:00 PM EDT on June 26, 1997, as part of the last of six image sequences used for optical navigation to Mathilde.

The position of the asteroid against the star background was used to refine the pointing of the multispectral imager 11 hours later to acquire high resolution images of Mathilde's surface. This image was taken at a distance of 400,000 kilometers. At that time the asteroid was only barely visible, and was difficult to see because it appeared close to the sun as seen by the spacecraft. The streaks in the image are an artifact of the camera brought out by the image processing. Mathilde and the star background are black because the contrast was reversed (yielding a "negative" image) to enhance the dim objects' visibility.

This first image of asteroid 253 Mathilde, returned by the NEAR spacecraft just before 10:00 AM EDT on June 27, 1997, was taken from a distance of 1800 kilometers. Sunlight is coming from the upper right. The part of the asteroid shown is about 59 kilometers across, and the scale is approximately 230 meters per pixel.

The surface is heavily cratered, and the large shadowed area on the left may be a single impact gouge well over 10 kilometers deep. The angular form of the edge of the shadowed area suggests that large impacts may have spalled large pieces off the asteroid. This asteroid is very dark, reflecting only about 4% of the light falling on it, but was imaged easily by the sensitive NEAR multispectral camera.

This image mosaic of asteroid 253 Mathilde is constructed from four images acquired by the NEAR spacecraft on June 27, 1997. This was taken from a distance of 2,400 km. Sunlight is coming from the upper right. The part of the asteroid shown is about 59 by 47 km across. Details as small as 380 meters can be discerned.

The surface exhibits many large craters, including the deeply shadowed one at the center, which is estimated to be more than 10 kilometers deep. The shadowed, wedge-shaped feature at the lower right is another large crater viewed obliquely. The angular shape of the upper left limb of the asteroid results from the rim of a third large crater viewed edge-on. The bright mountainous feature at the far left may be the rim of a fourth large crater emerging from the shadow. The angular shape is believed to result from a violent history of impacts.

These are views of the three asteroids that have been imaged at close range by spacecraft. The image of Mathilde (left) was taken by the NEAR spacecraft on June 27, 1997. The Galileo spacecraft took images of the asteroids Gaspra (middle) and Ida (right) in 1991 and 1993, respectively. All three objects are presented at the same scale. The visible part of Mathilde is 59 km wide x 47 km high. Mathilde has more large craters than the other two asteroids. The relative brightness has been made similar for easy viewing; Mathilde is actually much darker than either Ida or Gaspra.

This view of 253 Mathilde, taken from a distance of about 1,200 km, was acquired shortly after the NEAR spacecraft's closest approach to the asteroid. In this image, the asteroid has been rotated so that the illumination appears to come from the upper left. This portion of Mathilde shows numerous impact craters, ranging from over 30 km to less than 0.5 km in diameter.

Raised crater rims suggest that some of the material ejected from these craters traveled only short distances before falling back to the surface; straight sections of some crater rims indicate the influence of large faults or fractures on crater formation. The number of craters as a function of size, and the number of each size within the visible area, are similar to values seen on asteroid 243 Ida, viewed by the Galileo spacecraft in 1993. A major difference between Ida and Mathilde appears to be the abundance of very large craters: Mathilde has at least 5 craters larger than 20 km in diameter on the roughly 60% of the body viewed during the encounter.

The NEAR spacecraft obtained two different views of asteroid 253 Mathilde on June 27, 1997. The image at left was obtained as the spacecraft approached Mathilde with its camera pointed near the direction of the Sun; only a few of the prominent ridges on Mathilde are illuminated.

The visible area at left is 29 km high, and the phase angle (the angle from Sun-Mathilde-spacecraft) is 136 deg. As the spacecraft receded from Mathilde, it observed the asteroid (about 60 km across) almost fully lit by the Sun at a phase angle of 43 deg; (right image). Mathilde's irregular shape results from a long history of severe collisions with smaller asteroids. The largest visible crater is 30 km in diameter.

^{(Credit NASA-JPL)}