Clementine Image Browser
Data server from the Clementine space mission. Contains images, search tool, time-lines, and mail.
IAU: Minor Planet Center
The official body that deals with astrometric observations, and orbits of minor planets, asteroids, and comets.
NASA's Marshall Space Flight Center
Specializes in development of advanced earth-to-orbit and space propulsion systems, and technologies.
National Space Science Data Center
Provides access to a wide variety of astrophysics, space physics, solar physics, lunar, and planetary data from NASA space flight missions, in addition to selected other data, models, and software.
PDS - Planetary Data System
Solar system exploration science data archive, maintained at JPL.