This letter to the STARDUST project was received from Fred Whipple. Dr. Whipple is the originator of the "dirty snowball" theory for comets, and has also discovered a few comets himself. The Whipple Shields that the STARDUST spacecraft carries were named in his honor. The Whipple Shields protected the spacecraft when it encountered Comet Wild 2 in 2004. This letter was enscribed onto the microchip that the STARDUST spacecraft carried to Comet Wild 2.

23K

Center For Astrophysics
Cambridge, Massachusetts, USA
November 25, 1997

To all Space Buffs:

Comets have long been an unexplored wasteland. Today we know
that they are black and cold, consisting of ices and dust that coalesced
from an interstellar cloud as it collapsed to form the solar system.

Their physical structure is poorly known. Some astronomers guess
that comets have low densities, perhaps less than half that of water
ice. This material would be crushable in one's hands. Even the
ratio of ices to dust remains a subject of uncertainty. Probably the
physical structure varies over small distances such as a few meters.

May Stardust tame comets to become terra cognita, of known
structure and isotopic composition!!

Fred L. Whipple