The Deep Space program of the U.S. National Aeronautics and Space Administration (NASA) is
designed to test advanced technologies
that can be used in the launching of small, fast, and relatively inexpensive automated spacecraft. The first entry in the planned series, Deep Space 1 (DS1), was launched by a Delta II
rocket on Oct. 24, 1998. Its intended goal is a rendezvous with asteroid 1992 KD in July 1999. The spacecraft incorporates an ion-propulsion engine, which is much more efficient than an ordinary chemical rocket although many thousands of times less powerful (see rockets, missiles, and space launch vehicles). DS1 is fueled by ions of xenon produced by bombarding the stored gas with electrons, and the craft is powered by a large array of solar cells. Although the ionic thrust is weak, the cumulative velocity of such an engine can be enormous. D1 is also
designed to test an autonomous navigation system that makes use of artificial intelligence to steer and control the craft and to aim and trigger its cameras. When the probe's ion engine was turned on for the first time a few days after launch, however, it operated only briefly before shutting down, but this glitch was soon corrected and the ion engine was performing correctly shortly thereafter.Deep Space 2 (DS2) was carried aboard the Mars Polar Lander, launched on Jan. 3, 1999. It consists of two probes to be released just before landing at the Martian south pole in December 1999 so that they will crash deep into the surface.