Deep Space 1
Launch Date: October 24, 1998
The primary mission of Deep Space 1 was to test its payload of twelve advanced, high risk technologies. The most heralded of these was the first use of ion propulsion. This type of engine uses xenon gas which is ionized by bombarding it with electrons. The positively charged ions can than be used to produce a very small amount of thrust but by thrusting continuously over time, acceleration builds. A similar system is now driving the Dawn spacecraft towards the asteroid belt and many future missions will likely adopt the lightweight but powerful propulsion method.
Comet Borrelly's coma, dust jets, and nucleus - This is a composite of images acquired by NASA's Deep Space 1 spacecraft, showing some of the features in comet Borrelly's coma, dust jets, and nucleus. The range to the comet in this view is about 4800 kilometers (3000 miles). Borrelly's nucleus is about 8 kilometers (5 miles) end-to-end so the field of view is about 40 kilometers (25 miles) on each side.
The colors show about three orders of magnitude in brightness (the purple about 1/1000, blue about 1/100, and red about 1/10 the brightness of the nucleus). The red bumps near the nucleus are real, showing where the main jet resolves into three distinct narrow jets that likely come from discrete surface sources.
Among the other technologies tested were: Autonav, an autonomous navigation system designed to reduce ground intervention; Remote Agent, remote intelligent self-repair software, SDST (Small, Deep-Space Transponder), a miniaturized radio system; MICAS (Miniature Integrated Camera And Spectrometer), a smaller, lighter combination of prior instruments; PEPE (Plasma Experiment for Planetary Exploration); SCARLET (Solar Concentrator Array of Refractive Linear Element Technologies); and the Beacon Monitor experiment, where the spacecraft sends only a status signal during cruise, which reduces cost.
Following its primary mission, Deep Space 1 embarked on an ambitious extended mission that culminated in a daring encounter with comet Borrelly on September 22, 2001. Despite being past its intended lifetime and crippled from its long journey, DS1 completed its assignments perfectly, returning the best pictures and other scientific data ever collected at a comet. These data will reveal much to scientists about the nucleus and the coma (the cloud of gas and dust surrounding the nucleus). Subsequent comet missions will benefit from what DS1 found at comet Borrelly, thus improving the chances these other missions will meet with success by being better prepared.