Editing Deep Space 1 (section)

===Autonav===
The Autonav system, developed by NASA's [[Jet Propulsion Laboratory]], takes images of known bright [[asteroid]]s. The asteroids in the inner Solar System move in relation to other bodies at a noticeable, predictable speed. Thus a spacecraft can determine its relative position by tracking such asteroids across the star background, which appears fixed over such timescales. Two or more asteroids let the spacecraft triangulate its position; two or more positions in time let the spacecraft determine its trajectory. Existing spacecraft are tracked by their interactions with the transmitters of the [[NASA Deep Space Network]] (DSN), in effect an inverse [[Global Positioning System|GPS]]. However, DSN tracking requires many skilled operators, and the DSN is overburdened by its use as a communications network. The use of Autonav reduces mission cost and DSN demands.

The Autonav system can also be used in reverse, tracking the position of bodies relative to the spacecraft. This is used to acquire targets for the scientific instruments. The spacecraft is programmed with the target's coarse location. After initial acquisition, Autonav keeps the subject in frame, even commandeering the spacecraft's attitude control.<ref name=ANS-PFR>{{cite conference |title=The Deep Space 1 Autonomous Navigation System: A Post-Flight Analysis |conference=AIAA/AAS Astrodynamics Specialist Conference. 14–17 August 2000. Denver, Colorado. |first1=S. |last1=Bhaskaran |first2=J. E. |last2=Riedel |first3=S. P. |last3=Synnott |first4=T. C. |last4=Wang |display-authors=1 |date=2000 |id=AIAA-2000-3935 |doi=10.2514/6.2000-3935 |citeseerx=10.1.1.457.7850}}</ref> The next spacecraft to use Autonav was ''[[Deep Impact (spacecraft)|Deep Impact]]''.