Thank you for visiting the Deep Space 1 mission status information site, frequently referred to throughout the solar system, except near the south pole of one of Saturn's moons and on 2 intermittently inhabited islands in the Northern Pacific Ocean on Earth, as the most authoritative known site for information on this technology validation mission. This message was logged in at 6:45 pm Pacific Time on Friday, December 18.

DS1's ion propulsion system is continuing to propel this flying laboratory, but now it is under control of DS1's autonomous navigation system, developed by JPL and affectionately but unimaginatively known as AutoNav. The spacecraft had been thrusting since Monday. The operations team turned the thruster off this afternoon to give AutoNav its chance at the helm. This sophisticated system commanded the ion propulsion system to pressurize its xenon tanks for thrusting, and commanded the spacecraft's attitude control system to turn the spacecraft to thrust in the direction AutoNav desired. AutoNav also determines how much power to devote to the ion propulsion system, which uses electricity to ionize and accelerate xenon. To do this, AutoNav has knowledge of how much power the advanced solar arrays can produce and how much power the spacecraft consumes apart from the ion propulsion system. The solar arrays generate less power as the spacecraft recedes from the Sun, and the spacecraft will consume more power as it ventures farther from the hot Sun because it will need to operate its heaters more. But AutoNav knows how far the spacecraft is from the Sun, so it can calculate how much power is available for the ion propulsion system. It chose throttle level 78, and the ion propulsion system began thrusting under instructions from AutoNav. The operations team watched carefully as AutoNav executed each step flawlessly, demonstrating another powerful capability in DS1's set of advanced technologies. As the spacecraft continues its orbit around the Sun, AutoNav will update both the direction in which the ion thruster points and the throttle level at which it thrusts. Two hours after the beginning of thrusting, the first update occurred, and the team watched again as AutoNav commanded the updates. These updates will occur every 12 hours over the weekend and into next week, when the ion propulsion system will be turned off again for more technology validation activities. AutoNav has many capabilities. Today's successful demonstration of its control over the ion propulsion and attitude control systems is another step in preparing NASA for an exciting future in which many of the responsibilities normally fulfilled by human controllers will be transferred to intelligent spacecraft.

Deep Space 1 is over 24 times as far away from Earth as the moon. Each day it moves about 225,000 kilometers, or about 140,000 miles, farther from Earth. As the complex ballet of the solar system proceeds, DS1 travels more than 250,000 kilometers, or almost 160,000 miles, farther from the Sun every day. To continue this nerdy if not compulsive accounting of distances, consider that if ion propulsion had not been used, DS1 would be over 100,000 kilometers or nearly 65,000 miles closer to the Sun than it is now. Without the gentle but steady thrust of this exotic propulsion system, DS1 would be over 130,000 kilometers, or more than 80,000 miles, closer to Earth.

Each NASA mission has a well documented set of objectives that must be satisfied. Earlier this month, DS1 met the criteria for minimum mission success. That was achieved by completing 200 hours of thrusting with the ion propulsion system and collecting extensive data on the performance of the advanced solar array, provided by BMDO, and the radio transponder built by Motorola. While other important experiments on these and other technologies have already been accomplished, and many more lie ahead, the mission now ranks as another success in NASA's long and impressive history of travels beyond Earth orbit.