Thank you for visiting the Deep Space 1 mission status information site, the most respected site in the inner solar system and the most envied site in the outer solar system for information on this bold and exciting mission. This message was logged in at 4:00 pm Pacific Time on Sunday, February 20. This log is an edited transcript of a telephone recording. If you would like to access the same information from any place with a telephone, please call 1-800-391-6654 and select option 3.

As Deep Space 1 continues its travels far from Earth, the focus of the control team's work is to write new computer programs for the stalwart little craft. As faithful readers of many species know, after having successfully completed its primary mission last year, DS1 accepted a new, bonus assignment. This extended mission represents NASA's desire to continue to reap as many rewards as possible from the investment made in DS1. But in November the spacecraft's star tracker ceased operating. During the subsequent two months, the DS1 operations team devised a new method of controlling the spacecraft so that its main antenna could be pointed at Earth even without the sensor that had previously been so important. Since then, this innovative technique, which (as described in detail in the previous log) involves monitoring the strength of DS1's radio signal to determine exactly where it is pointed, has been used repeatedly to conduct communications with the spacecraft. But a new system is under development that will allow DS1 to point without the aid of mission controllers.

The star tracker, whose inspirational name derives from its function of tracking stars, had been responsible for helping the spacecraft determine how it was oriented in space. This was not part of the autonomous navigation system, one of the advanced technologies DS1 tested during its primary mission; rather, it was part of what is called the attitude control system. To reduce the attitude control system's regular reliance on distant Earth, engineers would like to replace the method of observing the radio signal to calculate the spacecraft's orientation. Of course, all there is to work with is what is already on board; the only new "equipment" that can be provided is computer programs. So engineers are writing new software that will allow the computer to control the pointing using images from the camera, another one of the 12 technologies that was included so that its innovative design could be tested in space. This new method builds on the autonomous navigation system's capability to analyze the camera's pictures.

The star tracker worked by photographing the stars wherever it was pointed and analyzing the pictures to find familiar patterns. This is similar to how you might orient yourself at night if you knew the constellations. But the star tracker and the camera have very different designs, including how large a section of the sky they see at one time and how fast they can take a picture and transfer the electronic image to the computer. Nevertheless, DS1 engineers are making good progress on a very clever new system that should allow the spacecraft to operate without frequent assistance from Earth. In effect, engineers are building a new attitude control system on DS1 from across the solar system. A tremendous number of complex technical details has to be worked out, but the small team that has accomplished so much is working hard to restore our deep space emissary's capabilities.

The new software will be radioed to the spacecraft in May; then, following a few weeks of tests, DS1 will return to thrusting with its ion propulsion system to propel it to an encounter with a comet next year. When DS1 was launched, controllers had in mind that if the mission were successful and if the spacecraft remained healthy, NASA might extend its flight to conduct an encounter with Comet Borrelly in September 2001. The mission went so surprisingly well that they were able to plan for it to visit two comets instead of one. But now that the star tracker has stopped, the spacecraft has fallen behind in its schedule of thrusting, so there is not enough time to do the thrusting necessary to keep both appointments. The DS1 science team met last month and concluded that the originally planned target should be kept. By the way, the science team is happily analyzing the infrared observations of Mars made by DS1 in November and returned in January once the new method of pointing the main antenna at Earth was developed. The observations are believed to be the best of their kind ever collected.

Although the primary mission concluded last year, one of the most important events of the mission took place this month. Over 100 engineers and scientists from NASA as well as other government agencies, private industry, and academia gathered to discuss the results of the testing of DS1's payload of 12 technologies. As the hundreds of trillions of devoted readers know, DS1's mission was to test these important, high-risk technologies in order to reduce the cost and risk of future science missions; DS1 took the risks so that future missions would not have to. That means that in addition to exercising the technologies, the results had to be disseminated to potential users. So a symposium was conducted in which detailed engineering information on all aspects of the technologies was presented. These new capabilities may be considered to be tools in the tool boxes of designers, and now some important and exciting space missions that previously were unaffordable or impossible have become feasible.

Deep Space 1 is now over 1.7 times as far from Earth as the Sun is and nearly 670 times as far as the moon. At this distance of more than 256 million kilometers, or 159 million miles, radio signals, traveling at the universal limit of the speed of light, take 28 and a half minutes to make the round trip.

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