Dr. Marc Rayman's Mission Log
 



  November 25, 1998

Mission Update:


Thank you for visiting the Deep Space 1 mission status information site, now in its second month on the list of most frequently visited logged sources in the Milky Way galaxy for information on this technology validation mission. This message was recorded at 7:35 pm Pacific Time on Wednesday, November 25.

Deep Space 1 is now in powered flight. The ion propulsion system on Deep Space 1 is thrusting smoothly and gently at this moment and has been doing so since shortly before 3:00 pm Pacific Time on Tuesday. As part of an ongoing series of tests to gain insight into why the ion thruster turned off prematurely in its first test, the operations team commanded it on yesterday for the first time in 2 weeks. This was part of an experiment designed principally to study currents and voltages in greater detail, but the team was fully prepared for the spacecraft to begin thrusting. Your loyal correspondent, probably representative of the entire team, had low expectations but high hopes that thrusting would resume. The system did come to life just as it was designed to; indeed, the beginning of thrusting was even smoother than in the first test 2 weeks ago. It is probable that the reason the thruster stopped then is that a small piece of contamination caused a temporary short circuit. This will be studied more thoroughly as part of the overall assessment of the ion propulsion system. Because of the new software that was radioed to the spacecraft late last week and loaded into the ion propulsion system's computer controller, this success will provide even greater information on the thruster than the team had originally planned. After letting the thruster operate at a low throttle level overnight, the operations team raised the throttle level twice this morning to gain further data on its performance. It was returned to the intermediate level before noon. DS1 has now operated its thruster for a longer uninterrupted time than any deep space probe. The data that are being returned are extremely valuable, and this is an important step in DS1's charter of evaluating high-risk technologies critical for NASA's future space science missions.

The ion propulsion system is one of 12 advanced technologies being validated on DS1. The system is a product of the NASA NSTAR program, a cooperative effort between JPL and the Lewis Research Center. The industrial participants in this exciting technology are Hughes Electron Dynamics Division; Moog Inc.; Spectrum Astro Inc.; and Physical Science Inc.

A skeleton team will monitor the spacecraft over the 4-day Thanksgiving holiday. With the rapid development phase for DS1 and the intense activities since launch, during which many important technology validation data were collected, the operations team will attempt to recapture remnants of normal life and have some time to rest. Your faithful correspondent will remain diligent and update this log if events warrant.

Deep Space 1 is now more than 13 times as far away from Earth as the moon. Radio signals, traveling at the universal limit of the speed of light, take more than half a minute to make the round trip. JPL astronomers managed to take a picture of the diminutive craft using one of the world's largest telescopes on Palomar Mountain on November 16 when DS1 was at a distance of 3.7 million kilometers or 2.3 million miles from Earth. The reflected sunlight from the spacecraft was 4 million times dimmer than our humble eyes could detect. You can see the picture by visiting the Press Releases/Images page.





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