Dr. Marc Rayman's Mission Log
 



  December 14, 1998

Mission Update:


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 logged source in the outer solar system for information on this technology validation mission. This message was logged in at 8:30 pm Pacific Time on Monday, December 14.

DS1's ion propulsion system is continuing to propel this flying laboratory. Thrusting resumed today following nearly a week of coasting.

The thruster was commanded off last week so that other activities could be conducted with the spacecraft. The first was the activation of another advanced technology, the plasma experiment for planetary exploration, affectionately known as PEPE. This device measures charged particles in space, both electrons and charged atoms, or ions. The device combines several functions into a unit of lower mass and lower power consumption than on traditional science missions. The activation of PEPE was very complex and required two days. Once it was activated it began making measurements of the stream of charged particles emanating from the Sun, known as the solar wind, just as it was designed to. Then on Thursday, benefiting from the success of Tuesday's and Wednesday's activation, a streamlined activation procedure was tested successfully, thus assuring that it can be turned on more easily in the future. PEPE was developed by the Southwest Research Institute in San Antonio and the Los Alamos National Laboratory. The testing of PEPE on DS1 is another step in preparing NASA for its future of smaller, less expensive missions to explore the solar system.

DS1 conducted telecommunications tests Tuesday and Wednesday nights of last week. These tests were scheduled when the spacecraft was within view of a Deep Space Network antenna in Goldstone California. NASA also has antennas in Madrid, Spain and near Canberra, Australia for communicating with probes in deep space, but only certain antennas at Goldstone are capable of receiving the special signals DS1 sent. The DSN and DS1 had planned an extremely ambitious set of activities, all of which proceeded very very smoothly. DS1 used another of its advanced technologies, a very small, lightweight amplifier for radio signals at a frequency about 4 times higher than the current standard frequency used for deep-space missions. This frequency band, meaninglessly called Ka-band, is like another channel in the radio spectrum and offers the possibility of sending more information with less power, important for future small but capable spacecraft. The preliminary view of the vast volume of data collected shows that the generation and transmission of these signals worked as hoped on the spacecraft, and the reception and processing of the signals at the DSN was similarly successful. DS1 also put the main portion of its radio system through further tests, and it continued to operate as planned. That unit, built by Motorola and known by the inspiring appellation Small Deep Space Transponder, combines many functions normally performed by separate elements into one low mass unit. The low mass, high efficiency Ka band amplifier was made by Lockheed-Martin.

On Friday, DS1 collected data on another of its 12 advanced technologies, a combination camera/imaging spectrometer. This device is designed to collect black and white pictures as well as make measurements in the infrared and ultraviolet. The data collected on Friday and in future activities will aid in characterizing the device in detail and in refining software to allow DS1's autonomous navigation system to use the pictures.

Also on Friday, the ion propulsion system was turned back on. The throttle level that was selected was too high, so the spacecraft batteries supplemented the power provided by the solar arrays. When the batteries reached a predefined level, software on board turned off the ion propulsion system and placed the spacecraft in a safe state. The operations team commanded the thruster back on today at a lower level. The ion propulsion system will be turned off later this week and again next week for other activities.

Each NASA mission has a well documented set of objectives that must be satisfied. On December 2, 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 transponder. 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.

Deep Space 1 is now about 22 times as far away from Earth as the moon.





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