Dr. Marc Rayman's Mission Log
 



  March 20, 1999

Mission Update:


Thank you for logging in to the Deep Space 1 mission status information site, the most respected site in the Milky Way galaxy and the most envied page elsewhere in the local group of galaxies for information on this technology validation mission. This message was logged in at 1:10 pm Pacific Time on Saturday, March 20.

Deep Space 1 has begun a new chapter in its voyage. With the ion propulsion system on the job again, it is providing a gentle and steady push. After successfully completing over 850 hours of operation from November through early January, this advanced technology has not been needed, except for two brief tests. Now that the operations team has completed a wide variety of experiments with many of the other technologies on board, the ion propulsion system is being put back to work.

Following a pattern that will be repeated each week through the end of April, on Monday the autonomous navigation system, familiar to you loyal readers of this log as AutoNav, turned the spacecraft and controlled the camera to collect the pictures of asteroids and stars it uses for determining where it is in the immense solar system. Following that, it analyzed these images and other data and correctly calculated its position. Next, it predicted where it will end up if it continues on its present course and determined what changes to make in the upcoming planned use of the ion propulsion system. AutoNav also turned the spacecraft to point the main antenna at Earth so that accumulated data on the health of the spacecraft and the results of various technology experiments could be transmitted. This also provided an opportunity for controllers to radio instructions to the craft. Finally, AutoNav turned the spacecraft to point the ion propulsion system in the direction it needed and fired it up. The engine came to life just as it was supposed to. Early each week, AutoNav will execute the same routine, and during the remainder of the week, only minimal contact will be established with the spacecraft to verify that it is operating correctly. Every 12 hours throughout the week, AutoNav updates the throttle level and the direction of thrusting.

If the spacecraft completes its scheduled thrusting through the end of April, it will be on a course to intercept an asteroid at the end of July. That encounter, while not a critical part of the mission, will allow another test of a portion of AutoNav and of the two advanced science instruments DS1 carries. In addition, the event offers the bonus opportunity to return exciting scientific data.

While the weekly cycle of about 6 and a half days of using the ion propulsion system and half a day for everything else continues, mission controllers can devote more time to planning for activities for May through July. These include a test of another sophisticated autonomy experiment and further tests of the other technologies, loading of new software in DS1's main computer, and encountering the asteroid. In the meantime, as long as the spacecraft continues with its current cycle, these reports may be updated less frequently, but your ever-faithful correspondent remains vigilant and will revise this log if events warrant.

In the week before thrusting was resumed, a complex set of observations concluded with the return of a large volume of data to characterize and calibrate DS1's experimental combination camera imaging spectrometer. Recent recordings have offered an idea of what this sophisticated device is capable of doing and its importance for future missions. To gain a comprehensive picture of its overall performance, it was used to collect images and spectra of a variety of targets, including selected stars and Mars.

Tests of other technologies on DS1 have continued as well. Regular experiments are now conducted with the 3 advanced technologies activated last month that are designed to help NASA achieve its objective of making spacecraft that are smaller and lighter, thus allowing them to be launched on more affordable rockets. One consists of electronic devices that are smaller and consume much less power than conventional microelectronics. Because spacecraft have to generate their own electrical power, this is important for future smaller spacecraft. These electronics are also expected to be more resistant to radiation, which all spacecraft are exposed to. These extremely low power electronics were developed by MIT/Lincoln Laboratories. Another new technology on board consists of a very small, lightweight set of on/off switches, developed by Boeing and Lockheed Martin. These switches can actually report to the spacecraft's computer on how much current and voltage they are controlling. Finally, DS1 carries a device known as a multifunctional structure. This places electronics right in a structural panel. The combination of these 2 important functions plus the ability to control the temperature all in one device offers the possibility of simplifying future spacecraft. This experiment was provided to NASA by the Air Force and built by Lockheed Martin. All 3 devices are working as designed and will continue to be operated regularly during the remainder of the mission to assess how they fare as they age, contributing to engineers' assessments of how applicable they are to spacecraft of the future.

Deep Space 1 soon will be half as far away as the Sun and is over 160 times as far away as the moon today. At this distance of 63 million kilometers, or more than 39 million miles, radio signals traveling at the universal limit of the speed of light take 7 minutes to make the round trip.




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