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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Deep Space 1 | 2/3 | https://en.wikipedia.org/wiki/Deep_Space_1 | reference | science, encyclopedia | 2026-05-05T13:10:04.519966+00:00 | kb-cron |
=== Beacon Monitor === Another method for reducing DSN burdens is the Beacon Monitor experiment. During the long cruise periods of the mission, spacecraft operations are essentially suspended. Instead of data, Deep Space 1 transmitted a carrier signal on a predetermined frequency. Without data decoding, the carrier could be detected by much simpler ground antennas and receivers. If DS1 detected an anomaly, it changed the carrier between four tones, based on urgency. Ground receivers then signal operators to divert DSN resources. This prevented skilled operators and expensive hardware from babysitting an unburdened mission operating nominally. A similar system was used on the New Horizons Pluto probe to keep costs down during its ten-year cruise from Jupiter to Pluto.
=== SDST ===
The Small Deep Space Transponder (SDST) is a compact and lightweight radio-communications system. Aside from using miniaturized components, the SDST is capable of communicating over the Ka band. Because this band is higher in frequency than bands currently in use by deep-space missions, the same amount of data can be sent by smaller equipment in space and on the ground. Conversely, existing DSN antennas can split time among more missions. At the time of launch, the DSN had a small number of Ka receivers installed on an experimental basis; Ka operations and missions are increasing. The SDST has since been used on many other space missions such as the Mars Science Laboratory (the Mars rover Curiosity).
=== PEPE === Once at a target, DS1 senses the particle environment with the PEPE (Plasma Experiment for Planetary Exploration) instrument. This instrument measured the flux of ions and electrons as a function of their energy and direction. The composition of the ions was determined by using a time-of-flight mass spectrometer.
=== MICAS === The MICAS (Miniature Integrated Camera And Spectrometer) instrument combined visible light imaging with infrared and ultraviolet spectroscopy to determine chemical composition. All channels share a 10 cm (3.9 in) telescope, which uses a silicon carbide mirror. Both PEPE and MICAS were similar in capabilities to larger instruments or suites of instruments on other spacecraft. They were designed to be smaller and require lower power than those used on previous missions.
== Mission overview ==
Prior to launch, Deep Space 1 was intended to visit comet 76P/West–Kohoutek–Ikemura and asteroid 3352 McAuliffe. Because of the delayed launch, the targets were changed to asteroid 9969 Braille (at the time called 1992 KD) and comet 19P/Borrelly, with comet 107P/Wilson–Harrington being added following the early success of the mission. It achieved an impaired flyby of Braille and, due to problems with the star tracker, abandoned targeting Wilson–Harrington in order to maintain its flyby of comet 19P/Borrelly, which was successful. An August 2002 flyby of asteroid 1999 KK1 as another extended mission was considered, but ultimately was not advanced on the basis that the scientific justification was not sufficiently strong when considering risk and cost. During the mission, high quality infrared spectra of Mars were also taken.
=== Results and achievements ===
The ion propulsion engine initially failed after 4.5 minutes of operation. However, it was later restored to action and performed excellently. Early in the mission, material ejected during launch vehicle separation caused the closely spaced ion extraction grids to short-circuit. The contamination was eventually cleared, as the material was eroded by electrical arcing, sublimed by outgassing, or simply allowed to drift out. This was achieved by repeatedly restarting the engine in an engine repair mode, arcing across trapped material. It was thought that the ion engine exhaust might interfere with other spacecraft systems, such as radio communications or the science instruments. The PEPE detectors had a secondary function to monitor such effects from the engine. No interference was found although the flux of ions from the thruster prevented PEPE from observing ions below approximately 20 eV. Another failure was the loss of the star tracker. The star tracker determines spacecraft orientation by comparing the star field to its internal charts. The mission was saved when the MICAS camera was reprogrammed to substitute for the star tracker. Although MICAS is more sensitive, its field-of-view is an order of magnitude smaller, creating a greater information processing burden. Ironically, the star tracker was an off-the-shelf component, expected to be highly reliable. Without a working star tracker, ion thrusting was temporarily suspended. The loss of thrust time forced the cancellation of a flyby past comet 107P/Wilson–Harrington. The Autonav system required occasional manual corrections. Most problems were in identifying objects that were too dim, or were difficult to identify because of brighter objects causing diffraction spikes and reflections in the camera, causing Autonav to misidentify targets. The Remote Agent system was presented with three simulated failures on the spacecraft and correctly handled each event.
a failed electronics unit, which Remote Agent fixed by reactivating the unit. a failed sensor providing false information, which Remote Agent recognized as unreliable and therefore correctly ignored. an attitude control thruster (a small engine for controlling the spacecraft's orientation) stuck in the "off" position, which Remote Agent detected and compensated for by switching to a mode that did not rely on that thruster. Overall this constituted a successful demonstration of fully autonomous planning, diagnosis, and recovery. The MICAS instrument was a design success, but the ultraviolet channel failed due to an electrical fault. Later in the mission, after the star tracker failure, MICAS assumed this duty as well. This caused continual interruptions in its scientific use during the remaining mission, including the Comet Borrelly encounter.