In beacon monitor operations, an on-board data summarization system determines the overall spacecraft health. Then it selects one of 4 radio tones to send to Earth to indicate how urgently it needs contact with the large antennas of the Deep Space Network, NASA's worldwide network of stations used to communicate with probes in deep space. These tones are easily detected with low cost receivers and small antennas, so monitoring a spacecraft that uses this technology will free up the precious resources of the Deep Space Network, thus allowing more spacecraft to explore the solar system without having to expand the network. Each tone is like a single note on a musical instrument. One tone might mean that the spacecraft is fine, and it does not need contact with human operators. Another might mean that contact is needed sometime within a month, while a third could mean that contact should be established within a week. The last is a virtual red alert, indicating the spacecraft and, therefore, the mission are in jeopardy.

Experiments conducted during DS1 addressed both the data summarization and the tone generation and detection (in both X-band and Ka-band), which agreed well with preflight models.

• Solar Electric Propulsion,   Frequently Asked Questions
• Solar Concentrator Arrays
• Autonomous Navigation
• Miniature Integrated Camera and lmaging Spectrometer
• Ion and Electron Spectrometer
• Small Deep Space Transponder
• Ka-Band Solid State Amplifier
• Beacon Monitor Operations
• Autonomous Remote Agent,   Frequently Asked Questions
• Low Power Electronics
• Power Actuation and Switching Module
• Multifunctional Structure