Brain Murmurs
Guerrilla computing in the mountains of Seattle
| Daniel Pasco worked at Lockheed Martin Astronautics from 1996 to 1999. During that time he wrote and tested the embedded electrical power system (EPS) software used on the Stardust, mars Odyssey, Mars Climate Orbiter, Mars Polar Lander, and Genesis spacecraft. |
Embedded Spacecraft Flight SoftwareThe EPS software provided a layer of control over the entire electrical power subsystem of several different spacecraft. The entire suite was written in ANSI C and ran in the VxWorks operating system. | |
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Component Power Control, Monitoring, and Fault Protection The EPS software provided power handling for all of the other tasks on the spacecraft including Telecom, Thermal, Articulation and Attitude Control, and Structures and Mechanisms. Components requiring power to be turned on or off for their hardware would send asynchronous messages to the EPS message queue. The software would then read the message, command the hardware to the requested state, and send a notification back to the client task reporting the new power state. The software was also responsible for commanding and monitoring relay switch states via the EPS Module Interface Card (EMIC). The EPS subsystem was also responsible for ensuring that switches actually responded to commands and maintain the commanded state. In the event of a significant hardware power failure the software was capable of requesting a spacecraft reboot through High Level Fault Protection. Propulsion and Ordinance Handling Rocket engine firing was controlled by the AACS subsystem, but EPS actually handled bringing the propulsion systems on line through the use of propulsion valves. Another EPS subsystem known as PIM was used to fire explosive bolts during key mission sequences including solar array, lander leg, and antenna deployment. Battery Charge Control The battery state of charge (SOC) was estimated or directly measured in a variety of different ways depending on the mission in question. In any case, the role of the battery module was the same: determine the battery state of charge, increase the charging rate if the SOC was too low, decrease the charging rate if the SOC was too high. Stardust Flight SoftwareHe also wrote the software responsible for steering the Stardust spacecraft during the Comet flyby phase of its mission. Also wrote another module responsible for aiming a mirror used to keep the comet's nucleus in sight of the spacecraft's camera during the flyby. He participated heavily in almost all spacecraft system tests and troubleshooting during his time at the company.Spaceflight OperationsDaniel also worked as a flight software specialist on the mission control team for the Mars Surveyor and Stardust flight operations and worked on console during maneuvers as a flight software liaison to the control team. His duties included monitoring onboard spacecraft software during critical mission phases and participation in spacecraft mission planning meetings. He also performed data collection and trending throughout time on the team.Dan ran a spacecraft test lab for Stardust consisting of several Sun workstations and real-time simulation software running on an SGI Origin 2000 system interfaced by a VME bus. He used this lab to validate spacecraft command sequences and operations before their use in operations. | |
