Automated Spacecraft Operations During Soil Moisture Active Passive Prime Mission

摘要

Autonomy and automation of spacecraft operations have been long sought goals to reduce costs and risks. Many different approaches depending on the particular mission's needs and characteristics have been tried and taken. Soil Moisture Active Passive (SMAP) is a science spacecraft mission measuring soil moisture, freeze/thaw and other parameters on a global scale, to support weather forecasting, disaster response and climate research. The spacecraft is fairly conventional and is in a sun synchronous near-polar low Earth orbit. The sole instrument is an L-band passive radiometer; the active radar component is currently inoperative. Automation is a characteristic feature of SMAP flight operations. The project practices “lights-out” operations, where the control room is not staffed, except for occasional real time or contingency activities. Operators nominally work only during regular business hours. Activities are planned and set up on a weekly cadence, and automated processes conduct data processing and commanding. Continuous downlink monitoring is enabled by a sophisticated notification architecture, along with weekly telemetry review by experts. A suite of tools and processes are used to implement the automation. Other tools and resources, while not strictly speaking automation, improve efficiency and reliability, which fundamentally achieve the same benefits as automation. As might be anticipated, there are challenges with a complex ground system that link together many disparate elements. On balance, spacecraft operational costs are estimated to be much lower than if the mission was flown in a conventional manner. In summary, the overwhelming majority of commanding during science phase are performed autonomously, without direct human intervention. A very low command error rate was achieved. It is proposed this concept of operations may serve as a useful model for future missions with similar characteristics.