Teck H. Choo

The MESSENGER Science Planning and Commanding System

MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is the first spacecraft to visit Mercury since the Mariner 10 flybys in 1974 and 1975 and will be the first spacecraft to orbit the innermost planet, beginning in March 2011. The science payload is designed to study all aspects of Mercury and its environment and consists of seven instruments and a radio science experiment. During the primary orbital phase of the mission, the MESSENGER team faces the challenge of scheduling science observations to meet all measurement objectives while operating in a thermally harsh environment in geometrically challenging orbits. An efficient, automated science planning and commanding system called MESSENGER SciBox has been developed to support orbital analysis and strategic planning activities prior to orbital insertion, and to schedule and command the instrument and spacecraft operation during the orbital phase. In this paper we present the architecture of MESSENGER SciBox and its application to pre-orbital simulation and inorbit operational usage.

Mini -RF Orbital Planning and Commanding System

We present an efficient science operations planning and commanding sys tem for the Mini -RF instrument. The Mini -RF instrument is a lightweight side -looking radar system that will use Synthetic Aperture Radar (SAR) to obtain images of the lunar polar regions to search for regions of water -ice deposits. The two missions that wi ll carry the Mini -RF instruments are the Indian Space Research Organisation (ISRO) Chandrayaan -1 lunar orbiter and the NASA Lunar Reconnaissance Orbiter (LRO). The Science Operations Planning and Commanding Subsystems, a suite of planning and commanding to ols, will be used by a small team of scientists to efficiently construct the operations schedule, and to modify any opportunity to maximize the science obtained.

Comprehensive Mission Simulation Contingency Analyses: Achieving Science Observation Plan Resiliency by Design

1 . Automated tools that simulate full orbital dynamics, instrument operation, and data acquisition as well as operational and resource constraints allow planners to develop schedules that are conflict free and fit within mission capabilities. Moreover, if the simulations have sufficient fidelity and are performed well enough in advance, they can also be used to identify and assess risks by analyzing the schedule for sensitivities to different contingencies. In this paper, we discuss a primary risk area for MESSENGER, available solid-state recorder (SSR) space, and describe how we used the tools in MESSENGER SciBox to model the instrument suite data generation, downlink telemetry volume, and the resulting SSR loading through the mission. We then discuss two examples to illustrate how this tool is used to design instrument operations and to analyze the impact of non- nominal downlink performance to specify required contingency responses using a combination of telemetry bandwidth increases and data decimation. Given this simulation and analysis, knowledge of the greatest risks and detailed plans for responses are already in place, providing greater assurance of mission success.

MESSENGER SciBox, An Automated Closed-Loop Science Planning and Commanding System

MESSENGER SciBox is an automated closed-loop planning and commanding system used to optimize orbital science operations for the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission. The system plans all science observations for the seven science instruments on the spacecraft and also automatically generates the command sequences that drive the instruments, the guidance and control system, the solid-state recorder, the solar panels, and the radio-frequency communication system. MESSENGER SciBox interacts with the instrument scientists, mission operations team, downlink processing system, and mission design engineers to form a closed-loop system. In orbital operation, the systems employ a feedback loop, with a one-week time step, to improve the system performance. Feedback inputs are used to predict observational performance, to track all science observations, to avoid planning redundant tasks, and to recover from operational anomalies. The software tool is automated because the entire process, from ingesting the feedback inputs to creating the spacecraft and instruments commands, can function without manual interaction. I. Introduction Science operation centers for most space missions generally consist of two components: the uplink system and the downlink system. The uplink system deals with planning and scheduling of science observations, whereas the downlink system deals with the processing of observations returned from the spacecraft. Traditionally, the planning and scheduling of science observations, and the creation of associated spacecraft and instrument commands for science operation, are so time-consuming and labor-intensive that little time is left for the planning team to have close interactions with the data processing team. Any such interactions tend to be ad hoc and informal. On some missions, the two subsystems are so decoupled that they are even housed in different institutions and on separate networks. The lack of tightly coupled interaction frequently results in inefficient use of resources and a less-thanoptimum operational schedule. In this paper we describe an automated planning and commanding system that uses a closed-loop iterative process to continuously refine the science operation schedule and to generate spacecraft and instrument commands for uploading to a spacecraft. The planning system iteratively interacts with the instrument scientists, mission operations center personnel, mission design team, and downlink processing system to produce a scienceobservation-packed operational schedule and to improve the precision of planned operations. The process of ingesting feedback information from the downlink system to the generation of spacecraft and instrument commands for uplink is completely automated. This closed-loop architecture has been implemented as part of science operations for the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft now in orbit about Mercury, and it has allowed the MESSENGER team to maximize scientific return for the community with a relatively small operational staff. The closed-loop architecture and its application to MESSENGER orbital operations are the focus of this paper.

Prometheus's Challenge: Scheduling MASCS Observations Using SciBox for Orbital Operations at Mercury

Performing scientific observations of a planet from orbit is a complicated endeavor for a spectrograph with a small field of view. Adding in a second spectrometer with a different field of view, and attempting to observe three different aspects of the planet with a total of five detectors, constrained by severe orbital, pointing, and downlink limitations, increase the challenge. On board the MESSENGER spacecraft, the Mercury Atmospheric and Surface Composition Spectrometer (MASCS), which consists of two separate instruments (the Visible and Infrared Spectrograph – VIRS – and the Ultraviolet and Visible Spectrometer – UVVS), will be facing precisely that challenge during the orbital operation phase of the mission to Mercury. As the cruise operations and three successive flybys of Mercury have demonstrated, manually sequencing observations for these two instruments is a labor-intensive task. In order to help schedule MASCS observations of both the surface and the planetary exosphere more efficiently, a planning tool called SciBox will be employed to generate the initial observation suite for each orbital period and coordinate MASCS observations with the other science instruments aboard the spacecraft.