Daniel Wenkert

NIPCs: The Operational Sandbox of Science Commanding

The Mars Reconnaissance Orbiter (MRO) and other JPL -operated deep space missions have achieved a reduction of operations complexity through the use of a non -interactive payload commanding paradigm. Traditionally, science p ayload commanding has been integrated with the commanding required to perform the engineering functions of the spacecraft. By operating the spacecraft such that much of the science commanding is performed independent of the rest of the vehicle, the science teams are empowered to freely operate their instruments and acquire their science data. Similarly, routine vehicle management, such as communication s, attitude control, and health and safety diagnostics; are performed by the engineering teams indep endently of the science teams. Non -Interactive Payload Commands (NIPCs) are command products that have been predetermined to be benign in nature with respect to the health and safety of the spacecraft . This paper present s pros and cons of using such an operating paradigm, identify up -front mission and spacecraft design implications, and demonstrate how MRO has benefited from t his design decision. I. Introduction N an era of heavily constrained budgets, N ational Aeronautics and Space Administration (N ASA ) has looked for ways to reduce mission cost through a reduction in operations complexity. With many recent missions over - ac hieving their mission objectives and mission life span, the se savings can be fur ther realized during commonly occurring extended missions . One approach many deep space missions operated by the Jet Propulsion Laboratory (JPL ) have pursued is the use of a no n-interactive payload commanding paradigm. This paradigm assumes that much of the science commanding may be performed independent of the rest of the vehicle, and th at th e management of routine vehicle functions , such as communications, attitude control, an d health and safety diagnostics ; may be performed independently of the science commanding . By partitioning the problem in this way and removing much of the interaction between these two spacecraft functions, a significant reduction of operational complexit y is achieved. A large part of this paradigm is the use of Non -Interactive Payload Commands (NIPCs), which are command products that have been predetermined to be benign in nature, with respect to the health and safety of the spacecraft . In operations, the y may be used without being subject to the same rigorous test and approval process to which typical engineering commands are exposed. By confining the NIPCs to a strict operational envelope, the science teams are given significantly freedom to operate thei r own instruments without risking the remainder of the flight system; as part of this functionality the science teams take responsibility for the correctness and safety of their commands. When this division is performed effectively, both the engineering an d the science teams can complete their objectives with minimal impacts to each other, thus reducing the necessary interaction between the teams and the overall cost and complexity of mission operations. The NIPC paradigm itself may not be applicable to all mission types. In the remainder of this paper, we will compare and contrast the operations concepts of several operating deep space missions and detail the NIPC concept. We will also present pros and cons of using such an operating paradigm, identify up -front mission and spacecraft design implications, and specify how the Mars Reconnaissance Orbiter ( MRO ) has embraced this concept. Finally, we will suggest how the NIPC concept might further evolve to offer a greater reduction of operations cost and comple xity, while potentially increasing a missions capability to perform its objectives.

Enabling International Data Relay at Mars

The most commonly used mode of communications between Earth and a Mars surface mission is ultrahigh frequency (UHF) radio relay via a Mars orbiter. There are four orbiters and two surface rovers operating at Mars and by October there should be five orbiters and three landers or rovers. There has been some collaboration between ESA’s Mars Express orbiter and NASA’s rovers, but 2016 is when Mars relay becomes fully international. In October, ESA will deliver the ExoMars Trace Gas Orbiter (TGO) and Entry, Descent, and Landing (EDL) Demonstrator Module (EDM) lander to Mars. The ExoMars program includes both ESA and ROSCOSMOS, with NASA participation (the Electra UHF transceiver on TGO). NASA orbiters will provide relay for EDM and future ESA Mars landers and rovers. TGO will provide relay for NASA’s current and future surface assets (as Mars Express will continue to do).

Relay communications support to the ExoMars Schiaparelli lander

The European Space Agencys ExoMars Trace Gas Orbiter (TGO) arrived at Mars on October 19, 2016, three days after releasing the Schiaparelli Lander on a ballistic trajectory to Meridiani Planum. During the separation event, and subsequently during Schiaparellis Entry, Descent, and Landing (EDL), the NASA-provided Electra Ultra-High Frequency (UHF) payload onboard TGO was used to record signals from the Schiaparelli Lander for post-processing on the ground to recover both tracking of the landers carrier signal and reconstruction of the landers 8 kb/s telemetry. In addition, ESAs Mars Express orbiter recorded the Schiaparelli signal, with ground post-processing providing independent tracking of the lander carrier signal, and the Giant Metrewave Radio Telescope near Pune, India was configured to provide real-time detection of the lander carrier signal. While an anomaly in the latter stages of EDL led to loss of the lander, these critical event data sets, and in particular the telemetry reconstruction enabled by the TGO Electra recording, proved essential in enabling detailed diagnosis of the anomaly. While the loss of the lander during EDL precluded the planned surface relay operations, the preparations for that activity provide important lessons learned for future Mars relay support scenarios.