PUNCH Mission Planning and Operations

We discuss mission planning and operations flow for the PUNCH mission. PUNCH comprises four small satellites in a low earth sun-synchronous polar orbit. The four satellites function as one distributed instrument imaging the solar corona and inner heliosphere. In nominal operations, the four spacecraft each take synchronized polarized white-light images in an eight-minute sequence at a stable attitude, conduct a synchronized roll to maintain approximate nadir-pointing, and repeat the imaging-roll sequence ad infinitum. Ground station contacts for data download and command upload can happen on an individual spacecraft without disrupting these science operations. Constellation spacing and conjunction avoidance is performed with small propulsive maneuvers, which do require interrupting the science sequence for that spacecraft. The SwRI-developed mission planning software “SIMPL” is the crucial interface between the ground data network, flight dynamics, science operations, and mission operations teams. SIMPL generates hours-long ground station contact request windows up to 4 weeks in advance, which are then combined with Flight Dynamics-generated spacecraft ephemerides and ground station schedules to lock in specific ground station contact times. Quaternions for each spacecraft are generated by Flight Dynamics for each 8-minute science sequence and are revised with every new orbit determination. SIMPL generates ground-side commands and spacecraft-side command loads, which includes the planned contacts, the science acquisition and roll sequences, and any other scheduled spacecraft activity.