Unique Challenges of Mission Operations on SunRISE, A Low-Cost NASA Science Constellation

Advances in SmallSat technology make them an increasingly viable option for innovative, low-cost NASA science missions. The size and cost of these platforms enables constellation architectures that were previously untenable, and which offer major science upside. However, these complex architectures must be paired with equally advanced mission operations systems to achieve success. New operations practices must be designed to meet the unique needs of a low-cost, science-focused constellation, and it is not clear whether operations will be simpler for such missions than their larger counterparts.The Sun Radio Interferometer Space Experiment (SunRISE), set to launch no earlier than September 2024, has navigated these challenges as part of operations development over the last 2.5 years. SunRISE is a constellation of six identical 6U CubeSats orbiting slightly above GEO. Together, these vehicles will form the first space-based radio interferometer, referred to collectively as the "observatory." They will observe radio bursts from solar coronal mass ejections and solar flares over a 12-month science phase.This paper explores key operational challenges and solutions faced on SunRISE. Chief among them is meeting observatory availability requirements, developing a ground system to support a small operations team, and hardware availability for observatory-level testing.Each SunRISE vehicle contacts the Deep Space Network (DSN) once per week in a five-hour pass. Multiple-Spacecraft-Per-Aperture is used to batch the six vehicles into two total DSN passes per week, with three vehicles each. These DSN passes are not sequential and can be separated by up to 48 hours. Once-weekly contacts, combined with two disparate passes to contact the entire observatory, poses a significant challenge to constellation management. In order to meet observatory availability requirements, the operations system must minimize mistakes during weekly contacts and ensure that missed contacts do not result in loss of observing time.The ground system plays a crucial role in navigating the challenges of SunRISE. It must handle multiple parallel data streams and provide functionality so operators can efficiently manage a constellation. This was achieved with a unique development process enabled by the small team culture of missions like SunRISE.Operating six vehicles, especially simultaneous operation of three vehicles during a single contact, requires significant operator training. However, full-observatory testing is expensive and difficult to configure. SunRISE navigated this with a "minimum viable" approach. A comprehensive series of single-vehicle thread testing was used to prove out capabilities and processes. Then, a major activity, the Interferometer Level Performance Test, served as the key testing and training point for anything that required six vehicles to test.The test campaign and resulting operations system demonstrate the type of innovation required to support low-cost, science-focused SmallSat constellation missions. Flexibility and creative freedom are crucial to successful operations development for such missions, which will certainly have unique and specific challenges depending on institution, vendor, and objectives.SunRISE is managed by NASA's Jet Propulsion Laboratory, who also provides the payload and mission operations, with spacecraft buses and integration from Space Dynamics Lab, and PI and science data system from the University of Michigan.