From:https://ntrs.nasa.gov/api/citations/20230011368/downloads/R5_Fact_Sheet_2023-07.pdf

The Realizing Rapid, Reduced-cost high-Risk Research project, or R5, is a series of
CubeSats that are intended to rapidly and affordably get technology prototypes into Low
Earth Orbit (LEO). By accelerating the on-orbit demonstration of technologies, engineers
and scientists will be able to more quickly prove them and make them available to NASA
missions and other users. In order to create spacecrafts fast and cheap
enough to hit project objectives, R5 is leaning heavily on commercial-off-the-shelf (COTS) hardware and is developing processes to intelligently select and screen these
components for the space environment. R5 is also reducing cost and schedule by
substantially reducing the traditional process used to build spacecraft. As R5 develops
these new methodologies, the findings will be shared with the small spacecraft community
so that others can follow the successes and avoid repeating the failures.

The baseline R5 spacecraft configuration is a 6U (2x3U) bus and of that approximately 3U is payload volume. The bus form factor and included subsystems can be tailored
extensively to best match payload needs. As R5 is intended to support a broad variety of
payloads and missions, the bus must have reliable telemetry systems for beaconing, an
attitude determination and control system (ADCS), relatively high-performance compute,
flexible flight software system, and a very flexible internal configuration. While some
subsystems are completely COTS, others are combinations of custom hardware and
integrated COTS components. The demonstration of these systems will enable
the use of traditionally expensive and long-lead time subsystems (like propulsion) on
much shorter timescales and for a small fraction of the cost.