CAPSTONE Extended Mission: A Cislunar Testbed for Autonomous SmallSat Technologies

The Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment (CAPSTONE) is a 12U small satellite technology demonstration mission supporting NASA’s return to the Moon. Managed by NASA’s Small Spacecraft & Distributed Systems (SSDS) program, formerly the Small Spacecraft Technology program, within the Space Technology Mission Directorate, CAPSTONE exemplifies the program’s charter to rapidly develop and demonstrate capabilities for small spacecraft applicable to exploration, science and the commercial space sector.

CAPSTONE was originally funded by SSDS as a pathfinder for Gateway, a Moon-orbiting outpost part of NASA’s Artemis program. The mission reduced risk for future cislunar missions by validating innovative navigation technologies and characterizing the dynamics of the Near Rectilinear Halo Orbit (NRHO). CAPSTONE launched on June 28, 2022, onboard a three-stage Rocket Lab Electron vehicle, successfully completing its primary mission objectives in 2024.

To increase the value of this existing on-orbit spacecraft, NASA extended its partnership with Advanced Space of Westminster, Colorado to continue CAPSTONE’s operations past the primary mission. The extended mission advances space technologies, further characterizes the lunar orbital environment, and provides additional operational insight to support Artemis mission planning. Current operations are planned to continue for 18 months beyond the primary mission.
In collaboration with NASA’s Goddard Space Flight Center (GSFC), CAPSTONE will demonstrate and test technologies that enable autonomy and standards-based, interoperable communications and networking in the challenging cislunar environment. This paper highlights several planned experiments for this lunar orbital asset.

1. Software-Defined Satellite: On Earth, when we suspect the compromise of a computer or simply want to repurpose it, we wipe the machine back to bare metal and rebuild it with a new operating system and applications. Spacecraft use flight computers and performing such operations on orbit has not been possible. Using data and experiences from on-going CAPSTONE flight tests, we’ll discuss NASA’s Software-Defined Satellite experimentation. NASA will demonstrate fundamental operations required to repurpose an on-orbit spacecraft. These include securely rewriting the field-programmable gate array (FPGA) bitstream, wiping and replacing an operating system kernel, upgrading core Flight System (cFS) applications, and rebuilding the user applications. The extended mission demonstrates how an existing commercial spacecraft can be repurposed remotely - from a distance of about 400,000 kilometers - to test new concepts and applications.

2. Autonomous Navigation, Guidance and Control (AutoNGC): Current spacecraft operations in cislunar and beyond are heavily reliant on ground-based infrastructure and a standing army of personnel. As cislunar and deep-space operations expand in support of sustained lunar presence and future Mars exploration, new approaches to spacecraft navigation are necessary. Assets such as the Deep Space Network (DSN) and Near Space Network (NSN) are limited and increasingly oversubscribed. GSFC’s autoNGC software enables autonomous navigation capability that can greatly reduce reliance on ground infrastructure and allow future deep space missions to operate with a reduced ground footprint.

3. Communications and Networking: CAPSTONE continues to provide a platform to explore and demonstrate novel ways to use its onboard IRIS radio. Demonstrations include data relay with the Lunar Reconnaissance Orbiter to possibly support lunar surface and far side missions, Delay Tolerant Networking demonstrations, and the use of commercial ground stations to communicate with a spacecraft in NRHO.

Beyond CAPSTONE’s demonstration of new capabilities, this work highlights the value of extending spacecraft missions to maximize the return on an on-orbit investment, especially in times of constrained budgets. This paper presents lessons learned from conducting experiments in NRHO on a platform that is owned and operated by a commercial entity and explores the unique aspects encountered by experimenters using an “experimentation-as-a-service” concept.