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Completed TRL 4 (started at 4, targeting 8)
The PY4 mission aims to enable autonomous swarms of small spacecraft by both reducing the manufacturing cost and integration effort required for individual spacecraft, and by advancing guidance, navigation, and control algorithms that increase autonomy and reduce or eliminate the need for expensive sensor, actuator, and propulsion hardware.
The advent of CubeSats and availability of low-cost commercial rideshare services have increased interest in missions involving formations or swarms of multiple spacecraft. Such mission concepts offer the promise of continuous coverage of Earth for observation and communication services, large baselines for high-resolution radio and optical astronomy, and distributed in-situ measurements of the ionosphere and solar wind. However, current methods for performing the basic relative-navigation and formation flying functions required for multi-spacecraft swarms involve expensive, specialized hardware; highly centralized coordination and control, typically performed by ground operators; and limited ability to function beyond low-Earth orbit (LEO) due to reliance on GPS or other global navigation satellite system (GNSS) signals.
PY4 consists of four 1.5-unit (1.5U) CubeSats and builds on the PyCubed open-source avionics platform and the previous V-R3x mission. PY4 successfully demonstrated high-data-rate mesh networking, precise inter-satellite ranging, range-based relative orbit determination, and magnetorquer-only sun pointing. PY4 is led by Carnegie Mellon University and is funded by NASA’s Small Spacecraft Technology program. NASA’s Ames Research Center provided support for integration and testing.
PY4 makes use of COTS long range (LoRa) radio modules that perform both communication and two-way time-of-flight ranging between spacecraft. These range measurements are fused with orbital dynamics models and other navigation measurements — such as occasional GPS measurements from a single “anchor” satellite — to determine the full orbital parameters of the entire swarm. Simultaneously with ranging and networking experiments, the four PY4 spacecraft also collect total-ionizing dose (TID) radiation measurements once every 30 seconds with the intent of creating dense temporal and spatial dose-rate datasets.
Current methods for performing the basic relative-navigation and formation flying functions required for multi-spacecraft swarms involve expensive, specialized hardware; highly centralized coordination and control, typically performed by ground operators; and limited ability to function beyond LEO due to reliance on GPS or other GNSS signals.
PY4 consists of four 1.5U CubeSats and builds on the PyCubed open-source avionics platform and the previous V-R3x mission. PY4 successfully demonstrated high-data-rate mesh networking, precise inter-satellite ranging, range-based relative orbit determination, and magnetorquer-only sun pointing, which advances technology relevant for future, cost-effective swarm missions.
This technology is relevant for missions in Earth orbit, deep space, and all applications that utilize multiple spacecraft that fly in formation.
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