Description: Current autonomous rendezvous and docking (AR&D) capability in low Earth orbit (LEO) is constrained by sensor and effector mass, power, and accuracy limits. To this end, NASA Johnson Space Center has developed a GPS receiver, called DRAGON (Dual RF Astrodynamic GPS Orbital Navigator), specifically to address the sensor constraints. The proposed innovation includes creating a small, low-cost, and versatile technology demonstrator to validate and increase the technology readiness level of DRAGON and other state-of-the-art miniaturized sensors and effectors in an on-orbit AR&D operational scenario. For Phase 1, a demonstration platform was developed that utilizes two picosatellites in LEO, and relative GPS as the primary sensor. These satellites were launched as a single unit from the SSPL (Space Shuttle Payload Launcher) on STS 127, to separate and transmit DRAGON data. The picosatellite technology demonstrator was at a TRL of 7 at the end of Phase 1. For Phase 2, NASA plans a second flight, and the technical objectives are to further characterize the DRAGON receiver and develop navigational solutions using DRAGON data. Additional technologies addressed include the development of a simple low-cost, low-mass three-axis stabilization and pointing system for small satellites, WiMax transceiver capabilities, and video camera capabilities. The technologies should be at a TRL of 6 at the end of Phase 2.

Benefits: The validated miniaturized sensors and effectors will be applicable to a variety of missions for DoD, companies, and universities, and the demonstrator platform itself will be plug and play, and available and adaptable to other mission validations. As an example, PM&AM Research has been working in laser-based micro-space propulsion with the AFRL Space Propulsion Directorate for many years, which has led to a number of applications of distributed systems based on picosats. Our concept will help realize such distributed systems. The communities with immediate interest include: responsive space, midcourse ballistic missile defense, and space situational awareness. PM&AM Research is working with DoD in each of these, and a suitable platform for specific test scenarios will allow us to perform test and evaluation measurements/scenarios attractive to these customers. These anticipated development efforts are expected to lead to follow-on efforts and eventual products, which may require the involvement of the large integrators.

Autonomous rendezvous and docking will be utilized in the Constellation Program for unmanned cargo vehicles and in space assembly. The proposed technology demonstrator platform is being designed to specifically validate enabling devices and other critically needed technologies for Constellation, such as NASA Johnson Space Center's DRAGON GPS system, docking mechanisms, miniaturized sensors and control effectors, control algorithms, and navigation solutions. Moreover, it is anticipated that the technology demonstrator platform itself will be plug and play, and available and adaptable to further mission validations.