Project LEDsat : Using LEDs to improve orbits and attitude determination of LEO satellites

Project LEDsat is an international effort to investigate the use of Light Emitting Diodes (LEDs) for applications on satellites in Low Earth Orbit (LEO). These applications include improved orbit determination by making the satellite visible even in Earth shadow, distinguishing satellites by using different flash patterns on satellites in simultaneous launches of multiple satellites, attitude determination, and telemetry.Optical observations are often used for determining the orbit of uncooperative spacecraft and space debris and they provide the possibility to significantly improve the Two-Line Elements (TLE) orbital parameters estimation with a small set of optical data. However, a comparison between optical and other positioning data is not easily available for the uncooperative nature of the observed objects. LEDSAT will offer a unique opportunity to compare the optical orbit determination results to the on-board Global Positioning System (GPS) receiver data and to the laser ranging measurements allowed by on-board retro-reflectors, hence providing the chance to verify, improve and cross-correlate the optical stand-alone orbit determination techniques for space debris. An Italian student team from Sapienza Space Systems and Space Surveillance Laboratory (S5Lab) at Sapienza - University of Rome is developing the 1-Unit Cubesat LEDSAT. The satellite project is realized within the European Space Agency Fly Your Satellite! Programme, that will offer a satellite launch opportunity for the International Space Station in late 2019, in addition to technical support for the satellite development process. The satellite mission consists in testing a Light Emitting Diodes (LED) -based payload as calibration target for the current methodologies and techniques for optical-based orbit determination of space objects. A student team from the University of Michigan is developing a 3U CubeSat LED mission called PHAROS. Initial efforts here are centered on a balloon payload to test visibility of LEDs, trajectory information from LEDs and other sources, and attitude determination of the payload. The primary goal is to verify the optical link budget used for future spacecraft missions.We will review the current status of both of these missions, and how lessons learned will benefit knowledge of the increasingly congested LEO environment.