Darren Rowen

LEO to ground optical communications from a small satellite platform

A pair of 2.2 kg CubeSats using COTS hardware is being developed for a proof-of-principle optical communications demo from a 450-600 km LEO orbit to ground. The 10x10x15 cm platform incorporates a 25% wall-plug efficient 10-W Yb fiber transmitter emitting at 1.06 μm. Since there are no gimbals on board, the entire spacecraft is body-steered toward the ground station. The pointing accuracy of the LEO craft, which governs the data rate capability, is expected to be ~ 0.1-0.2 deg. Two optical ground stations, located at the Mt. Wilson observatory, have receiver apertures of 30 and 80 cm. Launch of the CubeSat pair is anticipated to be mid to late 2015.

CubeSat-Scale High-Speed Laser Downlinks

The recent surge in the development of new commercial services hosted by satellites in low Earth orbit will lead to rapid increases in the demand for data downlinking, presenting a challenge for conventional radio-frequency communication systems. Optical communication systems offer a significant but so far unrealized potential for ultrahigh- volume downlinking. A number of demonstration laser communication missions have flown in space, but no optical systems are in routine operational use. Existing optical communication systems are typically too large for use in next-generation small commercial satellite systems.

On-orbit characterization of space solar cells on nano-satellites

The Aerospace Corporation has been building, testing, and flying miniature satellites in the pico-and nano-satellite class for over a decade. Significant advances have been made to the bus avionics unit and other satellite subsystems during this time. The advances have enabled various on-orbit tests and experiments, one of which has been to host space solar cell experiment payloads. Recent solar cell flight experiments on Aerospaces CubeSats (AeroCubes) demonstrated several subsystems can simultaneously operate to obtain precise measurements of space solar cell performance. Low cost, rapid return CubeSat missions can be valuable development tools for advancing the readiness level of space technologies.

Along for the Ride: Experience with Flexible Mission Design for CubeSats (Invited)

The AeroCube-4 CubeSat, a picosatellite in a 10-cm cube form factor with a mass of 1 kg, was delivered by an Atlas V launch vehicle into a 480 x 780 km altitude orbit inclined at 65 deg. Despite being deployed into this unconventional orbit, AeroCube-4 has succeeded in performing many missions beyond its original design, including formation control via differential drag and Earth imagery for forest-fire geolocation and sunglint. Under normal circumstances, a mission designer would not select the AeroCube-4 orbit for these activities. The nature of the CubeSat paradigm demands flexibility on the part of the mission designer and on how he or she interacts with the spacecraft designer, working in a community where the orbit may not be known until after the spacecraft is built. The wide-ranging activities of AeroCube-4 are discussed, as are the mission-design challenges that grew out of this satellite’s less-than-optimal orbit.