June 2012 Edition - Emergency Communications...
OPS: NRL Journal: Nanosatellite Experimental Platforms
By the editors of the NRLs SPECTRA Magazine
Two nanosatellites designed and built by NRLs Naval Center for Space Technology were placed in orbit to evaluate nanosatellites as platforms for experimentation and technology development. They were launched from Cape Canaveral Air Force Station on December 8, 2010, as secondary payloads on board a Space Exploration Technologies (SpaceX), Inc., Falcon 9 launch vehicle.
NRLs nanosatellites are part of the CubeSat Experiment (QbX) of the National Reconnaissance Office (NRO). Cubesats are standardized, cube-shaped satellite platforms measuring only 10 cm (about four inches) on a side. NRO wants to demonstrate the feasibility of placing payloads on cubesats to accelerate technology evaluations and deploy new capabilities with markedly reduced costs over traditional satellite platforms.
Three cubesats attached end-to-end are referred to as triple-unit (3U) platforms. On this launch, NRL deployed two 3U cubesats with Colony I buses built by Pumpkin Inc. of San Francisco, California, and provided by the NRO.
NRLs tiny 3U cubesats contained components comparable to large satellites, including command telemetry and data handling, an electrical power system with batteries and solar arrays, an attitude control system with magnetic torque coils and reaction wheels for three-axis attitude control, and a UHF radio with antenna. Each subsystem essentially fit on a 4 x 4 inch circuit board.
Engineers from the NRL Spacecraft Engineering Department tested and integrated the nanosatellites before launch, and communicated successfully with them after deployment. The tracking, telemetry, and command (TT&C) radio was fully functional, providing reliable two-way data transfers; and the flight software, ported from previous and ongoing NRL programs to the Pumpkin Colony I processor, provided an onboard scheduler for routine vehicle control and operation.
Deployments, including arrays and antennas, were verified shortly after launch, said Dr. Stephen Arnold, a computer engineer with the Spacecraft Engineering Department. We were able to command the satellites and receive stored and real-time telemetry from the onboard systemsin all, the spacecraft operated as expected, and the checkout and experimentation were successful.
Spacecraft attitude operated in a novel space dart mode, so called because of the shape and attitude of the deployed satellite. In this mode, atmospheric drag in the low orbit (300km) provides a stabilization torque that, used with the onboard reaction wheels and torque coils, provides stable pointing to within five degrees of nadir throughout the orbit.
It was expected that the QbX vehicles would remain in orbit for approximately 30 days, said Arnold. In the end, one orbited for 29 days and the other for 39 days before each succumbed to the effects of atmospheric drag and was destroyed during re-entry to Earths atmosphere.
Flight software, antennas, and the TT&C radio were designed, built, and integrated by NRL, as was the developmental communications payload. Environmental testing of the completed package was performed in NRLs extensive spacecraft testing facilities. Ground stations on the east and west coasts provided coverage for command loads and data collection, controlled via VPN from NRLs Blossom Point Satellite Tracking and Command Station in southern Maryland.
The primary payload launched aboard the SpaceX Falcon 9 was the Dragon capsule. Developed by SpaceX and sponsored by NASAs Commercial Orbital Transportation Services (COTS) program, the Dragon capsule is part of an initiative to develop private spacecraft to ferry cargo to and from the International Space Station.
Return To Top
Return To Top