NASA has developed a new technology for space optical communications, including communications from the Earth to spacecraft in Earth orbit and in deep space, such as at the Moon and Mars. The innovation changes the architecture of space optical communications so that a new laser beam pointing technology is used to improve optical data transmissions from spacecraft. This technology will detect a signal laser beam and then return a modulated laser beam to the ground terminal or other transmitter station in a new way. This new design can replace current methods that either use a laser together with a pointing, acquisition, and tracking (PAT) procedure in the spacecraft, or a powerful ground-based laser with a retro-reflector in the spacecraft.
The Space Optical Communications Using Laser Beams (SOCULB) will provide the capability to amplify a laser beam that is received in a modulating retro-reflector (MRR) located on a satellite in low Earth orbit, and also to improve the pointing procedure between Earth and spacecraft terminals. This technology will use a cat’s eye lens for pointing, and laser arrays to strengthen the reflected laser beam from the spacecraft. The system does not pose any electrical safety issues because microelectronic components are used that operate at voltages below 10 volts and with currents below 100 miliamps (mA). The laser radiation received at the ground terminal will not pose a danger to human health because of the low transmitted power. In addition, the vertical-cavity surface-emitting laser (VCSEL) chosen for this application can operate in the 1550-nm wavelength range, where the maximum permitted exposure level for the eyes is orders of magnitudes higher than at other wavelengths. This simplifies testing of the devices on the ground. Wavelengths in the 1550-nm range are the usual wavelengths for optical communications.
SOCULB requires minimal maintenance; its components are simple, static, and reliable; it’s compact, with no moving parts; and does not need a vibration isolation platform. Potential applications include use in CubeSat communications, the spacecraft industry, and in small satellites.