Apr 15, 2016: It is a well known fact that to send and receive data from an orbiting spacecraft, radio-frequency communication is required. This has been the only and most reliable way to communicate since 1957, the year in which Sputnik 1 was launched. Now, scientists at NASA have developed ‘light’ based modem for all their communication strategies.
First ‘light’ based modem revealed by NASA
Sputnik made use of two radio frequencies: 20.005 and 40.01 MHz. The US first satellite, Explorer 1, had frequencies at 108.00 and 108.03 MHz. These days space communication require a large radio spectrum wavelength for all sorts of competing purposes ie; GPS, television broadcasts and weather satellite imagery.
Radio communications have some limitations as radio spectrum is only one small interference-prone slice of the larger electromagnetic spectrum. The main limitation is it can only offer relatively slow data rates.
As radio band happens to be one of two frequency ranges capable of transmitting across Earth’s atmosphere, we have a very limited choice here. Higher frequencies and ultraviolet frequencies are mostly absorbed, as are the infrared frequencies. The option of electromagnetic “windows” representing frequency ranges that can pass between Earth and space relatively unchanged is left. Radio is one, while the other is the even narrower band of visible light.
NASA engineers have taken a major step in making communications possible via light in the form of the first-ever integrated-photonics modem. The “potentially revolutionary” technology offers data rates between 10 to100 times that of radio communications and could be in Earth-bound telecommunications as well. Other important applications are medical imaging, advanced manufacturing methods, and national defense.
This new technology is known as Integrated LCRD LEO (Low-Earth Orbit) User Modem and Amplifier (ILLUMA), will be put to testing conditions in 2020 as part of NASA’s multi-year Laser Communications Relay Demonstration (LCRD) mission. The technology shall be installed aboard the ISS as part of the program. The LCRD is a full system featuring not just the ISS payload but two dedicated ground stations unlike NASA’s prior laser-communications effort, which was sent into orbit with the Lunar Atmosphere and Dust Environment Explorer in 2013. Together, the link can attain data rates of up to a gigabit per-second.
The driving technology behind the LCRD is integrated photonics. The basic idea lies in building circuits just as you would for a normal electronic device using lithographic techniques. But electrons shall be used in place of photons, e.g. particles of light. Basis of this, the modem is implemented and make sense of laser-based communication.
Mike Krainak is leading the modem’s development program at Goddard and states “the technology will make optical-system design simple. It will reduce the power consumption and size of optical devices, and improve reliability, all while enabling new functions from a lower-cost system. It is quite evident that our strategy to leverage integrated-photonic circuitry will lead to a revolution in Earth and planetary-space communications.
Another hot terrestrial application in process by the NASA engineers is in data centers. It forms a large part of the internet’s backbone of fiber-optics, which is dedicated to managing the interface between optical information and data saved in servers. LCRD promises that same hardware on a small chip.