Context: NASA’s Psyche spacecraft, currently over 16 million kilometres away in space, successfully fired a laser signal at Earth.
Components of Deep Space Optical Communication
- Laser Transmitter: It is mounted on spacecraft such as Psyche to generate a laser beam. The laser emits light in the form of photons, which is focused into a narrow beam.
- Modulation: The information needed to be transmitted is encoded onto the laser beam through a process called modulation.
- Telescope/Collector: On the ground or at spacecraft, a large telescope or collector is used to receive the incoming optical signal. The collector is designed to capture as much light as possible from the incoming laser beam.
- Photon Detection: The collected optical signal is then directed to a photodetector. The photodetector converts the incoming photons into electrical signals.
- Demodulation: The electrical signals are demodulated to extract the original information that was encoded onto the laser beam. This involves reversing the modulation process applied at the transmitter.
- Signal Processing: The demodulated data is processed by the communication system.
- Control Mechanism: It often includes feedback mechanisms to optimise the pointing of the laser beam. Precision pointing is crucial for maintaining a stable and strong connection over long distances.
NASA’s DSOC
- NASA’s DSOC experiment is the agency’s first demonstration of optical communications beyond the Earth-Moon system.
- This new technology will employ advanced lasers in the near-infrared region (1.55 µm) of the electromagnetic spectrum.
- The DSOC flight laser transceiver on board Psyche functions as a telescope, capable of receiving and transmitting laser light in precisely timed photon bursts.