Context:

• NASA’s Psyche spacecraft fired a communication laser to Earth from about 16 million kilometres away, demonstrating an important technology DSOC (Deep Space Optical Communications) that could define the future of communication in space.

NASA’s Psyche Mission fires lasers at Earth

• High-bandwidth optical communications: The Psyche Spacecraft is the first to carry a DSOC transceiver and will test high-bandwidth optical communications to Earth.

• Lunar Laser Communications: In 2013, NASA’s Lunar Laser Communications Demonstration tested record-breaking uplink and downlink data rates between Earth and the Moon using similar technology.
• Communications into Deep space: DSOC, however, is taking optical communications into deep space, paving the way for high-bandwidth communications far beyond the Moon and over 1,000 times farther than any optical communications test.

How has Space Communication done?

• Like wireless communications on Earth, spacecraft encode data on various bands of electromagnetic frequencies. 
• Use of Radio Wave: Currently, most space communication uses radio waves with the highest wavelengths but lowest frequencies in the electromagnetic spectrum.
• Radio waves are more widely used for space communication because of their desirable propagation properties and large wavelength compared to other electromagnetic waves.
• Properties of Radio Wave: the ability to pass through the atmosphere regardless of weather, pass through foliage and most building materials, and bend around obstructions.

Challenges in Space communication?

• Problem of Data Rates: Communicating with spacecraft far away from Earth is problematic due to high data rates.
• Scattering of Shorter Wavelengths: The shorter wavelengths (range of frequencies) carry more data per second but tend to scatter when in contact with any interference.

NASA’s Revolutionary New Technology: 

• The DSOC is a new laser communication technology that encodes data in photons at near-infrared wavelengths  to communicate between a probe in deep space and Earth. 
• This allows the spacecraft to communicate more data in a given amount of time.
  • DSOC will allow data rates at least ten times higher than radio telecommunications systems of comparable size and power.
• Benefits: DSOC can send scientific information, high-definition imagery, and streaming video to support humanity’s next giant leap: sending humans to Mars.
• Challenges: 
  • Extremely Precise Pointing: The flight laser transceiver and ground-based laser transmitter must point precisely. 
  • Reaching their targets like hitting a dime from a mile away while the dime is moving (A dime, or coin, that is less than 2 cm in diameter).

Source: Indian Express