NASA wants to use lasers to communicate with spacecraft.
Laser Communications
Laser communication systems, also known as optical communications, uses lasers to transmit data through space. It has many advantages over the radio systems that are typically used on spacecraft. Lasers require a lot less energy to operate and can send very accurate signals. However, lasers can not send messages through clouds, unlike radio waves. This can limit when these communication systems can send messages to Earth. Lasers travel at the same speed as radio waves (the speed of light), but can encode more data. This allows lasers to transmit between 10 and 100 times more information than radio waves. This is a game changer!
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After performing a lot of science, it often takes a long time for all of the data to be transmitted back to earth. After the New Horizons spacecraft made a flyby of Pluto in July 2015, it took until October 2016 to transmit all of its data back to Earth. [2]
Past experiments
NASA wants to learn to use laser antennas for deep space missions, including manned missions to the Moon and Mars. Having laser communications will allow for large amounts of scientific data and high-definition videos to be sent back to Earth quickly.
This is why NASA, and many other organizations have performed tests of high-speed laser communications over the last few decades. NASA’s Galileo probe, which explored Jupiter, was able to detect two lasers that came from Earth. In 2005, MESSENGER, while on it's way to Mercury was able to use lasers to receive and send messages with Earth. That test used MESSENGER’s laser altimeter, a science instrument which wasn’t designed for communications. [3]
In 2013, LADEE launched to explore the moon and carried with it an experiment called the Lunar Laser Communication Demonstration (LLCD). This experiment successfully used lasers to communicate with Earth both ways. It was able to receive data from Earth at a speed of 20 Mbps and send data to Earth at a speed of 622 Mbps. LLCD was able to send all of the science data that LADEE had collected in under five minutes, which would have taken days for the radio antenna to send! [4]
LCRD
After these test, NASA's Goddard Space Flight Center (GSFC) moved forward with development of the Laser Communications Relay Demonstration (LCRD). Now we get to the present. LCRD launched on December 5th, 2021 as part of STP-3. I wrote a blog post all about that mission. The instrument is attached to STPSat-6 and is about the size of a king-size mattress. LCRD will be capable of sending messages to and from Earth at a speed of 1228.8 Mbps, or 1.2 Gbps. It will communicate with two ground stations on Earth: Table Mountain, California and Haleakalā, Hawaii. Later on LCRD will communicate with the International Space Station via the ILLUMA-T instrument, which will launch next year and be added to the Kibo module. [5]
The future
NASA also has other experiments planned for the near future. The Psyche space probe, which will explore an asteroid by the same name, will carry an experiment called the Deep Space Optical Communications (DSOC). DSOC will send messages from far out in deep space. [6]
In addition, the Artemis II mission, which will send 4 astronauts around the moon in 2024, will stream HD video from the moon back to Earth using lasers. Live videos will be recorded with assistance from National Geographic.
Optical communications show a lot of potential and are already being implemented. Some Starlink satellites already use lasers to communicate with each other, and ESA's Sentinel 1A spacecraft has used lasers to send photos back to earth. [7]
Lasers could revolutionize spacecraft communications. They can allow more data to be sent and can save space on spacecraft. Eventually, radio communications may be mostly phased out and replaced with laser antennas. You can clearly see how fast lasers are in the table below which compares a radio antenna with some of NASA's experiments. I also added in my internet speed for comparison.
System | Maximum speed |
|---|---|
My internet | 22.4 Mbps |
Mars Reconnaissance Orbiter's radio antenna | 4 Mbps |
LLCD | 622 Mbps |
LCRD | 1228 Mbps |
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