Message reaches Earth from 16 million kilometers away

A message transmitted by laser reached Earth from an unprecedented distance of 16 million kilometers. The deep space experiment, conducted by NASA on the Psyche probe, marked the first optical transmission of data beyond lunar orbit, signaling an achievement that could transform the way spacecraft communicate.

What do you need to know:

• The Deep Space Optical Communications (DSOC) experiment, mounted on the Psyche probe, sent a laser in the near-infrared range, encoded with test data.
• DSOC, a two-year technology demonstration, reached its “first signal” on November 14, as announced by NASA’s Jet Propulsion Laboratory (JPL), responsible for both missions.
• The message came from a position approximately 16 million kilometers away, equivalent to around 40 times the distance from the Moon to Earth.
• It was aimed at the Hale Telescope at Caltech’s Palomar Observatory in California.

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This milestone was made possible by an incredibly precise maneuver that allowed DSOC’s laser transceiver to lock onto JPL’s powerful uplink laser beacon, located at the Table Mountain Observatory. This made it possible for DSOC to direct its downlink laser to the Caltech observatory, 80 miles away.

Achieving the first signal is one of many critical milestones for DSOC in the coming months, paving the way for high-data-rate communications capable of sending scientific information, high-definition images and video transmission in support of humanity’s next giant leap: sending humans to Mars.

Trudy Kortes, director of Technology Demonstration at NASA Headquarters, via IFLScience

Although optical communications have previously been used to send messages from Earth orbit, this laser transmission represents the greatest distance ever achieved. In laser transmission, photons move in the same direction and at the same frequency, allowing the transmission of large volumes of data at unprecedented speeds, encoding optical signals invisible to humans.

Typically, NASA uses radio waves to communicate with missions beyond the Moon. However, the advantage of lasers lies in the ability to pack much more data into narrower waves. According to NASA, DSOC aims to demonstrate transmission rates 10 to 100 times higher than radio communication systems.

Increasing data transmission capacity will enable future missions to carry higher resolution scientific instruments, as well as enabling faster communications in deep space exploration missions, such as live broadcasts from the surface of Mars.

Optical communication is a boon for scientists and researchers always seeking more from their space missions and will enable human exploration of deep space. More data means more discoveries.

Dr. Jason Mitchell, director of the Advanced Communications and Navigation Technologies Division in NASA’s Space Communications and Navigation Program

However, some challenges still need to be overcome. The greater the distance optical communication needs to travel, the more difficult it becomes, requiring extreme precision to direct the laser beam. Additionally, the photon signal weakens, taking longer to reach its destination and eventually creating communication delays.

During the test on November 14, photons took about 50 seconds to travel from Psyche to Earth. As Psyche moves further away, it will take about 20 minutes for the photons to return – enough time for both Earth and the probe to have moved, requiring adjustments to the lasers on both sides. To date, the demonstration of this innovative technology has been very successful.

The test was the first to fully incorporate ground assets and flight transceiver, requiring DSOC and Psyche operational teams to work together. It was a formidable challenge, and we have a lot more work to do, but for a short period of time, we were able to transmit, receive and decode some data.

Meera Srinivasan, DSOC operations lead at JPL