For the exploration of interplanetary space, it is essential to develop technologies capable of transmitting messages over longer distances – in this case, approximately 40 times the distance between the Earth and the Moon.
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NASA and the Psyche probe are at the forefront of this breakthrough. In November 2023, it demonstrated the use of lasers to cover nearly 16 million kilometers, with the aim of testing the capabilities of optical communications.
The new communication technology
The mission began with NASA's Psyche spacecraft, which aimed to demonstrate the feasibility of the Deep Space Optical Communications Experiment (DSOC). This experiment involved sending an infrared laser encoded with test data from the satellite to the Hale Telescope at Caltech's Palomar Observatory in San Diego, California.
The DSOC is one of the key instruments aboard the Psyche probe, which was launched in October 2023 aboard a SpaceX Falcon Heavy rocket. Its destination is an eponymous metallic asteroid orbiting between Mars and Jupiter, with the aim of studying its composition, as well as demonstrating this communication technology beyond the Moon.
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According to NASA, this technology demonstration reached “first light” in the early hours of November 14, 2023. At that time, the probe's flight laser transceiver, capable of sending and receiving signals in near infrared, was connected to a powerful laser beacon emitted from JPL's Table Mountain facility near Wrightwood, California.
This beacon allowed the transceiver to point its downward laser at Palomar's Hale Telescope, located 130 kilometers south of Table Mountain, while the two automated systems adjusted their alignment.
NASA stressed that this was the first test of optical communications in deep space, unlike experiments carried out in low Earth orbit and as far as the Moon.
The challenges and opportunities of technology
This feat is comparable to using a laser pointer to track a moving dime a mile away, because directing a laser beam millions of miles away requires extraordinary precision.
One of the main difficulties encountered during this demonstration was the need to compensate for the time it takes for light to travel large distances between the spacecraft and Earth.
For example, near-infrared laser photons took about 50 seconds to travel from Psyche to Earth. During this time, the spacecraft and planet both changed position, forcing both systems to constantly adjust.
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One of the goals of the experiment was to demonstrate data transmission speeds 10 to 100 times faster than those achieved with the most modern radio frequency systems.
While near-infrared radio and laser communications both use electromagnetic waves to transmit data, the near-infrared laser compacts the information into much smaller waves, allowing more data to be sent.
Furthermore, this technology represents a first step towards the development of high-speed communications systems capable of transmitting scientific information, high-definition images and even video, which is essential for future manned missions to Mars.
An asteroid in the future
The Psyche mission also aims to explore the metallic asteroid of the same name, which could provide clues to the formation of rocky planets. This asteroid is thought to be the partial core of a planetesimal, a primitive component of a planet, due to its high iron and nickel content.
The probe is expected to reach the asteroid in 2028 and enter orbit around it in August 2029. The scientific mission will last 26 months.
Article written in collaboration with our colleagues from Xataka.
