The Psyche probe paved the way to interplanetary laser communication – Futura

Ten years ago, NASA demonstrated that it was possible to communicate using lasers with a probe in orbit around the Moon: the Lunar Laser Communications Demonstration (LLCD) mission. The laser allows data to be sent faster, with less energy and a smaller device than with a traditional radio antenna. In preparation for the live-streaming limitations of future Mars astronauts, NASA is demonstrating today that it can communicate by laser at 40 times the Earth-moon distance.

The arrival of Homo sapiens on the moon was almost instantaneous for hundreds of millions of people in 1969. In fact, it takes barely more than a second for electromagnetic waves to cross the Earth-Moon distance. Armstrong and Aldrin’s images could also have been sent from our satellite with enough power to be received at relatively high speeds on our Blue Planet, explaining why the event was televised. But every physicist knows that the intensity of an electromagnetic wave varies from its source according to a law of 1/r2.

This explains why we have never had the equivalent of a live broadcast with the images captured by the Mars rovers, rather than the duration of tens of minutes to cover the distance between Earth and the Red Planet. For interplanetary probes beyond the orbit of Mars, the problem is even worse, as we clearly saw with the New Horizons mission, when it was sometimes necessary to wait for transmissions almost intermittently, if at all, for months before we even got any had the information contained in some of the images taken.

Fortunately, engineers know there is a solution to this problem of low radio transmission rates as we travel long distances from our celestial cradle: the laser.

A presentation of the Deep Space Optical Communications (DSOC) experiment. To get a reasonably accurate French translation, click on the white rectangle at the bottom right. English subtitles should then appear. Then click on the nut to the right of the rectangle, then click on “Subtitles” and finally “Auto-translate”. Select “French”. © NASA, JPL-Caltech, ASU

Interplanetary telecommunications 100 times faster?

In fact, this solution had been envisioned since the early years of the Seti Project research program. In fact, the idea that aliens might prefer to communicate across interplanetary and even interstellar distances using lasers is an old one. It was formulated by Schwartz and Townes as early as 1961, a year after Townes invented the laser and two years after Cocconi and Morrison proposed the basic concept of the Seti program.

In the case of terrestrial intelligence, it is estimated that the transmission rate of information and especially images captured by interplanetary probes can be improved by a factor of 10 to 100 or even 1,000, and this is the development of this technology – what could make this possible It is possible for us to broadcast the colonization of Mars almost live – that NASA has launched an experiment called Deep Space Optical Communications (DSOC).

The test was a first success on November 14, 2023, as the Psyche probe sent data towards the Hale Telescope, which equipped the equally famous Palomar Observatory in California, while it was about 16 million kilometers away, or about 40- times the size of the Earth. lunar distance, as explained in a NASA press release (however, this data was not yet the product of observations and measurements by the Psyche probe). An infrared laser was used and is expected to remain so for at least two years as the probe continues its journey to the main asteroid belt between Mars and Jupiter, during which time it tests the instrument used to communicate with Earth via laser.

“Achieving first light with the instrument is one of many critical milestones for DSOC in the coming months, paving the way for communications at higher data rates capable of sending scientific information, high-resolution images and streaming video “To support humanity’s next big leap: sending humans to Mars,” said Trudy Kortes, director of technology demonstrations in the Space Technology Mission Directorate at NASA Headquarters in Washington.


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