In October 2023, NASA launched its long-awaited on-again, off-again Psyche mission. The spacecraft is on its way to study the metal-rich asteroid 16-Psyche, an M-type asteroid that could be the remnant core of a planetesimal that suffered a collision long ago. But understanding the giant, metal-rich asteroid isn\u2019t the Psyche mission\u2019s only goal.<\/p>\n
It\u2019s also testing a new laser communication technology. <\/p>\n
<\/p>\n The new system is called Deep Space Optical Communications (DSOC.) DSOC uses infrared lasers to communicate between spacecraft and ground stations. In this first experiment, the Psyche spacecraft communicated with the Hale Telescope at Caltech\u2019s Palomar Observatory in San Diego County, California. Psyche was beyond the Moon when it communicated, and the distance between the spacecraft and the Hale Telescope was nearly 16 million km (10 million miles.) <\/p>\n The successful test took place on November 14th, and during the test, data was transmitted and received by both the spacecraft and the ground station, a phenomenon called \u201cclosing the link.\u201d The successful test is the DSOC\u2019s \u2018first light.\u2019<\/p>\n \u201cAchieving first light is one of many critical DSOC milestones in the coming months, paving the way toward higher-data-rate communications capable of sending scientific information, high-definition imagery, and streaming video in support of humanity\u2019s next giant leap: sending humans to Mars,\u201d said Trudy Kortes, director of Technology Demonstrations at NASA Headquarters in Washington.<\/p>\n The technology may be coming to fruition just in time. As our spacecraft instruments become more powerful and as the amount of data they send back grows, current spacecraft communication systems are struggling to keep up. High-bandwidth laser communication systems should relieve the bandwidth bottleneck that hampers existing missions. <\/p>\n Current spacecraft communication systems are based on state-of-the-art radio systems. But the infrared laser system at the heart of DSOC works with data transmission rates from 10 to 100 times greater than radio systems. <\/p>\n The benefits are obvious if the system can be perfected. <\/p>\n Currently, spacecraft communicate with Earth using NASA\u2019s Deep Space Network (DSN). The DSN is made up of three facilities around the world, separated by about 120 degrees. So, no matter where a spacecraft is, it can communicate with one of the facilities. The three facilities are in California, Spain, and Australia. <\/p>\n The DSN is reliable, and NASA allows other spacefaring nations to use the system. But since it\u2019s based on radio communications, it\u2019s becoming an outdated bottleneck. <\/p>\n While the DSN and other space communications systems are impressive, they\u2019re struggling to keep up with future plans. It can take up to 20 hours to transmit a 250-megabit data payload directly to Earth.\u00a0And it gets worse the further a spacecraft is from Earth.<\/p>\n NASA\u2019s New Horizons mission is an instructive example. When it performed its flyby of Jupiter in 2007, it transmitted data back to Earth at about 38 kilobits per second (kbps.) That\u2019s a little slower than old telephone dial-up modems from the past. The data rate dropped precipitously when it encountered its main objective, Pluto. The data rate plummeted to approximately 2,000 bits per second (bps) at that extreme distance. That\u2019s like the telecommunications equivalent to Morse code. <\/p>\n To reach those speeds, New Horizons had to use both its antennae and transmit to NASA\u2019s largest receiving dish here on Earth. It reached Pluto in July 2015, but it took until 2016 to transmit all of the data from the historic encounter. Imagine being a member of the New Horizons team waiting for critical, career-defining data.<\/p>\n \u201cMore data means more discoveries.\u201d<\/p>\n Dr. Jason Mitchell, Director, Advanced Communications and Navigation Technologies Division, NASA\u2019s Space Communications and Navigation (SCaN) program<\/cite><\/p><\/blockquote>\n<\/figure>\n DSOC\u2019s infrared laser system will be a huge improvement. It\u2019s similar to radio communications but uses tighter waves. This allows ground stations to receive more data, which is a critical problem with our rapidly-improving spacecraft. The DSOC on Psyche has only a 22 cm antennae, while the ground transmit antenna is 1 meter and the ground receiving antenna is 5 meters. At a distance of 0.4 AU, the uplink speed should reach 292 kbit\/s, and the downlink speed should reach 100 Mbit\/s. <\/p>\n DSOC does suffer from some drawbacks, though. For instance, downlink speeds are slower in the daytime. <\/p>\n Spacecraft instruments, and especially cameras, are generating more and more data. These speeds, and hopefully higher speeds in future DSOC systems, should be able to keep pace.<\/p>\n \u201cOptical communication is a boon for scientists and researchers who always want more from their space missions, and will enable human exploration of deep space,\u201d said Dr. Jason Mitchell, director of the Advanced Communications and Navigation Technologies Division within NASA\u2019s Space Communications and Navigation (SCaN) program. \u201cMore data means more discoveries.\u201d<\/p>\n This isn\u2019t NASA\u2019s first foray into DSOC. They\u2019ve been working on it for years, and they\u2019ve demonstrated it in Near-Earth Orbit and out as far as the Moon. But November\u2019s test was the first deep space test. While DSOC promises faster communication, it requires extremely precise pointing, and the precision required increases with distance. The system works by transmitting a laser beacon from Earth to the spacecraft. That helps stabilize the line-of-sight between the two and helps Psyche aim its downlink laser accurately. Further tests at greater distances are the next step.<\/p>\n \u201cWe were able to exchange \u2018bits of light\u2019 from and to deep space.\u201d<\/p>\n Abi Biswas, Project Technologist for DSOC at NASA\u2019s Jet Propulsion Laboratory.<\/cite><\/p><\/blockquote>\n<\/figure>\n There\u2019s also the latency problem. From the Moon, it takes about 2.5 seconds for a signal to reach Earth. In this test, Psyche was well beyond the Moon, and the signal took about 50 seconds to reach Earth. But while it\u2019s at the asteroid, a signal from the Psyche spacecraft will need up to 20 minutes to reach Earth. That latency problem doesn\u2019t go away just because the system is based on a near-infrared laser. Infrared light moves at the same speed as radio waves. <\/p>\n But even though there are future challenges yet to be overcome, the test was successful, and that\u2019s the only result NASA can hope for. <\/p>\n \u201cAchieving first light is a tremendous achievement. The ground systems successfully detected the deep space laser photons from DSOC\u2019s flight transceiver aboard Psyche,\u201d said Abi Biswas, project technologist for DSOC at JPL. \u201cAnd we were also able to send some data, meaning we were able to exchange \u2018bits of light\u2019 from and to deep space.\u201d<\/p>\n The future of space exploration is going to be more and more data-dependent. Imagine real-time (with a signal delay, of course) video from the surface of Mars, taken by high-resolution cameras on rovers. Imagine astronauts on the surface of Mars with real-time, Mars-hardened versions of Go-Pro cameras on their helmets. Imagine subscribing to the personal YouTube channel of a Mars astronaut. <\/p>\n Naturally, some people won\u2019t believe what they\u2019re seeing. But for those of us who follow along as space technology develops year by year, it will be another crowning moment. <\/p>\n![\"The](\"https:\/\/www.universetoday.com\/wp-content\/uploads\/2016\/06\/deep_space_network_aug2013_0-resize.png\")
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