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Artist’s impression of the lunar rover “MAPP” (Courtesy of Nokia)
The Apollo astronauts’ connection to Earth was primitive compared to what we enjoy today. The next generation of moonwalkers may have much higher-resolution ways to stay in touch with each other and with us here on Earth.
On July 20, 1969, an estimated 600 million people watched the live broadcast, which was out of focus and had extremely poor picture quality.
The historic event of humans first walking on the moon as part of NASA’s Apollo 11 mission was understandably overshadowed by technical issues, but today’s global audiences take high-definition live streaming for granted, and expectations for the next generation of lunar astronauts are likely to be much higher.
“Nobody is going to accept Apollo video quality,” said Matt Cosby, chief technology officer at Britain’s Goonhilly Earth Station, which communicates with satellites and spacecraft.
Goonhilly broadcast the moon landing television signal around the world and recently received the first signal from Intuitive Machines’ Odysseus spacecraft confirming that the United States had made the first soft landing on the moon in more than 50 years.
“Once we land, we expect to receive 4K resolution imagery from the moon in near real time, with up to 500 megabits of data coming back, which will make the images 10 times better,” Cosby said.
“In this age of social media, grainy black and white photos and videos of the lunar surface will not be acceptable. We need to get to higher frequencies to make that possible. It’s not a huge leap, but it’s necessary. It all depends on the investment.”
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The Mobile Autonomous Exploration Platform (Mapp) rover on the Lunar Outpost lunar probe will be one element of bringing a new communications network to the Moon (Courtesy of Nokia)
This investment is underway around the world: From 2021 to 2023, NASA’s LunarLites project at Glenn Research Center in Ohio will evaluate how Earth’s 4G and 5G technologies can be applied to a lunar environment, and two new projects are currently underway.
The Lunar Surface Propagation (LSP) project is studying how wireless communication systems will perform in the lunar environment.
“All of the Apollo missions landed near the mid-latitudes of the Moon, mostly around flat lava plains,” says Michael Zemba, NASA’s LSP principal investigator, “but with Artemis we’re interested in exploring the lunar poles.”
NASA’s Artemis program plans to send astronauts into lunar orbit in 2025, followed by a manned landing a year later. Antarctica is promising because of its persistent sunlight and the presence of frozen water ice in deep craters in permanent shadow that could provide a source of water and fuel. But the varied terrain also has a drawback: One potential landing site, Shackleton Crater, is 2 miles deep and 12 miles wide.
Regolith is more transparent to radio waves than Earth’s terrain – Michael Zemba
“Shackleton Crater is deeper than the Grand Canyon,” says Zemba. “These extreme conditions in Antarctica pose challenges for building wireless networks like Wi-Fi and 5G, which is why accurate and reliable models and simulation tools are essential. In principle, it’s the same idea as choosing a good spot to put your Wi-Fi router at home, but the crater is bigger than Manhattan.”
The fine lunar dust, or regolith, that covers the Moon’s surface to a depth of several metres also poses a challenge.
“Regolith transmits radio waves more easily than Earth’s terrain,” Zemba says, “so communications systems can sense invisible structures like underground rocks and craters that can affect their performance.”
As part of the 2022 simulation, NASA’s Desert Rats team revisited the Arizona desert. These field tests, once used to prepare for the Apollo missions, allowed NASA to compare theory with real-world data (albeit on Earth). But taking into account the lunar environment, an additional complication arises due to the shape of the moon’s orbit around Earth.
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The ambitious lunar exploration projects planned for the next few years will require much more advanced communications networks than Apollo (Credit: NASA)
“Earth is only visible from the lunar south pole for about two weeks each month,” says Zemba, “and even when it is visible, Earth is always less than 10 degrees above the horizon. This means that signals sent directly to Earth can be subject to interference from radio waves bouncing off terrain, a phenomenon known as multipath.”
This potential performance degradation needs to be taken into consideration. Meanwhile, in parallel with the Zemba LSP project, NASA’s Lunar Third Generation Partnership (3GPP) is researching ways to deploy wireless technology on the lunar surface.
“Operating a wireless system on the moon poses some fundamental challenges,” said Raymond Wagner, principal investigator for the Lunar 3GPP project.
“The extreme temperature and radiation environment alone can cause a variety of problems for commercial-grade electronics, and 4G and 5G systems are computationally complex and hardening them for the lunar surface is no easy task,” Wagner said. “Plus, we still have a ways to go to fully understand the radio frequency propagation environment on the moon.”
The availability of 4G and 5G on the lunar surface will allow astronauts on the moon to reliably communicate with their rovers, equipment, and crew.
Intuitive Machines’ IM-1 mission was a significant milestone in more ways than one. “Our next mission, IM-2 (scheduled for late 2024), is especially exciting because it also represents the first opportunity to demonstrate cellular connectivity and collect data on the lunar surface,” Zemba said.
“NASA funded Nokia Bell Labs to demonstrate a 4G link from the lander to the rover on this mission. This will be the first cellular network on the Moon and will be an exciting opportunity for both model validation and technology demonstration.”
The availability of 4G and 5G on the lunar surface would allow any astronauts on the moon to reliably communicate with their rovers, instruments, and crew, and data returning to Earth could be transmitted over a single link, providing an efficient means of communication even as demand for large ground stations surges.
On the far side of the Moon, there’s also the problem of maintaining communications with Earth when it’s out of view, and the only way to achieve this is via a relay satellite.
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Lunar Pathfinder could help prove the concept of lunar satellite navigation by using laser ranging from Earth (Credit: ESA)
In 2018, China launched the world’s first lunar relay satellite, Queqiao-1, to support the Chang’e-4 mission, the first soft landing on the far side of the moon. Queqiao-2 is due to be launched in the coming months.
NASA has launched a lunar relay satellite as part of the Lunar Communications Relay and Navigation System project, while the European Space Agency (ESA), a key partner in the Artemis program, is running Project Moonlight.
ESA is working with industry to set up a network of three or four communications and data relay satellites for the Moon, similar to how GPS is used on Earth.
The first step will be the launch of the Lunar Pathfinder technology demonstration mission in 2025, built and owned by the UK’s SSTL and put into orbit by commercial space transportation company Firefly Aerospace. It will be part of the Blue Ghost 2 mission, which will also include NASA’s lunar lander.
A new communications infrastructure for the Moon will be developed within the next few years.
ESA is carrying a navigation payload and has agreed to allow NASA to share its equipment and access its lunar relay communications services.
“We’re going to employ NASA’s laser reflector,” says Charles Cranston, SSTL’s Lunar Pathfinder project manager, which will help prove the concept of lunar satellite navigation by firing a laser from a ranging station on Earth to precisely measure the spacecraft’s distance and speed.
“We’ll also be taking a Global Navigation Satellite System (GNSS) receiver with us to make measurements of the GNSS at the furthest reaches of Earth to see if we can pick up weak signals there and use them to determine position,” says Cranston, who says it was developed for ESA by the Swiss company SpacePNT.
NASA/Michael Zemba
NASA scientists are planning how far a different signal could travel, comparing it to the journeys Apollo astronauts took to the Moon (Photo: NASA/Michael Zemba)
“Ultimately, when we combine all of this with our radio ranging, we get three points of position data that allow us to see how we could implement a navigation system on a satellite like Moonlight,” Cranston adds. “So we’re laying the foundation for the future Moonlight constellation.”
SSTL’s goal is to become the commercial provider of communications for lunar rovers and landers orbiting anywhere on the moon’s surface. “Currently, if you want to get data, you have to use either NASA’s Deep Space Network or ESA’s Estrack network,” Cranston says, referring to Europe’s global network of ground stations tracking spacecraft. “Currently, that network is extremely congested.”
As a result, government space agencies and private companies will be building new communications infrastructure for the Moon over the next few years. NASA’s proposed system is called LunaNet.
“LunaNet is trying to replicate the terrestrial internet around and on the Moon,” says Matt Cosby of Goonhilly, who is working with the UK Space Agency and the international community to define standards for this new lunar communications.
“The analogy I’ve heard is Netflix on the moon,” SSTL’s Cranston says. “Pick any streaming service you like. That’s the level of data throughput they want to achieve.”
The first opportunity for lunar walkers to directly test lunar communications will likely be NASA’s Artemis 3 mission, scheduled for 2026.
“Mobile communications on Earth have made some truly incredible advances over the last 10 to 20 years,” Zemba says, “and we’d be in a fantastic position if we could reliably deploy the same convenient technology on the Moon.”
