The Next Generation of Moonwalkers: High-Resolution Communication with Earth
In 1969, the world watched in awe as Neil Armstrong took his first steps on the Moon. However, the live broadcast of this historic event was far from perfect. The video quality was poor, and the images were out of focus. Fast forward to today, and we have high-definition live streaming at our fingertips. As we prepare for the next generation of moonwalkers, expectations for communication have skyrocketed.
Matt Cosby, the chief technology officer at the UK’s Goonhilly Earth Station, which communicates with satellites and spacecraft, acknowledges that the Apollo video quality will no longer be acceptable. He states, “We will expect 4K resolution from the Moon almost in real time coming from the landing. It’s going to be up to 500 megabits of data coming back so the images are going to be 10 times better.”
To meet these expectations, significant investments are being made globally. Nasa’s LunarLites project, conducted at its Glenn Research Centre in Ohio between 2021 and 2023, explored how Earth’s 4G and 5G technologies could be adapted for lunar communication. Two new ongoing projects have emerged from this research, including the Lunar Surface Propagation (LSP) project and the Lunar Third Generation Partnership (3GPP) project.
The LSP project focuses on studying how wireless communication systems will perform in the lunar surface environment. Michael Zemba, Nasa’s LSP principal investigator, explains that the Apollo missions landed near the Moon’s mid-latitudes and flat lava plains. However, for the Artemis campaign, Nasa is interested in exploring the poles of the Moon. The South Pole, in particular, offers sustained sunlit areas and frozen water ice in deep craters. But the varied terrain presents challenges for establishing wireless networks like Wi-Fi and 5G.
Zemba highlights one potential landing site, Shackleton Crater, which is two miles deep and 12 miles wide. He compares its depth to that of the Grand Canyon, emphasizing the need for accurate models and simulation tools to overcome the challenges of establishing wireless networks in such extreme conditions.
Another obstacle to overcome is the fine lunar dust, or regolith, that covers the Moon’s surface. Zemba explains that regolith is more transparent to radio waves than Earth’s terrain, which can impact the performance of communication systems. To address these challenges, Nasa’s Desert Research and Technology Studies (Desert Rats) team conducted simulations in a desert site in Arizona in 2022. These tests allowed the agency to compare theory with real-world data and gain insights into the lunar environment.
However, the challenges don’t end there. The geometry of the Moon’s orbit around the Earth poses additional complications. Zemba explains that from the lunar South Pole, Earth is only visible for about two weeks each month, and even then, it’s always less than 10 degrees above the horizon. This limited visibility means that a signal directly back to Earth can interfere with itself due to reflections of radio waves off the terrain, a phenomenon known as multipath.
To address these issues, Nasa’s Lunar 3GPP project is researching how to deploy wireless technologies on the Moon. Raymond Wagner, the project’s principal investigator, acknowledges that wireless systems face fundamental challenges in operating on the lunar surface. Temperature extremes and the radiation environment can cause problems for commercial-grade electronics. Additionally, hardening 4G and 5G systems for lunar conditions is a significant undertaking. Understanding the lunar surface radio frequency propagation environment is also crucial.
Despite these challenges, progress is being made. Intuitive Machines’ IM-1 mission marked a key milestone by confirming the US’s first soft-landing on lunar soil in over 50 years. The upcoming IM-2 mission in 2025 will demonstrate cellular connectivity on the Moon, thanks to funding from Nasa to Nokia Bell Labs. This mission will establish the first cellular network on the Moon, providing an opportunity for model validation and technology demonstration.
Once 4G and 5G networks are available on the Moon, astronauts will be able to communicate reliably with their rovers, instruments, and crew members. Data sent back to Earth can be transmitted over one link, streamlining communication when large ground stations are in high demand.
Maintaining communication with Earth when it is no longer within line of sight is another challenge. To overcome this, relay satellites are necessary. China launched the world’s first Moon relay satellite, Queqiao-1, in 2018 to support its Chang’e 4 mission. Nasa and the European Space Agency (Esa) are also launching Moon relay satellites as part of their respective projects.
Esa’s Moonlight program aims to create a network of three or four communications and data-relay satellites for the Moon, similar to how GPS works on Earth. The Lunar Pathfinder mission, scheduled for launch