Infrastructure, technologies and standards for Moon missions

Imagine multiple spacecraft orbiting overhead while rovers criss-cross the lunar surface. Hundreds of missions are planned for the Moon in the next two decades, both by nations and by private operators.

“The Moon is getting to be very busy,” says Tanja Masson-Zwaan, Assistant Professor and Deputy Director of the International Institute of Air and Space Law at Leiden University.

“So why is this important? We need a coordinated lunar time to have position, navigation, and timing capacity on lunar activities.”

Descending landers, astronauts moving between mission sites, and a wide array of scientific and commercial operations will all need clear radio signals to avoid disrupting each other.

All those operators must effectively “speak the same language” for navigation, communication, science and logistics, Masson-Zwaan added in the latest ITU Space Connect webinar on future lunar and orbital communications.

Along with complex radio spectrum harmonization, operations on the Moon could follow a common timekeeping standard known as Coordinated Lunar Time, or LTC, potentially maintained through a dedicated atomic clock.

LTC – much like Earth’s Coordinated Universal Time (UTC) – would provide a shared reference for any communication to, from or between lunar missions.

The reference clock would have to be set up on the Moon to avoid gravitational time dilation. An Earth-based atomic clock brought to the Moon will physically tick faster, by about 58.7 microseconds (millionths of a second) per day, than an identical clock left on Earth.

The differences are due to the Moon’s lighter mass and weaker gravity. And the resulting time divergences, although miniscule, can quickly become problematic for space navigation.

Shared space infrastructure

Custom, mission-by-mission arrangements for signalling and communicating, which are the norm today, will no longer suffice, says Scott Pace, Director of the Space Policy Institute and Professor of the Practice of International Affairs at George Washington University.

Pace described an “operational shift” from isolated point-to-point links toward “persistent lunar and deep space networking,” with lunar networks, just like those on Earth, requiring “shared infrastructure, servicing a wide variety of people, wide variety of purposes.”

A network following common standards would ultimately be easier for all lunar missions and operators, as opposed to “trying to schedule hundreds of end-to-end hops” for each major communication, he said.

But familiar Earth-based Internet protocols don’t transfer smoothly to lunar or outer space environments.

“It takes a long time for signals to transit through interplanetary distances,” Pace explained. “Also, planets move, so the connectivity that you might rely on from a ground-based system also isn’t there.”

What’s ultimately needed is a solar-system Internet, adapted to handle movable transmission and reception sites, as well as long time delays. Compared to the networks we know, this would have to be “a much more dynamic system physically,” Pace says.

Emerging technologies

The connected space future may therefore depend on delay-tolerant networking (DTN) to enhance spectrum efficiency and quantum key distribution (QKD) solutions to ensure trusted and resilient communications. Artificial intelligence (AI) will also be increasingly crucial for rapid information and data processing in space.

But the real challenge, according to Professor Guifei Jing from Beihang University, will be to ensure that space-based services, from today’s Earth-observation systems to future lunar communication networks, are accessible to all countries.

“We have thousands of Earth-observation satellites operating in orbit, but their services – like images, like processing – and the real support for decision makers are not accessible to everyone on the Earth,” he noted.

Going forward, developing countries will need support to adopt advanced AI-enabled systems for space use.

Learn more about Earth observation at the frontline of climate action.

Standards needed

The time to set out technical standards for lunar communications is now.

“We should not wait for the technology to start thinking about the regulatory framework or the other way around.” Masson-Zwaan said. “We should really try to make that happen hand-in-hand.”

The International Telecommunication Union (ITU) already upholds principles like openness, neutrality and equitable access to shared infrastructure for radio spectrum and technology coordination.

Masson-Zwaan suggested ITU could play a key role “in convening us and having people listen to each other.”

Pace recommended multi-stakeholder coordination for the Moon based on the existing ITU model for developing technical standards.

Early decisions on protocols, timing, and spectrum may be hard to reverse as space activity grows, he noted. “We need to be thinking very carefully about standards right now.”

Play back the webinar: Beyond the Horizon: Framing the Future of Space Communications

The series continues

ITU’s Space Connect series explores the space ecosystem and pathways to future communications, with upcoming sessions set to highlight policy challenges, emerging space innovations and more.

Check out recent and upcoming discussions in the series.

Learn more about the ITU Radiocommunication Sector (ITU-R) and its Space Services Department.

Header image credit: ITU

Inset image: Adobe Stock (AI generated)