Direct-Dialing Mars?

On its way to explore a distant asteroid, NASA’s Psyche spacecraft has done something that may be even more significant than its original mission. The craft is going to examine the mineral content of a deep-space asteroid, in the hope it can teach us more about the composition of the Earth’s own core.

In the process, however, it has also shattered expectations for the effectiveness of deep space communication using laser technology.

On board Psyche is a new laser technology that can transfer data back to Earth at speeds far exceeding NASA’s expectations. In one test, it beamed a 15-second ultra-high-definition video to Earth from 19 million miles away. In another, it transmitted engineering data a whopping 140 million miles back home.

As part of these tests, NASA aspired to achieve transmission rates of 1 megabit per second. The new laser accomplished 25 megabits per second, which is comparable to broadband.

The new laser’s success has experts thinking about how advancements in laser technology could not only reshape deep space communications, but also communications with other planets.

The top planet that comes to mind? Mars. And for good reason: it’s the most likely spot for humans to establish their first significant colonies on the surface of another world.

Recently, Elon Musk accelerated his timeline for establishing self-sustaining colonies on the Red Planet, anticipating as many as a million people living on Mars within the next 20 years, not 40 to 100 years as originally estimated. The New York Times even found Musk’s rocket company, SpaceX, has ramped up its efforts to build sustainable Martian habitation and make colonization a reality in the next two decades.

If Musk (or someone else) succeeds, the key to phoning home from the Martian colonies may lie in the new laser technology—or advancements based on it—currently aboard Psyche.

Phoning home from Mars

On average, Mars is about 140 million miles from Earth. The laser communications technology demonstrated aboard Psyche could make that distance feel much closer.

“What has been demonstrated to date shows the potential for increased communication speed over Earth-Mars distances,” said Francis Bennet, an astrophysics researcher at The Australian National University.

Advancements in laser communication are indeed promising, said Karol Masztalerz, a researcher at the University of Manchester in the U.K. who has published work on optical communications systems. Lasers are especially promising for high-bandwidth datalinks, he said.

“In the context of Earth-Mars communication, optical communication could enable significantly faster downlinks of scientific data from [Mars],” Masztalerz said. “We might even see ‘live-stream’ video from Mars.”

More importantly, the increased bandwidth could streamline workloads for mission controllers on Earth working on Mars missions that lead to colonization—or who work with colonies once they are established. Both are critical to the eventual success of off-world cities because today’s methods of communication are woefully inadequate for such a task.

Today, NASA relies on the Deep Space Network to facilitate communication between Earth and various spacecraft. This network, however, is old and largely relies on radio communication. The sheer volume of missions has also overloaded the network, leading to the loss of data from some missions.

Running even more missions to get people to Mars and then establishing colonies there requires a fundamental rethink of the current communications infrastructure. Today’s spacecraft, satellites, and telescopes take in far more data than ever before, putting strain on existing methods of data transfer. Quite simply, much more bandwidth and speed are needed—for communication with Mars, and space communication in general.

Laser has the potential to solve the problem.

The ups and downs of laser communication

Successful laser communication between Earth and Mars could transmit data (using today’s technology, to say nothing of near-future technology) at a rate far higher than radio communications.

For instance, the technology demonstrated on Psyche is 10 to 100 times faster than today’s best radio communications technology, depending on the distance between communication sources. That’s because this type of system encodes data into photons at “near-infrared wavelengths,” according to NASA. As such, it can transfer far more data over long distances in the same amount of time that radio does, including between Earth and Mars.

So, let’s build more lasers and colonize the Red Planet, right?

It’s not that simple. (Though it is a necessary step being actively pursued.)

No level of advancement in laser communications technology will significantly impact latency, said Masztalerz. Even if we can transmit far more data, we are still fundamentally restrained by the distance between Earth and Mars.

“This delay is inherent and unavoidable,” he said.

However, new laser communications technology has now been proven to be far superior to current radio communications infrastructure, so you can expect more laser infrastructure to be built as we get closer to a human-inhabited Mars.

“There will always be a need for radio communications for resilience, but I think optical will be the future of these systems,” said Bennet.

We do need to overcome some engineering challenges to get there (and thus to Mars).

The key issues, said Masztalerz, are familiar ones when it comes to laser communication technology. We’ll need to pay attention to cooling the high-powered laser arrays needed to communicate with Mars and ensure coherence in multi-beam systems. We also need more efficient and lower-noise detectors that can be used on Earth and in space, according to Bennet.

“We need more large-aperture optical systems on Earth to act as receivers here, and we need more high-powered laser systems to be able to transmit over that kind of distance.”

Basically, we’ll need to be patient. It is more than possible that Elon Musk’s urgency will get us closer to Mars habitation faster, but we still need to build out significant infrastructure to facilitate communication between any type of colonization effort run by SpaceX or anyone else.

“While optical links are already being used successfully on Earth-orbiting satellites, the infrastructure required for interplanetary communication is still under development,” said Masztalerz.

Logan Kugler is a freelance technology writer based in Tampa, Florida. He is a regular contributor to CACM and has written for nearly 100 major publications.