With these words Buzz Aldrin described the vast void of the lunar landscape before he set foot on its surface for the first time in July 1969. But what if the moon – or rather, its orbit – wasn’t so bleak after all? What if it was, say, more like the gridlocked traffic of a Los Angeles rush hour? What if actually?
Considering that a total of 12 people have walked the lunar surface in human history, this might seem like a daunting hypothesis. However, it’s also a worrying notion that researchers at the University of Arizona, a university that helped map the lunar surface for Aldrin’s famed Apollo 11 mission, are on the right track.
Their plan — for which the university recently received a $7.5 million grant from the Air Force Research Laboratory’s Space Vehicles Directorate — essentially entails the world’s first lunar air traffic control system. It’s designed to keep tabs on space traffic in the currently untracked cislunar region between our planet and the moon, helping to avoid congestion on the moon – and maybe even deadly collisions.
And there’s a lunar mission near you sooner than you think.
Like a discarded parking lot in space
It was NASA scientist Don Kessler, in 1978, who first pointed out the danger posed by the extremely high density of objects circulating in low-Earth orbit and that this could set off a cascading chain reaction of possible collisions. (Watch the beginning of the 2013 film Gravity to see how devastating this can be.)
Today, about 23,000 pieces of space debris are being tracked, zipping around the Earth at about 17,500 miles per hour. Of that, only 3,500 are active payloads, while the rest – everything from dead satellite cores to discarded rocket parts – are inactive but still potentially dangerous debris.
“Let’s imagine, since the invention of the automobile, you take the car from the factory and then fill it up [drive it until it runs out of gas], drop it and get a new car,” Vishnu Reddy, associate professor at the University of Arizona’s Lunar and Planetary Laboratory, told Digital Trends. “We did that in space. Every time a spaceship runs out of fuel – and it could be a perfectly functioning spaceship – you drop it and launch a new payload. [Over time] Things get accumulated.”
The problem, he said, is one of visibility: both literally and figuratively. “Space is an unsolvable problem,” Reddy explained. “It’s not like an environmental disaster, is it? You know, there’s an oil spill, you see the pelicans covered in oil, it triggers a visceral response. You show everyone a spot in the sky and most don’t care. It’s like, why should I care – until the phone stops working or the GPS stops working or the football stops playing on the TV. Then people react.”
Debris polluting the lunar orbit
While Earth-orbiting space junk has received a little attention, the problem of space junk on the Moon has been largely exposed. That’s because this isn’t a problem, at least for now.
According to Reddy’s own statements, the lunar orbital channel is currently still relatively free. Compared to the thousands of cataloged objects orbiting Earth, there are only a few dozen payloads orbiting the moon. Of the small handful of satellites in lunar orbit, the only notable ones (possibly the only ones at all) are NASA’s Lunar Reconnaissance Orbiter, two Artemis spacecraft (P1 and P2), and China’s Chang’e 5-T1. That’s less congestion than the equivalent of driving another car during a several-hour drive through rural Wyoming.
A conceptual image of the Artemis 1 Orion pod. NASA
But just because it’s Wyoming today doesn’t mean it won’t be the LA Freeway tomorrow. Or, to avoid exaggeration, at least a little busier than it is now.
“We had the first exploration of the moon in [1960s]’ said Reddie. “Then there was a quiet period in the middle for the last 50 years or so. But now there’s renewed interest in lunar exploration. We expect up to 50 payloads to fly to the moon in the next eight years. We want to avoid the kind of situation that we have on Earth [taking place] around the moon, even in lunar orbit.”
This could also prove disruptive to satellites and potentially dangerous to space missions – both crewed and unmanned.
The idea of taking a proactive approach to air traffic control is of course not new. This is exactly what happened with traditional terrestrial air traffic control. The first serious attempts to develop rules for the surveillance and control of air traffic were made in 1922, a few years after the first International Air Convention of 1919. The first person who could officially call himself a professional air traffic controller, Archie League of St Louis, Missouri, began working in 1929. With 173,000 passengers flying in the US in 1929, compared to 926 million passengers carried in 2019, the sky wasn’t exactly crowded. Still, a solution was felt to be needed – even if it would likely be based on projected growth.
“I come from the world of asteroid tracking”
As the saying goes, the first step to solving a problem is realizing that there is a problem at all. However, when it comes to solving a problem of this complexity, admitting the problem is far from the biggest hurdle. Fortunately, Reddy said, at least initially, that many of the current technologies used to track objects from Earth can be used to track lunar orbits.
Reddy and his students at the Lunar and Planetary Laboratory use special sensors at the university’s Biosphere 2 research facility to characterize cislunar objects. This suite of equipment includes several telescopes dedicated to space domain awareness, including one built by a group of engineering students from the University of Arizona.
“You can do a lot with it [the ground-based optical telescopes] we already have for geostationary stuff,” Reddy said. “They’re just fainter, so you have to expose the image for a long time and get a deeper image.”
His own background, he noted, was “principally defending the planet.” “Coming from the world of asteroid tracking, so many of the tools we apply to this particular problem draw on planetary defense tools and technologies,” he explained. “The asteroid community has been tracking really small objects, far from Earth, for decades. We use a lot of software and techniques [for this project].”
I want to become a moon model
The ultimate goal of this project – and it’s already further along than you might think – is to build a model that accurately depicts every object orbiting the moon. It will then highlight possible conjunctions (the fancy space term for crashes) between those objects and active payloads. Reddy said the tool will be used for this year’s launch of Artemis 1, NASA’s debut Super Heavy Lift launch vehicle, aiming to send an unmanned Orion spacecraft into retrograde orbit of the moon.
The researchers will also make their model available to private space companies. “If a manufacturer comes to us and says, ‘Hey, we’re going to do this mission to the moon, can you please look for conjunctions?’ Yes, sure,” said Reddy. “It’s a service we’re going to offer. We want to avoid creating debris. It makes us more work to keep track of many things. Not that we’re lazy, but if we can avoid it and keep it [lunar orbit] clean, that’s better for all of us.”
A good question is how much enforcement power a space traffic control system like this would have. For the sake of argument, let’s assume that a Chinese satellite poses a possible existential threat to an American space launch — or, as that airspace becomes more populated, two spacecraft risk a possible collision. Who gets to be the one claiming right of passage in a possible alien chicken game? Difficult question. “I don’t think we have any enforcement power,” Reddy said. “It’s more of an academic exercise [right now].”
Another future challenge yet to be unwrapped could be launching actual space missions to deploy additional orbital resources that can help monitor areas not visible from Earth, such as: B. Objects hidden behind the moon. (Who knows: this could even serve as a dry-run for similar initiatives on other planets like Mars, which would require building entirely new infrastructure due to the difficult monitoring from Earth. “I think we’re already planning to do something for that.” management of space traffic around Mars,” he said.)
For now, however, the team will be pleased to see this proof of concept prove its value as a tool in support of our continued space interests – and reignite the lunar fascination.
“Our goal is to mature this and show that something like this can be sustained and useful,” Reddy said. “Then we pass it on to the people who have the real responsibility for keeping this going.”