When Buzz Lightyear yelled “To Infinity and Beyond” I wonder if he was concerned about encountering traffic in space?
Probably not. After all, he was just a toy.
But Purdue University researchers aren’t playing games, and they are concerned with traffic in space – for real.
With the number of missions – flown by government and commercial entities – growing annually, especially those to the moon and back, there’s likely to be some traffic issues in outer space.
While you’re likely to survive an auto crash on the way to work or the grocery store, spacecraft collisions can be much more disastrous and the impacts far more far reaching.
To prevent those spacecrafts from running into each other – or even parts of each other – Purdue University engineer Carolin Frueh is investigating how to observe and track all human-made objects and predict their potential impact in the Earth-moon neighborhood, called the cislunar region.
According to Frueh, a Purdue associate professor of aeronautics and astronautics, the reality is that solutions for space traffic in the cislunar region will be moving targets. The methods she is developing are intended to adapt to this region as traffic changes.
“There will never actually be a final answer to a space traffic management problem because as the commercial sector grows and the capabilities and types of vehicles that you have change, the problem will evolve, too,” she explains. “So when we think about the techniques that we want to use, we also have to be sure that what we have in mind can evolve over time.”
You would think there would be plenty of space in outer space without having to worry about relatively small spacecrafts and other manmade orbiting objects colliding, but the cislunar region is far less understood than near-Earth orbits, which extend 24,000 miles beyond Earth’s surface. Most satellites as well as the Hubble Space Telescope and International Space Station reside in near-Earth orbits.
Even with all that real estate in space, researchers have already seen issues with collisions of satellites with various objects. And those collisions can have far-flung impacts. Collisions in the near-Earth orbit have created 130 million pieces of space debris orbiting the Earth and a rogue rocket booster crashed into the moon’s surface last March.
The number of satellites orbiting the earth complicates matters.
SpaceX founder Elon Musk was recently criticized for saying “tens of billions” of satellites could be accommodated in the near-Earth orbit. That claim has since been repudiated as “overly optimistic” by experts.
The number of satellites has been steadily increasing: Over 5,400 satellites are currently in orbit in the near-Earth orbit, according to the Union of Concerned Scientists. That figure is projected to rise dramatically as SpaceX works quickly to expand Starlink – its constellation of satellites – with nearly weekly launches.
To address forthcoming traffic in space Frueh has been pulling from her research on how spacecraft becomes debris. She works with space agencies around the world to improve databases of space objects.
Together with her student, Surabhi Bhadauria, Frueh is developing a way to create visibility maps that would show the best regions telescopes should use to find and track human-made objects in cislunar space — including active satellites, dead satellites and fragments of satellites.
Frueh’s visibility maps run on models that more quickly and comprehensively indicate where telescopes should go to observe as much of the cislunar region as possible.
The science and technology of Frueh’s method is complicated, but it differs from current methods in at least two key ways. The maps allow space observers a more defined area to look by averaging out all the orbits a telescope might use rather than integrating each orbit change over time like other mapping methods must do. Frueh’s method also doesn’t require any additional computational time to show which satellites can be observed under which conditions from various locations.
Compared to other approaches, these maps better address the fact that space and traffic patterns in space are always changing.
Frueh’s work isn’t confined to outer space. It also could have a dramatic impact right here at home.
Her research indicates that pieces from a fragmented satellite can travel long distances in a relatively short time. Frueh and her student, Ariel Black, recently presented a study at the 2023 AAS/AIAA Space Flight Mechanics Meeting showing fragments from space collisions can travel effortlessly all the way back to Earth from cislunar space.
