Expended rockets are falling to Earth as more frequent rocket launches make space more accessible.
In May, a 23-ton Chinese rocket landed in the Maldives in the Indian Ocean, ending days of speculation over where it would land.
In March, the four-ton top stage of a SpaceX Falcon 9 rocket broke apart above the Pacific Northwest, creating a spectacle.
Large projects like broadband satellite constellations, on top of rockets, are just now ramping up, so the current drizzle of falling space trash is certain to continue.
Now, a group of scientists believes they’ve found the perfect prototype for tracking the approaching celestial storm: dozens of cameras that maintain a constant eye on Spain’s sky.
The Spanish Meteor and Fireball Network (SPMN), which was created to detect natural fireballs, detected a Falcon 9 rocket stage burning up over the Mediterranean Sea in February.
The discovery suggests that, when combined with other “fireball networks” around the world, the SPMN could be a useful tool for helping space organizations understand and mitigate the terrestrial risks of space debris, reducing the chances of a rocket crashing through a roof to a vanishingly low level.
“Fireball networks can be very valuable for the aerospace community because we have very exact information on the items that are moving through space,” says Josep Trigo-Rodrguez, an astrophysicist at the CSIC-IEEC in Barcelona and the SPMN’s coordinator.
THE NETWORK OF SPANISH FIREBALL
Falling rockets were never supposed to be tracked by the SPMN. The 200 or so cameras,
which are spread out across 37 locations around the Iberian Peninsula, have been watching the night sky for the dazzling streaks left behind when meteors slam into Earth’s atmosphere for a quarter-century.
Every year, the network’s scientists catalog hundreds of fireballs, which they employ for two objectives.
They begin by looking ahead to see where the space pebbles might have landed.
Researchers used the network to successfully recover a meteorite from Northern Spain in 2004, which was just the 10th meteorite found in this manner at the time.
Second, they look backward to try to figure out where the meteor came from in space.
Astronomers have discovered streams of smaller debris coming from more dangerous asteroids and comets by calculating the original orbits of these objects.
“We’re attempting to figure out where the dangers from space come from,” adds Trigo-Rodrguez.
A MAN-MADE FIREBALL
The team is now attempting to control dangers that originate closer to home.
Three of the network’s cameras picked up a fireball on Feb. 16 that looked to be heading across the crown-shaped constellation Cassiopeia from their perspectives in southern and eastern Spain.
But this fireball moved in a way that the SPMN has never seen before. Meteors from outer space arrive hot,
speeding through the atmosphere at a high angle and glowing for only a few seconds.
This thing lingered in the sky for several minutes. Because objects in Earth’s orbit move more slowly and travel roughly parallel to the ground, SPMN researchers quickly recognized it had to be a piece of space debris.
The team determined the object’s precise journey through the atmosphere by adjusting algorithms generally used to examine the frenzied flashes of natural fireballs to suit the leisurely arc of the debris.
The researchers then compared the route to debris orbits published in a US government registry and discovered that they were identical.
Their fireball was the upper stage rocket from earlier that night’s SpaceX launch of 60 Starlink satellites.
The team published its findings in a pre-print on Sept. 2 that was accepted for publishing in the Journal Astrodynamics.
“To our knowledge, this is the first time someone has done it utilizing wide-field imagery,” adds Trigo-Rodrguez, referring to the way the network cameras capture large regions of the sky.
DEBRIS IN SPACE TRACKING
It won’t be the last, either. Launches of rockets are becoming more common, and SpaceX is one of a few businesses working on swarms of thousands of internet satellites.
Before swan plunging into the atmosphere, these satellites will operate for about five years.
Trigo-Rodrguez anticipates that the updated software, which was created by his Ph.D. student Eloy Pea-Asensio, an aeronautical engineer at the Autonomous University of Barcelona, and CSIC-IEEC, will detect a lot more falling debris in the future. According to him, there are three basic reasons for doing so.
To begin with, recognizing space debris may assist eyewitnesses who are concerned about odd lights in the sky.
For example, the March occurrence in the Pacific Northwest was dramatic enough for one observer’s child to inquire, “Mom, are we ok?”
Second, tracing the paths of the things may lead to their recovery. Collecting satellite shards may have some scientific worth (Trigo-previous Rodrguez’s research discovered that molten metal balls can simulate natural meteorites, earning them the joking term “meteor wrongs”).
But, more crucially, it may aid researchers in determining what can withstand a fall from orbit and whether the debris is hazardous.
Following that, the public’s knowledge of where rocket and satellite parts end up might put pressure on space agencies to act properly.
Most rocket stages crash into oceans due to a combination of luck and design (the majority of the Earth is water, and launches often aim for the middle of the Pacific), but countries are legally liable for any damage.
A nuclear-powered Soviet satellite, for example, fell in northern Canada in 1978, strewing radioactive material across a 600-mile-long swath of the country.
The Canadian government charged the Soviet Union 6 million Canadian dollars (about $18 million in today’s terms) and got only half of that amount.
Trigo-Rodrguez believes that fireball networks capable of detecting space debris could improve transparency.
“All of the world’s space organizations should take care to place all of these rockets on the appropriate trajectories to decay far away from people,” he argues.
Fireball networks are already spreading over the world, spurred on by a scientific desire to collect meteorites.
The “Global Fireball Observatory,” which is still growing, is made up of networks from Australia, Canada, the United States, the United Kingdom, Argentina, Morocco, and other countries.
It would only take a minor software upgrade to have them ready for artificial fireballs.
Trigo-Rodrguez says, “We can develop tighter cooperation with [the] aerospace [community] to exploit all of the infrastructures we have already built.”