The common area over Earth has become a trash pile, and we can't agree on the best way to resolve it. For over 50 years, we’ve launched tonnes of refuse into the heavens and the count of objects is growing innumerable.
Future launches are curbing the amount of potential shrapnel in low-orbit, however, the overall attitude when it comes to space is ‘just one more couldn't hurt.’
Decades of stray shrapnel in the form of exhausted rocket stages, errant bolts and paint chips, dead satellites and the remnants of tests form a high-speed barrier of crowded orbiting metal. And the future looks bleak with the continued rise of satellite constellations, a group of artificial satellites working together as a system.
Why is it such an issue?
As of November 2020, there were over 22,000 objects larger than 10cm currently being tracked by the U.S. Space Surveillance Network. While 1,000 of these are operational spacecraft, that means 21,000 pieces of debris are zooming around Earth at 29000 km/h that can cause catastrophic damage to spacecraft and satellites.
Even tiny pieces of space debris can have catastrophic effects. This image shows the result of a lab-test impact between a block of aluminum and a small aluminum sphere traveling at nearly 7 kilometers per second. Credit: ESA
Satellite constellations are not an issue because of the satellites themselves, as each constellation requires thousands of spacecraft launches. The future big players in satellite constellations are SpaceX’s Starlink, OneWeb’s mega constellation, and Amazon’s Project Kuiper, which is projected to launch up to 3,200 satellites soon.
For more information on Satellite constellation politics, click here.
The ISS routinely changes orbit to avoid catastrophic impacts with space debris.
The more the congestion grows, the more common the close-calls have become between orbiting objects. For example, the US150 billion dollar International Space Station has to change its course to avoid hazardous debris often. It gets worse.
A collision between larger shrapnel pieces threatens more mini-shreds of metal, making the low-Earth orbit even worse. For example, the February 2009 decommissioned 950-kilogram Russian Cosmos satellite and the 560-kilogram active commercial Iridium spacecraft collision created an enormous amount of debris. The satellites collided accidentally at a speed of 11,700 m/s (42,000 km/h) and an altitude of 789 kilometres above the Taymyr Peninsula in Siberia. It was the first time a hypervelocity collision occurred between two satellites and produced approximately 1,000 pieces of debris larger than 10 cm.
Below is the spread of shrapnel after just 20 and 50 minutes, respectively.
Removing shrapnel from low orbit should be a top global priority, says Donald Kessler, a retired NASA senior scientist for orbital debris research.
In the late 1970s he foretold the possibility of a scenario called the Kessler syndrome: as the congestion of space debris rises, so does the exponential cycle of debris-generating collisions that could eventually render low-Earth orbit too perilous to sustain most space activities.
“There is now agreement within the community that the debris environment has reached a ‘tipping point’ where debris would continue to increase even if all launches were stopped,” Kessler says. “It takes an Iridium-Cosmos-type collision to get everyone’s attention. That’s what it boils down to.... And we’re overdue for something like that to happen.”
As for the Kessler syndrome, “it has already started,” he says. “There are collisions taking place all the time—less dramatic and not at the large size scale.”
What Solutions Are Coming?
There has not been a shortage of possibilities for possibly removing debris from Kessler’s nightmare scenario. Several solutions have been proposed for getting rid of our orbital trash, including giant foam balls, laser blasts, harpoons, puffs of air, solar sails, including robotic arms and tentacles.
A new entrant in grappling with this troubling state of affairs is the recently launched End-of-Life Services by Astroscale Demonstration (ELSA-d) mission.
A Japanese satellite services company, Astroscale, has developed ELSA-d, a two-satellite mission comprising two satellites: A “servicer” satellite will remove residual debris from orbit, while a “client” satellite will be used when space debris will accumulate. The project aims to show the capability of capturing stable or even tumbling objects that can be disposed of or serviced in space using magnetic technology. A multi-phase test program will be executed, ultimately leading to servicer and client deorbiting together and becoming one during their fiery dip into the Earth’s atmosphere.
A Russian Soyuz rocket lofted ELSA-d on March 22 along with a multitude of other small satellites into space, and the satellite is now in Earth's orbit. Following the liftoff, Astroscale’s founder and CEO Nobu Okada stated ELSA-d will demonstrate its debris-removal skills and “propel regulatory developments and advance the business case for end-of-life and active debris removal services.” The launch is a step toward discovering “safe and sustainable development of space for the benefit of future generations,” he said.
Although ELSA-d and other technical manifestations of its kind are certainly positive advancements for removing orbital debris, they should not be mistaken for a complete solution. Despite their meager successes, such missions are slipping short of resolving the dynamic issue at hand, and the proliferation of space debris persists largely unabated.
What's the Complete Solution?
“From my perspective, the best solution to dealing with space debris is not to generate it in the first place,” says T. S. Kelso, a scientist at CelesTrak, an analytic group that keeps an eye on Earth-orbiting objects. “Like any environmental issue, it is easier and far less expensive to prevent pollution than to clean it up later. Stop leaving things in orbit after they have completed their mission.”
Unfortunately, there’s no singular complete solution to the problem of space junk.
Removing large rocket bodies is a significantly different task than removing the equivalent mass of a lot more smaller objects, which are in a wide range of orbits, he observes. As rocket launch costs fall drastically, innovations by companies like SpaceX open the floodgates for satellites to reach low-Earth orbit, where some will fail and become drifting, debris-generating hazards. “Many of these operators are starting to understand the difficulty and complexity of continuing to dodge the growing number of debris.”
Alice Gorman, a space archaeologist and space junk expert at Flinders University in Australia, says space junk ranges from nanoparticles to whole spacecraft such as the European Space Agency’s Envisat, which is the size of a double-decker bus. These larger objects are at the top of the priority list for removal.
There are also objects such as despin weights (solid lumps of metal) and thermal blankets, which are ultra-thin. “They’ll cause different types of damage and may need different strategies to remove. There is no way that a one-size-fits-all approach is going to do it,” Gorman says.
One to ten-centimeter-sized debris particles pose the most serious risks, she says. “There’s far more of them than whole defunct spacecraft, and there is a far greater probability of collision,” Gorman says. “While debris this size might not cause a catastrophic breakup, collision with it can certainly damage working satellites and create new debris particles.”
Gorman is concerned about the effects of mega constellations of satellites being added to an already dense low-Earth orbit environment. “We also know that orbital dynamics can be unpredictable,” she says. “I want to see some of these mega constellation operators releasing their long-term modeling for collisions as more and more satellites are launched.”
Active orbital debris removal is technically challenging, Gorman says. “However, the big issue is that any successful technology that can remove an existing piece of debris can also be used as an anti-satellite weapon,” she says. “This is a whole other can of worms that requires diplomacy and negotiation and, most importantly, trust at the international level.”
According to Mariel Borowitz, academic associate at Georgia Tech’s Sam Nunn School for International Affairs, the ability to close in on spacecraft and perform servicing or sabotage has been of significant interest to military planners in recent years.
“These rapidly advancing technologies have the potential to be used for peaceful space activities or for warfare in space,” she says. “Given the dual-use nature of their capabilities, it’s impossible to know for sure in advance how they’ll be used on any given day.”
Where do you stand in terms of space debris and keeping launch providers accountable for their mess?
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