(Vadim Sadovski via Shutterstock)
SpaceX's Starlink satellites are designed to burn up in the Earth’s atmosphere after they retire. But don't expect the same with the company's plan to operate up to 1 million orbiting data centers.
SpaceX is indicating to the Federal Communications Commission it’ll retire the bulk of the orbiting data centers by sending them into graveyard orbits, rather than de-orbiting them into the atmosphere.
The company’s January application to the FCC for the 1 million constellation already mentioned it could retire some of the satellites “around Earth or into heliocentric disposal orbits” around the Sun. But in a filing on Friday, SpaceX got more specific while answering the US regulator’s questions about the orbiting data centers.
The 7-page filing includes a preliminary estimate for the various orbits of the 1 million satellites, indicating 80% of the constellation will reside between 680 kilometers and 1,000km orbits around the planet. The remainder will occupy orbits in the 500km range.
(FCC/SpaceX)The filing then says it “plans to dispose of all satellites operating below 600 km through controlled atmospheric reentry in compliance with all applicable orbital debris mitigation rules, guidelines, and best practices.” But for satellites operating above 600km, the company is requesting the option to retire them outside of atmospheric re-entry.
“Providing SpaceX with flexibility to dispose satellites operating above 600 km altitude into Earth disposal orbits or heliocentric orbits would serve the public interest because such methods may be more reliable and sustainable than passive atmospheric reentry,” the company wrote. “In these circumstances, disposal into other orbits would more successfully achieve the Commission’s objective to ensure the prompt removal of satellites from operational orbital regimes and thereby protect the long-term sustainability and usability of low-Earth orbit.”
But the same request also suggests most of the orbiting data centers will eventually become floating space junk when each satellite is designed to only operate for five years, according to SpaceX’s original FCC application. In March, the company also revealed the initial space data center satellites will span 109 meters (357 feet) in length, making them longer than the International Space Station.
(SpaceX)Although space is vast, the sheer scale of SpaceX’s orbiting data center system means retiring so many satellites in a graveyard orbits could still result in dangerous collisions over time, said Hugh Lewis, a space debris expert and professor of astronautics at the University of Birmingham.
“Using Earth graveyard orbits would not be a good idea. The derelict ODCs (orbital data centers) would accumulate in graveyard orbits at a rate of about 800,000 satellites every 5 years, or 160,000 every year on average,” he told PCMag in an email. “The collision risks in the graveyard orbits would quickly reach unsustainable levels, with the potential for fragments from any collisions there to reach all important Earth orbits.”
The filing doesn’t elaborate on why SpaceX wants to retire the satellites in space, except to say it “may be more reliable and sustainable.” But the orbiting data centers will be significantly larger than a Starlink satellite while carrying GPU chips and cooling that might struggle to disintegrate in an atmospheric re-entry.
Lewis also said the company is likely concerned about de-orbiting so many objects into the Earth’s atmosphere, amid existing concerns about burning Starlink satellites could release harmful ozone-depleting gases.
“In the amounts that re-entering SpaceX ODCs might generate, the effects could be substantial and damaging,” he said. "In any case, the abandonment of such a high number (and mass) of objects in any Earth graveyard orbit is not what I’d call environmentally responsible or sustainable. It is kicking the can (or satellite) down the road and leaving the mess for future generations to clean up. One could argue that we could reuse or recycle the components and materials, but until we have the infrastructure in orbit that could undertake such actions, it is still abandonment or orbital littering.”
(Maciej Frolow via Getty)SpaceX didn’t immediately respond to a request for comment. But the company’s original FCC application does mention developing “future hardware recycling and material harvesting” for the decommissioned satellites. The retired satellites will also hold enough fuel for maneuvering, including during the disposal process.
Back in March, the company also indicated to the FCC it’ll launch the orbiting data centers in phases, starting with “a significantly smaller number of satellites.” These satellites will also be retired by de-orbiting them into the atmosphere to monitor for potential environmental effects. Some analysts also suspect SpaceX's proposal is more of a long-term plan when it's unclear if orbiting data centers will ever beat terrestrial data centers in energy, performance and cost. Whether the FCC will approve the orbital data center plan remains unclear.
In the meantime, Lewis pointed out SpaceX’s estimates for the various orbits contain two apparent mistakes. If you add up all the satellites in the table, you get 1,198,120, instead of 1 million. The other issue deals with how the data center satellites are supposed to orbit Earth in a “sun-synchronous” orbit, enabling them to constantly receive sunlight and reap the energy benefits.
“The inclination needed for a sun-synchronous orbit at 700 km is about 98.2 degrees (whilst at 750 km it is about 98.4 degrees), but the table shows 97.2 degrees for this group. That doesn’t inspire confidence!” Lewis told PCMag.