SpaceX is demanding a retraction from the FAA for a report that estimates debris from deorbiting Starlink satellites “would be expected” to kill or injure someone every two years. In a letter to the agency reviewed by SpaceNews, SpaceX principal engineer David Goldstein called the guesstimate “deeply flawed” and based on outdated data. But the fundamental point made by SpaceX is that its internet-beaming satellites are specifically designed to routinely fall out of low earth orbit and burn up entirely on reentry. So far, they’ve been right.
SpaceNews said a satellite tracker has counted 358 Starlink satellites that have been scrapped and there have been no reports of debris getting to the ground. “To be clear, SpaceX’s satellites are designed and built to fully demise during atmospheric reentry during disposal at end of life, and they do so [emphasis in original],” Goldstein wrote in the letter. “Extensive engineering analysis and real-world operational experience verify this basic fact.”
The report also claimed there was a remote possibility a chunk of Starlink debris would take out an aircraft in flight. The report was ordered by Congress and the FAA commissioned Aerospace Corp., a federally funded nonprofit, to do the study. Goldstein said Aerospace Corp. used a 23-year-old NASA study as the basis for its conclusions. That study looked at the amount of debris that hit the ground from falling Iridium satellites that were “not even built to be fully demisable.” SpaceX has about 5,000 Starlink satellites in low earth orbit and plans to have about 14,000 there when the system is fully built out.
“Fully demisable.” Do we have NASA to thank for that, or SpaceX?
BTW, Wikipedia defines “demisable” as, “Capable of being leased. a demisable estate.”
I guess if a satellite buys the farm, the farm would be able to be leased…. 🙂
The Starlink engineer should have said what actually happens to the re-entry debris: It burns up. Or if he really wants to use big words, It incinerates.
Dictionaries don’t always list other possible uses of a word. Considering “demise” is to “cease to exist”, there is no reason why “demiseable” can’t mean something that was designed to, at some point, cease to exist.
“The victim was found pinned under the Internet after it fell from the sky.”
Regarding the idea that aircraft might be subject to a higher risk level, my totally inexpert evaluation would be that if it ain’t demised before reaching 40,000 feet, it ain’t gonna be gone at the surface either.
You’re correct – the report did state that the debris traveling through navigable airspace would be the same as what hits the ground. The report also assumes multi-fatalities for aircraft impacts.
Good point. Much higher per-incident fatalities, also larger point of critical impact area to raise incident likelihood. I won’t give up air travel quite yet though.
In addition to being designed to burn up on re-entry, I think SpaceX has the satellites re-enter over the open ocean. The Starlink sats are being disposed of in a controlled manner. They are not simply allowing their orbits to decay.
The FAA analysis seems pretty fair:
“If SpaceX is correct in reporting zero surviving debris, as SpaceX reports in FCC filings, and Starlink is a fully-demisable spacecraft, the rise in reentry risk is minimal over the current risk.”
But, “if the expected large constellation growth is realized and debris from Starlink satellites survive reentry, the total number of hazardous fragments surviving reentries each year is expected to reach 28,000, and the casualty expectation … would be 0.6 per year, which means that one person on the planet would be expected to be injured or killed every two years” (both on page 6 of the report).
In other words, SpaceX had better get demisability right.