Astronomers worry about impact of Amazon satellites
Welcome to the age of the satellite megaconstellation.
Within the next few years, vast networks, containing hundreds or even thousands of spacecraft, could reshape the future of Earth’s orbital environment.
Much of the attention on these strings of satellites has been placed on the prolific launches of SpaceX and OneWeb, but the focus is now turning to Amazon. Last month, the Federal Communications Commission approved a request by the online marketplace to launch its Project Kuiper constellation, which, like SpaceX’s Starlink and OneWeb’s network, aims to extend high-speed internet service to customers around the world, including to remote or underserved communities hobbled by a persistent digital divide.
The Kuiper constellation would consist of 3,236 satellites. That’s more than the approximately 2,600 active satellites already orbiting Earth. While Amazon’s hardware is a long way from the launchpad, SpaceX has already deployed hundreds of satellites in its Starlink constellation, including 57 additional satellites it launched on Aug. 7; it may expand it to 12,000 or more. Facebook and Telesat could also get into the internet constellation business.
The rapid influx of satellites into low-Earth orbit has prompted pushback from professional and amateur astronomers. Starlink satellites are notorious for “photobombing” astronomical images with bright streaks, damaging the quality and reducing the volume of data scientists collect for research. While SpaceX plans to mitigate the effects of its launches on astronomical observations, scientists and hobbyists in the community worry about the lack of regulation of constellations as more entrants like Project Kuiper join the action.
“We don’t yet have any kind of industrywide guidelines,” said Michele Bannister, a planetary astronomer at the University of Canterbury in New Zealand. “We don’t have an industry body that’s producing good corporate citizenship on the part of all of these enthusiastic companies that want to launch, and we don’t have any regulatory setup in place that’s providing clear guidelines back to the industry.”
She added, “To me, honestly, it feels like putting a bunch of planes up and then not having air traffic control.”
Burning twilight
Since the first group of Starlink satellites launched in May 2019, many sky watchers have lamented their bright reflected glare. The light pollution is particularly pronounced when the satellites are freshly deployed and headed toward their operational orbits. At this point, they are perfectly positioned to catch sunlight at dawn and dusk, scuttling astrophotos and telescope observations. Starlink must be replenished constantly with new satellites, so these trails will be an ongoing problem.
“Most ground-based observatories actually start in twilight,” said Julien H. Girard, a support scientist at the Space Telescope Science Institute in Baltimore. “We start taking data even when the sky is not completely dark, especially in the nearinfrared and infrared wavelengths.”
The satellites may create the most problems for widefield observatories that survey expansive regions of the night sky at once. The motion of satellites through the frame can obstruct observational targets or overwhelm them with light. Astronomers can use software to remove satellite trails to some extent, but that may not completely fix the images.
“There’s no doubt that the astronomical community can still do science with the presence of those constellations, but it’s a burden,” Mr. Girard said.
The light pollution could mess with the view of countless tantalizing astronomical targets. For instance, scientists are beginning to discover interstellar objects in Earth’s own solar neighborhood, such as Oumuamua, a weirdly elongated rock spotted in 2017 that hails from an unknown star system, or Comet Borisov, which was spotted more recently.
Megaconstellations are uniquely positioned to interfere with detections of these cosmic wanderers.
“One of the prime discovery times for interstellar objects is in that period of sky near astronomical twilight, or dawn and dusk, which is when these satellites have their biggest impact,” Ms. Bannister said.
So far, astronomers have put most of their attention on Starlink because SpaceX was the first company to launch big batches of satellites. OneWeb’s constellation poses a different set of problems for radio astronomers because of the altitude of its orbit. Its future has been uncertain since it declared bankruptcy and began acquisition talks.
But now that Amazon has the FCC’s approval, the Starlink satellites will have company both in orbit and in the discussion about the effects of these networks on astronomy.
“Kuiper would easily have as much of an impact on both optical and radio astronomy as other satellite constellations,” said Jeff Hall, the director of the Lowell Observatory in Arizona and the chair of the American Astronomical Society’s Committee on Light Pollution.
The Amazon constellation will have far fewer satellites than Starlink, but its array will be deployed into three orbits, all higher in altitude than SpaceX’s current network. (Starlink is licensed to occupy higher orbits than Amazon, although SpaceX recently sought FCC permission to operate at altitudes comparable to Project Kuiper, too.)
“Some of those higher orbits are looking like they are actually going to be more problematic for astronomical imaging because they are going to be, basically, visible for longer,” Ms. Bannister said, though it’s not clear how the light pollution from these constellations will compare.
“The companies don’t publish what reflectance their satellites are going to have, so it’s hard to model,” she said.
As the quantity of satellites spirals upward, the risk of crashes does as well. Collisions between satellites add to hazardous orbital debris. Imagine if all the broken glass and prickly detritus from a car wreck kept moving at high speeds above the highway, requiring vehicles to plow through it. That’s how the orbital lanes in space work, so it will be essential that protocols governing space traffic are able to keep pace with these megaconstellations to prevent clips and crashes.