Satellites threaten astronomy, but some scientists see an opportunity

Every night, the stars in the sky compete with thousands of satellites. The number of intruders is only growing as satellite constellations proliferate, with companies planning to launch orbiters in the tens of thousands to beam internet and other communications signals back to Earth. Among them are SpaceX, which has already launched thousands of Starlink satellites, and Amazon, which plans to launch its Project Kuiper constellation later this year.

For astronomers who study the universe from the surface of our world, this is a growing problem.

“It’s a hot topic,” said Eric Burns, an astronomer at Louisiana State University. “We are dealing with such a large number of satellites that they limit the sensitivity of ground-based telescopes.”

Many astronomers have been very critical of the current and future effects of satellite constellations on their studies. But Dr. Burns and other scientists plan to make cosmic lemonade from orbital lemons. What if, they ask, all those interfering satellites could help advance the field of astronomy by expanding ground-based access to satellite signals?

What these astronomers see is the potential for a new type of telescope that mega-constellations could provide. In an upcoming proposal that Dr Burns and his colleagues plan to share with private companies building satellite constellations, they hope thousands of tiny gamma-ray detectors can hitchhike in space with the satellites. . Taken in isolation, each individual detector would be weak. But operating together inside a mega-constellation of several thousand satellites, the power of such a system would rival Swift and Fermi, two NASA-run gamma-ray observatories in space.

The impact would be significant. Gamma-ray bursts are the hallmark of the most catastrophic events in the universe since the Big Bang. Further research into the phenomena could help answer today’s most important questions, such as what constitutes the cores of neutron stars or how the behavior of dark energy could reveal the shape of the universe.

“This is about as big a set of questions as can be asked in astronomy,” Dr Burns said. “We will be able to treat the thousands of gamma-ray detectors as a single extremely powerful coherent telescope looking all over the universe, which would be more sensitive than anything that has been done before.”

The idea is not without precedent. In 2011, Iridium Communications worked with scientists to superimpose research instruments in space. About 30 Iridium satellites — which typically transmit voice and data communications to Earth — also house dosimeters that measure radiation in low Earth orbit as part of the REACH program, a collaboration between the U.S. Air Force and scientists.

And all of Iridium’s more than 60 satellites carry magnetometers for the AMPERE program, run by the Johns Hopkins Applied Physics Laboratory, which studies how energy enters Earth’s ionosphere from its magnetosphere.

Alexa Halford, associate lab chief at NASA’s Goddard Space Flight Center, says Iridium readings are an important source of radiation data. His work reveals the connection between Earth’s magnetosphere and its atmosphere and how the two work together to protect the ground from heavy radiation rains from space.

Dr Halford said the way satellite mega-constellations interfere with telescopes on the Earth’s surface needed more attention.

“Ground-based astronomy is extremely important and we have to be responsible,” she said.

On the other hand, she sees great potential in putting scientific instruments on more satellites.

“More data can give us a more complete picture,” Dr. Halford said. “I would find it hard to say no.

SpaceX already shares some data with scientists as part of an arrangement that could benefit both parties.

Tzu-Wei Fang, a National Oceanic and Atmospheric Administration scientist specializing in space weather forecasting, began collaborating with SpaceX after a disastrous launch in February 2022. SpaceX saw 38 of its 49 newly deployed Starlink satellites fail. ignite.

Dr. Fang’s autopsy documented how a minor geomagnetic storm had increased air density at altitudes where low Earth orbits take place. So, instead of cruising into orbit, the Starlink satellites slammed into dense, hot air and separated.

“Nobody can drag very well in low Earth orbit right now because we don’t have the right satellites,” she said.

After this incident, SpaceX agreed to share position and velocity data from its roughly 4,000 Starlink satellites for a year, giving Dr. Fang and his colleagues the opportunity to study the type of orbital drag that had destroyed the satellites. This could potentially lead to better space weather predictions, giving satellites more time to react to increased air density by reaching a safer orbital altitude, “which will ultimately benefit everyone,” he said. Dr Fang.

Obtaining scientifically useful data from satellite constellations presents technical hurdles. Satellites in low Earth orbit move very quickly, completing a full orbital circuit in about 90 minutes. It is therefore not easy to combine data from a constellation of many satellites.

And for scientific equipment to be able to roll into orbit, there are strict limitations. Low-Earth-orbit communications satellites, like SpaceX’s Starlink, have a short lifespan of about five years, so detectors should be inexpensive. In contrast, the Hubble Space Telescope cost around $16 billion in today’s dollars, but is expected to last around 40 years.

Any additions could not be added at the last minute. Satellite engineers would need to modify their designs to accommodate new payloads with upgrades such as larger power sources and data links.

None of the companies that build huge constellations of satellites have said they would be willing to deploy gamma ray detectors or other new sensors that would help scientists. When asked to comment on the idea, SpaceX declined to respond and OneWeb, which recently completed another smaller constellation, never responded. Project Kuiper, the constellation of online retailer Amazon that could launch its first satellites later this year, said it invited Dr Burns to submit its proposal.

Dr Halford suggested increasing the number of partnerships with constellation operators was a way to benefit everyone without further cluttering the skies. “It’s not a good answer, but I think it’s the best we’ve got,” she said.

So far, the burden of dealing individually with wavering companies like SpaceX has frustrated astronomers. Dr Burns thinks it might be time for the government to ensure that mega-constellations harm science as little as possible.

With greater participation, Dr. Burns hopes scientists and satellite makers can learn to work together. “I think this idea of ​​scientific instruments on the mega-constellations themselves would be a benefit to both sides,” he said. “If they’re open to that, that’s an even bigger solution.”