UW News

February 9, 2022

New IAU center to focus on solutions to satellite interference in astronomical observations

Starlink Satellites pass overhead near Carson National Forest, New Mexico, photographed soon after launch.M. Lewinsky

For many people, the night sky is a beautiful sight. But to astronomers, the night sky is becoming louder, brighter and busier — to the point of drowning out the cosmos that they seek to study.

Satellite constellations are one of the main culprits. These are networks of satellites launched in recent years into low Earth orbit for applications such as broadband networks. The satellite constellations in place are already interfering with astronomical observations, with private companies planning to hoist thousands more in the coming decade.

At a press conference on Feb. 3, the International Astronomical Union launched the Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference — to be hosted jointly by the National Science Foundation’s NOIRLab and the U.K.-headquartered Square Kilometre Array Observatory. The center will coordinate collaborative multidisciplinary international efforts with institutions and individuals — including researchers at the University of Washington’s Data Intensive Research in Astrophysics and Cosmology Institute, or DiRAC Institute — and will work across multiple geographic areas to help mitigate the negative impacts of satellite constellations on ground-based optical and radio astronomy observations as well as humanity’s enjoyment of the night sky.

Satellite constellations introduce large amounts of “noise” into images and data collection runs by Earth-based observatories. For example, they reflect sunlight, and appear as streaks across images of cosmic objects. That does more than ruin a good picture: The streaks can obscure objects and reduce the scientific utility of astronomical images. In addition, their uplink and downlink transmissions can interfere with radio astronomy.

“We’re witnessing a new era as skies fill with thousands of bright satellites,” said Meredith Rawls, a research scientist with the Vera C. Rubin Observatory and the DiRAC Institute at the UW. “In just the last two years, astronomers have realized this will impact our ability to achieve science goals from ground-based facilities like Rubin Observatory.”

DiRAC is a supporter of the new center, and Rawls spoke at the press conference about the critical need to understand the impact satellite constellations will have on astrophysical research and other endeavors, such as identifying and tracking potentially hazardous near-Earth asteroids.

“There is no limit on the number or brightness of satellites streaking across the night, and as a result, not only is science impacted, but so are astronomers’ careers and the shared human experience of a dark sky,” said Rawls.

This image of Venus and the Pleiades shows tracks from Starlink satellites. The reflective surfaces of the satellites, coupled with the fact that they are orbiting around Earth, mean that astronomical observations that require very long exposures capture “tracks” of the satellites in their images.T. Hansen/IAU OAE

In 2020, Rawls began studying interference from SpaceX’s Starlink satellites, which are part of a network to market broadband access to underserved regions. She leads the Trailblazer Project, which will be an online repository for images with satellite interference. Dino Bektešević, a UW graduate student in astronomy, is working with Rawls on the project, along with undergraduate students at the UW and other institutions. Trailblazer will contribute to one of the new center’s core aims: the creation of a “SatHub” platform to coordinate the sharing, analysis and dissemination of images with streaks and other interference caused by satellites.

“We are building Trailblazer to be an open data repository for astronomical images with satellite streaks, with two goals: giving astronomers with messed-up images something useful to do with them; and enabling studies of how the rapidly-changing satellite population is actually impacting ground-based optical/near-infrared astronomy,” said Rawls.

The center has other hubs for community engagement and advocating for new policies and regulations, as well as for interfacing with private companies and government agencies.

The International Astronomical Union called for the establishment of the center in 2021. It aims to bring together astronomers, satellite operators, regulators and the wider community and acts as a bridge among all stakeholders to protect the dark and quiet skies. The center builds on the vast amount of work carried out by the two host institutions, along with other supporting institutions across the world like the DiRAC Institute.

“The new center is an important step towards ensuring that technological advances do not inadvertently impede our study and enjoyment of the sky,” said IAU President Debra Elmegreen. “I am confident that the center co-hosts can facilitate global coordination and bring together the necessary expertise from many sectors for this vital effort.”

The vision of the center is to become the leading voice for astronomical matters that relate to the protection of the dark and quiet sky from satellite constellations and to act as a hub of information and resources for stakeholder groups.

“Continuing to preserve a dark and quiet sky is essential for both astronomy and for sustaining the curiosity of future generations, who find inspiration from simply looking up,” said Matt Mountain, president of AURA, which operates NOIRLab under a cooperative agreement with the NSF.

For more information, contact Rawls at mrawls@uw.edu.

Adapted from a press release by NSF’s NOIRLab.