A team of scientists has been tracking a bright object in the sky. But it’s not a star. It’s a new type of commercial satellite. Astronomers are trying to understand how its brightness and transmissions will interfere with Earth-based observations of the universe — and what can be done to minimize these effects as more of these satellites are launched.

In a published Oct. 2 in Nature, the team reports its first detailed assessment on how the satellite — — could impact astronomy.

“While there is only one BlueWalker 3 satellite, it is one of the brightest objects in the sky, and a harbinger of where low-Earth orbit is heading for sky observers,” said co-author , a research scientist with the 91̽��’s and the Vera C. Rubin Observatory in Chile.

Building on initial observations made shortly after its launch, these new results complement of this unusual satellite. The paper includes details of how the satellite’s brightness changes over time, as well as the visibility of jettisoned hardware. With companies intending to deploy more commercial satellites in the coming years, this paper highlights the need for pre-launch impact assessments.

“The interference of satellites in astronomy has become an increasingly pressing issue over the last few years,” said first author Sangeetha Nandakumar of the University of Atacama in Chile.

BlueWalker 3 was launched into low-Earth orbit on Sept. 10, 2022, by . The craft is a prototype for a planned constellation of more than a hundred satellites for use in mobile communications. Observations made shortly after launch showed that the satellite was among the brightest objects in the sky.

To better understand its impact on astronomy, the International Astronomical Union’s , or CPS, initiated an international observing campaign. As part of this initiative, both professional and amateur observations were contributed from across the world from sites in Chile, the United States, Mexico, New Zealand, the Netherlands and Morocco.

“It is exciting that we could incorporate images from many different telescopes and visual observations from highly skilled amateur observers in this analysis,” said Rawls. “It’s an example of the kind of thing that is possible only when folks from many institutions and with many backgrounds work together with a common purpose.”

The CPS is co-hosted by NSF’s and the , an international partnership. The CPS facilitates global coordination of efforts by the astronomical community — in concert with observatories, space agencies, industry, regulators and other sectors — to help mitigate the negative consequences of satellite constellations on astronomy. Its four working groups — or hubs — pursue different projects analyzing different types of interference from satellites and other sources.

“This paper brings together observers from across the globe under the umbrella of the CPS SatHub to better understand the ramifications,” said Rawls, who co-leads SatHub. “This is the first peer-reviewed research to quantitatively measure the high brightness of BlueWalker 3 and discuss the impacts on astronomy.”

The newly released data show an abrupt increase in the brightness of BlueWalker 3 over a period of 130 days — coinciding with the complete unfolding of its antenna array — followed by fluctuations over the subsequent weeks. Data also showed a relationship between the varying brightness and other factors after unfolding, such as the satellite’s height above the horizon and the angle between the observer, the satellite and the sun. The team also used a subset of the observations to calculate the satellite’s trajectory over time. Comparing the predicted path with the observations collected, they could evaluate the accuracy of these predictions and observe how its elevation declined over time due to atmospheric drag and other factors.

In addition, they observed the launch vehicle adapter attached to BlueWalker 3 decoupling from the satellite. This component reached magnitude 5.5 in brightness, exceeding maximum recommendations set out by the IAU to avoid the worst impacts of satellites on optical astronomy.

“These results demonstrate a continuing trend towards larger, brighter commercial satellites, which is of particular concern given the plans to launch many more in the coming years,” said co-author and CPS scientist Siegfried Eggl of the University of Illinois at Urbana-Champaign. “While these satellites can play a role in improving communications, it is imperative that their disruptions of scientific observations are minimized. This could preferably be achieved through continuing cooperation on mitigation efforts, or, if that is not successful, through a requirement for pre-launch impact assessments as part of future launching authorization processes.”

“Besides the effect on visible observations, BlueWalker 3 could also interfere with radio astronomy, since it transmits in radio frequencies close to those that radio telescopes observe in,” said Federico Di Vruno, co-director of the CPS. “The novel aspect of BlueWalker 3 is that it uses frequencies that are normally used by terrestrial transmitters.”

Observations of BlueWalker 3 will continue, with plans by astronomers to observe its thermal emission later this year. Astronomers will continue to discuss this topic at this month.

“This is a global issue, since satellites approved by any country are visible in the night sky across the world, highlighting the importance of international coordination,” said co-author Jeremy Tregloan-Reed of the University of Atacama and the CPS.

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

Adapted from a by the IAU.

Space urgently needs special legal protection similar to that given to land, sea and atmosphere to protect its fragile environment, argues a team of scientists. The scientific, economic and cultural benefits of space should be considered against the damaging environmental impacts posed by an influx of space debris — roughly 60 miles above Earth’s surface — fueled by the rapid growth of so-called satellite mega-constellations.

In a published April 22 in Nature Astronomy, the authors assert that space is an important environment to preserve on behalf of professional astronomers, amateur stargazers and Indigenous peoples.

“We need all hands on deck to address the rapidly changing satellite situation if we can hope to co-create a future with dark and quiet skies for everyone,” said co-author , a research scientist with the and the 91̽��’s , or DiRAC Institute.

The team, led by Andy Lawrence, a professor at the University of Edinburgh’s Institute for Astronomy, reports that the installation of large clusters of hardware in Earth orbit — some consisting of tens of thousands of satellites to deliver broadband to Earth — are congesting space. In addition, rocket launches are polluting the atmosphere and pieces of broken satellites, which race at high speed through orbital space, threaten working satellites in their path. Streaks from satellite flares also cause light pollution, which increasingly disrupts research.

The Chile-based Rubin Observatory, which aims to carry out a , is predicted to be badly affected, for example.

“Rubin Observatory will be one of the most severely impacted astronomy facilities by large numbers of bright satellites due to its large mirror and wide field of view — the same characteristics that make it such a remarkable engine for discovery,” said Rawls. “I care a lot about how satellite streaks affect science, but the case for dark and quiet skies is much larger than that.”

Addressing these issues will require a holistic approach that treats orbital space as part of the environment and worthy of environmental protection at both national and international levels, said the authors. They urge policymakers to consider the environmental impacts of all aspects of satellite constellations — including their launch, operation and de-orbit — and to work collaboratively to create a shared, ethical, sustainable approach to space.

“We are standing on a watershed in history,” said Lawrence. “We can cheaply launch huge numbers of satellites and use them to the benefit of life on Earth — but this comes at a cost. As well as damaging stargazing, the space industry may be shooting itself in the foot.”

Rawls has also been involved in efforts to protect and preserve the night sky through the recently established International Astronomical Union Centre for the Protection of the Dark and Quiet Skies from Satellite Constellation Interference. The center aims to bring together sky-observer stakeholders to collaborate on quantifying, mitigating and disseminating the impacts of satellites.

The new article in Nature Astronomy stems in part from a legal case related to how the U.S. government licenses and authorizes commercial space launches. An — filed on behalf of Lawrence with input from Rawls and co-author , associate professor of aerospace engineering and engineering mechanics at the University of Texas at Austin — argues that U.S. environmental regulations should apply to the licensing of space launches. The case, which could set a precedent in the growing campaign for “space environmentalism,” is currently before the U.S. Court of Appeals for the District of Columbia Circuit.

“We believe that all things are interconnected and that we must embrace stewardship as if our lives depended on it,” said Jah. “Traditional ecological knowledge holds a key to solving this wicked problem.”

Jah recently co-founded the startup Privateer Space together with Apple co-founder Steve Wozniak and Alex Fielding, CEO of Ripcord. Privateer Space plans to take a novel approach to mapping the objects in orbit accurately, in nearly real-time, to enable the sustainable use of space by a growing number of operators.

“The largest challenge we have is in recruiting empathy and compassion toward solving these environmental crises,” said Jah. “If we can find innovative ways to enable the general public to project themselves into this dire condition, and feel concern to address it, the Earth, and all of the lives she sustains, wins.”

Other co-authors on the paper are Aaron Boley, associate professor of physics and astronomy at the University of British Columbia; Federico Di Vruno, a scientist with the Square Kilometre Array Observatory, based in the U.K.; Simon Garrington, associate director of the Jodrell Bank Observatory at the University of Manchester; Michael Kramer, director of the Max Planck Institute for Radio Astronomy in Germany; Samantha Lawler, assistant professor of physics at the University of Regina in Canada; James Lowenthal, professor of astronomy at Smith College; Jonathan McDowell, an astrophysicist with the Harvard-Smithsonian Center for Astrophysics; and Mark McCaughrean, a senior advisor with the European Space Agency.

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

Adapted from a by the University of Edinburgh.

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.

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 on Feb. 3, the 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 and the U.K.-headquartered . The center will coordinate collaborative multidisciplinary international efforts with institutions and individuals — including researchers at the 91̽��’s , 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 , a research scientist with the 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.

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 , which will be an online repository for images with satellite interference. Dino Bektešević, a 91̽��graduate student in astronomy, is working with Rawls on the project, along with undergraduate students at the 91̽��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 by NSF’s NOIRLab.