Scientists have concluded that the world’s largest communications satellite outshines nearly every star in the sky. The phenomenon is not new, however, the increasing number of satellites and the lack of darkness in some parts of the world due to these devices is concerning the scientific community.
1. BlueWalker 3
The new telecommunications satellite called BlueWalker 3 outshines 99% of the stars visible from a dark location on Earth, according to observations reported in Nature. BlueWalker 3 is the most brilliant recent addition to a sky that is already swarming with satellites.
The huge satellite was developed by the telecommunications firm AST SpaceMobile in Midland, Texas. It was launched on 10 September 2022 as a prototype for a satellite fleet designed to make mobile broadband available almost anywhere. The company plans to provide broadband coverage with a fleet of 90 similar satellites, including 5 that are scheduled to launch in early 2024.
Nature research paper: The high optical brightness of the BlueWalker 3 satellite https://t.co/ecoxvVlxwS
— nature (@Nature) October 3, 2023
Professional and amateurs scientists came up with a scientific way of quantifying the brightness emitted by satellites and BlueWalker 3 in particular.
BlueWalker 3’s huge array of antennas and white colour mean that it reflects a considerable amount of sunlight back towards Earth, making it shine even at twilight. Professional and amateur astronomers embarked on an international observation campaign to assess the impact of BlueWalker 3 in the sky, ultimately spotting it from locations in Chile, the United States, Mexico, New Zealand, the Netherlands and Morocco.
2. Threat to scientific observations
The spaceflight company SpaceX alone has launched more than 5,000 satellites into orbit, and companies around the globe have collectively proposed launching more than half a million satellites in the coming years — a scenario that astronomers fear could hamper scientific observations of the Universe. According to Patrick Seitzer, an emeritus astronomer at the University of Michigan, Ann Arbor, who was not involved in the researh, the Nature study shows that there are no boundaries to satellite brightness.
I’m concerned that we’re going to see a very large number of large satellites launched in the next decade, and it will change the appearance of the night sky forever.
Patrick Seitzer, Astronomer at the University of Michigan
3. Space debris
In a statement to Nature, AST SpaceMobile said that it is currently working with NASA and astronomy groups to address space debris caused by satellites. In mid-2019 many astronomers were caught by surprise when SpaceX successfully launched 60 satellites, creating a ‘train of stars’ that glided through the night sky. Now, low Earth orbit is littered with thousands of commercial satellites. If captured by a telescope during a long exposure, such objects can leave a bright streak that renders the data unreadable.
🔊 Latest on the Nature Podcast: Astronomers are worried by a satellite brighter than most stars https://t.co/MKv5IatjDu
— nature (@Nature) October 5, 2023
Astronomers have long steered their telescopes to avoid the brightest of these objects. According to Jonathan McDowell, an astronomer at the Harvard–Smithsonian Center for Astrophysics in Cambridge, Massachusetts, that workaround will still be possible if AST SpaceMobile launches a fleet of satellites similar to BlueWalker 3. The bigger concern, he says, is that other companies might also launch constellations of large satellites. If that happens, Seitzer says, “then the night sky will be irreversibly changed”.
A coalition named CPS is currently studying ways of tackling these issues alongside SpaceX and AST SpaceMobile.
