Jacinta Bowler
Jacinta Bowler is a science journalist at Cosmos.
They were published in the Best Australian Science Writing 2023.
The company that owns the world’s biggest commercial satellite is responding to concerns from astronomers about its brightness but says: “Solving significant problems for humanity often comes with challenges.”
The company has highlighted technology which it says will go some way to solving the problems.
A study released on Monday confirmed concerns by astronomers that the satellite BlueWalker 3 is incredibly bright in the night sky.
The company that owns the satellite – AST SpaceMobile – has responded to an article in Cosmos saying it is ‘working to address the concerns of astronomers’.
The apartment sizes satellite launched in September last year has become one of the flashpoints for astronomers to try to preserve the skies from low orbit satellite ‘mega constellations.’
These projects provide internet (and in AST SpaceMobile’s case a mobile phone network) using very large numbers of satellites which can reach places which have found it difficult to access because of cost or technology.
But the study in Nature published on Monday found that at Bluewalker-3’s brightest, it was brighter than almost any star in the sky.
These satellites can create issues for both optical and radio astronomers. For optical astronomers, it’s the satellites reflecting the light from the Sun down to Earth, potentially covering an important astronomical object or overwhelming their delicate equipment.
For radio astronomers, the issue is about the radiowaves that the satellites transmit to provide internet and mobile phone access, as they can obscure similar wavelength radiowaves from space.
AST SpaceMobile says Bluewalker-3 is a prototype, and there will be changes before the next satellite is launched.
They told Cosmos in an email that their project requires less satellites than other companies (such as Elon Musk’s Starlink) making them a better option for astronomy despite their size.
“While other constellations may require thousands of satellites to achieve their coverage goals – there could be as many as 58,000 in orbit by 2030, according to a recent US government report – we plan to provide substantial global coverage with around 90 satellites,” the company wrote.
They also said it is not broadcasting in the US National Radio Quiet Zone and other radioastronomy locations such as the SKA telescope in South Africa and Western Australia.
“Solving significant problems for humanity often comes with challenges,” they said.
“In this case, we are working to address the concerns of astronomers by using roll-tilting flight manoeuvres, which significantly reduce apparent magnitude; planning to equip our next-generation satellites with anti-reflective materials; [and] sharing detailed ephemeris or celestial location data to help astronomers plan observations.”
This complicated problem, which will require cooperation between astronomers and communications companies, is explained in detail in Cosmos’ issue 98, and available at ‘Galaxy In the Desert’.