NZ researchers say satellite is too bright in night sky

A team of researchers from the University of Canterbury (UC) have found a satellite launched last year is too bright, making it hard to conduct astronomical observations.

The UC researchers are part of an international coalition who have spent the last 130 days tracking the BlueWalker 3 satellite, which has been labelled as "unusual".

The satellite was launched into orbit in September last year by AST SpaceMobile — and was a prototype for a planned "constellation of similar models" forming a network for mobile communication.

Shortly after launch, it was determined the satellite was "among the brightest objects in the sky".

The researchers found an "abrupt increase" in the brightness of BlueWalker 3 — which coincided with the unfolding of an antenna array.

Michelle Bannister, one of the researchers involved, said it's important to understand how man-made objects can affect the night sky — for everyone, not just astronomers.

"Satellites have become an increasingly common sight in New Zealand's skies in the last four years," she said.

"When prototype designs for big sets of satellites like BlueWalker 3 go up, it's really important to see how they affect our sky. Various companies are trying out different ideas, some of which have thousands of units built."

"The interference of satellites in astronomy has become an increasingly pressing issue over the last few years," researcher Sangeetha Nandakumar from the Instituto de Astronomía y Ciencias Planetarias, Universidad de Atacama Chile, said.

The paper also found that an adaptor, which held the satellite to its rocket when launching, was found to exceed the maximum brightness recommendations set out by the International Astronomical Union.

Researchers recommended that as companies launch more and more commercial satellites, pre-launch impact assessments are needed.

In a statement, an AST SpaceMobile spokesperson said 2.6 billion people around the world are offline.

"Our mission is to democratize access to knowledge and information regardless of where people live and work," the statement read.

"While other constellations may require thousands of satellites to achieve their coverage goals... we plan to provide substantial global coverage with around 90 satellites."

However, the company acknowledged that "solving significant problems for humanity often comes with challenges".

The spokesperson said AST SpaceMobile is working to address astronomers' concerns, including by collaborating with NASA.