Low orbit satellites could disrupt astronomers studying the stars

By Pol Allingham via SWNS

Massive low-orbit communication satellites could disrupt astronomers studying the stars, scientists claim.

Astronomers fear the new tech could thwart our progress in understanding space.

An international team of observers has found the BlueWalker 3 satellite is one of the brightest objects in the night sky – outshining all but the most prominent stars.

Astronomers are concerned that, left unchecked, groups of large satellites could disrupt our ability to watch stars from Earth.

Radio astronomy, which studies the radio waves emitted by objects in space, could also be affected.

Companies are planning ‘constellations’ of satellites, which could be hundreds of objects orbing earth to deliver mobile and broadband services anywhere in the world.

However, these often-large satellites must be in ‘low-Earth’ orbit, relatively close to the earth – this could further disrupt night-sky observations.

Astronomers from the IAU Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (CPS), including Imperial College London researchers, have studied the impact of BlueWalker 3.

Dr. Dave Clements, from the Department of Physics at Imperial, said: “The night sky is a unique laboratory that allows scientists to conduct experiments that cannot be done in terrestrial laboratories.

“Astronomical observations have provided insights into fundamental physics and other research at the boundaries of our knowledge and changed humanity’s view of our place in the cosmos.

“The pristine night sky is also an important part of humanity’s shared cultural heritage and should be protected for society at large and for future generations.”

BlueWalker 3 is a prototype of a constellation of over one hundred similar satellites, built to boost our phone signals.

It was launched into low-Earth orbit on September 10 2022 by AST SpaceMobile.

Within weeks, observations revealed the satellite to be one of the brightest objects in the sky.

CPS corralled professional and amateur astronomers to watch the satellite from Chile, the US, Mexico, Aotearoa New Zealand, the Netherlands, and Morocco.

The data documented just how bright BlueWalker 3 was over 130 days.

They discovered its brightness sharply increased when they unfolded the array of antennae – at 64 square meters, it is the largest commercial antenna system ever dispatched to low-Earth orbit.

The satellite’s trajectory over time was also calculated, comparing its predicted path with reality.

Doing so allowed the authors to evaluate how accurate the predictions are and how factors such as atmospheric drag can change it.

Documenting satellites’ locations is key for astronomers to avoid them or know where they will be.

However, avoiding the brightest is challenging – astronomers mainly have to mask the satellite’s position and sacrifice the data for that portion of the sky.

Radio astronomy could also be affected because BlueWalker 3 uses wavelengths close to those that radio telescopes use.

Some telescopes work within designated radio quiet zones. However, restrictions only apply to terrestrial transmitters leaving the satellites free to transmit.

Dr. Mike Peel, co-lead of IAU CPS's Sathub and researcher in the Department of Physics at Imperial, said: "BlueWalker 3 actively transmits at radio frequencies that are close to bands reserved for radio astronomy, and existing observatory protections from radio interference may not be sufficient.

“Further research is therefore required to develop strategies for protecting existing and upcoming telescopes from the numerous satellites planned for launch over the next decade.”

Though the team, writing in the journal Nature, noted the satellite constellations are important for improving worldwide constellations, they feel they could severely trouble progress in understanding space.

Deploying the satellites should take into account the side effect of the operation, and minimize the impact on astronomy, the scientists said.