But like any wilderness, the night sky can be polluted. Since Sputnik 1 in 1957, thousands of satellites and pieces of space junk have been launched into orbit.

For now, satellites crossing the night sky are largely a curiosity. But with the advent of satellite constellations – containing hundreds or thousands of satellites – this could change.

The recent launch of BlueWalker 3, a prototype for a satellite constellation, raises the prospect of bright satellites contaminating our night skies. At 64 square metres, it’s the largest commercial communications satellite in low Earth orbit – and very bright.

Pollution of the night sky

While spotting satellites in the night sky has been a curiosity, the accelerating number of satellites in orbit means pollution of the night sky could become a serious problem.

On a clear night, particularly near twilight, you can see satellites travelling across the night sky. These satellites are in low Earth orbit, just a few hundred kilometres above Earth and travelling almost 8 kilometres every second.

Apps and websites allow you to identify or predict the arrival of particular satellites overhead. And it is genuinely fun to see the International Space Station travelling by, realising that on that speck of light there’s a crew of astronauts.

But in the past few years, the pace of satellite launches has accelerated. SpaceX has made satellite launches cheaper, and it has been launching thousands of Starlink satellites that provide internet services.

Roughly 50 Starlink satellites are launched into orbit by each Falcon 9 rocket, and initially produce a bright train of satellites. These initially produced UFO reports, but are now sufficiently common to not be particularly newsworthy.

Once the Starlink satellites disperse and move to their operational orbits, they are near the limit of what can be seen with the unaided eye.

However, such satellites are bright enough to produce trails in images taken with telescopes. These trails overwrite the stars and galaxies underneath them, which can only be remedied by taking additional images. Short transient phenomena, such as a brief flash from a gamma ray burst, could potentially be lost.

BlueWalker 3

While Starlink is the largest satellite constellation in service, with thousands of satellites in orbit, others are planned.

Amazon’s Blue Origin plans to launch more than 3,200 Project Kuiper satellites, and AST SpaceMobile plans to launch 100 BlueBird satellites (and perhaps more).

The recently launched BlueBird prototype, BlueWalker 3, has produced genuine alarm among astronomers.

While BlueWalker 3 was initially quite faint, it unfolded a 64 square metre communications array – roughly the size of a squash court. This vast surface is very good at reflecting sunlight, and BlueWalker 3 is now as bright as some of the brightest stars in the night sky.

It’s possible the operational BlueBird satellites could be even bigger and brighter.

Large numbers of satellites this bright could be bad – very bad. If there were thousands of satellites this bright, sometimes you would be unable to look at the night sky without seeing bright satellites.

We would lose that sense of wilderness, with an almost constant reminder of technology in our sky.

There could be a big impact on professional astronomy. Brighter satellites do more damage to astronomical images than faint satellites.

Furthermore, many of these satellites broadcast at radio frequencies that could interfere with radio astronomy, transmitting radio waves above remote sites where radio observatories observe the heavens.

A precipice?

What happens next is uncertain. The International Astronomical Union has communicated its alarm about satellite constellations, and BlueWalker 3 in particular.

However, the approval of satellite constellations by the US Federal Communications Commission has had relatively little consideration of environmental impacts.

This has recently been flagged as a major problem by the US Government Accountability Office, but whether this leads to concrete change is unclear.

We may be on the edge of a precipice. Will the night sky be cluttered with bright artificial satellites for the sake of internet or 5G? Or will we pull back and preserve the night sky as a globally shared wilderness?

• Michael J. I. Brown is an Associate Professor in Astronomy, Monash University
• This article first appeared on The Conversation

The post BlueWalker 3, an enormous and bright communications satellite, is genuinely alarming astronomers appeared first on Stuff South Africa.

AST SpaceMobile’s Bluewalker 3, launched on 10 September 2022, is built to connect directly to cell phones down here on earth. Its brightness has offended a group of international scientists who say it is a threat to their work and to humanity’s view of the universe.

It has a 64-square-meter array of solar panels and antennas. Observations of the bright object by members of the International Astronomical Union (IAU) around the world note how the satellite is as bright as some of the brightest stars in the universe. The union says it is almost as bright as the 15th and 16th brightest stars in the world – the Antares and Spica stars respectively. However, the observations by other studies note that it may be as bright as the 22nd brightest star.

Shine bright like a… satellite?

History is unfolding! We've deployed #BlueWalker3's 693-square-foot array, which is now the largest-ever commercial communications array in low Earth orbit.

Read more about this important milestone here: https://t.co/4kupfxn3vO pic.twitter.com/KnE9CeWOCT

— AST SpaceMobile (@AST_SpaceMobile) November 14, 2022

Read More: Starlink, Amazon and others are racing to fill the sky with bigger satellites to deliver mobile coverage everywhere on Earth

Bluewalker 3 is a test model from a company that plans to offer 5G connectivity here on earth from space. It is part of over 100 “bluebirds” that the company plans to use for 5G and is designed to eliminate mobile network dead zones. Not unlike Musk’s Starlink satellites.

Earlier this month, AST SpaceMobile CEO Abel Avellan said the company aims to improve access to cellular broadband.

“Every person should have the right to access cellular broadband, regardless of where they live or work. Our goal is to close the connectivity gaps that negatively impact billions of lives around the world,” says Avellan.

Read More: Landsat turns 50: How satellites revolutionized the way we see – and protect – the natural world

Astronomers are also concerned about the potential strong transmission of radio waves by mega-constellations.

Here in SA, the director of the Square Kilometer Array, Philip Diamond, says orbiting cell towers are not subjected to the same quiet-zone restrictions meant to safeguard radio astronomers from terrestrial cellular network interference.

“New satellites such as BlueWalker 3 have the potential to worsen this situation and compromise our ability to do science if not properly mitigated,” says Diamond in an article by CNET.

The IAU says it is working with industry experts to address issues on innovation and anti-reflective material.

Source: AST, CNET

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