Satellite constellations: Astronomers warn of threat to view of Universe

[nitpicker]

Satellite constellations: Astronomers warn of threat to view of Universe

By Rebecca Morelle
Science correspondent, BBC News

2 hours ago

Astronomers are warning that their view of the Universe could be under threat.

From next week, a campaign to launch thousands of new satellites will begin in earnest, offering high-speed internet access from space.

But the first fleets of these spacecraft, which have already been sent into orbit by US company SpaceX, are affecting images of the night sky.

They are appearing as bright white streaks, so dazzling that they are competing with the stars.

Scientists are worried that future "mega-constellations" of satellites could obscure images from optical telescopes and interfere with radio astronomy observations.

Dr Dave Clements, an astrophysicist from Imperial College London, told BBC News: "The night sky is a commons - and what we have here is a tragedy of the commons."
(snip)

[Bearware]

1. This is not a tragedy of the commons, it is the tragedy of the ground based Astronomy buggy whip!

Put telescopes in orbit (preferably high or solar orbit) or better yet launch the parts BUILD and MAINTAIN them in orbit.

A few large telescopes (9 meters if launched from earth or far larger if built-in orbit) could collect far more and higher quality data in a few years than all the existing optical telescopes on earth put together.

I suppose Space is a commons but it is pretty large.

[Igel]

2. There are some good reasons for ground-based technology.

Ease of access for repair and upgrading, for example, as well as size.

You put a 30-meter reflector in space.

[Bearware]

3. I would say there were good reasons for ground-based technology that are now obsolete

Orbital telescopes have been incredibly expensive because of launch costs and the huge expense of making a onetime folding spacecraft to fit in a cramped area that must work nearly perfectly when deployed in orbit.

Because of SpaceX, launch costs are cratering and with SpaceX's Starship being available in a few years, there will be a payload bay 9 meters in diameter and 8 stories high with a lift capacity around 100 tons. If it were braced properly one could put an optical mirror approaching 9 meters onboard in fully assembled telescope with limited amounts of folding for solar panels etc.

However, it makes far more sense to just launch components with robots to assemble them in orbit. There is no need to make a mirror more massive just to be able to survive launch. There is no need to make them fit in a single rocket. It is time to send the components for building very large to huge mirrors (maybe hundreds of meters in diameter) from scratch. What could be a better place to make a mirror than in micro-gravity in the vacuum of space. Making a lightweight near optically perfect mirror using liquid mercury in a round container that is accelerated perpendicular to the surface and also spun in a circle.

After the first time, the process could be repeated to create multiple copies very cheaply. Image what could be done with two 100+ meter optical telescopes on opposite sides of the earth's orbit. If they are built using robotics they can be maintained and upgraded as needed. When a significant astronomical event happens, in most cases, all you have to do is turn two or more telescopes to point at the event. No waiting for night time, temperatures to settle, clouds to move and avoiding interference from aircraft, satellites etc.