On Monday, January 6th, 2020, another SpaceX Falcon 9 blasted off from Cape Canaveral,
carrying another 60 Starlink internet communications satellites, bringing the full size of the
constellation to 180.
With just three launches, SpaceX becomes the largest satellite operator in the world.
But the company is just getting started.
They’re planning to do this again every couple of weeks during 2020, bringing the
total number of satellites in the constellation to about 1440, which is enough to provide
high-speed internet services to the United States and parts of Canada.
Shortly after launch, as the satellites are raising their altitude, they’re clearly
visible to the eye as they streak across the sky in a close train.
Astronomers aren’t happy.
One of the big topics at this year’s meeting of the American Astronomical Society in Honolulu,
Hawaii was the impact of Starlink and the other upcoming internet constellations on
astronomy.
Astronomers already have to deal with satellites photobombing their photographs of space, but
they were surprised at just how bright the Starlinks were.
There are about 18,000 satellites and pieces of space junk flying overhead which are being
constantly monitored and reflect a significant amount of sunlight.
Right now there are only about 200 satellites and pieces of space debris visible with the
unaided eye.
During an average night, 600-700 satellites pass overhead any spot on Earth from astronomical
sunset to astronomical sunrise, when telescopes are doing their science.
During the winter, when the nights are long, the satellites are only visible shortly after
sunset, and right before sunrise at low angles which aren’t great for observing.
But during the summer, with its shorter nights and higher angle of sunlight, some observatories
can see satellites pass through their field of view all night long.
We get this here in Canada during the summer when the International Space Station will
pass right overhead, and then 90 minutes later, do it again.
It’s exciting the first few times, and then it becomes a pain to remove from your astrophotos.
The Starlink satellites fly at 550 kilometers, low enough that they limit their visibility
to the beginning and end of the night for most of the year.
According to astronomers at the AAS meeting, they’re brighter than 99% of the objects
in orbit, reaching 5th magnitude - or just visible with the unaided eye - without any
kind of brightness mitigation.
More worrying, though, could be future satellite constellations.
Starlink has 180 satellites today, but they’ve applied for permission to fly as many as 42,000
satellites, starting with 12,000 over the next 8 years or so, which means they’ll
have 5 times the number of satellites launched by the rest of humanity combined.
Another satellite company, OneWeb, has already launched a handful of their internet satellites
as well, and these fly at an altitude of 1,200 kilometers.
This means that they’re fully visible for their entire flight overhead, although they’re
less bright, seen at only 8th magnitude.
That’s still bright enough to leave a bright streak through powerful observatories.
Amazon has filed for its own satellite internet service, proposing over 3,000 which will fly
at 590, 610 and 630 kilometers.
Higher than Starlink and so visible for longer.
Perhaps the greatest worry is the new all-sky survey telescopes like the Vera Rubin Observatory
(previously known as the Large Synoptic Survey Telescope).
This instrument continuously scans the skies, night after night, helping astronomers find
asteroids, comets, new supernovae, and really anything that changes from night to night.
The Vera Rubin Observatory has such a wide field of view and takes so many images that
there will be multiple Starlink passes in every photograph.
According to one astronomer, the satellites could provide a similar profile to galaxies
in brightness.
So, be prepared for galaxies appearing and disappearing in your data.
Even more worrisome could be their impact on radio telescopes, which have already gotten
overwhelmed by broadcast satellites.
Catching a powerful transmission from a satellite can completely burn out a radio telescope
receiver.
What can astronomers do to deal with this?
And what are satellite companies doing to minimize their impact on astronomy?
I’ll talk about that in a second, but first I’d like to thank:
Vasil PostFapShame
Sergusy Christian Behrendt
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Patricia Cooper, SpaceX’s vice president of satellite government affairs was at the
AAS meeting and presented SpaceX’s perspective on the situation.
She outlined the company’s short-term plans to build the constellation, but also how they’re
going to mitigate the impact of the satellites on science and astronomy.
Like astronomers, SpaceX was surprised at how bright the satellites are seen from Earth.
When they first launch, the satellites are easy to see with the unaided eye.
According to Cooper, this is because the satellites open their solar panel in a configuration
that reduces drag.
Once they reach their operational altitude, they change their angle, making them invisible
without a telescope or binoculars.
In order to decrease the brightness, they tried a few methods of darkening one satellite
in the most recent launch of 60.
It’s too early to know if their techniques were successful, though, we’ll have to wait
until February for the satellites to reach their final altitude and proper tests can
be done.
This is going to be an ongoing process, with astronomers giving feedback to Starlink with
each test.
Until they can settle on the most effective method, the majority of Starlinks will be
flying without any darkening strategy.
And they’ll stay in space for about 5 years until they de-orbit.
The downside of painting the satellites black is that it changes their profile in the infrared
spectrum.
What makes them less visible in some telescopes could make them much brighter in infrared
observatories.
It’ll probably end up being a compromise.
SpaceX is also providing real-time tracking information for all the satellites to other
companies and telescope operators.
This will help reduce the chances of an impact, as well as give astronomers warning when a
Starlink could pass through the field of view and saturate their detectors.
Telescopes could be programmed to automatically avoid observing regions of the sky where Starlinks
are expected to pass through.
Finally, SpaceX will be releasing launch trajectory information for new batches of satellites,
to help astronomers observe around the times when the bright launch train might be flying
through their field of view.
Although astronomers were very frustrated with Starlink and the age of global satellite
constellations, they were pleased that SpaceX is actually working with them to mitigate
the impact.
Because regulators have already approved the satellite launches, astronomers can’t rely
on new laws, they’ve got to work with SpaceX to lower the brightness of Starlink.
Astronomers have already had 6 meetings with SpaceX to figure out a strategy, and they’ve
described the company as open and responsive to their suggestions to mitigate brightness.
Many people have suggested in the past, and I’m sure I’ll get it in the comments here
too, why don’t astronomers just switch to space telescopes instead?
The reality is that ground-based astronomy is still a bedrock of the science, even with
lowering rocket costs.
A modern ground-based observatory with adaptive optics can reduce the impact of the Earth’s
atmosphere as if the telescope was in space.
Ground-based observatories can be easily built, upgraded and adapted with new science instruments.
Astronomy from the surface of the Earth is going to be vital for decades.
But with all this impact on astronomy, the reality is that humanity is going to want
to connect to the internet.
You’re here, watching this video right now.
And that’s because you’re wealthy enough, or in a densely populated enough area that
it’s feasible for an internet service provider to connect you to the internet.
You’re free to comment, communicate, and watch videos.
You can do your banking, shopping, educate yourself and search for jobs.
There are 5 million cell phone towers worldwide, and it’ll take many many more to go the
final mile and connect the rest.
Think of how much of an eyesore these towers already are.
Think about thousands of kilometers of ditches dug for fiber optics, or underwater cables
running through sensitive marine environments.
Think about the impact on radio telescopes when there are powerful 5G antennae blanketing
every corner of the Earth.
Satellite internet is probably the only way to bring the rest of humanity online without
a significant impact on the environment.
It’s too bad that more time wasn’t taken to reduce the impact on science and astronomy,
but this revolution in communication is inevitable.
The only way to know if it was worth it will depend on whether or not it was a benefit
to society.
Did it allow billions of people to join the global online community at an affordable price,
or did it only allow stockbrokers a way to shave a few nanoseconds off their trades?
We’re just going to have to wait and find out.
What do you think?
Let me know your thoughts in the comments.
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We did a whole video on Starlink, talking about how they work, what the plans are to
build and operate the constellation, and you can watch that here next.