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Hi Grant, yes there’s an awful lot of ‘junk’ up there, thankfully it doesn’t seem to cause much of a problem, but add another 50,000 satellites and who knows. They are relatively small though, so the impact may be minimal especially if 1130 is a success and the albedo of future satellites is reduced. It will be interesting to see what the results of the trial are.
Wouldn’t mind some time on the INT myself never mind anything larger, alas the impact of work and time precludes any such venture for the time being, so I’m stuck in the ‘back yard’ for now or at least when sky and time permits.
A fellow member of the IAA drew my attention to this:
https://astronomersappeal.wordpress.com
I haven’t looked through all the sources and links mentioned yet though.
I also see that the IDA have an article published in December on the subject of mega constellations as well
https://www.darksky.org/why-do-mega-constellations-matter-to-the-dark-sky-community/
Although I am still attempting to stay neutral and open minded, I am gradually growing more concerned.
I read the post wrong first time round, I was eating my dinner at the time! lol I went back later re-read and did my maths correctly this time ( I think) 🙂
djswan2002, I too would welcome an in-depth study into the impact of Starlink et al as it’s something that I certainly find concerning.
I’ve done a little digging around the internet and what I’ve found doesn’t look too good, I’ve tried to summarise my thoughts here as best as possible. This is by no means a study into Starlink, at best it’s a few random scribbles on the back of an envelope by someone who considers himself as a mere star gazer and no mathematician and certainly not an astronomer, but it’s food for thought, even if it may not stand up to scrutiny.
The number of proposed satellites
Starlink 42,000 (12,000 approved, paperwork submitted to International Telecommunication Union for 30,000 more)
Amazon 3,000
OneWeb 650 (possibly increasing to 2000)
TelSat LEO 300
Hongyun 320 (altitude 1,100km)
Total 46,270 New Satellites
Others who have proposed constellations but so far have no planed launches
Boeing 1,400
Samsung 4,600
The total number of new satellites then stands at a whopping 46,270 up to a possible 53,620 in the next decade. That is in addition to nearly 2,000 current operational satellites and 20,000 bits of space debris of which around 1500 are 100kg or above.
So what impact is this likely to have?
** Note Xilman pointed out a pretty dumb mistake I made when doing the following calculations, he quite correctly pointed out that I should have used steradians to work out the total number of square degrees, doing so gives a total of 41,253 not the erroneous figure of 129600 (now removed) that I initially came up with. The corrected maths follows **
So, to calculate the total square degrees that would be 360 / (2 x pi) = 57.3 (there abouts) and then (4 x pi) x 57.3^ = 41253 square degrees. (always the same value for any size of sphere).
That would then give us a concentration of 46,270 satellites divided across 41,270 square degrees
46,270 / 41,253 = 1.12 satellites per one square degree
So, if the moon covers an area of 0.2 square degrees (if memory serves me correctly) that equates roughly to one satellite for each area of the sky equal to five times the area of the moon based on the lower number of satellites or 1.38 satellites in the same area if using the higher number of 57,120. That seems quite a lot to me!
Starlink / Space x have said they will look at measures to reduce the albedo of their satellites, this may help, however some are suggesting that the solar panel cannot be altered and it’s the most reflective part. Additionally a few have mentioned on various forums that the combined effect of so many objects in or close to near earth orbits is going to cause a not insignificant occultation issue for DSO observations in particular asteroid hunting using the blink comparison technique.
I’ve only really concentrated on the increase in numbers of objects in NEO , there is of course other issues like the amount of RF these satellites will emit and the impact of the satellite to satellite links, which I recall reading somewhere were going to be done optically (is that some sort of laser or IR link perhaps), nor have I went into detail on the size of the satellites, indeed, information on the physical size of the satellites seems very sparse, an estimate made by one person on reddit puts the size at around 1.1m x 2.4m for the satellite body not including the solar panel. Cees Bassa from the Netherlands Institute for Radio Astronomy, calculated that up to 140 of the starlink mega constellation satellites could be visible at any one time if all the planned satellites launch (Forbes.com article).
Another article from Space.com highlights the brightness of these new satellites –
[Patrick Seitzer, an astronomy professor emeritus at the University of Michigan, said Wednesday (Jan. 8) during a special news conference at the 235th meeting of the American Astronomical Society (AAS) called “Astronomy Confronts Satellite Constellations.”
“We knew these tens of thousands[-strong] megaconstellations were coming, but based on the sizes and shapes of things currently in orbit, I thought maybe 8th or 9 magnitude,” Seitzer added. “We were not expecting 2nd or 3rd magnitude in the parking orbits, and we were certainly not expecting 4th to 5th magnitudes in the [operational] orbits.”]
In conclusion, will this amount to a change in astronomy as we know it? – Personally I’d say yes, but I’m not 100% sure, it may even render backyard astrophotography almost impossible, however there are many that say otherwise and even those who say it will have an impact on astronomy seem to be taking a wait and see approach. Again, speaking personally, I find the ‘wait and see’ approach as frankly bazar. Are we going to be in a position ten or twelve years from now when the astronomical community look up and say, ‘we can now say for certain this is having a big impact on us, would you mind taking your $30 billion per year earning satellites down please so we can do astronomy again?’ I can imagine the answer to that question would be short and to the point.
Smoking probably isn’t bad for you….
Nah, CFC’s couldn’t be damaging the ozone layer….
Dumping millions of tons of plastic every year is fine, it’s not an issue….
Putting tens of thousands of satellites in orbit around our planet is not going to be a problem………
Err, Houston…. We may have a problem!
Thanks Paul,
I see the error of my ways! Yes I should have used steradians.
Also, I want to point out that although it may seem I’m biased aginst Starlink et al, I’m not. With thirity plus years in the broadcast engineering and audio visual events sectors I’ve used more than my fair share of satellite links and I’ve no doubt (love them or loathe them) I’ll probably end up using one or more of the new systems. My concern is that there seems to be a lack of real hard (non biased, non emotional) facts out there on which any of us can make a real judgement. On one side there are those going…. ‘Nope, nothing to see here, won’t impact us at all…’ and then on the other side…. ‘It’s the end of civilisation as we know it, we’ll never see the stars again!’ Now I suspect that the big observatories will come up with a software fix in their image processing and likewise those who use stacking will delete all the frames that have been impacted before processing, so there’s work-arounds for both. But what about the guy in between (like me) who’s a bit old school and just likes to look up at the stars, take some long(ish) exposures from time to time, maybe use some blink comparison looking for DSO’s and have no desire to spend lots of time processing images. It’s a big enough struggle to get time for the hobby as it is, so to have exposures ‘photobombed’ by satellites continuously would be soul destroying.
Anyway, here’s the revised maths.
So, that would be 360 / (2 x pi) = 57.3 (there abouts) and then (4 x pi) x 57.3^ = 41253 square degrees as you quite rightly point out.
That would then give us a concentration of 46,270 satellites divided across 41,270 square degrees
46,270 / 41,253 = 1.12 satellites per one square degree
So, if the moon covers an area of 0.2 square degrees (if memory serves me correctly) that equates roughly to one satellite for each area of the sky equal to five times the area of the moon based on the lower number of satellites or 1.38 satellites in the same area if using the higher number of 57,120.
Is my maths correct?? That seems like an awfully high figure to me.
I will and do freely admit to being purely a stargazer at best so at best my calculations are nothing more than a laymans scribbles on the back of an envelope at best. I do fear though that the whole [subject, debate, discussion or whatever the current comments around the globe may be regarded as] is simply becoming lots and lots of peoples opinions and hard scientific data is proving very difficult to come by. In the meantime Starlink et al will continue to launch more and more satellites into orbit without anyone being able to conclusively prove if they will or will not be a problem. So, like David Swan (op) I’m curious to see if there is a study anywhere and if not it would be great to see someone pick it up as a project and run a proper in-depth impact study.
Thanks again to Xilman for pointing out the flaw in my initial calculations.
It’s all way above my head….. in more ways than one. 🙂
Àn interesting article on the BBC Website from December
