Star Timelapse and long exposure night photographers get annoyed by all the current debris, they need to clean up their photos from the light streaks. On the other hand, I remember reading about this town in the mountains that wanted to build a giant mirror on top of a mountain, so that they could prolong daylight in their valley.
Decluttering low-Earth orbit: It's time to tidy up space
111–120 of 136 posts
Re: Decluttering low-Earth orbit: It's time to tidy up space
#112Elon Musk's SpaceX Starlink: thousands of satellites that can be re-positioned en masse in time of need and meanwhile reserve a spot in the LEO surface. Useful in both communication and in denying the space to other classes of satellites.
>and in denying the space to other classes of satellites. Is this actually an issue? The earth has a surface area of 500M km^2 so if want 0.5km between each satellite you can fit 500M satellites at one orbit level. A few thousand spacex satellites is a drop in the bucket.
There are already near-misses happening from time to time.
https://medium.com/@leolabs_space/the-iras-ggse-4-close-appr...
https://spacenews.com/esa-spacecraft-dodges-potential-collis...
Add in thousands of new satellites from various race-to-the-bottom move-fast-and-break-things companies and Kessler syndrome seems less hypothetical and more inevitable.
"a bug in our on-call paging system prevented the Starlink operator from seeing the follow on correspondence on this probability increase"
Imagine if the other satellite operator had been similarly negligent, or if the satellite had been defunct. It will be somewhat ironic if a Musk-led operation grounds humanity on Earth for a decade or more.
Re: Decluttering low-Earth orbit: It's time to tidy up space
#113Earlier quoted context omitted.
I think the concern is that despite increased activity in space, most countries have slowed down the amount of dangerous debris being created. Meanwhile, India created about as much space junk in a day as the US creates in 1-2 years. That's despite claiming that the the test was in an orbit that wouldn't leave any longterm debris.
Easy to criticize other countries when you've already had your space race. I do find it annoying that space is usually jingoistic bullshit involving flags and rousing speeches instead of actual science. I'm glad ESA never went that way.
Absolutely. It's the same in case of climate change, easy to criticize other countries about their emissions when you've already had your industrial revolution. I mean, just look at this graph:
https://www.gapminder.org/tools/#$state$entities$show$countr...
I also agree with your point that sometimes space achievements are used for jingoistic purposes. But if you see the bigger picture (which most people don't sadly) you realize that it is a net positive overall for science and humanity. The jingoistic aspect is just a consequence of political reality.
Re: Decluttering low-Earth orbit: It's time to tidy up space
#114When I worked in insurance I'd often discuss satellite debris with our Head of Space. I'd always be told, this isn't something to worry about, since she makes bets on this stuff for a living (admittedly with other peoples money) I'll assume she's right.
Re: Decluttering low-Earth orbit: It's time to tidy up space
#115Earlier quoted context omitted.
I think the concern is that despite increased activity in space, most countries have slowed down the amount of dangerous debris being created. Meanwhile, India created about as much space junk in a day as the US creates in 1-2 years. That's despite claiming that the the test was in an orbit that wouldn't leave any longterm debris.
I think you should focus on the huge amount of garbage and carbon emissions produced everyday in the USA (biggest contributor to climate change), which is objectively a much bigger problem than this one-off event which media portrayed as some sort of catastrophe. It's "glass houses" all over again. Why should a nation of 350M people have ASAT capability in the interest of national security, but not a nation of 1.4B p…
Satellites help us fight climate change
Re: Decluttering low-Earth orbit: It's time to tidy up space
#116Earlier quoted context omitted.
And here it is! http://stuffin.space/?intldes=1970-008B
Wow, that’s a cool site! I’ve never seen orbiting satellites visualized like that. (But of course, also haven’t sought any out.)
Yes, this is really interesting. There are all sorts of interesting things up there. This one is particularly ironic:
http://stuffin.space/?intldes=1998-067NT
I'd never heard of the West Ford Needles:
https://space.skyrocket.de/doc_sdat/westford.htm
I wonder how the Lemur 2 satellites are named:
Re: Decluttering low-Earth orbit: It's time to tidy up space
#117Fun fact: A hobby satellite my father helped build as a way to justify procrastinating during university in the late 60s is now low Earth orbit space junk. He says he's rather embarrassed to have learned, post launch, that it would likely remain in orbit for 100,000 years. https://en.wikipedia.org/wiki/Australis-OSCAR_5 http://centralblue.williamsfoundation.org.au/oscar-5-the-fir... https://www.youtube.com/watch?v=hj…
> "Passive magnetic attitude stabilization was performed by carrying two bar magnets to align with the Earth's magnetic field in order to provide a favorable antenna footprint." Wow! I heard of this technique recently but I didn't realize it had already been deployed so long ago.
Dad is credited with developing that part of it!
Re: Decluttering low-Earth orbit: It's time to tidy up space
#118When I worked in insurance I'd often discuss satellite debris with our Head of Space. I'd always be told, this isn't something to worry about, since she makes bets on this stuff for a living (admittedly with other peoples money) I'll assume she's right.
Genuinely curious: the insurance industry worries about space?
Re: Decluttering low-Earth orbit: It's time to tidy up space
#119Earlier quoted context omitted.
Remember that, assuming circular orbits (which is fine for this discussion, I think), you have to fit satellites on great circle paths next to each other. For a single great circle you can fit a significant number of satellites in a chain, but turns out you don't want too many like that as all your satellites cover the same part of the earth. All great circles on a sphere will intersect in two places, which assures a…
But you imply those mitigations must be made to correct the "natural," initial orbital state, when in reality, the orbits were never truly circular or co-spherical. It's not useful to make a simplifying assumption, if the solution to the problem is to reverse the resulting simplifications.
After I finished the comment I almost went back to modify that intro, but figured the gist of it would be ok.
What I was trying to do was show how we move from the mental model of dots on a balloon (there is so much space on the balloon! the dots are tiny!) to rings around a ball. In order to make sure the dots don't intersect with each other simply spread them out appropriately. In order to make sure the rings don't intersect each other make some of them slightly bigger, or stretch them a bit.
The resulting orbits are still, approximately, great circles on the same sphere - just perturbed a bit.
Re: Decluttering low-Earth orbit: It's time to tidy up space
#120Earlier quoted context omitted.
A sun-synchronous orbit is a polar orbit where the satellite passes over each part of the earth at the same time every day. That is very useful if you want to photograph things at regular intervals using cameras (stable light, no nighttime) or if your satellite uses solar panels as these orbits can be such that the satellite never falls into the earth's shadow.
They still go in to shadow once per orbit typically.
A dawn-to-dusk sun-synchronous orbit completes most of its orbits in full view of the sun:
> This means that, for most of the year, PROBA2 will have a full-time view of the sun, and will not experience eclipses of the sun behind the earth. However, because the orbit does not follow the terminator exactly, PROBA2 will experience brief periods of several weeks when eclipses of the sun by the earth do occur, specifically around December each year. During approximately 80 days (from November until January), visible eclipses occur every orbit with a duration ranging from a few minutes in November up to a maximum of 18 minutes and back to 0.