Decluttering low-Earth orbit: It's time to tidy up space(economist.com)
economist.com
Decluttering low-Earth orbit: It's time to tidy up space
https://www.economist.com/leaders/2021/01/14/its-time-to-tidy-up-space
135 comments
And here it is!
http://stuffin.space/?intldes=1970-008B
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:
http://stuffin.space/?intldes=2018-111N&search=lemur%202
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:
http://stuffin.space/?intldes=2018-111N&search=lemur%202
wow, there seem to be a lot more blue dots around - these are all junk; the red one are fewers - these are active sats. Also if there is a longer sequence of red dots on the same orbit then these are all spacelink satelites. Amazing site, thanks!
what kind of black magic is that ?
There should be also stuffin.ocean and stuffin.atmosphere
CO2 / plastic.
When the society is mature enough to clean the mess created ?
P.S. Sorry for offtopic rant
CO2 / plastic.
When the society is mature enough to clean the mess created ?
P.S. Sorry for offtopic rant
Your father's satellite is very high (1400km, 1000km above the ISS) at the edge of what is classified as low earth orbit. It will be up there for a long while but the chance of it ever hitting anything is infinitesimal.
That makes the very big assumption that the density of other things to hit doesn’t massively increase.
That makes a big assumption we can't remove the junk before the density is high enough
It is worthy of note that SpaceX is pitching Starship for active debris removal in space.
It is worthy of note from https://spacenews.com/upper-stages-top-list-of-most-dangerou... that in a list of the 50 most concerning objects in orbit, 78% are rocket bodies, and 80% were launched before 2000 when various mitigation strategies for space junk began to be improved.
There is therefore a Pareto principle at work here. We are tracking over 25,000 objects, but only a few of them contribute most of the risk, and we aren't adding as much to the risk as the number of launches would make you think.
It is worthy of note from https://spacenews.com/upper-stages-top-list-of-most-dangerou... that in a list of the 50 most concerning objects in orbit, 78% are rocket bodies, and 80% were launched before 2000 when various mitigation strategies for space junk began to be improved.
There is therefore a Pareto principle at work here. We are tracking over 25,000 objects, but only a few of them contribute most of the risk, and we aren't adding as much to the risk as the number of launches would make you think.
Infinitesimal over 100,000 years? I'm not losing any sleep over it personally, but that's a long time.
The surface area of the sphere at 1400km is far greater than the earth's surface area. And satellites at that altitude are traveling much slower. Put together, the probabilities would akin to a handful of birds flying on earth, at random altitudes/places/directions, and two of them colliding.
> The surface area of the sphere at 1400km is far greater than the earth's surface area
It's only about 50% larger (1+1400/6371)^2 = 1.49
It's only about 50% larger (1+1400/6371)^2 = 1.49
This! How likely would collisions be on a sphere the size of the earth? How do the probabilities change from low earth orbit to higher orbits?
"much slower" is still >7000 m/s
Yes but at that altitude their orbital period is about 1/2 that of low orbits, meaning that even if two orbits do cross paths, there would be fewer potential collisions in a given time. They are 'slower' in relation to size of the sphere they occupy.
90 mins at 400km vs 110 mins at 1400km
I guess that makes sense since the Earth’s radius is around 6400km so from 400 to 1400km is really a change from 6800 to 7800km which is proportionally similar to a change from 90 to 110 minutes.
Edit: I just looked up the formula for orbital period and it turns out period is proportional to radius^(3/2) (See: https://en.m.wikipedia.org/wiki/Orbital_period)
Edit: I just looked up the formula for orbital period and it turns out period is proportional to radius^(3/2) (See: https://en.m.wikipedia.org/wiki/Orbital_period)
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Yeah, that statement makes a lot of assumptions about the next 99,950 years.
That's true, but the chances of quite a lot of things happening over 100,000 years are fairly big.
Almost everything we do carries a small but non-zero risk of something which, if you stretched it over a hundred thousand years, would almost certainly be realized.
On the other hand, the average damage from a collision in space within 100,000 years is also pretty small.
Almost everything we do carries a small but non-zero risk of something which, if you stretched it over a hundred thousand years, would almost certainly be realized.
On the other hand, the average damage from a collision in space within 100,000 years is also pretty small.
I wonder how the odds stack up against the odds of a human being hit by a meteorite? Those kind of odd's/statistics I can get my head around.
Suppose there are just two satellites orbiting at the same altitude, a bit higher, let's say 5 orbits a day (ISS orbits 18 times a day, roughly). The two satellites cross each other's path twice per orbit. Over the course of a year, that's 3650 potential collisions. Given the length of their orbit might be 50,000 km, then the average distance between these two crossings is 13 km. Over 10 years, that reduces down to 1.3 km. Over 100, 130m. Over 100000, it's 0.130m. They are gonna collide.
Of course, I am assuming a few things, like their orbits don't decay, they aren't exactly synchronized (i.e. they drift, and will eventually cross every point on the other's), but also that the uneven gravity of Earth doesn't corral them into narrower orbital paths (which it absolutely will, increasing the chances of collision).
That's for only two satellites. There are literally thousands. And when they smash apart, they can each generate hundreds more killer-sized fragments.
Kessler syndrome is a very real possibility on a long timescale.
We should be more careful the junk we put in space.
Of course, I am assuming a few things, like their orbits don't decay, they aren't exactly synchronized (i.e. they drift, and will eventually cross every point on the other's), but also that the uneven gravity of Earth doesn't corral them into narrower orbital paths (which it absolutely will, increasing the chances of collision).
That's for only two satellites. There are literally thousands. And when they smash apart, they can each generate hundreds more killer-sized fragments.
Kessler syndrome is a very real possibility on a long timescale.
We should be more careful the junk we put in space.
> Launch date: 23 January 1970
Phew, 23 days earlier your father would have had to code all timestamps in negative.
Joke apart, which OS did such satellites run? Unix? Probably not, since timestamps only started in 1970. Just "C"? Even today, how do you register time on satellites? With Unix timestamps (a long since 1970-01-01)? Can they synchronize based on objective points (stars or Earth position to the sun) or are satellites always resynchronized from Earth signals?
Phew, 23 days earlier your father would have had to code all timestamps in negative.
Joke apart, which OS did such satellites run? Unix? Probably not, since timestamps only started in 1970. Just "C"? Even today, how do you register time on satellites? With Unix timestamps (a long since 1970-01-01)? Can they synchronize based on objective points (stars or Earth position to the sun) or are satellites always resynchronized from Earth signals?
I have to say that the assumption of a hobbyist satellite in 1970 to be able to run UNIX is pretty amusing, considering (Wikipedia):
> In a 1970 survey, The New York Times suggested a consensus definition of a minicomputer as a machine costing less than US$25,000 (equivalent to $165,000 in 2019), with an input-output device such as a teleprinter and at least four thousand words of memory, that is capable of running programs in a higher level language, such as Fortran or BASIC.
I think it’s safe to say that the biggest issue with launching computers running UNIX into space in 1970 probably was not the lack of a standardized time stamp :-)
> In a 1970 survey, The New York Times suggested a consensus definition of a minicomputer as a machine costing less than US$25,000 (equivalent to $165,000 in 2019), with an input-output device such as a teleprinter and at least four thousand words of memory, that is capable of running programs in a higher level language, such as Fortran or BASIC.
I think it’s safe to say that the biggest issue with launching computers running UNIX into space in 1970 probably was not the lack of a standardized time stamp :-)
I have no knowledge of old-style satellites, but have worked on cubesats (low earth orbit) reasonably recently.
Star trackers give you location in orbit and orientation of your satellite. I don't believe you can get absolute time from them, especially given that Earth time is somewhat decoupled from Earth's orbital dynamics.
What you can do is get time using GPS, like you would on the ground. Not sure if that's possible for higher orbits, but definitely for low orbits. There have also been some experiments with laser-based synchronization (a PPS-style signal, I believe?) and you could get a coarse sync with a regular old radio uplink.
Star trackers give you location in orbit and orientation of your satellite. I don't believe you can get absolute time from them, especially given that Earth time is somewhat decoupled from Earth's orbital dynamics.
What you can do is get time using GPS, like you would on the ground. Not sure if that's possible for higher orbits, but definitely for low orbits. There have also been some experiments with laser-based synchronization (a PPS-style signal, I believe?) and you could get a coarse sync with a regular old radio uplink.
Back then most satellites were likely just hardwired electronics, possibly with some limited remote command support. Sure, there were exceptions for high profile missions such as space probes and spy satellites.
IIRC there have been some proposals to use Pulsar signals on satellites/probes not just for time synchronization but more importantly navigation. Not sure if it's actually in production use yet.
IIRC there have been some proposals to use Pulsar signals on satellites/probes not just for time synchronization but more importantly navigation. Not sure if it's actually in production use yet.
> "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.
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!
Small world. I got to know the A05 guys really well when I put together a new team at UniMelb to do the same thing a few years ago. Even got some cringeworthy lines in this documentary with them.
https://vimeo.com/191605076
https://vimeo.com/191605076
We'll figure out how to clean it up when or if it's ever a problem. He shouldn't worry about it.
What people forget is all the natural junk up there. Space is not "clean". Something like 100 tons of rock, mostly dust, falls onto earth from space every day. That isn't stuff in orbit, but given the capture effects of our moon there is likely a significant amount that does achieve some sort of stability. That amount probably outweighs everything we have ever put up there.
https://astronomy.com/magazine/ask-astro/2014/07/space-debri...
The real problem isn't that space is getting full of our junk, but that our junk is in a very narrow band of orbits that we use for very specific missions: Sun synchronous polar orbits used by imaging satellites. Look at how these orbits all cross paths at the poles. That's the danger zone. While the military cares deeply about these orbits, civilian infrastructure in space (geosynchronous communications sats, GPS etc) are well beyond any real danger. Or, at least they are in orbits where danger from natural debris is vastly greater than from space junk.
https://astronomy.com/magazine/ask-astro/2014/07/space-debri...
The real problem isn't that space is getting full of our junk, but that our junk is in a very narrow band of orbits that we use for very specific missions: Sun synchronous polar orbits used by imaging satellites. Look at how these orbits all cross paths at the poles. That's the danger zone. While the military cares deeply about these orbits, civilian infrastructure in space (geosynchronous communications sats, GPS etc) are well beyond any real danger. Or, at least they are in orbits where danger from natural debris is vastly greater than from space junk.
But there's an enormous difference between cosmic dust, which generally doesn't pose any threat to satellites or spacecraft, and the man-made "junk" that are essentially destructive whizzing bullets, cannonballs, and worse. The total mass is essentially irrelevant, what matters is the mass of individual objects.
> Or, at least they are in orbits where danger from natural debris is vastly greater than from space junk.
Are you sure? A quick online search reveals only two satellites appear to have been destroyed -- an Iridium satellite was destroyed in 2009 when it was hit by a junked Russian satellite, while in 1993 the European satellite Olympus was destroyed by a meteor.
So it would seem that so far, natural debris and space junk are tied 1-1. Why do you think natural debris is that much more of a risk?
> Or, at least they are in orbits where danger from natural debris is vastly greater than from space junk.
Are you sure? A quick online search reveals only two satellites appear to have been destroyed -- an Iridium satellite was destroyed in 2009 when it was hit by a junked Russian satellite, while in 1993 the European satellite Olympus was destroyed by a meteor.
So it would seem that so far, natural debris and space junk are tied 1-1. Why do you think natural debris is that much more of a risk?
>> natural debris and space junk are tied 1-1
There are plenty of sats that have just stopped working, even broken apart, for unknown reasons. Telling the difference between a defect and a meteor impact is mostly impossible. Lots of spacecraft have just stopped working for unknown reasons. Until we start inspecting every failed satellite, as we do aircraft, we won't really know.
And note where the 2009 collision happened: over the arctic. This was one polar orbit colliding with a near-polar orbit, right in the danger zone I mentioned above.
There are plenty of sats that have just stopped working, even broken apart, for unknown reasons. Telling the difference between a defect and a meteor impact is mostly impossible. Lots of spacecraft have just stopped working for unknown reasons. Until we start inspecting every failed satellite, as we do aircraft, we won't really know.
And note where the 2009 collision happened: over the arctic. This was one polar orbit colliding with a near-polar orbit, right in the danger zone I mentioned above.
a rock the size of pebble or as small as a grain of sand will cause a very bad day when you realize that some of the objects have incredible amounts of kinetic energy due to the speeds involved (the speed of the rock or the speed of the thing to be damaged).
For many satellites the biggest cross sectional area are solar panels. So the most likely part of a satellite impacts by debris will be there.
In terms of probability with debris impacts on satellites the common effect is a slight drop in power output from the solar panels [0].
Keep in mind stuff in orbit is pummeled by micrometeoroids pretty regularly. These are literally dust size grains of material in orbit. They face pretty constant abrasion yet remain fully functional.
[0] https://www.space.com/20925-space-station-bullet-hole-photo....
In terms of probability with debris impacts on satellites the common effect is a slight drop in power output from the solar panels [0].
Keep in mind stuff in orbit is pummeled by micrometeoroids pretty regularly. These are literally dust size grains of material in orbit. They face pretty constant abrasion yet remain fully functional.
[0] https://www.space.com/20925-space-station-bullet-hole-photo....
But that's the entire point -- fragments of space junk can be the sizes of pebbles you're talking about.
Cosmic dust, on the other hand, is just dust. It can be abrasive but satellites are designed to handle it, as is the ISS. It may have high velocity but the fact that its mass is miniscule means it can be shielded against.
Cosmic dust, on the other hand, is just dust. It can be abrasive but satellites are designed to handle it, as is the ISS. It may have high velocity but the fact that its mass is miniscule means it can be shielded against.
> The real problem isn't that space is getting full of our junk, but that our junk is in a very narrow band of orbits that we use for very specific missions: Sun synchronous polar orbits used by imaging satellites.
What's the significance of these orbits?
What's the significance of these orbits?
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.
[1] https://proba2.sidc.be/about/launch
> 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.
[1] https://proba2.sidc.be/about/launch
Many of the sun synchronous sats are earth imaging sats and are placed to take pictures at the same time of day when there are short shadows.
Thanks for sharing this use use case too though, pretty neat.
Thanks for sharing this use use case too though, pretty neat.
Probably not a HN tier comment, but there's a great anime about space debris cleanup.
https://en.wikipedia.org/wiki/Planetes
https://www.youtube.com/watch?v=CZ-OyT4ivkM
https://en.wikipedia.org/wiki/Planetes
https://www.youtube.com/watch?v=CZ-OyT4ivkM
This anime is brought up in a lot of threads on space debris, and as others attest is excellent. It's a fully fleshed out and plausible future, where people have jobs cleaning up space debris, and it explores many of the issues that may await that kind of work in the future.
Your comment epitomises the golden rule of Hacker News, that you should post "anything that gratifies one's intellectual curiosity".
Your comment epitomises the golden rule of Hacker News, that you should post "anything that gratifies one's intellectual curiosity".
It was extremely good for its time. For instance, the creators asked scientists to estimate the efficiency of solar panels at the time, and computed the area needed for the space stations they drew. Truly incredible that they went to these lengths.
Nonetheless, it is very dated. Fusion power looks a lot worse today than it did back in 2003. The fusion-powered space Jovian exploration ship would be right at home in today's sci-fi (just as much the future today as then), but He-3 as a reason to go into space as been eviscerated. People who still (unrealistically) hope for a fusion game-changer are more often touting proton-Boron, and He-3 doesn't even fundamentally change problems of ignition conditions and radiation, it just mitigates it.
They also didn't do much to predict radical reduction in launch costs. In the PlanetES world, it still felt very expensive to get into space. They didn't go unless they had a corporate sponsor or were filthy rich. I don't even remember anything that hinted at booster re-usability, which is now (astonishingly) reality.
There's also the obvious fact that sending people to do trash pickup was always more Hollywood than reality. They knew that then.
Nonetheless, it is very dated. Fusion power looks a lot worse today than it did back in 2003. The fusion-powered space Jovian exploration ship would be right at home in today's sci-fi (just as much the future today as then), but He-3 as a reason to go into space as been eviscerated. People who still (unrealistically) hope for a fusion game-changer are more often touting proton-Boron, and He-3 doesn't even fundamentally change problems of ignition conditions and radiation, it just mitigates it.
They also didn't do much to predict radical reduction in launch costs. In the PlanetES world, it still felt very expensive to get into space. They didn't go unless they had a corporate sponsor or were filthy rich. I don't even remember anything that hinted at booster re-usability, which is now (astonishingly) reality.
There's also the obvious fact that sending people to do trash pickup was always more Hollywood than reality. They knew that then.
There was massive amount of in space infrastructure and lots of people. Even though they did space mining there is no way they would be able to put all that in place without RLVs. IIRC they even show them a couple times, basically big NASP like SSTO aerospaceplanes.
They also have regular transcontinental flights going through space, even though its IIRC not clear if its sub orbital ballistic trajectories or FOBS like partial orbit ones.
Still, many would-be hard SF films get this completely wrong - huge space stations and/or interplanetary spaceships yet they launch it all on rather dated looking expandable boosters!
Already The Martian it's pushing is pushing it with using basically improved EELVs (launched by ULA, none the less!) yet having hundreds if not thousands of tons of equipment and propelant in place.
Interstellar or Ad Astra is bad shit insane - dinky ELVs and multiple interplanetary colonization attempts and humongous space ship in the former and KFC & artillery fireballs on the Moon in the former. And Ad Astra even has booster stages being dropped when launching from Mars because hey, why not waste even more resources!
They also have regular transcontinental flights going through space, even though its IIRC not clear if its sub orbital ballistic trajectories or FOBS like partial orbit ones.
Still, many would-be hard SF films get this completely wrong - huge space stations and/or interplanetary spaceships yet they launch it all on rather dated looking expandable boosters!
Already The Martian it's pushing is pushing it with using basically improved EELVs (launched by ULA, none the less!) yet having hundreds if not thousands of tons of equipment and propelant in place.
Interstellar or Ad Astra is bad shit insane - dinky ELVs and multiple interplanetary colonization attempts and humongous space ship in the former and KFC & artillery fireballs on the Moon in the former. And Ad Astra even has booster stages being dropped when launching from Mars because hey, why not waste even more resources!
The opening of PlanetES is actually funny. They show a ton of historic rockets, even suggesting a progression over time, but then it hardly makes it to the then-present day of 2003. It's like "over time, rockets got bigger, and then question mark".
Adding couple space related yet quite plausible anime/manga series:
https://en.m.wikipedia.org/wiki/Rocket_Girls - basically space flight marketing for highschoolers created in cooperation with JAXA - has a pretty good description of using a biosuit
https://en.m.wikipedia.org/wiki/Space_Brothers_(manga) - a near future "so you want to be an astronaut, eh? " story - very realistic description of what you need to do before actually going to space (38 volumes/99 anime episodes)
https://en.m.wikipedia.org/wiki/Starship_Operators - a space opera that has quite minimal super science and a lot of hard physics - lasers vs overheating, detection/stealth in space (and the lack thereof), signal propagation issues, how to turn big ships quickly enough to use thrusters/fire axial weapons, using neutrino detectors to spot enemy warships based on neutrinos from their nuclear reactors
Various UC Gundam series - pretty accurate description of O'Neil Island 3 space colonies, mass drivers, orbital infrastructure in general - zero g only ships & stations
https://en.m.wikipedia.org/wiki/Rocket_Girls - basically space flight marketing for highschoolers created in cooperation with JAXA - has a pretty good description of using a biosuit
https://en.m.wikipedia.org/wiki/Space_Brothers_(manga) - a near future "so you want to be an astronaut, eh? " story - very realistic description of what you need to do before actually going to space (38 volumes/99 anime episodes)
https://en.m.wikipedia.org/wiki/Starship_Operators - a space opera that has quite minimal super science and a lot of hard physics - lasers vs overheating, detection/stealth in space (and the lack thereof), signal propagation issues, how to turn big ships quickly enough to use thrusters/fire axial weapons, using neutrino detectors to spot enemy warships based on neutrinos from their nuclear reactors
Various UC Gundam series - pretty accurate description of O'Neil Island 3 space colonies, mass drivers, orbital infrastructure in general - zero g only ships & stations
Fantastic series!
Also a great manga, some very nice editions are available
I also enjoyed that.
There's a near-future hard science fiction manga and anime series Planetes, about these cleaning workers:
https://en.wikipedia.org/wiki/Planetes
We have a nice podcast episode on this topic. We go into a few scenarios on how this might end and how it could be fixed.
(You can skip the first 30 seconds of intro)
https://www.predictions-podcast.com/2020/03/14/space-debris-...
(You can skip the first 30 seconds of intro)
https://www.predictions-podcast.com/2020/03/14/space-debris-...
Meanwhile india: https://en.wikipedia.org/wiki/Mission_Shakti
btw: The article is behind a paywall :(
btw: The article is behind a paywall :(
Meanwhile USA has 25x the debris (as of June 2019). Glass houses...
https://orbitaldebris.jsc.nasa.gov/quarterly-news/pdfs/odqnv...
https://www.businessinsider.in/us-russia-china-and-india-sta...
https://orbitaldebris.jsc.nasa.gov/quarterly-news/pdfs/odqnv...
https://www.businessinsider.in/us-russia-china-and-india-sta...
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.
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 people? We're seeing what happens when power is concentrated in the hands of a few (Trump/Parler bans) and it cannot be allowed to happen at a geopolitical level, in the interest of world peace (it sounds crazy but it has worked post WW2).
It's possible to care about more than one thing at a time. It's also possible to take a broader look at a problem such as arms control and say that in the long term the proliferation of capabilities is detrimental to humanity as a whole and ask how we can make progress in the other direction. Sadly with nationalism still trending upwards in much of the world I recognise this is a difficult propsition at the moment.
Satellites help us fight climate change
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.
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$countr...
I also agree with your point that sometimes space achievements are used for jingoistic purposes. But if you see the bigger picture (which most people don't sadly) you realize that it is a net positive overall for science and humanity. The jingoistic aspect is just a consequence of political reality.
https://www.gapminder.org/tools/#$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.
> In the long term, this accumulation of junk may lead to a chain reaction, known as Kessler syndrome, that would make some low-Earth orbits unusable.
I read about it, and it seems a little counter-intuitive for me. I would expect that in a collision in space, some of the kinetic energy would be used in internal structural changes, and not all converted to the resulting motion.
Am I wrong here? If not, does it still preserve enough kinetic energy after collision to promote this chain reaction? And how long until lower space ring is actually unusable?
I read about it, and it seems a little counter-intuitive for me. I would expect that in a collision in space, some of the kinetic energy would be used in internal structural changes, and not all converted to the resulting motion.
Am I wrong here? If not, does it still preserve enough kinetic energy after collision to promote this chain reaction? And how long until lower space ring is actually unusable?
Imagine two objects hitting each other perpendicularly, as opposed to head on.
Plenty of momentum could be conserved and thrown out in a median vector.
Edit: Not only that, but even if 90% of momentum was lost - it only takes another satellite going in the opposite direction to supply all the energy. Here's what 2 ounces of plastic does at 15,000mph to a block of aluminium. https://imgur.com/gallery/8NwAhgK
Edit: Not only that, but even if 90% of momentum was lost - it only takes another satellite going in the opposite direction to supply all the energy. Here's what 2 ounces of plastic does at 15,000mph to a block of aluminium. https://imgur.com/gallery/8NwAhgK
It depends on the material. If they are flexible, and deform easily, a lot of energy would be converted into structural damage, I would presume.
> it only takes another satellite going in the opposite direction to supply all the energy
I see, indeed the next collision will supply a lot of external momentum.
> it only takes another satellite going in the opposite direction to supply all the energy
I see, indeed the next collision will supply a lot of external momentum.
Material properties essentially become completely irrelevant when things hit into other things at speeds that greatly exceed the speed of sound in either material. At that point, you get best results if you just model both objects as fluids.
interesting insight! thanks
> It depends on the material. If they are flexible, and deform easily, a lot of energy would be converted into structural damage, I would presume.
At those speeds, everything is "flexible" in the sense that even metal just flows in a fluid-like manner (see picture linked in the comment).
Also, the material would have to somehow convert the energy of an entire car crashing into it at full speed. Except the car is only an inch wide.
At those speeds, everything is "flexible" in the sense that even metal just flows in a fluid-like manner (see picture linked in the comment).
Also, the material would have to somehow convert the energy of an entire car crashing into it at full speed. Except the car is only an inch wide.
1/2 an ounce (14 grams) according to that link. Even more nuts!
You are right that the collisions will dissipate some of the mechanical energy will be dissipated into heat and technically collisions will reduce the duration it takes for the mass of debris that are in orbit. I am not sure if that has a significant impact on top of the atmospheric drag though.
However, the Kessler syndrome is not about the total mass of debris in orbit, but the number of individual debris. So while before the collision we had 2 nicely aggregated debris, after the collision you will have thousands of small ones.
The small ones will tend to deorbit faster on average, because of the loss of energy mentioned above and also because their aggregated surface area increases, but you still have more debris. And when we are talking about multiple decades/centuries of lifetime, these debris will collide with other satellites, creating a positive feedback loop, increasing the numbers of debris exponentially, at least initially.
Obviously this is just the beginning of the process, which will end up with a maximum number of debris and then a decrease towards zero, but that timeline is extremely long and therefore not really relevant to us.
However, the Kessler syndrome is not about the total mass of debris in orbit, but the number of individual debris. So while before the collision we had 2 nicely aggregated debris, after the collision you will have thousands of small ones.
The small ones will tend to deorbit faster on average, because of the loss of energy mentioned above and also because their aggregated surface area increases, but you still have more debris. And when we are talking about multiple decades/centuries of lifetime, these debris will collide with other satellites, creating a positive feedback loop, increasing the numbers of debris exponentially, at least initially.
Obviously this is just the beginning of the process, which will end up with a maximum number of debris and then a decrease towards zero, but that timeline is extremely long and therefore not really relevant to us.
I see, thanks for taking the time to answer me =D
Is this really a thing... orbit is a vastly bigger place than the earths surface... you’d have to try pretty hard to hit that junk wouldn’t you?
Check this site out, it's a catalogue of known stuff in space http://stuffin.space/
The ISS has regular enough operations required to dodge debris detected approaching for a near miss in space that I think it's definitely a concern for future operations.
Consider as well that stuff in orbit is going ~25,000km/h or more and at that speed even a small bolt would decimate a spacecraft on impact.
The ISS has regular enough operations required to dodge debris detected approaching for a near miss in space that I think it's definitely a concern for future operations.
Consider as well that stuff in orbit is going ~25,000km/h or more and at that speed even a small bolt would decimate a spacecraft on impact.
I always dislike those visualisations as it gives the impression it’s crowded, because the dots aren’t to scale.
Are the orbits in opposing directions? If not, then the 25k number isn’t meaningful right? Their relative velocity is what matters
That’s interesting about the ISS I hadn’t heard of that as a regular thing.
Are the orbits in opposing directions? If not, then the 25k number isn’t meaningful right? Their relative velocity is what matters
That’s interesting about the ISS I hadn’t heard of that as a regular thing.
Just to follow up on the ISS, they have made a total of 20 avoidance maneuverers and they do it if they calculate the chance of hitting as greater than 1 in 10000.
So it is a thing, but I wouldn’t call < 1 per year regular
So it is a thing, but I wouldn’t call < 1 per year regular
From what you can read on the Internet, yes it appears to really be a thing. Read up on Kessler Syndrome to understand a bit more on the subject.
The problem is not just about satellites, but random debris flying unpredictably on orbit. When there starts to be a critical number, the odds to hit something start to raise in the "very possible" territory.
The Wikipedia page for Kessler Syndrome even state that, currently, one satellite is destroyed every year by junk. That's only going to increase if nothing is done.
The problem is not just about satellites, but random debris flying unpredictably on orbit. When there starts to be a critical number, the odds to hit something start to raise in the "very possible" territory.
The Wikipedia page for Kessler Syndrome even state that, currently, one satellite is destroyed every year by junk. That's only going to increase if nothing is done.
The issue is not in passing through the junk - that's like passing through the asteroid belt. We don't (or at least used to not) even plan a specific path through the asteroid belt, as the chance of hitting anything on the way through is so low.
The problem is if you want to stay in an orbit alongside the junk.
The dynamics of orbital mechanics are interesting, to say the least, but it in no way maps to the surface of some sphere.
A somewhat useful analogy is to imagine two circular racetracks, that intersect with each other in two spots. Each racetrack is like an 'orbit', and racecars going around them are satellites.
Make the racetracks really big, and put a car on each track. Have the cars drive around non-stop forever. The chance of them hitting each other on any lap is extremely small. However, if you let the cars go for a long time, and one of them completes a lap a little bit faster than the other, the times that they both cross the intersection will slowly get closer and closer together. Eventually, they will crash. If you put more cars on the track, the chance of two of them colliding increases. If everyone time they crash they create lots of baby cars, well you get Kessler Syndrome.
This is only a problem for these racetracks because they touch. We protect against this in the orbital world by keeping satellites in different orbits, that don't cross. The problem is that the orbits can shift over time due to gravitaional inconsitencies, and solar flares causing the atmosphere to bleed off into space, and the moon, etc. With lots of long lived satellites in low earth orbit, the chance for a crash increases. But even if we do get lots of baby satellites the other orbits farther out will remain useable (like geostationary orbits), you just have to be a little careful when crossing the low earth orbits on the way out.
The problem is if you want to stay in an orbit alongside the junk.
The dynamics of orbital mechanics are interesting, to say the least, but it in no way maps to the surface of some sphere.
A somewhat useful analogy is to imagine two circular racetracks, that intersect with each other in two spots. Each racetrack is like an 'orbit', and racecars going around them are satellites.
Make the racetracks really big, and put a car on each track. Have the cars drive around non-stop forever. The chance of them hitting each other on any lap is extremely small. However, if you let the cars go for a long time, and one of them completes a lap a little bit faster than the other, the times that they both cross the intersection will slowly get closer and closer together. Eventually, they will crash. If you put more cars on the track, the chance of two of them colliding increases. If everyone time they crash they create lots of baby cars, well you get Kessler Syndrome.
This is only a problem for these racetracks because they touch. We protect against this in the orbital world by keeping satellites in different orbits, that don't cross. The problem is that the orbits can shift over time due to gravitaional inconsitencies, and solar flares causing the atmosphere to bleed off into space, and the moon, etc. With lots of long lived satellites in low earth orbit, the chance for a crash increases. But even if we do get lots of baby satellites the other orbits farther out will remain useable (like geostationary orbits), you just have to be a little careful when crossing the low earth orbits on the way out.
Kurzgesagt has made a video about space junk.
End of Space – Creating a Prison for Humanity
https://youtube.com/watch?v=yS1ibDImAYU
What we need is a fleet of teleoperated VASIMIR-engined trawlers with electromagnetic fishing nets to clean up space garbage. What about funding? A levy on satellite launches and operators under the polluter pays principle. Perhaps this could be structured as an addition to insurance premiums, considering the purpose is perpetuation of access to Earth orbit and outer space for the sake of future generations and for all mankind.
curious of the price of de-orbiting an m6 screw (say m = 4g, v = 8000m/s) given it has the same kinetic energy as a small car (m = 1000kg v = 16m/s).
You don't need to get rid of all those 8km/s. Just enough to drop down into the atmosphere, the rest is a shooting star.
Remote propulsion by ablation:
https://en.wikipedia.org/wiki/Laser_broom
yes, that's the only system that makes sense to me for small objects. with a good international policy that prevents ppl from missiles at satellites to show power and, maybe, also one that prevent ppl to put any crap in LEO now it has got that cheap..
Can a large magnetic pulse for a short duration get shards to at least come together & somehow be yeeted down towards earth?
Unlikely for several reasons. The volume of space is enormous, many shards aren't ferrous, and a magnetic field that intense would damage things on the ground.
Sounds like a great idea! Although I imagine the size of pulse required would probably be such that it would have some less than desired secondary effects on the upper atmosphere, technologies at ground level and the various early warning systems deployed by our nuclear-armed nations... .
I suppose a large blob of magnetic gel might be more useful, attached at the front of a rocket. Magnetic and gel like substance to trap any parts, dust, an debris from collisions.
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.
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One cool way of de-orbiting satellites is to brake against the Earth's magnetic field with a conducting wire. This is actually already a product.
https://www.tethers.com/deorbit-systems/
https://www.tethers.com/deorbit-systems/
There were couple demo sats launched a few months ago. One with the tether, one without. https://www.dragracersat.com/
When 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?
Yeah my firm has a "Head of Space" definitely the best title in the company bar none. Space premium not our biggest line by any stretch, but the Specialty Re guys write a bit and the team at Lloyd's write quite a lot.
Insurance is a fascinating industry ripe for digital innovation. However, sadly, the deals are primarily written based on the quality of your relationships.
Insurance is a fascinating industry ripe for digital innovation. However, sadly, the deals are primarily written based on the quality of your relationships.
If they are insuring things in or going to space, then yeah! That's exactly what they're paid to do (well the analysts and actuaries).
Suppose you put a largeish amount of polyurethane foam in orbit, possibly around some scaffold to take up even more space, had it inflate when up there and had it absorb any wandering garbage for a while.
How long would it take for the giant garbage mound to deorbit and burn?
I'm not exactly sure how you imagine the collisions to play out. If you think anything gets "stuck" in your foam, you're underestimating the speeds at which objects in orbit move. It's more like shooting a railgun at your impactor. I also recommend Netwon's impact depth approximation: https://en.wikipedia.org/wiki/Impact_depth
For the purposes of deorbiting junk it may be sufficient to just impart some delta-v, but you neither want that to be uncontrolled collisions sending stuff into even more erratic orbits, nor would you want to risk generating even more tiny pieces.
For the purposes of deorbiting junk it may be sufficient to just impart some delta-v, but you neither want that to be uncontrolled collisions sending stuff into even more erratic orbits, nor would you want to risk generating even more tiny pieces.
I don't have a good feel for the numbers either, but surely if you make the Space Sponge big enough, things will get caught in it.
There is almost certainly a better material to use as well, but I don't think either of these practical concerns invalidates the idea.
Of course, big enough Space Sponges to make a practical difference would be very visible to the naked eye.
There is almost certainly a better material to use as well, but I don't think either of these practical concerns invalidates the idea.
Of course, big enough Space Sponges to make a practical difference would be very visible to the naked eye.
Well, the reason why I brought up Newton's impact depth formula is that it quite clearly shows you have to have enough "braking" material up there. Distributing it over a greater area reduces the effectiveness proportionally.
The problem in the end is launch costs. Yes, we're getting better, but that doesn't mean we can shoot up a "visible to the naked eye"-sized impactor. Not to mention what difficulties an object of that size would bring for non-garbage that also occupies those orbits.
Lastly, I have no idea how much research there has been in containing the fragmentation of hypervelocity impacts. But presumably it would be an important part of the mission to not generate more garbage.
The problem in the end is launch costs. Yes, we're getting better, but that doesn't mean we can shoot up a "visible to the naked eye"-sized impactor. Not to mention what difficulties an object of that size would bring for non-garbage that also occupies those orbits.
Lastly, I have no idea how much research there has been in containing the fragmentation of hypervelocity impacts. But presumably it would be an important part of the mission to not generate more garbage.
OK, you've convinced me.
Even if launching costs ever makes this feasible, any Space Sponge big enough to be efficient would be a big collision problem in itself.
Even if launching costs ever makes this feasible, any Space Sponge big enough to be efficient would be a big collision problem in itself.
There’s a lot of junk but it’s spread out over a lot of space. You probably won’t catch much by accident. Also, it may be going dramatically faster than your catcher, in which case it would be less like a mitten catching a ball and more like a mitten catching a bullet.
Sure, but there's also a lot of uh mitten in this case, getting progressively denser as more stuff gets trapped in it.
I don't think there's that many ways to trap all the tons of hyperfast shrapnel we've up up there, unless we can get starlink to just sporadically throw small nets around in hopes of catching enough junk on any given throw?
No, your "mitten" is getting blown apart, not getting progressively stronger. Your intuition is not tuned for space. Imagine trying to strengthen a structure by firing extremely high-powered bullets at it. "I have a tree near my house that is about to fall on us... how should I fire my high-powered rifle at it to reinforce it so it stays up?"
I suspect if you did the analysis, you'd find rather than it getting denser over time, you'd find most bits of space debris (even tiny ones) would have enough energy to explode your catcher...
[deleted]
A spherical Whipple shield might be able to capture debris. A 1 mm thick aluminum shell with a radius of 100 m would mass 810,000 kg. If SpaceX's Starship can achieve launch costs of 10/kg, that's $8 M per sphere.
But passive objects are only as likely to provide value as the ratio of the number of the total volume of the sacrificial objects to the total volume of assets, so you'd want a bunch of them.
Since the debris of interest is really just the material traveling in orbit, a cylinder might be more efficient, if some primitive attitude control could be included efficiently.
But passive objects are only as likely to provide value as the ratio of the number of the total volume of the sacrificial objects to the total volume of assets, so you'd want a bunch of them.
Since the debris of interest is really just the material traveling in orbit, a cylinder might be more efficient, if some primitive attitude control could be included efficiently.
It might help to put it in a suborbital trajectory, so it would basically go up, squirt, expand to a huge size, and drop back down, being hit by the intended object as it falls. You'd need a lot of foam to knock significant delta-v off the junk, and it would be catastrophically smashed by the thing impacting, but most of it would drop straight back down, and the bits blasted into orbit would be small and light enough to deorbit themselves.
Because of orbital mechanics, anything that would be traveling faster than the scaffold would be at a higher orbit and wouldn't be able to be caught.
The exception to this would be if the object were in an elliptical orbit, which would allow for contact to be made with the scaffold at its perigee, which be impossibly rare.
The exception to this would be if the object were in an elliptical orbit, which would allow for contact to be made with the scaffold at its perigee, which be impossibly rare.
If you'd ever build an artificial "sponge moon" with the goal of assimilating as much spacejunk as possible you'd probably not want to circulate its orbit. But I doubt you'd ever face that decision, given the absurd materials requirements imposed by orbital collisions.
Faster orbits are lower, not higher.
This is in fact correct, orbital velocity is sqrt(G*M/r) for circular orbits.
Wouldn't this be a matter of simply getting it to an useful starting position?
what if that thing had an elliptical orbit?
In addition to the other objections, the polyurethane would likely disintegrate.
Elon 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.
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.
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.
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 collision if you have satellites in them both (without active avoidance). So you have to separate the great circles on to different sized spheres, or add a little eccentricity to make sure the rings don't touch.
There is still a lot of space, but comparing to the size of the surface of the earth is not very informative when dealing with orbital dynamics.
All great circles on a sphere will intersect in two places, which assures a collision if you have satellites in them both (without active avoidance). So you have to separate the great circles on to different sized spheres, or add a little eccentricity to make sure the rings don't touch.
There is still a lot of space, but comparing to the size of the surface of the earth is not very informative when dealing with orbital dynamics.
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.
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.
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.
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.
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.
For other space related content, check out The Orbital Index: https://orbitalindex.com
A nice newsletter about space stuff (I have no affiliation, just a fan)
A nice newsletter about space stuff (I have no affiliation, just a fan)
My first thought was the game Hardspace:Shipbreaker
https://hardspace-shipbreaker.com/
https://hardspace-shipbreaker.com/
> The best idea, though, is to attack the problem at its roots. The littering of space is an example of the “tragedy of the commons”, in which no charge is made for the use of a resource that is owned collectively.
Garrett Hardin's article which created and promoted the "tragedy of the commons" doesn't describe historical "commons" at all, which were all managed over extended periods of time by complex rules and social norms. The "tragedies" happened primarily when capitalism emerged and demanded an end to the historical management of commons, allowing the interests of capital to destroy them.
Space might actually be the first really good example of "the tragedy of the commons" inasmuch as it was a new, globally accessible (i.e. not geographically determined) resource which began to be used without any establishment of the usual norms and rules that accompanied historical commons. Something similar presumably happened with the oceans, but their physical nature (i.e. stuff sinks, and stuff moves) hasn't created an issue in the same way that is now happening in orbit.
Garrett Hardin's article which created and promoted the "tragedy of the commons" doesn't describe historical "commons" at all, which were all managed over extended periods of time by complex rules and social norms. The "tragedies" happened primarily when capitalism emerged and demanded an end to the historical management of commons, allowing the interests of capital to destroy them.
Space might actually be the first really good example of "the tragedy of the commons" inasmuch as it was a new, globally accessible (i.e. not geographically determined) resource which began to be used without any establishment of the usual norms and rules that accompanied historical commons. Something similar presumably happened with the oceans, but their physical nature (i.e. stuff sinks, and stuff moves) hasn't created an issue in the same way that is now happening in orbit.
@dang, I thought paywalled articles weren't allowed.
According to the FAQ[1]:
> It's ok to post stories from sites with paywalls that have workarounds.
> In comments, it's ok to ask how to read an article and to help other users do so. But please don't post complaints about paywalls. Those are off topic.
I can read the article fine, so I presume there's some level of free access before you trigger the paywall.
[1] https://news.ycombinator.com/newsfaq.html
> It's ok to post stories from sites with paywalls that have workarounds.
> In comments, it's ok to ask how to read an article and to help other users do so. But please don't post complaints about paywalls. Those are off topic.
I can read the article fine, so I presume there's some level of free access before you trigger the paywall.
[1] https://news.ycombinator.com/newsfaq.html
Non-paywalled version: https://archive.is/GaWcS
Why "deorbiting"? Considering the cost of putting it there, wouldn't it be better to group the debris in a junkyard? Tell the jawas, maybe they're interested in managing it.
https://en.wikipedia.org/wiki/Australis-OSCAR_5
http://centralblue.williamsfoundation.org.au/oscar-5-the-fir...
https://www.youtube.com/watch?v=hjhto6wUQYQ