Dear PT5
How are you doing?
Right now you’re just over 4 million kilometres away. That’s apparently 0.026847 AUs and you’re so far away that it takes just under 14 seconds for light to travel from you to us. You’re keeping your distance, and I think that’s safest. For all of us. Let me explain.
That’s an impression of all the space junk orbiting the Earth There’s a distinct ring of space debris that we can see there as well as a more diffuse, pervasive cloud. It’s a scary image, but also a nebulous one. The European Space Agency have got us covered on that.
Scientific models estimate the total number of space debris objects in Earth orbit to be in the order of:
• 29,000 – for sizes larger than 10 cm
• 670,000 – for sizes larger than 1 cm
• More than 170 million – for sizes larger than 1 mm.
Any of these objects can cause harm to an operational spacecraft. For example, a collision with a 10-cm object would entail a catastrophic fragmentation of a typical satellite, a 1-cm object would most likely disable a spacecraft and penetrate the ISS shields, and a 1-mm object could destroy sub-systems on board a spacecraft. Scientists generally agree that, for typical satellites, a collision with an energy-to-mass ratio exceeding 40 J/g would be catastrophic.
All of this sounds bad, doesn’t it? It’s actually so much worse. In 1978. NASA scientists Donald J Kessler and Burton G. Cour-Palais hypothesized that once the ‘space pollution’ got thick enough, a collision between objects would become inevitable. So a big object would hit a smaller object and shatter, and then the pieces would hit smaller pieces and shatter and then those pieces would…actually let’s let Sandra Bullock demonstrate this.
Kessler Syndrome, as it came to be known, is very, very bad. So much so that it’s scientific names actually sound worse. Collisional Cascading. Ablation Cascading. It’s all basically just multi-syllabic versions of ‘You don’t want to be here’ Oh and just for extra giggles, there’s some debate over whether or not we’re already seeing a Kessler Effect wave form. There’ve only been four confirmed collisions between satellites but they’ve all taken place since 2009 so while there isn’t consensus, there is evidence. So much so in fact that there’s a couple of prime suspects for how it’ll start.
This is Envisat. It’s been in orbit for 22 years, and its about twice your size. It was intended as an Earth observation satellite and did good environmental science until it was replaced by the Sentinel series that does the same job. The problem isn’t so much Envisat itself as the neighbourhood its in. It orbits at 785km, which is the busiest ‘lane’ of space. The debris is tightly packed up there, and two catalogued objects pass within 200m of Envisat every year. Which doesn’t sound much at all, does it? Until you remember that it weighs 8000 tons and it’s 20m long and all of that is travelling at about 28,800 km an hour with two objects at least passing within 200m of it regularly.
This is normally the point where people start to think about having a bit of a sit down and maybe breathing in and out of a paper bag for a while.
Envisat isn’t alone either. The Starlink program puts constellations of satellites in orbit to provide reliable nternet coverage for areas that struggle with coverage. Starlink is a triple controversy magnet with the world’s richest, shrillest bigot only one of those problems. The others are the light pollution the huge network of satellites causes for ground based astronomers and the third is the obvious concern about Kessler Syndrome. Right now there are over 6000 Starlink satellites in orbit although, in fairness, SpaceX have made it clear they’re in a low orbit and therefore likely to fall to Earth in five years if they malfunction. So shooting stars rather than fragmentation grenades basically. Cautious yay!
There’s an element of Kessler storms that almost seems attractive. Taking the sky from us because we didn’t play nicely enough with it appeals to that nascent sense of justice we all have. But it appeals to our sense of something greater too. If we fix the Earth, and we can, then we can fix the sky too and this is one of those lovely instances where science and fiction do the Predator fist bump and starting getting stuff done. There are all sorts of fun Thunderbirds style pieces of tech being looked at, including drag fishing for junk, something the he RemoveDEBRIS team are in the process of developing. There’s also, and this is a favourite, the Laser Broom.
These would be ground (Or station) based lasers that would sweep space debris out of the way. If you’re thinking ‘…navigational deflector’ that’s exactly what it is. The science is solid too, essentially ablating or blowing a small amount of the target debris away and using the minor amount of thrust from that to push the debris out of the way. Fired from the ground, the laser would lose a lot of power as it pushed through the atmosphere. Fired from space, it would lose almost nothing. Then again, if you’re thinking ‘…orbital laser cannon’ then I promise you are not alone.
It’s an imperfect solution, but what isn’t? Even the space junk itself comes from human error, or chance, or accident and at this time I’d like to have a moment of silence for Piers Sellers’ favourite spatula, lost on a shuttle mission in 2006. ‘Spatsat’ as it became known orbited the Earth for four months before burning up. As Sellers put it:
“NORAD sent me a nice note which had a blue square with an X in the middle of it, and some coordinates,” he told us. “This was apparently where the ashes of the spatula fell in the Atlantic, about four months after STS-121.”
Ave, Spatsat. But if space junk as small or smaller than a spatula can be tracked from the ground then that’s the first step towards removing it and one last solution speaks to that and is by far the most obvious: recycle it for cash. There’s gold in the sky and a lot of other high value material too. All we have to do is go get it. The other most elegant solution is also the most capitalistic. Gather, process and recycle the debris. Use the past not as a prison but as a foundation. Clear skies for a clear future. After all, who doesn’t feel better after tidying up?
Have a great week, PT5
Space Junk
- https://www.space.com/most-dangerous-types-space-junk
- https://en.wikipedia.org/wiki/Envisat
- https://www.esa.int/Space_Safety/Clean_Space/How_many_space_debris_objects_are_currently_in_orbit
- https://www.starlink.com/gb
- https://www.wired.com/2009/02/spacestuff/
- https://aerospace.org/article/space-debris-101#:~:text=There%20have%20been%20four%20documented,new%20debris%20in%20the%20future.
Kessler Syndrome
- https://en.wikipedia.org/wiki/Kessler_syndrome
- https://en.wikipedia.org/wiki/Donald_J._Kessler
- https://historycollection.jsc.nasa.gov/JSCHistoryPortal/history/oral_histories/Cour-PalaisBG/Cour-PalaisBG_3-1-04.htm
- https://aquarid.physics.uwo.ca/kessler/iwp5.html
Kessler Syndrome Solutions
- https://www.nhm.ac.uk/discover/news/2018/september/net-to-catch-space-debris-around-earth-is-successfully-deployed.html
- https://en.wikipedia.org/wiki/Laser_broom
- https://memory-alpha.fandom.com/wiki/Navigational_deflector
- https://fas.org/publication/how-do-you-clean-up-170-million-pieces-of-space-junk/
Gravity
- https://en.wikipedia.org/wiki/Gravity_(2013_film)
SpatSat
- https://www.popularmechanics.com/space/a16220/space-spatula/
- https://www.nbcnews.com/id/wbna14839475