Kessler?s Syndrome
"Space," it says, "is big. Really big. You just won't believe how vastly hugely mindboggingly big it is. I mean you may think it's a long way down the road to the chemist, but that's just peanuts to space." The Hitchhikers Guide to the Galaxy.
The above not withstanding bits of it are more equal than others (with apologies to Orwell) and we (man) are endangering some of the bits that are most important to us. Which brings us to the Kessler?s Syndrome. This is not some emerging zoonotic or intergalactic pathogen but a runaway chain reaction involving space debris. On the face of it this may seem a strange subject for this site and of only tangential relevance but if you will bare with me I will try and show that it is becoming one of those everyday things we take for granted but which have the potential to undergo a catastrophic failure with wide ranging and potential dire consequences. This is a concept FluTracker regulars should find very familiar. As there is no earthly reason why you should know very much about rocket science or satellite orbits I have written a short introduction in the box at the end with a number of links for greater detail. If you are happy with the Jargon skip it, if not read it now.
Kessler?s warning relates to the LEO but with the importance of the GEO orbit the same could apply to both. If a satellite is hit - or worse still explodes - it many produce many high speed pieces of space junk, if there are enough satellites and other pieces of space junk in the vicinity a chain reaction can destroy all satellites in that orbital region and leave a dense debris field rendering any further attempts to enter orbit extremely hazardous. This could bar us from entering space for 1000s of years. Unlike criticality in a Uranium fission reaction where 3 neutrons are released and at least one needs to impact with a fissile nucleus for the reaction to be sustained, here an impact could produce none or tens of thousands of debris pieces making it much less predictable. About a year ago China decided to hit one of their defunct satellites with a projectile in a test ? this test doubled the debris field in that LEO orbital area (the NY Times has an excellent graphic showing how in just a few days this had distributed itself all around the globe. Also shows a Hubble solar panel with all of its hits - Links below). The US has now hit one of their failed spy satellites with a rocket. (They claim to prevent danger to humans from Hydrazine fuel but a quick look at N2H4 will show this as miscible with water, has freezing and boiling points similar to water and a 3-3-3 NFPA 704 rating so not exactly a major threat to survive re-entry nor to life on the ground if some of it does)
Position Paper on Space Debris Mitigation
Implementing Zero Debris Creation Zones
http://iaaweb.org/iaa/Studies/spacedebrismitigation.pdf
The Military Use of Space
http://www.parliament.uk/documents/upload/postpn273.pdf
US 'to shoot down spy satellite'
http://news.bbc.co.uk/2/hi/americas/7245578.stm
http://news.bbc.co.uk/2/hi/americas/7256741.stm
The military uses of space
http://www.parliament.uk/documents/upload/postpn273.pdf
Impact suspected for loss of Russian satellite
http://space.newscientist.com/article/dn8934-impact-suspected-for-loss-of-russian-satellite.html
Debris Mitigation Improves, but More Work Urged
http://www.space.com/spacenews/archive06/Geo_013006.html
Geostationary Orbit Impact Detector (GORID)
http://esapub.esrin.esa.it/pff/pffv7n1/drov7n1.htm
Littered Skies (NY Times animation and graphic on debris damage & distribution)
http://www.nytimes.com/2007/02/06/science/20070206_ORBIT_GRAPHIC.html
"Space," it says, "is big. Really big. You just won't believe how vastly hugely mindboggingly big it is. I mean you may think it's a long way down the road to the chemist, but that's just peanuts to space." The Hitchhikers Guide to the Galaxy.
The above not withstanding bits of it are more equal than others (with apologies to Orwell) and we (man) are endangering some of the bits that are most important to us. Which brings us to the Kessler?s Syndrome. This is not some emerging zoonotic or intergalactic pathogen but a runaway chain reaction involving space debris. On the face of it this may seem a strange subject for this site and of only tangential relevance but if you will bare with me I will try and show that it is becoming one of those everyday things we take for granted but which have the potential to undergo a catastrophic failure with wide ranging and potential dire consequences. This is a concept FluTracker regulars should find very familiar. As there is no earthly reason why you should know very much about rocket science or satellite orbits I have written a short introduction in the box at the end with a number of links for greater detail. If you are happy with the Jargon skip it, if not read it now.
Kessler?s warning relates to the LEO but with the importance of the GEO orbit the same could apply to both. If a satellite is hit - or worse still explodes - it many produce many high speed pieces of space junk, if there are enough satellites and other pieces of space junk in the vicinity a chain reaction can destroy all satellites in that orbital region and leave a dense debris field rendering any further attempts to enter orbit extremely hazardous. This could bar us from entering space for 1000s of years. Unlike criticality in a Uranium fission reaction where 3 neutrons are released and at least one needs to impact with a fissile nucleus for the reaction to be sustained, here an impact could produce none or tens of thousands of debris pieces making it much less predictable. About a year ago China decided to hit one of their defunct satellites with a projectile in a test ? this test doubled the debris field in that LEO orbital area (the NY Times has an excellent graphic showing how in just a few days this had distributed itself all around the globe. Also shows a Hubble solar panel with all of its hits - Links below). The US has now hit one of their failed spy satellites with a rocket. (They claim to prevent danger to humans from Hydrazine fuel but a quick look at N2H4 will show this as miscible with water, has freezing and boiling points similar to water and a 3-3-3 NFPA 704 rating so not exactly a major threat to survive re-entry nor to life on the ground if some of it does)
The principles are all fairly simple ?for every action there is an equal and opposite reaction? so when a rocket goes up ? or sideways - propellent is ejected at speed in the opposite direction. Getting a Kg of payload into orbit requires enormouse amounts of energy and the higher the orbit the more energy required (Delta-v is a measure of the energy required to move from one state to another). The most popular orbits are low earth (LEO - because they are cheapest to achieve) and Geosynchronous/Geostatioanry (GES/GEO as they allow station keeping above a fixed ground position at a minimal fuel requirement). Kinetic Energy is calculated as the product of mass & velocity; in the absence of air resistance velocities are high, typically 10km/sec, at these speeds a 3mm particle would pack the same punch as a bowling ball at 100km/hr. The atmoshere has no clear top it just thins into space, 75% is within the first 11km and re-entry effects can be noticed from about 120km but to be totally clear of all atmosphere 10,000km is about right. A bodies gravitational effects are taken to act from it centre of gravity (in the earth?s case this is the middle of the core) and fall off in line with the reverse square law. The distance to the Earth?s surface is 6370km. From the surface LEO covers 160 to 2000km with GEO at 35,794km (other sites of interest: International Space Station ISS 500km, GPS 20,230, Hubble 589km)
Implementing Zero Debris Creation Zones
http://iaaweb.org/iaa/Studies/spacedebrismitigation.pdf
The Military Use of Space
http://www.parliament.uk/documents/upload/postpn273.pdf
US 'to shoot down spy satellite'
http://news.bbc.co.uk/2/hi/americas/7245578.stm
http://news.bbc.co.uk/2/hi/americas/7256741.stm
The military uses of space
http://www.parliament.uk/documents/upload/postpn273.pdf
Impact suspected for loss of Russian satellite
http://space.newscientist.com/article/dn8934-impact-suspected-for-loss-of-russian-satellite.html
Debris Mitigation Improves, but More Work Urged
http://www.space.com/spacenews/archive06/Geo_013006.html
Geostationary Orbit Impact Detector (GORID)
http://esapub.esrin.esa.it/pff/pffv7n1/drov7n1.htm
Littered Skies (NY Times animation and graphic on debris damage & distribution)
http://www.nytimes.com/2007/02/06/science/20070206_ORBIT_GRAPHIC.html
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