I just found out about the Kessler syndrome. Basically it posits that as more and more space debris collides (breaking into smaller and smaller pieces), the Earth will become shrouded in a basically impenetrable shield trapping us on the planet for many generations to come.
At first blush this might not seem to be a real issue but objects as small as a fleck of paint can become a hazard once they reach orbital speeds of up to 22,000 mph (34,500 km/h) as the 7 mm-diameter circular chip in the cupola window of the ISS can attest to.
So, OK, real but what are the actual chances we could become earthbound?
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The problem isn’t as dramatic as portrayed in the film Gravity, but it is a significant long term threat, particularly in the upper part of Low Earth Orbit (LEO) where even small debris can persist for thosands of years and pose a persistant hazard by creating more debris upon impact. LEO has become more crowded, particularly with the burgeoning commercial small satellite industry, and while most of these are currently located somewhere below 200 nmi altitude where they or any debris that is produced should decay within a few decades, there is greater incentive to place satellites in higher or more elliptical orbits, especially when dedicated small satellite launchers become available. Although there is a general agreement among most nations that satellites will be deorbited or moved to specified graveyard orbit within 25 years of end of operation, there is no legal enforcement of this, and with smaller satellites such as the CubeSat standard, there is little space or mass for a propulsion system. Some methods of deorbiting such as using light pressure or electrodynamic tethers are being developed but still take up critical operational and payload space. The problem in Medium Earth Orbit (MEO) is less immediate but potentally more persistant, since debris at those atlitudes will persist indefinitely (thousands of years).
The United States Strategic Command Joint Space Operations Center (JSpOC) tracks debris of 10 cm or larger, but smaller debris from operations in past eras where there was less concern about the hazards of orbital pollution may pose a persistant hazard. There is also debris from launch vehicle upper stages and inadvertant or failed deployments, and the potential of debris from anti-satellite operations or deliberately contaminating orbit to deny access to space. None of this is going to cause a sudden unavailability of orbital space in the near term, but over a longer period enough debris could accumulate to make particular orbits, and potentially entire ranges of orbital altitudes unusable without a concerned effort to clear them of debris by methods not yet demonstrated even as a proof of concept. A cascading debris syndrome could result in denial of LEO or MEO space and hazard to launch operations indefinitely.
It’s a real problem with no clear solutions other than preventing debris accumulation as much as possible.
The manga and anime series Planetescovers this. The story is set in the near future and Kessler syndrome is mentioned specifically by name but has not occurred. The danger is recognized and if a company wishes to operate in space, it must contribute to the clean up. Since it is a cost rather than a revenue center, the corporations react to it as you might expect and the Debris Collection Section of each is looked down upon by the rest of the company and given the minimum of staffing and equipment to earn the points – awarded by the amount and difficulty of collection – needed so they can continue to operate.
I have not read the manga but the anime is one of the hardest s-f works ever, testing out at at least five on the Mohs scale.
Link. Hell, in the English DVD release, an extra has an interview with Kessler himself. In case you can’t tell, it’s one of my favorite anime series, right up there with Ghost in the Shell.
I am not an expert (or even an informed layman) when it comes to orbital mechanics, but doesn’t an object’s velocity have an impact on the orbital altitude? In other words, if I put two objects in orbit and then accelerate one significantly, doesn’t it change to a different orbit/altitude?
The reason I ask is that I was under the (probably mistaken) impression that objects at the same orbital altitude are traveling at approximately the same speed. In other words, the difference in the velocity of two objects at a given orbital altitude would be fairly small (i.e., not the hundreds of MPH required for a catastrophic collision).
Objects in the same circular orbit and inclination will have the same velocity. Objects in orbits inclined to one another or in crossing elliptical orbits with different apsides can have relative velocity differences that make a rifle bullet seem like a wiffle ball in comparison.
If the objects were both in circular orbit, in the same orbital plane, and at the same altitude, then they would have the same velocity. But in real life, the orbit can be elliptical, and in different planes. An object in a highly elliptical orbit would be much faster at its lowest point than an object that’s in a circular orbit at that altitude. Or the objects may each be in a circular orbit, but tilted at a large angle, so where their orbits intersect, the relative speed will be huge.
Yeah, the relative speed of two colliding objects in orbit won’t be the same as either one’s speed relative to the Earth, but it’ll still be within an order of magnitude of that, which is still too damn fast to be colliding at.
This seems like a “Tragedy of the Commons” type of problem. Every actor can contribute to the debris but no one restrains them or cleans up after them.
Well, except it is going to be everyone’s problem if nations and corporations involved in space industries don’t address it. Big telecomm and weather satellites in GTO and GSO are high enough that it is unlikely that they will be threatened by random debris fields, but anything in MEO or lower could potentially be affected by debris from an impact event at that altitude or higher, including GPS and GLONASS satellites, lower or eccentric orbit surveillance and communications satellites, and of course all of the small sats operators anticipating working in LEO in what is poised to be a massive new multibillion dollar industry of tracking and commercial marine and aviation surveillance. And once it starts happening, it will continuously cascade until the debris is removed, either by natural processes of the drag of tenuous molecular atmosphere or by some deliberate method of removing debris that has yet to be worked out practically. This may be compounded if measures aren’t taken now to prevent the militarization of orbital space, and effort that China has been undertaking in earnest for the last decade.
Stranger, if the worst case scenario happens, what exactly does this really mean? Would you still be “safe” in very high and very low orbits? Some of the doom and gloom articles make it sound like this would make satellites unfeasible. It certainly would make them more expensive - but couldn’t you send outer planets probes (or even manned expeditions) up through gaps in the junk? Even the worst case scenario, the probability of an impact over the few hours it takes to transfer to a high orbit would be very small, right?
brings to mind a few years ago … i believe science-channel aired it … mini-series spanning three years (2012-2014) … documentary/movie entitled “alien encounters”. the third, and final season, contained two episodes … how humans were interacting 'n controlling space debris. and, yes, since it was part documentary … they used the term “kessler syndrome” within the story line. external link external link
that’s all i got.