Thursday, October 01, 2015

Unthinkable thinking

Back in the day, 1969 in fact, I remember sitting up late one East Coast evening watching astronaut Neil Armstrong step onto the moon. As he set down a U.S. flag, I remember remarking to a friend: "Damn, the first thing we do when get there is litter!"

These days, humans have put up thousands of satellites orbiting the earth. These provide the backbone for our everyday communications, for our scientific understanding of the planet including tomorrow's weather, and even the GPS in our cellphones and my Garmin watch. Soon we'll need that mapping capacity to direct our self-driving cars. We count on all that stuff floating around up there without even thinking about it.

But apparently all that orbital clutter makes for an new threat, a consequence of our profligate habit of thinking that the universe is so big we can just leave stuff lying around. According to Charlie Stross,

Kessler Syndrome, or collisional cascading, is a nightmare scenario for space activity. Proposed by NASA scientist Donald Kessler in 1978, it proposes that at a certain critical density, orbiting debris shed by satellites and launch vehicles will begin to impact on and shatter other satellites, producing a cascade of more debris, so that the probability of any given satellite being hit rises, leading to a chain reaction that effectively renders access to low earth orbit unacceptably hazardous.

This isn't just fantasy. There are an estimated 300,000 pieces of debris already in orbit; a satellite is destroyed every year by an impact event. Even a fleck of shed paint a tenth of a millimeter across carries as much kinetic energy as a rifle bullet when it's traveling at orbital velocity, and the majority of this crud is clustered in low orbit, with a secondary belt of bits in geosychronous orbit as well. The [International Space Station] carries patch kits in case of a micro-particle impact and periodically has to expend fuel to dodge dead satellites drifting into its orbit; on occasion the US space shuttles suffered windscreen impacts that necessitated ground repairs.

If a Kessler cascade erupts in low earth orbit, launching new satellites or manned spacecraft will become very hazardous, equivalent to running across a field under beaten fire from a machine gun with an infinite ammunition supply. Sooner or later you'll be hit. And the debris stays in orbit for a very long time, typically years to decades (centuries or millennia for the particles in higher orbits). ... And then there's the nightmare scenario: a Kessler cascade in geosynchronous orbit. The crud up there will take centuries to disperse, mostly due to radiation degradation and the solar wind gradually blowing it into higher orbits.

There's an interesting discussion at the blog where I found this about how immanent and how destructive this might be. Evaluating it goes way beyond my expertise though I found the conversation interesting.

Humans evolved to make more and more and more -- because more was good for survival. Having managed to make so much more we're screwing up the planet, apparently we've also spread the malady into near-space.

Maybe it's just my apparently endless head cold doing my thinking, but looking at us through this lens, it's hard not to conclude there's simply too much of us.


Terry Moon said...

So much for the fantasy that when the earth is made uninhabitable because of pollution and climate chaos we can just go someplace else.

Hattie said...

Well sounds as if you have one of those bugs that drags down your mood. I have got to say that I, the cavewoman blogger,have never believed humans could leave this planet and settle elsewhere. The earth is our one and only home.
Hope you are feeling better soon.

janinsanfran said...

Yes, being sick for a week drags down my mood. Just hoping it is abating, although now that the gungus is receding, all I want to do is catch up on missed sleep.

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