There's an interesting Q&A in today's Inquirer about space junk, entitled "Why we need a trash code for outer space." The danger it presents is not so much of falling on our heads (most of it burns up in the atmosphere) but of staying up there in orbit in perpetuity, ready to smash into something that may not be, but might then become, more space junk.
The green connection, of course, is that it's an issue of litter that has been created, unwittingly or not, and who should be responsible for clearing it up, i.e. cleaning the environment, which in this case is one of several orbits around the earth.
Most of the junk in question - tiny bits of machines that have collided and can do still more damage as they whiz around at dizziyingly high speed - is not a threat to us down here, but to other (super-expensive) stuff up there. And the scenario of their ability to become weaponized junk seems to have been largely disregarded in their deployment.
There's increasing discussion about internalized costs vs. externalized. In short, it merely means tracking the ultimate costs of something and being accountable for them in going forward with it. In the junked-up orbit situation, as with other large-scale industries, costs (here, the very real risk of unintentionally destroying our own, and other nations', technology) have not been internalized. If they had, there would already be a plan for how to rectify the problem.
The situation away up there in space mirrors (until said mirror gets cracked by a fleck of paint traveling at 29,000 miles an hour) the one down here. The entire point of "green" is about bringing externalized costs - those that "somebody else" has to pay - back inside their proper realm, whether that's a given industry, a particular company, a unit of product, or our own homes and lives. Paul Hawken was out in front of this issue and his The Ecology of Commerce contains an important treatment of it.
While nations bicker over needed industrial regulations and back at home we dicker over CFLs vs. LEDs or which things to recycle or not recycle, there's one clear area where every single person on the planet can drastically reduce cost externalization: Our food.
It's now clear that choosing to consume meat and dairy - foods that we absolutely do not need, according to the American Dietetic Association - is choosing to keep animals enslaved and killed as well as choosing to increase the level of greenhouse gases and many other pollutants closer to home. Maybe you and I can't do much about the trash in outer space, but we can choose to avoid foisting those extreme costs on others, by eating vegan.