Sep 05 2017

Sustainably Using Space

space-debrisIt does seem that human civilization has grown to such a point that sustainability is becoming a significant issue in many domains. Prior to the last century or so the world was relatively large compared to human population. For most of human history it seemed as if resources were limitless – we could pull fish out of the sea without worrying that they would run out. Resources and disposal locations were treated like bottomless pits.

It is becoming increasingly clear that our population, our industry, and our appetites are now large enough that infinite sustainability is no longer something we can blithely assume.

It is also true that over the last couple of centuries there have been many premature warnings about “peak whatever”, or some way in which our civilization would not be sustainable. So far technology has advanced to fill in any gaps. This has given any new warnings about sustainability a reputation for screaming that the sky is falling, and makes it easy to dismiss. They were wrong before, so why should we worry now? Technology will eventually change the game and everything will be fine.

The classic errors that lead to these premature warnings were simplistically extrapolating from current trends, and not considering the development of new technology. The phrase “if current trends continue” should always be looked at with a skeptical eye. Historically, current trends rarely continue. You have to consider what is driving those trends, and if there are any feedback loops that will tend to moderate them. Also, we have proven a very clever species and I would not underestimate our ability to find innovative solutions.

At the same time those who too easily dismiss warnings about sustainability are making logical errors. First, we can’t assume that because some scientists were wrong before that means that scientists are wrong now. We can actually learn from the past and correct prior error. The second error is to fail to consider the fact that we are living on a world with finite resources. We may be getting better and making more with less, but there are ultimate limits. At some point the warnings are going to be correct, and we need to figure out when that is.

Finally – it is misguided to take the position that someone will find a solution. In the past prior warnings have not materialized because we did find solutions. But we have to look for solutions – we can’t just assume they will magically appear.

In the end we need to approach all questions about sustainability on a case-by-case basis. We can’t make assumptions either way.

Sustainability is also not just about resources. Antibiotic resistance, and pesticide resistance are potentially huge problems that are not about finite resources. In these cases we simply need to use our technology efficiently and optimally to minimize unintended consequences that have the potential to render the technology less effective.

Space as a Finite Resource

One of those finite resources that does not get a lot of attention in popular discussion is space. Perhaps this is because space, more than any other resource, does truly seem limitless. Space is really big and it is difficult to imagine how it can be limited.

However, in this context we are talking about Earth orbit. There is still a great deal of real estate between low Earth orbit and geosynchronous orbit, but that usable space is finite and we need to maintain it. It is part of a critical infrastructure for satellites used for communication, GPS, and monitoring weather.

We have been and continue to use orbital space as a bottomless pit. We put up satellites with no worry about what happens to them at the end of their lifespan. In other words – we have not been using space sustainably. Now our sloppiness is likely to bite us in the backside.

NASA estimates there is currently more than 500,000 marble-sized or larger pieces of space debris. They report:

“There are more than 20,000 pieces of debris larger than a softball orbiting the Earth. They travel at speeds up to 17,500 mph, fast enough for a relatively small piece of orbital debris to damage a satellite or a spacecraft. There are 500,000 pieces of debris the size of a marble or larger. There are many millions of pieces of debris that are so small they can’t be tracked.”

That is a lot of junk. Because these pieces are moving at high speeds relative to other things in orbit, like satellites, collisions are likely and have the potential to do catastrophic damage. Some scientists fear a worst-case-scenario of a chain reaction of collisions – a piece of space junk hits a satellite and shatters it into more space junk, that then collides with other satellites, until orbital space is so full of junk it is essentially unusable.

Even if we never get to this worst-case, orbital debris is a hazard, to any astronauts or assets in space.

So now we have to figure out how to deal with the tons of junk we have been dumping into space over the last 60 years. There is no easy way to deal with it. In order to grab something in orbit you essentially have to match its orbit, which takes fuel. You then need to deorbit the space debris and move onto the next bit of debris. We simply don’t have the technology to do this right now. We also need to do this without interfering with functioning satellites.

There are many ideas on the table, however. A recent report, focusing on a new proposed technology called the Brane Craft, reports:

Super-thin ships like Brane Craft aren’t the only tech under construction to wrangle space debris. The European Space Agency is also considering robotic arm grippers, nets, harpoons, and tethers. Another European team is planning to launch its RemoveDebris mission in late 2017 or early 2018, which will practice capturing CubeSats with a net and harpoon. Aeroscale, a satellite services company based in Singapore, is planning to capture debris using magnets. And researchers at Stanford University and NASA’s Jet Propulsion Laboratory in Pasadena, California have designed a gripper inspired by gecko feet that could latch onto satellites and other large debris.

Researchers have even considered zapping debris with a ground-based laser. “You can slow things down just as they come over the horizon by pointing these very high-powered lasers at them,” Derleth says. This would gobble up much less energy than launching a spaceship and sending it after individual chunks of debris. However, such a laser could potentially be turned into an anti-satellite weapon.

The Brane Craft itself is a thin sheet that can envelop small debris and change its orbit, even to deorbit it. Small debris will just burn up in the atmosphere and pose no danger to the ground.

I like the ground-based laser idea. This could be an international effort with agreements to use it only to deal with orbital debris, and not as a weapon.

In addition space agencies are working on standards so that anything new that gets put into orbit has a plan for what happens at the end of its life. This will likely include some technique to self-deorbit. Essentially we need to properly dispose of our satellites when we are done with them.

We could also essentially tax any company that wishes to put something in space, with the money used for efforts to clean up space junk. So, if you want access to the limited resource of orbital space, you need to pay for that access with a little clean up.

We need to do whatever is necessary so that over time the amount of space junk decreases rather than increases, until it reaches a sustainable equilibrium.




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