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.

 

 

 

13 responses so far

13 Responses to “Sustainably Using Space”

  1. DisplayGeekon 05 Sep 2017 at 12:31 pm

    “One man’s garbage is another man’s treasure.”

    I believe that we are looking at this “problem” in the wrong manner. Yes, small marble sized objects are a potential danger to functioning sats and could eventually become even worse due to the cascade effect of collisions creating more debris causing more collisions causing more debris. This we need to address.

    One concept that I’ve been toying with for decades is that of using a volatile, water perhaps, placed in a counter orbit to the majority of the junk to clear a path so to speak. That is, most junk is orbiting west to east since launches that take this direction take advantage of the base rotation of the Earth. Of course, some orbit in a much more inclined orbit, notably those from “spy” sat missions. If launches with water as payload were to take an east to west suborbit (elliptical orbit that intersects with the Earth), then release the water as a gas into the path of known small debris, it would form a tiny (relative to the orbits involved) cloud which would decelerate the debris such that its new orbit intersects with the atmosphere below (commonly called a “deorbit”). The water gas would eventually be too tenuous to effect other objects, but will have cleared a patch of sky before its own orbit took it back to the atmosphere.

    As to larger objects. Yes, by all means send out collection craft, preferably permanent ones in orbit that use solar sails or microwave sails to slowly adjust their orbits… collect the junk. But not to deorbit them! No, pull them together into recycling centers to use the mass of metal and precious unused volatiles still in tanks. Use them to build a true space industry. Deorbiting mass that was launched at great cost seems to be the most wasteful idea of all.

    Someday an entrepreneur with vision will turn trash into treasure. That idea is used in passing in the SciFi novel that will soon be published, “All the Stars are Suns”.

  2. mrron 05 Sep 2017 at 2:44 pm

    Swiss students are developing a project “CleanSpace”:

    http://espace.epfl.ch/CleanSpaceOne_1

    I spoke with the person in charge (at recent drone days https://dronedays.epfl.ch/, no special access), who made some interesting points:

    – this is a proof of concept, the future is hopefully a recycling station in orbit rather than sending things back down to burn.

    – technology for capture or destruction of satellites is slowed down by risk of being also used as a weapon; neutral Switzerland has an advantage here, that no one thinks they want to destroy hostile satellites.

  3. bachfiendon 05 Sep 2017 at 5:33 pm

    DisplayGeek,

    Using water sounds like a good idea. I wonder why someone hasn’t already thought of it? It has the advantage that it would decelerate smaller pieces of space junk more than intact satellites (which could be fitted with small jets in future to correct their orbital altitude if necessary).

  4. Nidwinon 06 Sep 2017 at 6:02 am

    Isn’t it too cold up there to be able to use water, especially as a gas, without it becoming ice too soonish?

  5. Karl Withakayon 06 Sep 2017 at 11:01 am

    Water in the vacuum/ near vacuum of space will flash boil and then very rapidly freeze. It will not stay in a gaseous state.

    Any gas (that remains as gas at the temperature of space) released in the vacuum/ near vacuum of space will expand to fill available space (dissipate) and will not form a cloud.

  6. bachfiendon 06 Sep 2017 at 11:15 am

    i think it would still work by forming a cloud of very small ice crystals.

  7. Karl Withakayon 06 Sep 2017 at 11:56 am

    I doubt it.

    Among many other things, I’m not sure how well those ice crystals would form any semi coherent cloud capable of producing enough force to make a difference; plus you’d have the problem of deploying said cloud close enough to the target to hit it without the risk of the deploying system colliding with the target at extremely high closing velocity.

    Additionally, it’s an fairly expensive proposition to launch any payload into orbit.

    Doing so for the purpose of de-orbiting a relatively small amount (relative to the amount of junk that needs to be dealt with) of space junk, it going to be cost prohibitive.

    Until and unless energy costs drop an order of magnitude or so, I don’t see individual launch missions being funded for general space junk cleanup.

  8. Karl Withakayon 06 Sep 2017 at 12:22 pm

    to clarify, I don’t see individual launch missions being funded for -individual- general space junk cleanup.

  9. Steven Novellaon 06 Sep 2017 at 7:07 pm

    from 2009
    https://www.treehugger.com/clean-technology/clearing-space-junk-from-earths-orbit-by-launching-water-at-it.html

  10. bachfiendon 06 Sep 2017 at 8:59 pm

    Steve,

    ‘Using water sounds like a good idea. I wonder why someone hasn’t already thought of it?’

    So someone has already thought of it. What needs to be done is to try it out and see if it could possibly work. It might turn out to be cheaper than the alternatives if it works.

  11. Haggardon 06 Sep 2017 at 10:07 pm

    The idea of “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.” seems to be the most appropriate and effective way to deal with this problem, concerning future missions or commercial operations.

    The idea of a tax does not appeal to me. Unless the tax is so grossly expensive that it would require most companies to find an end of life solution to avoid the tax, it will likely be a fairly useless plan to deal with the waste.

    It is likely that companies will then just factor the tax into operating expenses and avoid the actual problem of dealing with their waste. It seems to be the way things are dealt with on the ground, so it is not reasonable to expect space to be much different.

    This is also assuming that it is very expensive (both monetary and technologically) to deal with space waste… which it seems to be. We don’t even have a working solution for cleaning up space, but surely, there is available technology to bring something safely back to its end of life in a way that does not significantly pollute space.

  12. DisplayGeekon 09 Sep 2017 at 7:42 pm

    I see Dr. Novella found a reference to the same idea. Bully !!! However, I can’t say that they were “First”… as I have been thinking about this for decades (2009 was less than a decade ago) and I have been proposing and talking about his idea for quite a while, at least since the early ’90s when I spoke with a good friend who was doing some calculations on energy and delta V requirements on various “moon shot” concepts from going to the stars to moving cometary mass to Mars for terraforming. She was well connected with some of the first extra-solar planet hunters… So… who knows.

    A few clarifications. One, releasing water as a liquid will indeed cause flash boiling creating two species of water… gaseous and a frozen snow from the cooling effect of the boiling… but the gas is still created… and it isn’t the best way of releasing the water. If the water is heated and released at low pressure with no liquid available, it can remain as a very low density gas with little chance of cooling to become a solid before it is done its job. Oh… and “clouds” don’t ever have tensile properties… the key is simply that an expanding low pressure (so low that the mean free path is a bit less than a micron) gas volume just in front of the path of the debris, the molecules won’t turn to snow before the interaction between the debris and the gas particles transfers momentum enough to cause a deorbit “burn”.

  13. ndesouzaon 13 Sep 2017 at 11:23 am

    Are there any environmental concerns with just “burning up” all of the smaller space junk in the atmosphere?

    I imagine there’s some unsavory heavy metals mixed in there.

    Small scale is undoubtedly not a big deal, but is this a ‘sustainable’ solution, or will it lead to unforeseen terrestrial problems?

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