Earth Now Has a Ring
If you’re Sci-Fi fan, you’ve undoubtedly seen more than one movie depicting a habitable planet bearing a striking resemblance to Saturn; the main character looking up to see a large, color set of ring spanning from horizon to horizon. And if you were tempted to scoff at the prospect as being no more than an artifact of a fertile imagination, think again. Though the natural ring systems found in our solar system are observed exclusively around gas giant planets — planets with no solid surface on which to land and a crushing gravitational field — Earth does nonetheless have its own ring system. It’s a artificial ring composed entirely of thousands of satellites, both operational and dead, spent rocket bodies plus many more thousands of space hardware fragments that are the products of accidental collisions with one another, secondary collisions of fragments with fragments and even the intentional shooting down of the Fan Yun 1C spacecraft by China as part of an anti-satellite weapon test in 2007. That one event drastically increased the number of pieces of space junk and made much of low earth orbit a much more dangerous place, the impact of which (pun intended) is felt so much more so now that we have people there aboard the International Space Station, tending the orbital laboratory 24 hours a day, 365 days a year.
Two nights ago such a piece of debris came uncomfortably close to the space station… again. It’s not the first time, and will certainly not be the last. The event underscores the need for a plan to be put in place to 1) stop placing more junk into orbit and 2) begin to remove that which is already there. The US is in the position to lead the charge, but so far there’s been nothing more than talk while one orbit after another fills up with junk at an exponential rate.
Perhaps it wouldn’t be quite so bad if Earth’s ring could at least treat us to the same color display as Saturn with it’s shimmering reds, greens and blues wrapping around the planet’s equator, but it is not to be. What we have is a belt of hypervelocity junk, which represents an increasing menace to space navigation, itself set to increase as commercial, human space flight begins to come into its own.
There are things the government can do right now to help alleviate some of the threat. As it stands, US policy for retiring a spent weather satellite in the geosynchronous orbit is not to return it to earth once its life is over as it should be but to simply boost it into a higher — so-called super-synchronous — orbit and turn it off. This strategy continues to add to the population of junk; it cannot and should not be maintained in the future. It must change and the sooner, the better.
Even this strategy is not adhered to by all spacecraft operators. SpaceNews reports that, “In 2008 and 2009 alone, four geostationary orbiting satellites — the U.S. EchoStar 2 and the Russian Gorizont 33, Raduga 1-5, Cosmos 2371 and Cosmos 2379 — were all left to expire on the geostationary arc without performing end-of-mission orbit-raising maneuvers. EchoStar 2 failed suddenly in orbit and could not be moved.” Then, of course, there is the occasional errant spacecraft like Galaxy 15, which recently ceased responding to commands from the ground and is now plowing uncontrolled through geosynchronous orbit.
The White House has issued orders to NASA and the DOD to begin researching techniques for the mitigation and removal of space debris, but this could take many years before an effective, affordable strategy of space junk removal is put in force. There are thousands of pieces of junk, and to physically remove each one could cost many millions of dollars per piece. Then again, one can easily see the potential for jobs creation in the endeavor.
In the meantime, policy must change. We must adopt strict rules to prevent spacecraft operators from leaving dead satellites in space. Let’s not wait until the multi-billion-dollar International Space Station is crippled or destroyed before we become proactive.
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Space Collisions and Opportunity for Entrepreneurship
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Imagine if, whenever automobiles became undriveable, the owner could simply pull over to the side of the road and abandon the vehicle. It wouldn’t take long before the derelicts accumulated to the point where they were a hazard to driving. Perhaps those cars are completely clear of the road, perhaps not. Perhaps they have been driven out of gas, and maybe some have full tanks. And maybe a driver in distress looking for a place to pull over to change a tire could avoid the junk cars or perhaps he would hit one full of fuel and… well, you get the idea. There are a lot of unknowns in this situation. And we all agree that leaving junk vehicles on the side of the road is a completely unacceptable practice. No local government anywhere in the country would allow such a thing.
Yet this is exactly the kind of thing going on above our heads. Operators of obsolete, debilitated or depleted spacecraft are doing something very similar to “pulling over.” They’re placing these spacecraft into what’s called a “graveyard orbit” then turning them off and abandoning them. A clearer case of “out of site, out of mind” thinking, you will never find. And it will take a change of space policy to fix this situation, one written by legislators savvy to these operations practices. They will need to understand that current policies to “de-orbit” spacecraft abjectly fail to remove risks imposed by derelict spacecraft, due in great part to the false sense of security created by the term.
For the record, the term “de-orbit” is not synonymous with re-entry and thus a return to earth! It simply means to remove an object from the orbit it currently occupies. In the case of geosynchronous orbiting spacecraft like those used to carry television signals or even weather observation satellites, end of life means being placed into a super-synchronous or “graveyard “orbit. Translation: boost it up another 350 km (about 217 miles), turn it off and forget about it. All responsibility for the dead piece of space junk you’ve just generated is then relinquished by all currently-existing policies and international agreements. Were the practice to be used sparingly, there might be a legitimate argument that there is no need for concern. When this strategy was initially adopted, this was the case, but no longer. Today, spacecraft operators are continually replacing spacecraft and placing the defunct ones into the graveyard orbit, a convention that is unsustainable.
Part of the problem is attitudes. Many spacecraft operators subscribe to something known in the business as the “big sky” principle. Simply stated, it means that the sky in space is so vast that the likelihood of colliding with another object is infinitesimally small: essentially zero. But we’re beginning to see the fallacies in this thinking. Take for example the recent collision of an active US satellite with that of the defunct Russian Cosmos spacecraft. Both operated in low earth orbit where orbital velocities are much higher than geosynchronous orbit. The half-ton Iridium collided with the one-ton Cosmos at a relative velocity of roughly 15,000 miles per hour, generating some 1200 pieces of debris that will linger in the two original orbits for years to come as a hazard to navigation.
The problem of space debris is being tackled primarily from the standpoint of mitigation. That is, satellites and other objects such as spent rocket bodies are tracked, probabilities of collisions computed and notifications sent to operators when a significant risk is identified; the idea being to give them time to maneuver out of the way. As we can see from the example just given, it’s a strategy that is not perfect.
Some very ingenious engineering solutions for removing spent satellites from orbit have recently been published. One example is the “Terminator Tether” by Tethers Unlimited. Designed for satellites flying in low earth orbit, it’s a devise that is bolted onto the spacecraft before launch. When the satellite is at the end of its life, the device deploys a 5-kilometer-long tether below the spacecraft, which then takes advantage of the physics of interactions between the tether and the earth’s ionosphere to produce a drag on the spacecraft. That drag slows down the satellite until it no longer has sufficient speed to remain in orbit, at which point it enters the atmosphere and burns up. Tether Applications offers a similar device and though they have not re-entered any spacecraft, has flight tested some of their designs.
Devices like the tether are a great idea for future satellites, but what about those that are already up there? Many ideas have been put forward for their removal from using low-powered lasers to gradually slow down the satellite until it falls from space to literally blasting it out of the sky, which, as we’ve seen from example, is a solution that causes as many hazards as the problem it’s meant to solve. But any way you slice it, the problem of removing existing, dead satellites from orbit is one that presents a great challenge, one that seems ideally suited for the private sector.
An idea that I believe to have great merit and promise was recently proposed by attorney Jim Dunstan. He suggests levying fees on launch vehicle and spacecraft operators, which are then escrowed for the purpose of offering “bounties” on objects in orbit based on their size and the risk they pose. If consideration is given not to overburden the industry with too high a fee structure, this plan would simultaneously remove dangerous objects from space and the hazards to future space navigation they impose and create a new market for space entrepreneurs. And of course, the option for operators to themselves pay remediation companies for removal could also be explored.
This could, in turn, open yet another market: the salvage of spacecraft parts from orbit. Bear in mind that many of the dead spacecraft in orbit right now are in that state because they simply ran out of fuel, suffered a batter failure or other, similar problem that, while it ended the mission, did not destroy the spacecraft itself. The bulk of the spacecraft remains in tact and most of its components are still operable. How much is out there? Dennis Wingo, author of the book Moonrush: Improving Life On Earth with the Moon’s Resources (Apogee Books Space Series 43, Ontario, Canada: 260 pages) says, “There’s well over half a million kilos’ worth of hardware in GEO… There’s big solar arrays, there’s transponders: you could actually go up there and bring some of this stuff together, create a big transponder park, and recycle this hardware.”
The scenario is easy to envision whereby companies could establish a space station to serve as a base of operations, from which these and other commercial ventures are carried out. And it’s a scenario that can be played out using the scientific and engineering know how that exists in the private sector, now. These are yet more examples of the limitless opportunities that space has to offer us today!
I’ll borrow a term used by Mr. Wingo in his book by stating that government can act as the “macroeconomic enabler” such as they are today in helping private space companies with NASA’s COTS contract (see Commercial Human Space Transportation Now, May 11) and in the proposed plan to levee fees, which are then offered as bounties on dangerous space objects. Government and private industry can act in tandem to solve these problems and, in doing so, open up whole new industries and markets, but there’s much room for growing that symbiotic relationship. You can play a part in making that happen by writing or e-mailing your congressman and telling him or her that government and the private sector must work together and more often. Tell them that you want to see the limitless opportunities that space has to offer available for you and for your children. Tell them that space need not be either government or private sector but that they should be viewed as partners in space.
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