Space Debris Affirmative
Brink: A lot of Debris (3/7)
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Brink: A lot of Debris (3/7)Amount of space debris increasing now-making the lower earth orbit potentially uninhabitable. David 11(Leonard David has been reporting on the space industry for more than five decades. He is a winner of this year’s National Space Club Press Award and a past editor-in-chief of the National Space Society's Ad Astra and Space World magazines. He has written for Space.com since 1999., space.com, Ugly truth of space junk: No feasible solutions Debris continues to multiply, but there's no affordable way to eliminate it , 5/10/11, http://www.msnbc.msn.com/id/42975224/ns/technology_and_science-space/t/ugly-truth-space-junk-no-feasible-solutions/, rn) Point of no return The concern over orbital debris has been building for several reasons, said Marshall Kaplan, an orbital debris expert within the Space Department at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. In Kaplan's view, spacefaring nations have passed the point of "no return," with the accumulation of debris objects in low-Earth orbits steadily building over the past 50 years. Add to the clutter, the leftovers of China’s anti-satellite (ASAT) test in 2007. "The fact that this single event increased the number of debris objects by roughly 25 percent was not as important as the location of the intercept. The event took place at an altitude of 865 kilometers, right in the middle of the most congested region of low-orbiting satellites," Kaplan pointed out. Toss into the brew the collision of an Iridium satellite with an expired Russian Cosmos spacecraft in February 2009 — at an altitude similar to that of China’s ASAT test. As a result of 50 years of launching satellites and these two events, the altitude band from about 435 miles to a little over 800 miles has accumulated possibly millions of debris objects ranging from a few millimeters to a few meters, Kaplan said.
So what can be done? For a start, we can try not to make the problem worse. This can be as simple as ensuring that protective covers are tethered to spacecraft rather than jettisoned. It also includes sticking to international guidelines intended to minimise new debris, drawn up by the Inter-Agency Space Debris Coordination Committee (IADC), which represents all the world's major space agencies. These require, for example, that spacecraft in low Earth orbit must be made to re-enter the atmosphere and burn up within 25 years of finishing their missions. Communications satellites in the high-altitude geostationary orbit cannot be brought down practically. Instead, the guidelines say operators should use the last of their satellites' fuel to boost them into a "graveyard orbit" 300 kilometres higher up (see diagram, page 49). Yet even with these guidelines in place, Klinkrad says, "It is pretty common to leave your spacecraft stranded." Twelve satellites in geosynchronous orbit failed in 2008, but only seven were boosted in accordance with the guidelines. And more than 800 of the 1200 trackable objects near the geostationary corridor are not active satellites. The most recent drama there involved the communications satellite Galaxy 15, which became widely known as the "zombie satellite" (see "March of the zombie", page 48). Even if the guidelines were followed to the letter, the number of debris fragments would still go up. "We could even stop launching and the amount of debris would still rise," says Hugh Lewis of the University of Southampton in the UK. That's because accidental collisions would still happen. Kessler predicted that if nothing were done to remove debris, we would begin to suffer the consequences in 2000. As it turned out, the Iridium and Kosmos collision did not happen for another nine years. The main reason for our period of grace may be that modern satellites are manoeuvrable. When a piece of space debris is seen approaching, satellite operators can move their "bird" Brink: A lot of Debris (4/7)(continued) out of the way. Such ducking and dodging used to be rare.Not any longer. A few years ago, operators were receiving one or two warnings of space debris a month; now it can be two or three times a week. Every time a new warning comes in, they must begin a 72-hour tracking campaign using ground-based radar to refine the orbit of the object and establish whether to take evasive action or not. As if accidents weren't bad enough, in 2007 China launched a missile that destroyed their Feng Yun 1C weather satellite. It was an ostentatious display of military capability, perhaps intended as a warning to anyone thinking of putting weapons into space, but it also sent shock waves through space operations centres around the world. That incident, in combination with the Iridium smash in 2009, created so much debris that the number of fragments in low Earth orbit large enough to be tracked from the ground almost doubled. We must act now to avoid further dipping into the Kessler effect: the point of no return takes place around 2055. The Times in 10 (legit newspaper, Junk in space; Our world is surrounded by debris - and doing nothing is not an option, June 3 2010, http://www.lexisnexis.com/hottopics/lnacademic/. DT) Even after the shielding upgrade the risks seem unnervingly high, with a catastrophic risk of 5 per cent and a penetration risk of 29 per cent - 5 per cent short of Nasa's requirements. It was not surprising, then, that when the Columbia space shuttle disintegrated during re-entry in February 2003, one of the first causes considered was an orbital debris strike. "That tells you that they think of this as a fairly significant risk," Lewis says. But Johnson plays down these risks, arguing that the ISS is in a relatively low orbit, where there is less debris. Because of this, collision avoidance maneuvers are only necessary roughly once a year. Even so, Johnson admits that small debris does pose a threat. "The ISS has the greatest amount of shielding of any spacecraft deployed. But it can only shield against objects up to about 1cm." So since only objects bigger than 10cm can be tracked - or at best 5cm at very low orbits - this leaves an alarming gap. In light of this, Nasa is trying to improve its tracking capabilities, says Johnson. But this is small comfort to everyone else, as not every spacecraft carries a lot of armour. For the vast majority of satellites and spacecraft, even debris smaller than 1cm poses a risk. Without active debris removal, these risks are set to increase steadily over time. And despite the 25-year removal guidelines, it is inevitable that new debris will end up in orbit. "Not all spacecraft will be removed because they may suffer a failure," says Lewis. For example, geostationary satellites suffer only a 2 per cent failure rate. "Not all operators will follow the guidelines. It's not legally enforceable," says Lewis. How you define the point at which Earth's orbit will become unusable very much depends on your perception of what risks are acceptable. From Nasa's perspective, there is still plenty of time. "We're talking about hundreds of years of doing nothing before it gets to be a serious issue," says Johnson. But Nasa's idea of "safe" is unlikely to tally with that of the average space tourist. What's more, even if it does take 200 years to get to this stage, a tipping point will arrive long before that. A round 2055 we will start to see a shift in the main cause of debris. Exploding obsolete satellites will cease to be the main source of junk and collision debris will take over. "That's the critical point in our future," says Lewis. "In fact some people say we have already passed another critical point." This is the well-known space industry phenomenon called the Kessler syndrome. Ignoring the creation of new debris through collisions, this is the scenario in which the rate of objects being sent into orbit exceeds the rate at which they are being removed by atmospheric decay. In simple terms, it is the point at which we are putting more junk into space than we are taking out. Based on such a rudimentary definition, we are already in the Kessler syndrome. Directory: files files -> Answer True False 2 points Question 2 files -> Integer programming and game theory files -> 4 Integer Programming files -> Bpa vehicle Window Repair Scenario #1 task: Procure vehicle window relacement. 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