Aggregate too much debris in certain areas, and low-earth orbit becomes an increasingly difficult and far costlier environment for commercial companies. Today, satellite operators periodically manoeuvre their birds to avoid object strikes just as Nasa must do with the International Space Station. The key, however, is knowing what’s headed your way.
“Knowing where stuff is is the first part of the problem,” said Bill Ailor, a research fellow at the Aerospace Corp, which specialises in tracking space debris. “Over the longer term we need to be getting much better [tracking] data so satellite operators don’t move unnecessarily.”
To that end, some entrepreneurs see profit potential in helping to catalogue better all that junk up there, the detritus of decades of unmanned and manned space flight. From launch, to operations, to disposal, satellite operators need help monitoring orbital paths and the potential for objects to stray into a collision course.
One such business is LeoLabs Inc, of Menlo Park, California. Spun out of research centre SRI International last year, the company has announced it raised $4 million from a group of investors, including Airbus Ventures, the San Jose, California-based venture capital fund established by Airbus Group two years ago. LeoLab ‘s radar technology, to be used to keep an eye on all those pieces of high-speed trouble, evolved from research into earth’s ionosphere at SRI.
LeoLabs said it has opened a second radar-tracking facility, in Midland, Texas, joining one in central Alaska. Ultimately, the company aims to have a half dozen such sites. LeoLabs says its two radar centres can track 95 per cent of the 13,000 larger objects in low-earth orbit that the US Defence Department monitors. The company plans to track almost 250,000 objects as its radar network expands.
“Commercial space in low-earth orbit is growing so rapidly we really have to run quickly to keep up,” Dan Ceperley, LeoLabs’ chief executive officer, said in an interview.
The clutter in low-earth orbit has grown rapidly over the past decade. In January 2007, the Chinese government destroyed an aged weather satellite in a missile test, creating what was estimated to be 2,500 pieces of new debris. That was followed by the February 2009 collision of a defunct 1,900-pound Russian Cosmos satellite with a 1,200-pound Iridium Communications Inc. satellite 490 miles above Siberia, generating even more orbital waste.
“Both of those events greatly increased the amount of debris in the near-Earth space environment, thus pushing the threat posed by orbital debris even further towards what was described more than 15 years ago as ‘on the verge of becoming significant’,” the National Research Council wrote in a 2011 report .
Another potential threat lies with the European Space Agency’s Envisat earth-observation satellite, an eight-ton, 30-foot-long behemoth that ceased responding in April 2012. Envisat orbits at an altitude of 480 miles in a place where it could become a source of significant debris should it be struck. In its current state, the satellite will orbit for about 150 years before it degrades and falls into the atmosphere.
Yet even though there’s plenty of junk to track, the US has been generous about sharing data with its neighbours on the size of the stuff flying by and on where it is. Historically, the Defence Department has been the most authoritative tracker in deploying technology to monitor objects that could threaten satellites, both military and civilian, and Nasa missions. The US military now tracks some 20,000 orbital objects via radar and maintains a public database that satellite operators and others can consult.
The Air Force also alerts operators to potential collisions and has contracted with Lockheed Martin to construct a $1 billion next-generation “Space Fence” radar system capable of tracking as many as 200,000 objects. The new fence “will be able to track objects as small as a peanut M&M in low-earth orbit,” a Lockheed project manager said in November, when the Air Force and Army opened a new Air Force Space Fence Operations Center in Huntsville, Alabama. The project is expected to become operational late next year.
Ceperley, the LeoLabs’ CEO, says this public largesse about data sharing won’t dent business for commercial debris monitors. That’s because many operators are eager for richer automated data, greater debris detail and resolution, plus longer lead times for trajectory predictions, which would allow for better traffic management. As part of its service package, LeoLabs can also customise data to a customer’s specific needs.
Low-earth orbit is likely to see even more business ventures in coming years. Earlier last month, the Indian Space Research Organisation successfully launched 104 satellites for seven nations aboard a single rocket, most of them small “CubeSats” for a San Francisco-based imaging firm. These smaller satellites are far smaller and less-expensive than traditional designs, with thousands likely to be deployed over time.
Moreover, an array of companies, including Airbus and Richard Branson’s Virgin Galactic, are also exploring new ways to launch mini-satellites, moving beyond the domain of large, costly rockets. Advancements in such work would likely lead to even more objects to track for low-earth orbit operators.
Space-junk expansion also raises questions about the status and pace of a “collision cascading” effect called the Kessler Syndrome, in which flying junk collides and begets new junk, which collides with more junk again, eventually making low-earth orbit commercially dubious. The effect is named after Donald Kessler, a retired Nasa astrophysicist who described the scenario in a 1978 paper. Among debris researchers, a debate exists on whether this has already begun, Ailor said.
This nightmarish situation was illustrated dramatically, albeit in inaccurate Hollywood fashion, by Sandra Bullock and George Clooney in the 2013 film Gravity, which depicted the Space Shuttle’s destruction by debris after Russia explodes a satellite. In a 2007 interview, even Kessler said that many people had exaggerated the worst-case outcomes of his predictions.
“We’re not there yet, and I don’t want to raise this warning that the situation is spiralling out of control, because it’s just not,” Ceperley said, calling the Kessler scenario “kind of a bogeyman off on the horizon.”
Ultimately, governments will likely need to regulate “best practices” more closely for players operating in low-earth orbit, with rules mandating vehicle disposal and new funding for research into how to remove larger objects, Ailor and Ceperley said. “It’s kind of like the Wild West,” Ceperley said. “There’s this growing understanding that with more and more satellites going to space, [debris] could become a problem.”
There are also few techniques for safe disposal of a satellite at the end of its life, or one that goes kaput, or a spent rocket. Researchers have begun modeling a variety of approaches, including giant mesh tethers and a 50-gram, paper-thin spacecraft that would “blanket” space trash and propel it to the atmosphere, so it can burn up. “It’s very easy to get something into orbit, and it’s the dickens to get it out,” says Ailor.
Difficulty notwithstanding, the health of the commercial space business will be determined in part by the tidiness of that stretch of the final frontier reaching 1,200 miles into the sky. The more space junk there is, the more often satellites will need to be moved, and the better shielded they must be to withstand frequent plinks by space projectiles. Both of these boost operating expenses.
“It’s kind of the human way,” Ailor said. “You look at the oceans or the environment or anything, and you think it’s an infinite resource-and it isn’t.”
Credit of this source is from: http://gulfnews.com/culture/science/the-danger-of-earth-s-orbiting-junkyard-1.2006347