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Posts Tagged ‘space debris’

The idea is simple enough: at altitudes below about 560 miles, the drag of the atmosphere naturally decays orbits, causing smaller bits of debris to slowly lose their orbits over the course of a couple of decades. But above that limit small debris--the stuff smaller than 10 centimeters that is very hard to track--can stay up there for decades or even centuries, threatening to damage satellites and spacecraft.

A researcher at the U.S. NRL suggests releasing a cloud of tungsten dust at about 680 miles up, creating a layer of particles that will completely shroud the planet. The particles themselves will be just 30 micrometers across, but because tungsten is nearly twice as dense as lead they will still add effective weight to any small debris they latch on to.

This, the thinking goes, will drag small debris pieces down below that 560 mile marker over a decade or two, where natural forces will take over and the debris will burn up, scrubbing orbital space clean of small debris over the next 25 or 35 years.

If you haven’t begun verbally objecting to this idea at this point, feel free to begin now. First of all, what effect is this tungsten cloud going to have on all of the equipment we don’t want to deorbit, like our functioning satellites? What about the delicate optics on our science satellites and the the solar panels that keep our communications satellites powered up? And, as Tech Review notes, might this tungsten layer obscure our view of the cosmos, reducing the power of our earth-based telescopes?

Put another way, this problem began when we started putting stuff in orbit that wasn’t naturally there before. And while you’re not going to get an argument against human space ambitions on this site, we do respect the notion that perhaps putting more junk into space isn’t the answer here.

But, while the NRL paper does concede the idea needs some finessing, the major objections can be managed for if not dealt with outright. Future satellites could be designed to either move above the cloud or to exist within it. And the tungsten shouldn’t adversely affect the ones that are already up there anyhow, it says, as they are adequately shielded for heat and radiation already.

We’re still not sold, but desperate times call for desperate measures. If the day comes when the space debris problem gets so bad our satellites are falling from the sky anyhow--as some say it will--a tungsten cloud may be a reasonable solution to scrub the skies clean.

Read the paper at arXiv.

[Technology Review]

Space debris has already threatened the International Space Station, and satellites are in harm’s way all the time. But most of the time, the station or satellite in question can be moved out of the way, letting the space junk continue on its orbital path. It’s easier to fire a couple thrusters than to throw out a giant space net, tether or solar sail.

The laser system would take the opposite tack, nudging space junk and letting satellites stay put. It would ideally be based near one of the Earth’s poles, and would use photon pressure to disturb an object’s orbit, according to James Mason and colleagues at NASA’s Ames Research Center. Photons would target the debris every time it passed over the laser, and with enough pressure, it could nudge an object out of orbit enough to avoid a future collision.

It could even be used to de-orbit the space junk entirely, perhaps by moving it low enough that atmospheric drag causes it to re-enter the atmosphere — so long as it's small enough to burn up, so there would be no laser-propelled garbage raining down on Earth.

Previous space junk removal concepts have proposed blowing up or incinerating the debris, but a laser powerful enough to blow up some orbiting garbage would also be powerful enough to blow up some strategic assets, too. It’s a non-starter for political reasons.

This laser is pretty weak, however, at just 5 kilowatts. Mason and colleagues say it could nudge up to 10 objects a day.

They say it could reverse the “Kessler syndrome,” a phenomenon wherein new debris formation outstrips the pace at which it falls out of orbit and burns up. As Technology Review's arXiv blog explains, it’s named for NASA scientist Donald Kessler, who described the problem in the 1970s. He said colliding space junk could trigger a cascade of collisions that would create ever more space debris in ever more unpredictable orbits. This may already be happening, as evidenced by the collision between the Iridium 33 and Cosmos 2251 satellites in January 2009, as well as China’s destruction of its Fengyun 1C satellite in 2007. Both incidents created ongoing problems.

Mason and colleagues say much more research is needed, but the laser system could be a feasible, fiscally prudent alternative to space debris removal — nothing would be launched into space except photons, so there would be nothing else to add to the junk.

[via Technology Review]

JAXA, Japan's Aerospace Exploration Agency, is collaborating with Nitto Seimo Co, a fishing net manufacturer responsible for the first strong knot-less net, on a very special kind of net. This one will be made of super strong 1mm triple-layered threads, which when extended will span several kilometers of space. The net will be launched with a satellite, and when detached, will begin orbiting Earth, collecting the miscellaneous engine parts, particles, and abandoned satellites that litter that region.

Interestingly, the net is designed as a one-time-use tool. That's different from DARPA's proposed net strategy, which would employ hundreds of nets aimed at redirecting space debris into the atmosphere to be either burned up or land harmlessly in the South Pacific. But this Japanese net is much larger, intended to collect as much debris as possible, and then let the Earth's magnetic field slowly draw it closer and closer to the planet, at which point it (and all of the debris in its clutches) will combust in the atmosphere.

[Telegraph]

For most people – and even for the very companies and institutions causing the problem – all that orbiting detritus isn’t visible and has yet to cause a serious calamity or loss of life. It’s out of sight and couldn’t be further from the mind. But according to think tank RAND, the author of the DARPA report, the same principles used to approach pollution problems on Earth – even visibility problems – can be tweaked to work in space.

A Superfund for space, the report says, could make space polluters pay for the cleanup of low Earth orbit much as polluting industries are held accountable for cleaning up their fouled real estate on Earth. But, like Superfund, it could also support those cleanup efforts with help from the space community. But perhaps more importantly, it could help both governments and private industry reduce their outputs of space debris and cultivate a space culture in which creating debris is considered unacceptable.

One of the report’s authors likens the problem to this past summer’s BP oil spill in the Gulf of Mexico – the initial spill garnered some concern, but once the huge oil slicks and oil-laden birds became visible, public awareness (and righteous outrage) grew. By making the space debris issue a shared problem, a space Superfund could instigate more cooperative engagement to solve the problem.

And like the BP oil spill, the report’s authors acknowledge, simply having a “remedy” on the shelf won’t suffice. A space Superfund could develop and test effective methods of containing and dealing with space debris before a major disaster happens in space so that industry or agencies aren’t casting about for a solution while an orbital calamity is unfolding.

Because if containing a mess 5,000 feet underwater appeared difficult, just wait until the scenario is replaying itself 200 miles above the Earth.

[SPACE]

This pod could help reopen orbits that are currently inaccessible to future spacecraft due to the amount of shredded metal and empty hulls of dead satellites floating around. Using an ion drive, it will gently nudge these useless scraps out of orbit. Energia plans to have completed testing on the pod, which will have a nuclear power core, by 2020, and have it in service no later than three years after. It will have a lifespan of about 15 years, enough time to make a significant dent in our space debris problem.

Energia is also working on developing an “interceptor” spacecraft using similar technology. This craft would be able to derail any incoming comets or other outer-space projectiles that might be hurtling towards Earth, and change their trajectory just enough that they miss us.

[Space Daily via Fast Company]

A similar maneuver was planned just a couple of months ago when a piece of China's Feng Yun satellite threatened the station. This time, the junk is American, a piece of UARS.

Is it almost time to deploy the giant space nets? Or will we have to wait till space junk disables our communication networks and lands in our backyard?

[Astro Bob]

Villagers in the area awoke last night to quite a ruckus, thinking that an earthquake was underway. Upon exploration, they instead found what appears to be a sizeable chunk of the rocket used to launch Chang’e II toward the moon in a launch on Friday. Fortunately, the debris fell harmlessly onto rural land, injuring no one and causing no property damage. Had the space junk rained down on one of China’s many densely packed population centers who knows what might have happened?

The good news: though the rocket debris hurtling back to the surface intact wasn’t exactly part of China’s plan, Chang’e II is thus far a successful mission. The orbiter is China’s second lunar exploration mission and will spend six months observing the moon’s surface in high-res in search of future landing sites for spacecraft. Let’s hope that lunar touch-down is a bit less abrupt than last night’s rocket landing.

[CinaOggi via Gizmodo]