Feb 13, 2009

Q-n-A # 2: Mr. Obama, are you aware of the seriousness of space debris?

The recent space crash debris will orbit the Earth for next 10,000 years.
MOSCOW Russia – Debris from this week's satellite collision could circle Earth for up to 10,000 years, threatening many other satellites in an already-crowded area, Russia's Mission Control chief said Friday.
Vladimir Solovyov said Tuesday's smashup of a derelict Russian military satellite and a working U.S. Iridium commercial satellite occurred some 500 miles (800 kilometers) above Earth the busiest part of near-Earth space.
"800 kilometers is a very popular orbit which is used by Earth-tracking and communications satellites," Solovyov told reporters. "The clouds of debris pose a serious danger to them."
Solovyov told reporters even tiny fragments could pose a serious threat to spacecraft made of light alloys because both travel at such a high speed.
Most fragments are concentrated near the collision course, but Maj.-Gen. Alexander Yakushin, chief of staff of the Russian military Space Forces, said some debris was thrown into other orbits, ranging from 300 to 800 miles (500-1,300 kilometers) above Earth.
The U.S. military already tracks 18,000 objects in orbit, but no one has any idea yet exactly how many extra pieces of space junk were generated by the collision or how big they might be. Space experts say the collision created hundreds of fragments, maybe thousands, if tiny pieces are included.
Meanwhile, there's no global air traffic control system that tracks the position of all satellites.
The U.S. military only monitors certain threats in space because it lacks the resources to do everything, said Maj. Regina Winchester, spokeswoman for U.S. Strategic Command, which oversees the military Space Surveillance Network.
"With the amount of spacecraft and debris in orbit, the probability of collisions is going up more rapidly," said John Higginbotham, chief executive of Integral Systems Inc., a Lanham, Maryland-based company that runs ground support systems for satellites.
Tuesday's collision was the first high-speed impact between two intact spacecraft, NASA officials said. The Iridium craft weighed 1,235 pounds (560 kilograms), and the Russian craft nearly a ton.
Both NASA and Russia's Roscosmos agencies said, however, there was little risk to the international space station and its three crew members. The station orbits about 230 miles (370 kilometers) above Earth, far below the collision point.
Russian Mission Control spokesman Valery Lyndin noted the station's orbit has been adjusted in the past to dodge space debris, with Russian and U.S. space officials working together to perform such maneuvers.
Meanwhile, an unmanned Russian cargo ship docked smoothly Friday at the international space station delivering supplies for its three-member crew.
Lyndin said the Progress M-66 spacecraft delivered about 2.5 metric tons (2.75 tons) of water, food, fuel, oxygen and other supplies as well as a second new Russian-made, computerized space suit for space walks.
American astronauts Michael Fincke and Sandra Magnus are aboard the station along with Russian Yuri Lonchakov. The crew size will be doubled to six members later this year.
Picture shows actual space debris orbiting our planet....

Iridium satellites follow near-polar orbits at an altitude of 780 km. The network consists of 66 active satellites that fly in formation in six orbital planes. The planes are evenly spaced around the planet, each with 11 satellites that are equidistant from each other in the same orbital plane. In 2007, the company said it received about 400 notices per week that an object was coming within 5 km of one of its satellites, but the uncertainty in such calculations is large.

What really happened -
Two satellites smashed into each other on Tuesday, creating a mess of space debris that is still being counted.
The collision, which involved an Iridium communication satellite and a defunct Russian satellite, is the first to occur between two intact spacecraft but experts say it is unlikely to be the last.
How did this happen? New Scientist takes a closer look at whether the collision could have been avoided.
Is anyone keeping an eye on everything that's up there?
The most comprehensive catalogue of space objects is maintained by the Pentagon, which uses optical telescopes and radar to track more than 18,000 objects measuring 10 centimetres across or more. The US Air Force compiles data on the orbits of these objects. A large fraction of the information is made publicly available on the website space-track.org.
Does the US government calculate the risk of collision for every spacecraft?
No. The military regularly calculates the risk of collision for priority spacecraft, including military satellites, the International Space Station, and the space shuttle, when it is in orbit, warning operators if there is a risk of a close encounter.
But not all satellites are given that treatment. "There just isn't the manpower or computer capabilities to do that at this point," says Andy Roake, a spokesperson for Air Force Space Command.
Why is it so hard to calculate whether two objects will collide?
If every object orbiting the Earth stayed on a simple path, multiple observations of an object would yield precise estimates of its orbit and position. But orbits change.
Unexpected glitches - such as accidental releases of fuel - can shift a satellite's orbit.
But so can the drag from Earth's atmosphere, as well as gravitational tugs from the Sun, Moon, and Earth, which is somewhat squashed in shape. The military uses models of these environmental perturbations to help refine its estimates of satellite orbits.
How well can the military estimate satellites' orbits?
That's not clear, as the Pentagon may not release its best estimates of satellite orbits.
But space analysts say the data the Pentagon does make publicly available is not precise enough to accurately estimate the probability that two objects might collide.
Tuesday's smashup is a case in point. Using a collision prediction program to perform a retroactive analysis of the satellites' orbits, aerospace analyst T S Kelso found that the Pentagon's public data showed that the two satellites would have missed each other by 584 metres.
But he says the uncertainty in that distance could be several kilometers. "There's no reason looking at the data that was available [to think the Russian satellite] was an immediate threat," says Kelso, who has been working with Iridium to assess the risk that the debris could collide with other satellites in the firm's fleet (see image above right).
Could Iridium have predicted a collision?
Since Iridium likely communicated directly with its now-destroyed spacecraft, chances are the firm had a more precise measure of its position and orbit than could be determined by radar or telescopes.
Still, uncertainties in the orbit of the Russian satellite might have made it difficult for the firm to assess the probability of a collision. "It's like driving a car with a GPS unit and the windows blacked out. You know where you are, but you have no idea where the other cars are," says Brian Weeden, a technical consultant for the Secure World Foundation in Superior, Colorado.
Indeed, according to Reuters, John Campbell, Iridium's executive vice president for government programs, said at a forum in June 2007: "Even if we had a report of an impending direct collision, the error would be such that we might manoeuvre into a collision as well as move away from one."
At the time, Campbell said that Iridium was receiving an average of 400 reports per week of objects coming within 5 km of one of their satellites. The reports were issued by the US Strategic Command's Joint Space Operations Center. "The ability actually to do anything with all the information is pretty limited," he said at the time, putting the risk of a collision from the close approaches at "about 1 in 50 million."
But an Iridium spokesperson told Reuters that the company did not get a warning before Tuesday's collision: "If the organizations that monitor space had that information available, we are confident they would have shared it with us."

Watch the You-tube Video (debris from satellite collision, sorry this video has no sound)

1 comment:

  1. Hola que tal

    Soy Bocha, creador del blog Abran Cancha. Estoy muy interesado en tener un intercambio de links con tu blog, la verdad que me ha gustado mucho y seria un honor tenerlo entre mis enlaces. Un abrazo grande y te digo que aunque nuestro blogs sean de temáticas diferentes… el intercambio te ayudaría mucho, para que tus ideas puedan llegar a más gente.

    Agrégame a seguidores…



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