Military Power

The collision between a U.S. and a Russian satellite over Siberia may have been accidental and the first of its kind, but experts say more crashes will inevitably occur and could have geopolitical consequences.

There are about 18,000 identifiable, man-made objects in space, including operational and defunct satellites, spent rocket boosters and debris. Experts said that while the risk of satellite collisions like Tuesday's was exceptionally small, now one had occurred it made another more likely.

"The problem with collisions like this is that they don't destroy satellites, they just create smaller ones, like fast moving shotguns, that are potentially much more damaging," said Diego.

The crash of two satellites has generated an estimated tens of thousands of pieces of space junk that could circle Earth and threaten other satellites for the next 10,000 years, space experts said Friday.

Solovyov said debris from the collision could stay in orbit for up to 10,000 years and even tiny fragments threaten spacecraft because both travel at such a high orbiting speed.

"At physical contact at orbital speeds, a hypersonic shock wave bursts outwards through the structures," Oberg said in e-mailed comments. "It literally shreds the material into confetti and detonates any fuels."

Most fragments are concentrated near the collision course, but Maj.-Gen. Alexander Yakushin, chief of staff of the Russian military's Space Forces, said some debris was thrown into other orbits, ranging from 300 to 800 miles (500-1,300 kilometers) above Earth.

Satellite 33442 orbits the earth every 91 minutes, circling at an inclination of 56.1 degrees to the Equator and gradually slowing down, destined to fall into the atmosphere in late spring or summer and burn up. Aficionados of satellites know that 33442 is a toolbag. A spacewalking astronaut let it slip last year, adding one more tiny, artificial moon to the junk in low Earth orbit.

"We expect, when all is said and done, there will be hundreds if not thousands of pieces larger than the four inches. We expect there will be tens or hundreds of thousands of pieces down to a centimeter or a millimeter," said Nicholas Johnson, NASA's chief scientist for orbital debris.

That's on top of material that's been accumulating in space for decades. China intentionally destroyed an aging satellite of its own in 2007 to demonstrate a new missile's capability. The obliteration of that satellite left behind 2,500 trackable fragments, Johnson said.

A bad situation got worse Tuesday. The two satellites, an American Iridium and a Russian Cosmos, came together 491 miles above the Earth, striking one another at roughly a 90-degree angle and at about 22,000 miles per hour. It's unknown whether they struck body-on-body or clipped one another in a more glancing blow. What's certain is that they left behind two debris clouds that have put NASA and the Pentagon on alert.

The space pollution can actually get worse over time, because objects strike one another and spew out smaller fragments, said David Wright, a physicist with the Union of Concerned Scientists. He warned of the danger of a runaway chain reaction, with junk smashing into junk and creating a veritable fog of speeding detritus all around the planet.

"The number of debris particles is going to continue to increase for at least two centuries as debris runs into other debris and grinds down the large pieces to smaller and smaller pieces. All of those can be deadly at orbital speeds," Wright said.