Here’s a cool image I haven’t seen before. It was taken this past Wednesday by NASA photographer Lauren Harnett at NASA’s Johnson Space Center in Houston, Texas and shows the International Space Station (ISS) crossing directly in front of the gibbous moon. To acquire multiple images of such a face-moving target across the small span of the moon’s diameter, Harnett set the camera to continuous burst mode of 9 frames per second.
It looks like the ISS is in lunar orbit until you remember it’s only 243 miles away and the moon some 240,000 miles in the background. The space station is one of more than 800 active satellites orbiting Earth, with just over 50% belonging to the United States. The next big players are Russia and China. Civilian satellites that perform scientific, commercial and government work make up the majority of the fleet. Non-functioning satellites, spent rocket stages, paint chips, lost bolts and exploded remains of satellites are far more numerous. The total amount of so-called space junk is estimated at 6,000 tons. Here are the estimated numbers of pieces of orbital debris from the Union of Concerned Scientists:
* Total pieces larger than about 4 inches in Earth orbit: 18,000
* Total pieces 1/4″ inch to 4″: 560,000
* Total pieces 1/25″ inch to 1/4″: 330,000,000
An object just four inches across is big enough and moving fast enough to cause major damage or an explosion if it were to hit an active satellite.
One large spacecraft – the Russian Phobos-Grunt probe – will soon leave the ranks of orbital trash when it plunges to Earth and burns up in the atmosphere around January 15. In a case of serendipitously perfect timing, the new IMAX movie “Space Junk 3D” opens January 13 at the Omnimax Dome in St. Louis. The film highlights our dependency on satellites and presents possible solutions to cleaning up debris in low Earth orbit before the threat to active satellites and astronauts becomes too great. Under consideration are electromagnetic tethers to snare a satellite and carry it to a lower orbit where it could burn up harmlessly in the atmosphere, solar sails and lasers. I hope you have an Omni near you to see the show.