“Once the rockets are up, who cares where they come down?
That’s not my department,” says Wernher von Braun. — From the song “Werner von Braun,” lyrics by Tom Lehrer
The misconception about Earth orbit is, it’s gravity free. Nope. Sorry. In fact it’s gravity that keeps orbiting satellites from flying off into space.
Satellites aren’t free of Earth’s atmosphere either. Though very thin, there is air up there. It’s enough to add a tiny frictional component to orbital calculations.
If left in orbit long enough that tiny bit of drag begins to pull satellites back toward Earth. That’s what happened tonight with the Gravity field and steady-state Ocean Circulation Explorer – GOCE.
It was not unexpected. Without asking our permission GOCE was built with little concern for its demise.
The satellite was launched in 2009 to map variations in the Earth’s gravity. As the exaggerated image above shows, gravity isn’t the same everywhere. Knowing more about this force should allow scientists to know more natural phenomena like ocean circulation and Earth’s core. I have no problem with this science.
However, there is a part of GOCE that troubles me greatly. The satellite fell to Earth as an unguided missile a few hours ago! Sketchy estimates say 75% burned harmlessly before reaching ground. That left about 500 pounds intact. That was always the plan from day one.
Authorities have tried to be reassuring.
“In the 56 years of spaceflight, some 15 000 tonnes of man-made space objects have reentered the atmosphere without causing a single human injury to date.”–Heiner Klinkrad, Head of ESA’s Space Debris Office
True indeed… but why is there a “Space Debris Office” if this is harmless, like tinsel from the sky?
I’ve seen other quotes reminding us 2/3 of the Earth is covered by water and much of the rest of the planet is uninhabited. This was the same logic 16 year old learner’s permit holder Stef used to explain why she neither stopped nor looked while leaving our driveway. “There are never cars on our street,” she said at the time.
As of this hour no one’s called Progressive’s Flo to complain about space junk in the trunk. We were lucky.
This isn’t the first and probably won’t be the last time scientists play Russian roulette with incoming. Is this really the best way to do it?