What happens when a satellite stops working?

At some point in the near future, AT&T will be retiring two satellites. The satellite at the 119 location has been on its way out for years. That satellite was used primarily for standard definition programming. Hot on its heels, though, is the satellite at the 95 degree location. It’s been used for international programming.

The content on both satellites is moving quickly to the 99 and 103 locations, where much more massive, newer, and more capable satellites orbit the earth. But what becomes of those older satellites?

The simple fact

Satellites eventually wear out. Usually the first thing to go is the thruster fuel. Because satellites drift over time, small rockets are used to keep them in place. When those rockets run out of fuel, the satellite is finished with its life even if all the other components are working fine.

When a satellite has reached its end of life, its owners have two choices. They can tell the satellite to sink to its death back on Earth, but that’s actually more expensive. Even with the most controlled burn, you have to do a lot of prediction to make sure that the satellite’s parts don’t end up taking out a few blocks of a major city. It takes a lot of fuel to put a satellite into position where gravity will do its job, and that could shorten the life of the satellite by up to a year.

They paved paradise, and put up a parking lot

So, most satellites are sent not to Earth but to a parking orbit a few hundred miles further away from Earth. There they sit, and will probably sit forever. Is that a problem? Possibly. As these out-of-control satellites crash into each other, they crumble into smaller and smaller pieces that fly through space. If any of these pieces hits a working satellite it could damage it completely.

What eventually happens?

Because there’s no air up in that high parking orbit, those satellites will last a long time. They won’t rust or decay, other than getting a layer of dust on them from particles passing by. No one really knows how long a satellite could last up in space. Most satellites we’ve launched in the last 75 or so years are still up there, totally dead.

For now, they’re not a hazard to navigation. There aren’t really that many satellites and there’s a lot of empty space. They’re mostly clustered around the equator. Anything we launch, like a mission to Mars, could find its way around. The most unlikely scenario would be a chain of satellites sending junk hurling around the earth in a deadly chain reaction. In other words that movie Gravity was really really off base.

At some point we may find that there’s profit in sending ships up to high orbit to retrieve old satellites. This may be for historical purposes, so they can go to museums. Or, we may find that their long-term stay has affected them in some way that we may need to study. Such a mission wouldn’t be impossible but the return on investment is nowhere near there yet.

There’s a theory that eventually all this space junk will get so dense that it will be impossible to leave the planet. This is called the Kessler Syndrome, but not to worry — it’s not likely to happen soon if it happens at all. That’s the good news. If it looks like our own satellites are keeping us trapped on Earth, we have plenty of time to figure out how to blast ourselves out.