Did you get an accurate weather report today? Watch television? Use a GPS? If so, give credit where credit is due: thank a satellite.
These orbiting objects actually do even more, too. A few of their other jobs include creating maps, taking photos, providing global communications and connecting amateur radio stations.
Satellites provide benefits we’ve come to depend upon, but that help sometimes comes at a price. Though a satellite’s service life is usually long, its demise isn’t always smooth sailing.
Getting it together
Building and launching a satellite is a time-consuming process, and much of it is done by hand. Depending upon the size of the satellite, construction can take months or even years. New entrants into the satellite field hope to introduce automated methods to speed up manufacturing. This will make them both more accessible and less expensive.
No matter how satellites are constructed, they all need the same features:
- A frame or “bus” made from composite or fabricated from metal
- A power source, typically solar cells with battery storage
- A computer to regulate processes
- A radio transmitting and receiving system
- A way to govern altitude
Nothing is too good for these satellites. They’re built and tested under sterile conditions in temperature- and humidity-controlled environments. Once a satellite is good to go, a rocket from a business or national space agency carries it into space.
The rocket discharges the satellite after reaching just the right speed. This “orbital velocity” is about 27 300 km/h (17 000 mph), 240 km (150 miles) above Earth. Faster, and the satellite wouldn’t orbit. It’d continue on its merry way, far, far into space. Slower, and Earth’s gravity would cause the device to tumble down. So, after the satellite is released with precision, it travels ‘round and ‘round the planet, tirelessly performing its important function.
End of the line
The satellite stays in space, “tirelessly performing its important function” until it doesn’t. At some point, the device comes to the end of its lifespan or worse, hit with debris and damaged beyond repair.
There’s no trash collection in space. No one sends rockets back up to pick up an outdated satellite. It just keeps orbiting Earth. Useless.
No big deal. What harm could it do? Space is big enough to hold leftovers, right?
If it were just the one satellite, there might not be a problem. But space exploration and development has been going on for years, and there are multitudes of odds and ends circling the planet. In fact, about 29 000 pieces are at least 10 cm (4 inches) long.
But smaller fragments are there, too. About half a million specimens currently tracked. Most of these are in low orbit, less than 20 000 km (12 400 miles) from Earth. Millions more are too small to follow.
This “space junk” includes old satellites as well as smaller debris caused by collisions and explosions.
Perils in space
So humans are starting to clog space with garbage, much like they’re filling up Earth. However, in space, there’s an added hazard. While the planet’s trash stays put, space junk travels fast, up to 28 000 km/h (17 500 mph). At those speeds, even something very small, like a chunk of paint, can inflict damage as it smashes into a satellite or spacecraft — NASA had to replace more than one space shuttle window after it’d been battered by a paint fleck.
And those are only the tiny particles. Fragments just 6.3 cm (2.5 inches) long hit like hand grenades, inflicting serious damage and creating more debris. Space junk presents such a risk to spacecraft — especially crewed vehicles — that NASA has instituted evasive procedures and other interventions to prevent or handle collisions.
What to do, what to do?
Sometimes space junk takes care of itself, falling out of orbit, re-entering Earth’s atmosphere and burning up. For instance, in July 2016, a Chinese satellite launcher's second stage streamed across the sky in a fireball. Not all debris, however, goes up in a glorious blaze. In 2015, part of a SpaceX rocket was found in waters off the English coast.
Sure, spacecraft can keep steering around debris that stays in orbit. Astronauts might face wild rides not unlike those in certain science fiction movies, but collisions can’t always be avoided. For instance, in 2009, an obsolete Russian satellite wiped out a working U.S. satellite. As a result, thousands more bits of junk were sent orbiting.
Enough is enough. Clean-up plans are in progress. The European Space Agency, or ESA, has launched a Clean Space Initiative that includes removing debris. The first step: retrieving a defunct satellite in low orbit. The ESA plans to launch a trash-collecting satellite in 2023. It will use a device — perhaps a net or harpoon — to grab the non-functioning contraption. Then both will burn up upon re-entry.
Sound simple? It isn’t. The retrieval satellite will have to perform multiple functions: locate its target in space, follow it, secure it, synchronize obits and drag it down toward Earth for mutual destruction.
Now that the private industry has also entered the space race, the likelihood of more junk and further collisions is increasing. The ESA mission is an important step in getting humans to undo years of damage. Cleaning up our orbits will ultimately help pave the way for safer space exploration – manned and unmanned missions alike.
Featured image: 300 000 pieces of space junk by Steve Worsethandetroid (CC - Flickr)