Sounds imaginary and poetic, except for one thing; it’s a fact, and it’s a very serious problem. I am talking about space junk, or space debris, and it’s getting worse.
To review, space debris is the result of the residue of spent stages of rockets used to launch spacecraft and are discarded in orbit, and satellites that have outlived their usefulness. First of all, some of these rocket stages have exploded as a result of leftover fuel, scattering the remains. Satellites, once they are obsolete, are turned off and burnt out, falling apart with scrap metal, bolts, o-rings, and anything else comprising it are scattered in orbit. This space junk then orbits at speeds up to 18,000 miles per hour (28,800 kilometers per hour), with impacts to other satellites at a speed of 22,500 mph (36,000 kph), posing a threat to any functioning satellite and the International Space Station (ISS).
Compare these velocities to that of a bullet fired from a gun. On average, the bullet would travel at a speed of 3000 mph (4800 kph). This means that a piece of orbiting space debris travels at a velocity six times that of a bullet. Even the tiniest piece of space debris, traveling at these speeds can do extensive damage to a satellite upon collision.
The threat is increasing due to more space junk being created and has the potential to create unforeseen catastrophes.
Some space junk was created deliberately. In 2007, China launched an anti-satellite weapon for testing, using a dead weather satellite as a target 500 miles above the Earth’s surface. As a result, a cloud of space debris was formed, further threatening satellites in that level of orbit. This means nuts, bolts, shards of metal, all speeding at 18,000 MPH in a cloud formation around the Earth indefinitely, that will damage and destroy any satellite that crosses its path. That is how serious the threat is, and will remain so for hundreds of years.
Space junk comes in all sizes, from the size of a pebble, or a fleck of paint, to the size of school buses and bigger, and pose a serious threat to all satellites and the ISS.
There was an incident where a fleck of paint hit the windshield of a space shuttle while in orbit, and penetrated two layers of the glass. Had it been a small pebble or bigger, it would have been a disaster for the entire ship and crew.
This is a disaster waiting to happen. Satellites could collide with one another, forming smaller, hazardous debris. A chain reaction can then develop, with these pieces hitting even more satellites, forming more junk, hitting more satellites, exponentially expanding the cloud of debris, becoming a minefield.
If you look at a satellite image tracking Earth orbit, it will look like a force field completely surrounding the Earth, like a shell, or a barrier. This barrier may someday become impenetrable, meaning that no spacecraft will be able to pass it without a piece of space junk hitting and destroying it, thus creating even more space junk, increasing its impenetrability. This can happen, and it’s headed in that direction.
It already has, on a small scale. On February 10, 2009, Iridium-33, part of a constellation of communication satellites supporting cell phones, crashed into a dead Russian satellite, Cosmos 2251. The result was the destruction of both satellites and more space debris.
More recently, U.S. Defense Meteorological Satellite Program Flight 13 (DMSP-F13) exploded, creating 43 new pieces of space junk.
An average satellite in LEO orbits the Earth 16 times per day. Close approaches between two satellites within a few miles occur 1500 times per day. It is only a matter of time where pieces of space junk will destroy more satellites, creating the chain reaction described earlier in this essay.
It is estimated that over 6600 satellites have been launched. According to Wikipedea (Under that heading “Satellite”), there are 3600 satellites presently in orbit with only 1000 of these functioning today (500 in low Earth orbit, being 200 miles (320 km), 50 are in medium Earth orbit (at 12,500 miles or 20,00 km), and the rest, about 450, are in geosynchronous orbit (at 22,300 miles or 35,680 km). The rest, once they outlasted their usefulness and have been replaced, have either burned up in the Earth’s atmosphere or remained in orbit and are deteriorating.
In low and medium Earth orbit, up to 1000 kilometers (625 miles), there are an estimated 300 million pieces of space debris, ranging from a few millimeters to the size of a school bus. The total weight of all this junk is estimated to be about 6000 tons, being both defective satellites, its parts, and spent rocket stages, even lost items from astronauts while space walking. There was a time when garbage was thrown out of Soviet space stations, creating more litter, but fortunately, that practice was discontinued.
Beyond geosynchronous orbit (GEO), 22,300 miles (35,680 kilometers) up, the point where any satellite will hover over a fixed point on Earth 24 hours a day, there are over 400 dead satellites, jettisoned there in a graveyard orbit, to make room for other, newer satellites. These dead satellites will remain there for centuries, or more.
Before going any further, I would like to mention the once believed Big Sky Theory, where space is so big, that anything launched in orbit will not collide with anything else. Unfortunately, this theory has been disproven. Earth orbital space is smaller than we ever imagined. It is limited, and we are sending literally thousands of satellites up there, and the danger of them colliding is increasing.
LEO is 200 miles up, with most satellites, the Hubble Space Telescope, and the ISS orbiting in that area.
MEO, being mid Earth orbit, between LEO and GEO, holds weather satellites, the Global Positioning System (GPS), being a constellation of satellites, a given number in the same orbital evenly spread apart for constant, 24 hour, world wide communications. There are also constellations of other satellite systems, such as communication satellites, including one system named Iridium.
GEO carries mostly communication satellites, but there are proposals to place other kinds of satellites in that orbital path, such as solar power satellites, but that is way down the road. Still, GEO is an orbital path with their slots for satellites in great demand from many different countries and other entities.
There are solutions to this problem. Clean up the orbits of junk, and make Earth orbit safe for spacecraft. That is known and obvious. The difficulty will be developing new technology, sending people up there, which we plan to do anyway for other reasons, and, of course, money.
There are creative ways, even ways to make a profit doing this.
First, there is nature’s way. Every 11 years or so, sunspot activity increases to a point where solar flares and ultraviolet radiation hit the Earth’s atmosphere with such intensity, that the atmosphere expands. As it expands, the space junk in the area it expands into gets burned up, so as when the atmosphere contracts again to its normal state, there will be a clean orbit, but that’s only in LEO, and it will take centuries for this process to completely clean Earth orbit of debris.
Many live satellites, including the ISS, has shielding against debris, and the ISS has a system that can detect incoming space debris and is able to dodge it before colliding with it.
On Earth, there is a U.S. Space Surveillance Network, that tracks and catalogs space junk bigger than a softball. For now, debris the size of marbles are beyond detection, but that could change.
What are some of the ways to clean up Earth orbit, be it Low, Middle, or GEO?
My idea would be to hold up a large screen in orbit, a “flypaper,” catching marble sized and smaller debris until the screen couldn’t hold any more, wrap the whole thing up into a ball, and fling it in the atmosphere, where it will burn. There would be hundreds of these screens doing the job.
Japan invented the idea of the fishing net, catching similar debris and bigger, with a similar process.
Today, the amount of satellites properly disposed of is less than half the number of satellite that become defective. To improve on this, we can attach a tether on a new satellite before it is launch, have it hidden inside until, in 10 or 20 years, the satellite wears itself out and is no long functional, release the tether where it will drag the satellite down into the atmosphere to burn. An alternative to tethers would be solar sails, deployed when the satellite becomes defunct.
Another alternative is to have a small propulsion system attached to the satellite that, upon obsolescence, jettison the defunct satellite into the Earth’s atmosphere to burn.
At the present moment, lasers are being researched to track a piece of space garbage, no matter how small, and zap it, burning it in the atmosphere. This can be done both on the ground and in space. There is a proposal to attach a laser to the ISS to zap any piece of debris it detects, creating a clean and safe orbital path for the ISS.
A Japanese scientist, Dr. Toshikazu Ebisuzaki, proposed using a certain type of laser system called the coherent-amplification network device, developed for use in high-energy physics. In its full development, it would be mounted on a satellite, or the ISS, shooting down literally tens of thousands of pieces of space debris annually. Imagine have a fleet of satellites to perform this task.
I propose a fleet of laser satellites in different levels of orbit constantly searching and destroying space debris, cleaning up Earth orbit. This would be done on an international basis, involving the cooperation of all spacefaring nations, sharing in both the labor and the expense.
A space station in mid Earth orbit, with ships similar to the shuttle that could retrieve satellites for repair and upgrading on the station would save money and resources to the company owning the satellite. The damaged, defective, or outdated satellite can be retrieved, and a crew on board the station could repair and upgrade it, giving new life to the satellite for another decade or two. This would save the company the expenses of both building a new satellite and launching it.
One last way would be to salvage the satellite for recycling the materials itself, known as active debris removal, or ADR. There are laws on the books against this activity, so one would have to obtain permission from the company that owns the satellite. Any spent rocket stages are salvageable.
There is the option that is a company want a defunct satellite back, or is ordered by law to remove (this is possible), they can pay for the salvager to retrieve it and return it to its original owner.
Imagine a space garbage truck, picking up satellites and rocket parts. Imagine “mining” the graveyard orbit of all the space junk there, taking them back to a space factory to reprocess the metals and manufacture other goods. It is possible, with a space truck and a space factory.
There are problems and obstacles to this endeavor. Governments and private companies still own these defunct satellites, even when they are no longer operational and deteriorating in orbit, and they still retain their rights to this ownership. We may have to deal with each government and private entity on a one-to-one basis in removing these satellites and salvaging its materials. Of course, one incentive can be that if their satellite damages any other satellite, they would be held liable, so they may be more than glad to have it removed.
Technically, it may not be, at present, possible to reach and grab every piece of space junk, so more forms of space technology will have to be developed.
There is also the cost of salvaging the satellite, or rocket part.
If legal issues are resolved, the contents of the satellite or rocket stage could help pay for the salvaging process.
As of the present moment, we can only rely of the 11 year sun cycle and build future satellite with tethers, solar sails, or rockets for them to plunge into the atmosphere once they become obsolete.
Alastair Browne
Alastair Browne
- “Char Wars - How to Clean Up Space by Shooting Down its Junk;” The Economist, April 25, 2015, p. 75.
- NASA Orbital Debris Program Office; “Orbital Debris - Frequently Asked Question;” http://orbitaldebris.jsc.nasa.gov/faqs.html#16. 3. Rossettini, Luca; “Space Debris Prevention, Remediation, or Mitigation?” Space News, March 23, 2015, pp. 19, 21.
- Rossettini, Luca; "Space Debris Prevention, Remediation, or Mitigation?" Space News, March 23 2015, pp. 19, 21.
- Space Junk 3-D; Blue-Ray Video, RLJ Entertainment, Melrae Pictures and Red Baron Production, 2013.
5. Wikipedia, “Satellite,” http://en.wikipedia.org/wiki/Satellite.
