Space near the Earth is now permeated by clouds of debris. These clouds are created by collisions between spacecraft, satellites, and other debris fragments. They damage and destroy communications and scientific satellites, as well as world-wide space exploration and development missions such as the International Space Station. If nothing is done to remove the debris clouds before their growth rate becomes exponential, space will become inaccessible to humans.

Thus far, NASA and other agencies keep spacecraft such as the International Space Station away from space debris by constantly maneuvering whenever debris comes close. At the cost of $20 million per maneuver, this is an expensive reactive approach which does nothing to actually solve the problem. The fact is that debris needs to be removed from space in order to clear a pathway for the present and future. Furthermore, it is the small debris which pose the greatest threat to spacecraft today – because there are 600,000 pieces of 1-10cm debris in orbit, each of which has the explosive energy of a hand grenade upon impact with a satellite. It is PACA’s mission to safely de-orbit the 1-10cm sized debris.

To say that we would like to bring this issue before the United Nations isn’t saying enough. We need to translate our vision into action so that our world has a chance to build a peaceful future in space. To do that we need to secure the support of investors and partners. This is possible, as what we are proposing stands to benefit the companies which supply the satellites which provide telecommunication services to people around the globe. Without those satellites, there would be no business structure for those companies to prosper. It’s a win-win for everybody. Our planet, our future, our skies. Let’s remove the space junk.

We are seeking new friends and partners. If you would like to contribute, or if you simply want to learn more, email us at and we will send you information by email. Also visit our Facebook page to and follow us on Twitter. If you are a computer whiz, we need you to keep our momentum going on the internet. Visit our Links page for a list of our current collaborator websites. We’d love to add yours to our list!

And we are holding a contest for space debris ideas. We are seeking proposals from anyone who wishes to collaborate and improve PACA. In exchange, we have several prizes and are excited to offer you the chance to submit your ideas and become part of PACA. Email us at



Footage from a US Senate Hearing on Space Debris: Commerce, Science, and Transportation Subcommittee. (March 20, 2013)

From a Speech Given by James Finch, Director of Space Policy and Strategy Development Office of the Under Secretary of Defense for Policy:

In fact, if we ceased all launches tomorrow, the amount of space debris would continue a steady increase for more than a century as pieces of debris collide with each other, producing even more debris, that collide with each other, and so on. And that is the optimistic view! The world is not about to stop all launches. Space-based capabilities are too vital. They are vital to our global security, to our global prosperity, and to our global interconnectedness. With our continued use of space, the debris population will continue to grow. So, if we seek to maintain access to the space domain, both for ourselves and for future generations, we must take seriously the threat posed by space debris. And taking this threat seriously means that we must act differently.

Space tracking stations around the world can detect space debris down to the centimetre level. Long duration exposure experiments in space can inform us about the space debris population of micron size. Ground meteor radars are currently being investigated to determine whether they can provide useful information on the debris population of intermediate size (the peri-millimetre scale).
Legal implications of orbital space debrisConsideration of active measures to reduce space debrisSatellite design to minimise the effects of space debris impactsHypervelocity facilities to measure debris impact effectsModelling of orbital space debris and its effectsSatellite operations to minimise orbital space debrisSatellite design to minimise orbital space debrisMonitoring the orbital space debris environment
Orbital space debris is of increasing concern to all space agencies around the world, and is becoming the subject of legal discussions. The areas of concern are:
On the debit side, the removal of orbiting space debris may be due to a deliberate action or the result of natural orbital decay. In low Earth orbits, a satellite is subject to atmospheric drag, and this will eventually cause it to re-enter the Earth’s atmosphere. Unless the object is particularly large, it will completely ablate during this process, and there will be no visible remnant that reaches the ground. If the object is felt to pose a threat to life and infrastructure on the ground, then it is sometimes possible to cause a controlled re-entry with a fuelled de-orbit burn. Other spacecraft, such as the Space Shuttle may sometimes be directed to directly retrieve an ageing spacecraft of particular significance. In the past this has been only for satellite refurbishment, but in the future it might be due to environmental concerns.
More catastrophic than age related deterioration are satellite fragmentation events. These may result from collisions with other (external) objects, or they may be explosive, as when remnant fuel in an old spacecraft undergoes an exothermic reaction (ignites). Both of these type of events can produce an astounding number of small fragments that become a new source of space debris.
As satellites get old they deteriorate under the influence of the space environment. Outgassing can not only release gases, but may also take other materials with them, as the gas beneath a surface slowly makes it way into the surrounding environment. The strong solar UV in space can cause the deterioration of many materials. Paint and other surface materials may be expelled in flakes.
The initial and continuing source of space debris is the launch of satellites. Not only the satellites themselves add to the population of orbiting space objects, but often the last stages of the rockets that are used to place them in orbit also remain aloft for many years.

The video clip below indicates the sources and sinks that cause changes in the orbital space debris population.

The smaller pieces of orbital space debris now exceed the population of meteoroids in Earth orbit and are becoming an increasing threat to orbiting spacecraft. The larger the spacecraft and the longer it stays in orbit, the greater is the chance that it will be hit by a piece of orbital space debris.
It used to be thought that space was a very large and limitless place, and indeed it is, but those areas of space in which man has been orbiting satellites for over 40 years are now becoming crowded. Crowded not so much with useful satellites, but crowded with non-functional satellites, final stage launch rocket bodies, and with multitudes of smaller objects that have resulted from numerous satellite deteriorations and fragmentations. Collectively, this material is now referred to as Orbital Space Debris. It is supplemented by natural space debris (ie meteoroids) that also passes through Earth orbit.

One major recent development in Space Debris is the following article from


The Fermi telescope — launched in 2008 — searches the sky for signs of dark matter, black holes and spinning pulsars by seeking out sources of gamma-ray bursts, the brightest flashes of light in the universe since the Big Bang.
NASA tracks 17,000 objects larger than 4 inches (10 cm) across in orbit above the Earth every day. Only 7 percent of the objects tracked are currently active satellites.

In February 2009, another dead Russian satellite slammed into the U.S. communications satellite Iridium 33 in a space collision that spawned vast clouds of debris, one along each craft’s orbit. In 2007, China intentionally destroyed a defunct weather satellite in an anti-satellite test.

Space junk has been a growing threat to satellites and manned spacecraft in orbit, and collisions do occur from time to time. Last month, the European Space Agency held its sixth conference dedicated to combating the space junk threat in Darmstadt, Germany.

“A huge weight was lifted,” McEnery said. “I felt like I’d lost 20 pounds.”
“The maneuver, which was performed by the spacecraft itself based on procedures we developed a long time ago, was very simple, just firing all thrusters for one second,” Stoneking said. “There was a lot of suspense and tension leading up to it, but once it was over, we just sighed with relief that it all went well.”

The two spacecraft ultimately missed each other by 6 miles (9 km) when they passed one another on April 3, 2012.

“It’s similar to forecasting rain at a specific time and place a week in advance,” Eric Stoneking, the attitude control lead engineer for Fermi at NASA’s Goddard Space Flight Center said of predicting these kinds of impacts in a statement. “As the date approaches, uncertainties in the prediction decrease and the initial picture may change dramatically.” After making those calculations, scientists started planning to fire Fermi’s thrusters specifically designed to move the satellite out of the way if these situations arise. “It was clear we had to be ready to move Fermi out of the way, and that’s when I alerted our Flight Dynamics Team that we were planning a maneuver,” McEnery added.

The Russian space junk was travelling at a speed of 27,000 miles per hour (43,452 km/h) in relation to Fermi. If it had smashed into the space telescope the explosion of the two spacecraft would have released “as much energy as two and a half tons of explosives,” NASA officials said “My immediate reaction was, ‘Whoa, this is different from anything we’ve seen before!'” NASA’s Fermi project scientist Julie McEnery said in a statement.

Fermi mission scientists first learned of the space collision threat on March 29, 2012 when they received a notice that the space telescope and Cosmos 1805 would miss each other by just 700 feet (213.4 meters). The mission team monitored the situation over the next day and it became clear that the two spacecraft, traveling in different orbits, would zip through the same point in space within 30 milliseconds of one another, NASA officials said.

NASA’s $690 million Fermi Gamma-ray Space Telescope — which studies the most powerful explosions in the universe — narrowly avoided a direct hit with the defunct 1.5-ton Russian reconnaissance satellite Cosmos 1805 on April 3, 2012, space agency officials announced Tuesday (April 30). The potential space collision was avoided when engineers commanded Fermi to fire its thrusters in a critical dodging maneuver to move out of harm’s way.

A high-tech NASA telescope in orbit escaped a potentially disastrous collision with a Soviet-era Russian spy satellite last year in a close call that highlights the growing threat of orbital debris around Earth.

Climate change from greenhouse gas emissions might threaten spacecraft as well as people, a scientists suggested on Sunday, providing direct evidence that carbon dioxide from human activity is affecting the outermost portion of the Earth’s atmosphere.

In a study published in the journal Nature Geoscience, a research team led by John Emmert of the U.S. Naval Research Laboratory’s Space Science Division in Washington, described a new method for quantifying increases in carbon dioxide in the hard-to-measure portion of the upper atmosphere known as the thermosphere, which can’t be reached by balloons and aircraft.

In that region, more than 50 miles above Earth’s surface, carbon emissions cause cooling rather than warming because carbon dioxide molecules collide with oxygen atoms and release heat into space. Because such cooling makes the planet’s atmosphere contract, it can reduce drag on satellites and debris that orbit the earth, possibly having “adverse consequences for the orbital debris environment that is already unstable,” the researchers wrote.

Tracking space debris is a major preoccupation for the aerospace industry. Earlier this year, the Los Angeles Times reported on the issue, noting that a 2011 NASA study determined that there were more than 22,000 pieces of space debris larger than 4 inches orbiting the Earth — and that even tiny pieces of junk can inflict major harm on a spacecraft.

“Even tiny bits of debris, such as paint chips, can damage satellites and manned spacecraft when they’re traveling in low-Earth orbit at about 21,600 mph. An aluminum sphere half an inch in diameter has the potential to do as much damage upon collision as a 400-pound safe traveling at 60 mph. Larger items such as defunct satellites can pulverize the objects they hit in space, generating ever more pieces of dangerous floating trash,” the story explained.

According to the paper in Nature Geoscience, thermospheric density trends calculated from satellite orbits suggested that the cooling influence was in fact larger than computer models had predicted it would be. The new carbon measurements, which also outpace projections, may help explain that discrepancy, the authors wrote.

For further information:


A simulation of the Iridium telecommunications satellite constellation (green, red, and blue orbits) with space debris (orange points) generated by a collision that resulted in the destruction of an Iridium satellite in 2009.