by Dana Turse, Director of Space R&D Programs, Roccor
About 8,000 tons of man-made stuff are orbiting the Earth right now, and the amount is growing by 200 tons per year1. How concerning is this trend, and can we reverse it?
In 2009 a 1,000kg dead Russian Kosmos satellite flying at approximately 17,000 mph collided with an operational US Iridium communication satellite about 500 miles above the earth. The hypervelocity collision destroyed both vehicles, and caused US policy makers to wake up to the sobering reality that the growing orbital debris problem is on the verge of becoming a crisis.
To measure the magnitude of the problem, consider the following yardstick. Astrophysicists estimate that every year Earth is bombarded by between 2-8 tons of meteorites large enough to penetrate our atmosphere and light up the night sky – remnants of iron rock falling from deep space. So, bringing all 8,000 tons of man-made stuff down from Earth orbit in one year would be a man-made meteor shower 1,000 times larger than the natural shower we receive from the heavens every year.
In the 1930’s as earth-bound engineers were first spanning the continent with radio waves and commercial airliners, Hungarian physicist Theodore von Kármán defined mathematically the threshold into outer space. Since the dawn of the Space Age it is estimated that the civilized planet has hurtled millions of tons of elegantly engineered satellites over von Kármán’s Line in the sky. Fortunately, most of this hardware has escaped Earth’s orbit – either on trajectories into deep space or by returning to Earth as man-made meteorites. Unfortunately, a significant remainder of this stuff still remains in Earth orbit creating our generation’s first extraterrestrial legacy of environmental abuse.
These bits of orbiting debris aren’t floating “weightless” like an astronaut appears inside her spacecraft, they are hurtling around the earth literally faster than speeding bullets. Tracking these hypervelocity objects has become the obsession of the US Space Surveillance Network headquartered and Vandenberg Air Force Base, California. Figuring out what to do about them has become the obsession of many national organizations from NASA, who fears the risk of damage to the International Space Station, to the FCC, who regulates how we use satellites to satisfy our insatiable demand for global communications.
As von Kármán explained 80 years ago, at altitudes substantially below 60 miles – his threshold into space – things can fly on wings supported by air and at speeds of hundreds of mph. But above von Kármán’s Line the atmosphere thins; the engineering changes from aerodynamics to astrodynamics; and things fly only if they are going fast enough to resist Isaac Newton’s universal law of gravity. So, bringing down thousands of tons of hypervelocity space junk means figuring out how to slow these objects down… safely and economically.
The good news is that we know how to do this, and we have done this with most of the satellites we have launched since the beginning of the Space Age. Some have been designed to come back to earth under control – as happens with all re-supply missions to the International Space Station, and some have been designed to come back uncontrolled – as was recently witnessed when China’s 8-metric-ton Tiangong-1 Space Station disintegrated in a man-made meteor shower over the south Pacific. But until recently, there has been no requirement that all of the satellites we launch into space must come back to Earth after their useful life is over. So, the amount of junk continues to go up.
While the industry awaits international treaties and a global standard for reducing the space debris problem, the US Inter-Agency Space Debris Coordination Committee (IADC) recently mandated a 25-year de-orbit lifetime for all future spacecraft, and the FCC is now enforcing this standard on all US-based satellite users who apply for an FCC license. Yes, US satellites that carry radios that communicate with the ground must have an FCC license in order to operate… And that’s why the FCC is interested in space trash!
Very recently Roccor was approached by a satellite customer caught in the throes of this rapidly evolving space policy and environmental ethics dilemma. The customer was searching for the means to do the Mass of all objects in Earth orbit officially catalogued by the US Space Surveillance Network responsible thing – to de-orbit their satellite at the end of its life. But being very late in the development cycle on a satellite design without a rocket motor and sufficient fuel to allow a controlled de-orbit burn, the options were few. Moreover, at its orbital altitude of several hundred miles, von Kármán’s laws of rarified atmospheric drag predicted that the satellite would stay aloft more or less forever.
With little time and budget to spend, Roccor conceived an idea to add two tail-feather-light deployable sheets to an unused outer deck of the satellite. At the end of the satellite’s useful life, these so-called ROC™ FALL “feathers”2 will be extended out several meters in length and produce enough drag to slow the satellite gradually and ensure it de-orbits long before the IADC-mandated 25-year limit.
So, we know we can reverse the trend of increasing space debris, and we’ve shown it doesn’t have to break the bank. Moreover, we believe we should not wait for international treaties or further regulations from the US government to compel us to do so. The US satellite industry should embrace a Space Age leave no trace ethic and show the rest of the spacefaring nations how to protect the economic – if not environmental – sanctity of space.