Commentary | Trashing Space
Everyone talks about the weather, but no one does anything about it. We study it. We measure it. We look at it. There are tens of thousands of weather experts just in the United States. Our universities are producing thousands of new meteorologists each year. There are literally hundreds of libraries dedicated to weather data over the past hundreds of years. Yet the smallest library in the world would be one that is dedicated to weather modification methods and results.
Similar claims can be made regarding the near-Earth space environment and the orbiting debris that we have produced over the past 50 years. Just as weather affects our daily lives, so does the junkyard in low orbit. But in the latter case, the detrimental affects are growing worse by the year. We understand weather and have learned to deal with it as best we can. However, the eventual impacts and disposition of space debris are not understood. Unlike weather, space junk is truly man-made and will ultimately significantly hinder our modern economy and national security. It is a growing threat to space-based communications, weather forecasting, banking processes, scientific exploration, Earth observation and future space tourism.
For decades, the SETI Institute has expended a good deal of money and effort on the search for extraterrestrial intelligence. Although an interesting academic exercise, it has produced few results. More recently, NASA has been considering capturing an asteroid and moving it close to Earth for further study by astronauts. This is another interesting academic exercise, but with little expectation of exciting and useful results.
These and other space misadventures have absorbed a good part of our national space budget, all the while discouraging bright, young engineers from entering the field. Morale among space professionals within the government ranks has been devastated. Add to this the impact of sequestration and we have an indeed sad situation.
Meanwhile, new satellites are being launched at a rate of over a hundred each year. Most of these launches will eventually add to the already-large space debris population, which continues to grow at a faster and faster pace as the exponential explosion of orbiting junk continues unabated.
Yes, NASA and other government-funded projects are studying the challenges of debris on spaceflight safety and in-orbit operations. Books, studies and reports document the characteristics and history of man-made orbiting objects. There are probably millions of pieces of old satellites and upper stages in orbits near Earth. There have been many minor collisions between debris and operating satellites. There has been at least one collision between two intact satellites,33 and Cosmos-2251 in 2009. Although the Russian Cosmos satellite was inactive, Iridium was an operating satellite within a constellation of telephony satellites.
The U.S. Air Force Space Command (AFSPC) has been tracking debris for decades, and knows most of it is resident in low orbits with altitude ranging from about 600 to 1200 kilometers. Individual pieces that are at least 10 centimeters in size can be tracked, and there are over 22,000 of these. Smaller pieces number in the hundreds of thousands to millions. We know that every piece of low-orbiting debris is traveling at speeds in excess of 7 kilometers per second and relative speeds between debris objects can be higher than 14 kilometers per second.
AFSPC has been doing a heroic job of tracking and predicting debris dynamics, but the simple truth is that we lack the technology and equipment to accurately forecast relative collisions between satellites and individual debris objects. In fact, just recently AFSPC announced the shutdown of a portion of the debris tracking facilities, further reducing its ability to track and predict debris movements.
What is being done about space debris? The space community has worked hard to mitigate excessive proliferation of debris by establishing voluntary rules for spacecraft manufacturers and operators that help to minimize the creation of new debris. However, there is no system or program to remove or clean up near-Earth orbit. The Defense Advanced Research Projects Agency’s Phoenix program has been mistakenly characterized by some as a debris removal pathfinder. In fact, it is a program to demonstrate possible recycling of old geostationary satellite parts. Furthermore, there is not even one single program addressing the long-term environmental control of space. If space were to come under the jurisdiction of the U.S. Environmental Protection Agency, low Earth orbit would represent the biggest Superfund site ever.
Make no mistake, space debris is a threat to operating spacecraft and human spaceflight. The recent film “Gravity” depicts a possible future disaster for astronauts and space tourists. The level of this threat is building with time. So far, debris has been a nuisance and has created minimal damage. The threat has been “acceptable,” because the cost of cleaning it up is so much greater than the satellite damage so far. At some point in the not-too-distant future, the cost of cleaning up space may approach the value of continuing damage to satellites. However, any cleanup program will take years to implement and decades to carry out — figure at least 20 years to implement a debris cleanup program and 50 years to reduce the threat to acceptable levels.
Just as with the U.S. debt problem, you can kick the space trash can down the road, but it is not going away, just getting bigger.
Marshall H. Kaplan is a spacecraft systems engineer who has been conducting research on orbital debris remediation since 1970. He was a professor of aerospace engineering at the Pennsylvania State University and is a visiting professor of aerospace engineering at the University of Maryland.