March 25, 2012
The following resources were used in writing this document:
- “Scientists Battle Space Debris Threat”: CBS News, 23 April 2011
- “Space Debris”: Wikipedia
- “Space Junk Endangers NASA Satellites”: Elizabeth Montalbano, Information Week, 2 September 2011
- “Space Junk Janitors Should Sweep Up 5 Dead Satellites”: Biology & Nature, 27 February 2012
- “Space Junk to Triple by 2030”: Lenord Davis, Space.com, 9 May 2011
I can’t stand dirt. Dirty house, dirty car, dirty office, and I am making some changes. Fortunately, my wife is a “neatnick”. She also—CAN’T STAND DIRT. To further demonstrate the point, one evening, just before sundown, she looked through our den windows towards the setting sun and pronounced “we WILL clean these filthy windows inside and outside tomorrow”. I felt her “pane”. (Pardon the clever play on words!) Dirt is one thing, but I’m OK with a little clutter. I have several editions of Machine Design, Design News, Science and Technology, etc. sitting around waiting on the spirit to move me towards picking them up to read. The older ones I consider collector’s items. This is perhaps the only way I cannot be considered a hoarder.
The tiny blue dot we live on does have a significant problem with clutter SPACE JUNK– I will demonstrate as follows:
The digital photograph above shows the approximate position of debris remaining as a result of exploits in space, both ours and other countries, having the technology to launch rockets that carry payloads. Perhaps a more enlightening JPEG, given below, will be more helpful and further illustrate the issue faced by NASA and other space-related agencies. Please keep in mind all objects are moving. None are stationary; consequently, any depiction of position must be an estimate of position.
It has been estimated by Hugh Lewis from The University of Southampton that over this decade, there could be as much as a fifty percent (50%) increase in debris. Already, the International Space Station has had to fire thrusters to avoid moving “garbage” orbiting earth. The result would have been disastrous had this action not been taken. Some experts from NASA and within several university systems state we have already reached the “tipping point” and corrections would be virtually impossible and remarkably expensive. NASA estimates there are at least 500,000 pieces of debris orbiting earth and some of that debris is moving at 17,500 miles per hour. Of course, any “strike” at these speeds could produce life-threating damage to personnel and systems. Damage such as the one shown below could absolutely destroy delicate equipment and seriously injure, if not kill, astronauts.
The overwhelming number of particles are smaller than one centimeter; i.e., 0.39 inches, but others are of considerable size. Estimates are as follows:
- 1,500 pieces of debris weighing more than 100 Kg or 200 pounds
- 19,000 pieces of debris measuring between 1 to 10 centimeters; 3.9 inches
- An unestimated number of particles, mostly dust and paint “chips” resulting from collisions that have occurred with larger objects also orbiting. Some “guesses” put that number into the millions.
For the most part, the debris can be categorized as follows:
- Jettisoned garbage from manned spacecraft, purposefully disposed of into lower earth orbit
- Lost equipment; i.e. cameras, tools, measuring devices, fabric hold-down straps, nuts, bolts, cotter pins, etc.
- Debris from collisions tearing apart structures either jettisoned or lost
- Rocket boosters that orbit yet remain in space. Some, over time, experience decaying orbits, eventually falling to earth.
- Satellites that no longer function but still orbit in LEO (Low Earth Orbit) or HEO (High Earth Orbit). Generally satellites operate between 435 to 800 miles above the earth. When these satellites “die”, they do not accomplish reentry but simply stay aloft as dormant objects. Think of the number of telecommunication devices now orbiting the earth. Most will eventually fade and no longer fulfill their purpose, being replaced with newer technology.
With an ever increasing number of launches, engineers and scientists are designing into their products, systems that will provide for ultimate reentry when that system or component performs its function. Let’s assume a satellite has performed properly for nine years but now is dormant due to programmed obsolescence. What if, pulse jets could fire altering trajectory and orbit so reentry could be possible? If that reentry could be a controlled, one “chunk” of debris would be eliminated; consequently, eliminating possible damage to other orbiting bodies or future launches. This is the current mind-set being explored.
With at least fifty nations participating within the space environment, the amount of debris can only lessen but not be eliminated. At the present time, over 20,000 pieces of debris are being tracked from facilities such as the one below:
Facilities such as this can at least estimate collisions and, more importantly, any debris that may be in a decaying orbit that will eventually create reentry into earth’s atmosphere. Over the past ten to fifteen years several large pieces of debris have reentered although most fall into our oceans or uninhabited land. It becomes ever so critical to remain aware of location to preclude injury on the ground or provide successful future launches. Several government agencies, as well as universities, have undertaken programs to explore methodologies to reclaim or at least deflect debris that might be potentially dangerous. Monetary estimates, technical risk and overall complexities of design are significant, and we seem to be a long way from even mounting demonstration programs that will indicate possible success. This is one area that will be fascinating to watch over the next twenty years. Stay tuned.