Friday, October 28, 2011

Solution to the Problem of Orbital Debris

image of space debris courtesy Wikilimages
An article in Universe Today points out that space debris is a huge problem. The retired head of NASA’s Orbital Debris Program Office, Donald Kessler, wrote a report on this describing the situation as bad and getting worse. Mr. Kessler originally predicted the scenario of orbital litter becoming a major problem for the advancement of the space program and a danger to satellites back in 1976. The situation he described has come to pass and is appropriately designated the Kessler Syndrome. 
A report from NASA makes two conclusions:

1. “The  current debris population in the LEO region has reached the point where the environment is unstable and collisions will become the most dominant debris generating mechanism in the future.”

2. “Only remediation of the near-Earth environment – the removal of existing large objects from orbit – can prevent future problems for research in and commercialization of space.”

Active Debris Removal (ADR) is recommended by NASA. A proposed solution to this problem is advanced in this article from Wired Science. It may have merit but it represents a lot of money to be spent just to see if it works. This is where the Space Mirror steps in to save the day.

My original Space Mirror concept (drawing shown) can be scaled up easily to perform the task of getting rid of orbital space debris. The Space Mirror consists of two disc-shaped membranes of sheet plastic approximately 8 mils thick. These are jam-up, jelly-tight next to each other. They are 1000 feet in diameter and keep their shape via an inner-tube-shaped, inflated toroid with a sectional diameter of 10 feet. The circular edges of these membranes are attached by airtight seal to the inside radius of the toroid. One of the membranes is transparent and and the other is mirrored on the inside surface. When gas is introduced between them they expand, deforming into spherical surfaces capable of focusing the sun’s rays on a small area. The focal length ranges from about a mile to almost 5,000 miles. A unit containing gas cylinders, computers, radar, and solar panels attached by a flexible umbilical provides the essentials for directing and focusing the mirror. The radar and other sensors work with the computer to fire small thrusters around the outer surface of the tubular frame keeping the device aimed and in the proper orbit. Small, semi-autonomous robots roam the cavities of the framing tube and the surfaces of the membranes looking for and repairing small punctures. It sounds like a big thing but it all folds up for one payload in the new spacecraft from SpaceX, the Falcon Heavy.

It takes 7 trucks to move the same number of paper bags as one truck moving plastic bags. 

This device was originally devised to facilitate the construction of space habitats, melting captured asteroids or meteors and then inflating them to create habitable spaces. Recently, other applications have come to mind. With its ability to direct and focus large amounts of energy, it makes a perfect mechanism to sweep from the littered skies of Earth the small debris that will eventually inhibit exploration of space and utilization of near-Earth orbits. It will simply focus the sun’s energy on these objects and they will vaporize. If you doubt this, look at the results of using just 22 square feet of concentrated sunlight. It will melt steel and even rock. Now imagine 800,000 square feet of sunlight (over 36,000 times that power) concentrated on a small area. Now double that energy because sunlight is twice as strong in space, unhindered by atmosphere. Material would not only melt, it would become a cloud of vapor almost instantly - exactly what you want orbital space debris to do. Another great thing about this concept is that it can be tested right here on the surface before installing it in orbit.

The 1500 pieces of large debris can also be taken care of by selectively zapping them, causing explosive reactions to decelerate them and bring them down to burn up in the Earth's atmosphere.
These represent 98% of space debris by mass and it is feared collisions between them will cause an increase in the threat of orbital debris to mankind's space aspirations.

The answer to the plastic bag problem is reuse. This new device makes it easy. 

Due to the implications for military applications, the Space Mirror would have to be an international effort, controlled by a committee made up by representatives of countries investing in the project. It could be set up for a specified period of time to do its job of cleaning debris from orbit and then be decommissioned. It is something that needs to be seriously considered if mankind is to advance into the frontier of space without tripping over its own trash.

Glen Hendrix
Look for my scifi novel Transmat World at

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