Transmat World: How a Space Mirror Could Deal With Orbital Debris and the Threat of an Asteroid Strike

On August 20, 2075, in Kalispell, Wyoming, a young amateur astronomer is drinking ice tea to cool his thoughts about the 103 degrees F. outside his window at 9:30 in the evening. Climate change is relentless. Harold thinks this is fairly normal weather. It’s been nearly this hot most of his adult life.

Checking the laptop hooked to the homemade telescope in the plastic bubble on top of the house, he inputs values into a program and runs it. He runs it again. And again. He shows the results to several astronomer friends by email. They check it and verify the output. Soon thereafter, the world goes crazy.

Something happened to asteroid 2005 YU55. It was supposed to come within 237,000 miles of Earth on November 8, 2075. Now it is on a collision course. Some other asteroid came close to or bumped 2005 YU55 and slightly changed its direction. NASA has known for weeks but not released the information for fear of mass panic. The amateur astronomers have forced the issue, and NASA holds a press conference.

The head of NASA explains the situation is not as dire as it would have been just five years ago because of Project Drogon. Everybody knows about the large, focusing mirror in orbit because it has been efficiently vaporizing space debris cluttering orbital lanes near Earth for several years. Few gave thought to its second purpose until now. It’s shiny discs have been re-focused on 2005 YU55, and it is currently engraving an ablation trench in a spiral pattern as the asteroid sedately rotates every nineteen hours. The mirror is in an orbit that keeps it in sunlight 24 hours a day.

Not meant to cut the asteroid in pieces, the focused power of the mirror explosively evaporates the surface material it comes in contact with. This creates, in effect, a thruster on one side of 2005 YU55, gradually changing its course. The Earth is saved, and the young astronomer is made the new head of NASA. Well … yes, the story does kind of break down there. That would not normally happen in real life, but the description of a focusing mirror is not so hard to believe. We have the technology.

Imagine a mirror array with six circular pads in a circular array and one in the middle. Each pad is about 27 feet in diameter, made up of 120 flat panels per pad. Each panel is 2.25 feet square. Each panel is driven by a precision servomotor. With a total of 4,200 square feet, the mirror could concentrate 530,670 watts of power onto an area 2.25 feet by 2.25 feet. This is enough to vaporize most forms of matter. Note: Sun’s energy in space is 126.35 watts per square foot.

Drawing by Glen Hendrix in AutoCad. Click to enlarge.

The entire mirror is aligned with its target using a system similar to that of the Hubble telescope. Six gyroscopes and four reaction wheels can target the mirror to within .007 arcseconds. Let’s use 2005 YU55 as an example to show what that means. Let’s say we start beaming concentrated sunlight to 2005 YU55 when it is a hundred million miles from Earth, 400 times further than the Moon, about 38 days away. This accuracy guarantees the beam will hit within 40 feet of where it’s pointed. Since 2005 YU55 is about 1300 feet in diameter, it is a pretty sure thing it will be hit. The space mirror’s software will automatically track the asteroid on its path through space.

Drawing by Glen Hendrix in AutoCad. Click to enlarge.

To aim at objects beyond the orbit of Earth will require a reflector mirror about the size of the focusing mirror. It is much simpler, being a large, flat mirror that reflects the sun’s rays back to the focusing mirror when it’s pointed away from the Sun so that it can do its job. It will also need gyroscopes and reaction wheels as well as a suite of thrusters to position it. The whole thing could be lifted into orbit on a couple of Big Falcon Rocket trips with some assembly required, batteries included.

Drawing by Glen Hendrix in AutoCad. Click to enlarge.

The space mirror may be particularly adept at getting rid of that modern day scourge—space debris. The modularity of this design would allow a killing field to be set up for approaching debris, an invisible tunnel of dense solar energy. The idea would be to completely vaporize debris, turning it into a spreading gas cloud without the inertia to be harmful.

Astronauts working on reaction wheels of Hubble. Courtesy NASA.

Another application could be the smelting of ores in space. Nickel and iron from asteroids can be turned to steel. Ore from the Moon can be processed into aluminum. Off-world mining and other heat intense manufacturing processes will not be able to advance without this type of ancillary tool.

Mirrors in space might come in very handy for diverting asteroids, mining asteroids, smelting metals, terraforming Mars, vaporizing space debris, and paving small areas of the Moon with glass. Putting large mirrors in space, however, may have adverse political consequences for whatever nation or corporation that tries it. The main fear will come from those that don’t have a similar device in orbit worried that it could be used as a weapon. It would be possible to burn a hole in some other country’s spy satellite, start multiple fires in forests and brush lands, heat gas and oil lines until they rupture and burn, put a hole in a ship’s hull in the middle of the ocean, and on and on. Concerned parties would be looking at ways to guarantee the safe use of such tools, and they would have a legal basis for protest. One of the guiding principles of the Outer Space Treaty is “States shall not place nuclear weapons or other weapons of mass destruction in orbit or on celestial bodies or station them in outer space in any other manner; ....”

Perhaps the United Nations will evolve to have its own space force, like Trump has proposed for the United States. Trained members of this elite task force will go into space along with worker astronauts to check out the control software of space-based mirrors, their focusing capabilities, their accuracy in aiming and maintaining that target, and all the other things that could turn such a dangerous machine into a weapon. Space Marshall U.N.! It will make a great TV series. Maybe the fiction has to come before the fact as it has with so many such ideas in the past.