The Bottleneck Years

Chapter 52

Ecology 550 - Group 5 Overview, March 8, 2057

Notes on a lecture.

Spring term was near the half way point and Ecology 550 was ahead of schedule. I had been fielding a lot of questions about Group 5, so I decided to do an overview lecture on the UNGETF groups and wind up with some details on Group 5.

I made a list to structure the class. I opened a screen with my padd and projected the list.

• Group 1 - Reforestation, ongoing, effectiveness minimal.
• Group 2 - Stratospheric sulphates, effective but politicized.
• Group 3 - Iron fertilization, effectiveness uncertain
• Group 4 - Large scale CO2 capture, effective but costly
• Group 5 - Sunshade project, 4 subgroups, effectiveness to be seen
• Group 6 - Cloud makers, ongoing, effectiveness minimal
• Group 7 - Analysis
• Group 8 - Changing ocean pH, ongoing, effectiveness minimal
• Group 9 - Artificial biology, 10 subgroups, effectiveness unknown
• Group 10 - Genetic engineering, 15 subgroups, effectiveness unknown
• Group 11 - Albedo modifications, ongoing, effectiveness unknown
• Group 12 - [Your suggestion here]

"You will notice that the word 'effective' here is used exclusively to refer to climate change mitigation. These projects are undoubtably effective in other senses, not the least of which is garnering funds for their respective corporations.

"Several of these groups may be new to you because they are not getting a lot of publicity. All of them are in various stages of development. Some of them may seem a little far fetched.

"As you consider this list, I would like you to keep in mind the full life cycle of the materials used -- the sources of those components, the energy used in their development, the energy required for their operation and maintenance, as well as the energy required in decommissioning and the ultimate destinations of those components.

"Our financial system tends to ignore what economists call externalities, but that may be a luxury we can no longer afford. A complete life cycle analysis is required. A carbon capture technology whose fabrication creates more carbon dioxide than it will capture is more than useless. It would be part of the problem and we must understand that before we begin."

I gave a more or less standard description of all of the Groups, except 5.

"Perhaps the most outlandish item on the list is Group 5 - the Sunshade Project," I continued. "Most of its work has been overshadowed by the corporate publicity campaigns a couple of the companies are running. How do the Daedalus Project and the Moon colony fit together? What is the goal here? I can fill you in on some of the details."

The lecture hall became unusually quiet.

"The primary problem is how to get 200 million tonnes of building material into space. Current launch costs are around 27,500 UN Credits per kilogram, so launch from Earth is not practical.

"There are four subgroups in Group 5. The central subgroup is responsible for building the sunshield itself. The other three subgroups are proposing different ways to get material to the L1 point. As events unfold, only one subgroup beyond the central, will be funded to completion."

A host of blank looks greeted me at that point.

"Okay, how many of you have taken any physics?"

About a third of the class put up their hands.

"Well, I am sure you have all heard of Sir Isaac Newton. He first formulated a mathematical description of gravity in the 17th century. In the 18th century, the French mathematician and astronomer Joseph-Louis Lagrange used Newton's theory to calculate the point the between the Earth and the Sun where the gravitational attraction of the Sun exactly matches that of the Earth. That is the L1 point. An object deposited at that point will tend to stay put because of that balance."

I put up a simplified diagram of the Sun-Earth-Moon system showing the relative positions.

"The L1 point is where the sunshield is to be built. It is about four times as far away from the earth as is the moon.

"You have no doubt seen the reports from the Daedalus which is on its way to the asteroid belt. Their intention is to fit a smallish asteroid with atomic motors and bring it in to the L1 point."

A hand shot up in the front row.

"Yes?"

"Won't that be dangerous? What if the asteroid hits the Earth?"

"You're right, there is an element of risk involved, but we are already in danger. The Ecological Mandate had judged this risk to be less than the risk of accelerating temperature rise."

The student looked dubious, but nodded.

"The other bit of advertising I am sure you have seen is the moon robots. So far all they have up there are those semi-autonomous robots, but they will shortly be joined by humans. Their intention is to build a factory and rail-gun launch facility to shoot construction modules to the L1 point.

"Now if that seems a little far fetched to you, you're going to love the final proposal. This subgroup is proposing to construct a space elevator to geosynchronous orbit and beyond."

A stir went through the class.

"These folks have set themselves a host of interesting problems. So far they have demonstrated a cable, a cable construction robot and a cable maintenance robot. They haven't started building yet, as far as I know.

"Keep in mind that geosynchronous orbit is just under 36,000 kilometers, so these machines face a not insignificant task. The cable itself will weigh millions of tons and will require a very high tensile strength. Currently, the only material which meets these criteria is carbon nanotube.

"These companies tend to be quite secretive. I suppose that to be expected. However, I can tell you a little that is not commonly known. Construction is to start from geosynchronous orbit. The assembly robots that extrude the carbon nanotube cable --- it's actually a sheet that is wound into strands and spun into a cable --- are supplied by feeder bots shuttling from the geosynchronous anchor, and they will be working both toward and away from the earth to keep the centre of mass at the geosynchronous command centre."

"Once constructed, several forces will be working on the cable. Sunlight will push on it depending on where it is located with respect to the sun. Solar winds will hit it with electric charges. Higher energy particles will bombard the filament dislodging carefully placed atoms. By design the cable will have to be continuously regenerated to avoid catastrophic failures.

"In addition, humans have littered near earth space with thousands of bits and pieces of old rockets, tools and non-functional satellites. Debris of all sorts is liable to be swept up by the space elevator. This is impossible to avoid and will have to be dealt with on a case by case basis. A laser based protection system is envisaged.

"Finally, there is the Coriolis force which deflects any object in motion, such as robot assemblers, feeder suppliers or cable cars. As the deflection is opposite in each hemisphere, the cable has to be placed directly above the Equator to minimize the effect. I hear that land speculators are having fun in South East Asia, Africa and South America."

"That's about all I can tell you. As an engineering project, a space elevator ranks among the most significant humans have ever attempted. It could change life on earth forever. Easy access to geosynchronous orbit combined with light sail ships could bring the metals of the asteroids within reach. The elevator would be a major step towards colonization of the solar system.

"But for now, we are focused primarily on methane levels and how the elevator could be used in the Sunshade Project.

"Using the UNGETF numbering system, write a 1500 word essay discussing the effectiveness and progress of one Group that interests you. Don't be afraid to be critical. You shouldn't need more than 2 weeks, say by the 22nd."

Excerpted from _The Bottleneck Years_ by H.E. Taylor

For further information, see
A Gentle Introduction.

If you want a copy, see
The Deal.

Last modified August 6, 2013