This is reposted from email with permission from the author. A few modifications were made by me in addressing the pictures so that it would make sense in a post format rather than an email format. The credit goes to Gary and the artist conception made by his wife Stephanie (an architect).

(click each image for a larger version)

The first image shows a broad view of the River Colony. The second is slightly truncated (couldn't get all of it on the scanner). The second shows one of the curtain walls of the River Colony. The River Colony is divided up into segments along the river. These segments are like compartments in a submarine. The curtain wall acts as a pressure bulkhead enabling one segment to be sealed off should there be a loss of pressure accident. The curtain wall has large gate valves similar to those used in a dam (except air tight) to close off the segment. There is a redundant aqueduct system setup on the surface just outside of the glass ceiling of the colony. The aqueduct would enable bypassing of water around a depressurized segment. The glass ceiling (actually fuzed silica because there is no sodium carbonate on Mars to make glass) is much more complicated than shown in the artist's conception. The ceiling is double paned with water pumped through it from down river to up stream. The river provides irrigation water and heating for the colony. The river would have waste heat dumped into it from a large nuclear reactor. The entire river would act like a giant cooling tower convecting heat into the bedrock. The water in the double paned ceiling would be warm enough to prevent frost build up on the lower inside pane. The space between the two panes would be at least 2 meters thick in order to provide shielding from secondary cosmic rays (there are pregnant women and small children below). The water would also be laced with ozone or some other disinfectant to prevent algae buildup (a robot or a person on scuba tanks could swim between the panes to do maintenance and scrape off algae if necessary). The ceiling is obviously the trickiest part of the design. It has to withstand the enormous pressure of the air below it with almost insignificant counter-pressure from the Martian atmosphere. The pressure loading is reduced somewhat by the mass of the water recirculating between the glass panes but it is still enormous. The water would have to be almost 20 meters thick to completely counter the pressure from the air below (Mars gravity is 38% of the Earth's). Such a thickness would cut out too much sunlight and hinder agriculture. This leads to an interesting structural optimization problem of making the water thick enough to diminish the mass of the fuzed silica and support cables but thin enough to allow adequate light penetration. This optimization problem is further complicated by the need of the ceiling to be buildable and not fall to pieces in the event of accidental segment depressurization. I have shown suspension bridge technology as one method for building the ceiling.

The colony's air would come from the surrounding Martian atmosphere which is 95.5% carbon dioxide, 2.7% molecular nitrogen, 1.6% argon, 0.13% molecular oxygen and 0.07% carbon monoxide. Martian atmospheric gas would be compressed from 7 millibars to over 1 bar. The compression process would superheat the gas resulting in chemical dissociation into mostly carbon monoxide, atomic oxygen, nitrogen and argon. The carbon monoxide would be used for steel production. The Martian soil is 15% iron which is why the planet is red (it's rust). The nitrogen would be processed into urea and ammonia for agriculture. The oxygen and argon would be "waste products" from industrial activity to provide the colony's breathable atmosphere (the argon would dilute the oxygen to prevent fires). Because the atmosphere would be continually produced by industrial activity, the colony would be leaky in terms of it's atmosphere leaking past the ceiling and canyon walls.

The energy for industrial activity, atmospheric compression and water heating would come from nuclear reactors. An ideal energy source would be plutonium (Pu-239) from old nuclear weapons. The critical mass for plutonium from old thermonuclear "bomb pits" is between 6 - 15 kg. A plutonium mass of 257 metric tons was produced for weapon's use during the Cold War. This could provide the energy for 25700 reactor cores. If one assumes a reactor core operating life of 5 years and the plutonium was the only energy source for 340 years then the colony could have 377 reactors running simultaneously for the entire 340 years. If one assumed the original colony was 1000 people who came from Earth and the population doubled every 20 years then in 340 years the population would grow to 131 million people. Disposal of weapons grade plutonium on Mars makes Mars colonization feasible and rids the Earth of a deadly menace.

The published article concerning an earlier version the transportation system can be found in the "Journal of the British Interplanetary Society" (JBIS), Vol. 48, pp. 373-386. This earlier version had a design flaw in that the entry vehicles underwent too high a deceleration (greater than 5 gravities) if they entered the Martian atmosphere directly from a cycler orbit.
The revised design uses a two stage aeroshell. The first stage is a biconic similar to what was proposed in the Human Exploration and Design Study (HEDS) at the Johnson Space Center. This aeroshell shape has high Lift-divided-by-Drag (L/D) and thus enables high speed aerocapture to Mars orbit without exceeding 5 gravities deceleration. The initial orbit would be highly eccentric and enable entry to the surface if the vehicle had sufficient drag. The second stage aeroshells are like "peas in a pod". The first stage biconic splits in half, ejecting three high drag 70 degree half angle sphere-cones. Each sphere-cone carries 20 people. After lifting entry, the sphere-cones would crash land using the parachute, solid rocket and air bag landing method. The air bag would inflate with a crushable foam (it would not use the bounce method of Mars Pathfinder and MER).