"Truck computer," he said. "Decompress airlock."
"Decompression sequence in progress," the computer replied.
From below them the powerful exhaust fans began to remove the air from the inside of the lock and expel it out into the greenhouse. The airlock would not be reduced to a complete state of vacuum, as would have been the case had they been in space, but would instead be reduced to the atmospheric pressure outside. The outside air pressure was a greatly variable number on Mars. It changed constantly from day to day as vast portions of the mainly carbon dioxide atmosphere were constantly frozen and thawed and refrozen in the polar regions of the planet. The truck computer automatically established a link with the Martian Weather Bureau, which kept track of current conditions, and downloaded the latest barometric reading. Of course in addition to the constant shifting of pressure due to polar freezing, the pressure was different from place to place depending upon elevation as well. And, unlike on Earth, there were no oceans in which to base a standard 0 elevation. The MWB, as did the rest of Mars, used the elevation of New Pittsburgh, Mars' first settlement, as its standard. Since the Eden area greenhouse was nearly a thousand meters lower in elevation than New Pittsburgh, which sat atop a huge plateau, the computer had to do some adjustments of the figure it received. This was all a standard part of living and working in an environment where human beings were not meant to live and work. Most Martians hardly gave such things a thought although they frustrated Earthling to hysterics at times.
"Decompression complete," the computer told them ninety seconds after it had begun. "Airlock seal is intact. It is safe to egress."
"Got it," Lon said, looking up at the number printed on the access hatch. "Suit computer, establish radio link with Agricorp Eden Operations."
"Establishing link," the computer replied. A moment later: "Link is active."
Lon told the AEO computer that two workers would be atop greenhouse number A-594 near access panel A-594-12 for approximately one hour. He then asked the computer to open that particular panel for him. Once again he was asked for his name and social security number and once again his voiceprint was compared with that in the files. The computer then took the additional step of comparing Lon's stated mission with the work orders for the day that had been filed in its memory banks. At last, satisfied that Lon and Brent were not terrorists attempting to disrupt Agricorp operations and cut into profits, it consented to their request.
"Access panel A-594-12 is opening now," they were told.
There was a very slight hiss of mingling air as the square panel above them slid along its track. Red sand and dirt, blown up there by the constant wind that swept the planetary surface, dropped down upon them. Above them the natural red tint of the Martian sky, which had looked distinctly purple through the tinted glass roof, could be seen in all of its glory. The sky was completely cloudless. Cloud formations, while common in the higher and lower latitudes, were almost unheard of in the equatorial regions.
Lon climbed out first, stepping on the ladder that was a permanent part of the airlock's wall. He pulled himself out onto the glass roof and then kneeled down next to the hatch to pull up the two tool chests that Brent handed up to him. He set them to the side and then stood up, allowing Brent to extricate himself from the lock. This portion of the greenhouse roof was only a few meters from the southwest corner of the large building. Twenty meters below them was a paved access road that ran alongside. The road, which was used to access the roof if major repairs or renovations, those involving heavier pieces of equipment, needed to be done, had not been plowed in a while and had drifts of sand marring its surface. Back at the Agricorp operations building at the edge of the city (not to be confused with the Agricorp main building downtown — the Earthlings that ran the company certainly would not wish to work out of the same building as the common field hands) were large hydrogen powered trucks and even tracked vehicles that were used for heavy maintenance and repairs. On the other side of the road there was two hundred meters of open space — just enough to allow heavy equipment through — before the next greenhouse began. A narrow connecting tunnel near the far end joined the greenhouse to its neighbor which was in turn joined to its neighbor, and so on and so forth, all the way back to the main tunnel that led from the operations building to the first greenhouse. This allowed workers and heavy harvest machines, as well as container trucks, to get to where they were needed without having to go outside. It was through this system of tunnels and interior roads that Brent and Lon had driven their electric maintenance truck to where it was now parked.
Looking outward from the roof of number A-594, just poking upward from the western horizon, the tops of the Eden high rises could be seen some thirty kilometers distant. Aside from that the tinted blue of greenhouse after greenhouse, all a uniform twenty meters high and two square kilometers in size, covered the land like a blanket. Lon and Brent were at the near edge of the Eden area's agricultural land. They could only see to the horizon, which was not very far on Mars, so only about a half percent of the total number of greenhouses in the area were visible to them from twenty meters above the ground. And Eden's agricultural holdings, while the largest on the planet, were only twenty-two percent of the total on Mars. Eight other cities, all along the Martian equator, were centered among similar complexes of artificial growing environments. Staring out upon the sea of glass and steel and realizing that you were only looking at a minute fraction of what was actually there, one could begin to fathom why it was that Agricorp and the other food production companies of Mars were the most powerful entities in the solar system. Within those greenhouses everything from range cattle to marijuana to soybeans were produced year around, free of the perils of insects or weather. Nearly every type of food that was consumed by human beings or animals, whether they were on Mars or Earth or the Jupiter system, whether it was junk food or vegetables or meat, came from Mars in one way or another. It was hard to believe sometimes that all of this food production, which employed more Martians than anything else on the planet, and all of the wealth that came from it, most of which was sent back to rich stockholders on Earth, had been born as a simple experiment a hundred years before.
The first Martian colonists had come, not to grow food, but to exploit the rich deposits of iron ore that lay beneath the higher and lower latitudes of the planet. The supply of easily mined ore on Earth had been almost completely depleted in the early 21st century by the decade long World War III. The bloodiest conflict in human history had raged on three different continents and had killed more than two hundred million people. During the struggle, the combatants had mined iron ore at a mad pace from every available location on the planet turning it into guns, tanks, aircraft, ships, missiles, and bombs. By the time the last shell was fired and the formal surrender ceremonies were conducted, a large percentage of the reachable iron ore was gone forever, exploded into fragments that littered the battlefields of North America, China, and Eastern Europe.
Aside from wiping out the iron supply, World War III had also spawned the two spheres of influence that were now the constantly bickering entities of EastHem and WestHem. WestHem consisted of the North and South American landmasses and was ruled by Caucasians from the former United States and Canada. EastHem, the larger, though poorer of the two, consisted of Europe, Asia, Africa, and Australia. It was ruled by Caucasians of the former British Isles, Germany, and France. EastHem and WestHem had been the victorious allies of World War III, defeating the Asian Powers alliance of China, Japan, Korea, and India. The Asian Powers had launched a surprise attack on January 1, 2009 into Siberia and the Middle East before jumping across the Bering Straight into Alaska, Canada, and, eventually Washington, Oregon, and Idaho. Their goal had been a lightening fast capture of the world's petroleum supplies before the opposition had a chance to gear up to a war footing and stop them. They had come very close to achieving this goal in the first months of the fighting. Only a few lucky guesses on the part of the American Army and a few instances of bad luck on the part of the Chinese Army had allowed the Asian Powers to be stopped short of the Texas and California oil fields in North America. Here, the war had stagnated into a bloody stalemate for the next eight years, with millions upon millions dying but with the lines not moving much more than a few kilometers back and forth. Only the development of practical, portable anti-tank and anti-aircraft lasers had broken this stalemate and allowed the WestHem and EastHem alliance to slowly, grudgingly push the Asian Powers back and eventually destroy them with strategic and tactical bombing campaigns against their homelands.