By ordinary, communications between different places on a planet's surface use frequencies the ion-layers of the atmosphere either reflect or refract down past the horizon. But there is usually some small leakage to space, and line-of-sight frequencies are generally abundant. It is one of the annoyances of a ship coming in to port that space near most planets is usually full of local signals.
"I'll check," said Calhoun curtly. "Stand by."
The Candida would have arrived off Maya as the Med Ship had done, and called down as Calhoun had been doing. It was very probably a ship on schedule and the grid operator at the spaceport should have expected it. Space commerce was important to any planet, comparing more or less with the export-import business of an industrial nation in ancient times on Earth. Planets had elaborate traffic-aid systems for the cargo-carriers which moved between solar systems as they'd once moved between continents on Earth. Such traffic aids were very carefully maintained. Certainly for a spaceport landing-grid not to respond to calls for twelve hours running seemed ominous.
"We've been wondering," said the Candida querulously, "if there could be something radically wrong below. Sickness, for example."
The word "sickness" was a substitute for a more alarming word. But a plague had nearly wiped out the population of Dorset, once upon a time, and the first ships to arrive after it had broken out most incautiously went down to ground, and so carried the plague to their next two ports of call. Nowadays quarantine regulations were enforced very strictly indeed.
"I'll try to find out what's the matter," said Calhoun.
"We've got a passenger," repeated the Candida aggrievedly, "who insists that we land him by space-boat if we don't make a ship landing. He says he has important business aground."
Calhoun did not answer. The rights of passengers were extravagantly protected, these days. To fail to deliver a passenger to his destination entitled him to punitive damages which no spaceline could afford. So the Med Ship would seem heaven-sent to the Candida's skipper. Calhoun could relieve him of responsibility.
The telescope screen winked and showed the surface of the planet a hundred thousand miles away. Calhoun glared at the image on the port screen and guided the telescope to the spaceport city—Maya City. He saw highways and blocks of buildings. He saw the spaceport and its landing-grid. He could see no motion, of course.
He raised the magnification. He raised it again. Still no motion. He upped the magnification until the lattice-pattern of the telescope's amplifying crystal began to show. But at the ship's distance from the planet, a ground-car would represent only the fortieth of a second of arc. There was atmosphere, too, with thermals; anything the size of a ground-car simply couldn't be seen.
But the city showed quite clearly. Nothing massive had happened to it. No large-scale physical disaster had occurred. It simply did not answer calls from space.
* * * * *
Calhoun flipped off the screen.
"I think," he said irritably into the communicator microphone, "I suspect I'll have to make an emergency landing. It could be something as trivial as a power failure—" but he knew that was wildly improbable—"or it could be—anything. I'll land on rockets and tell you what I find."
The voice from the Candida said hopefully:
"Can you authorize us to refuse to land our passenger for his own protection? He's raising the devil! He insists that his business demands that he be landed."
A word from Calhoun as a Med Service man would protect the spaceliner from a claim for damages. But Calhoun didn't like the look of things. He realized, distastefully, that he might find practically anything down below. He might find that he had to quarantine the planet and himself with it. In such a case he'd need the Candida to carry word of the quarantine to other planets and thus to Med Service sector headquarters.
"We've lost a lot of time," insisted the Candida. "Can you authorize us—"
"Not yet," said Calhoun. "I'll tell you when I land."
"But—"
"I'm signing off for the moment," said Calhoun. "Stand by."
He headed the little ship downward, and as it gathered velocity he went over the briefing sheets covering this particular world. He'd never touched ground here before. His occupation, of course, was seeing to the dissemination of medical science as it developed under the Med Service. The Service itself was neither political nor administrative. But it was important. Every human-occupied world was supposed to have a Med Ship visit at least once in four years to verify the state of public health.
Med Ship men like Calhoun offered advice on public-health problems. When something out of the ordinary turned up, the Med Service had a staff of researchers who hadn't been wholly baffled yet. There were great ships which could carry the ultimate in laboratory equipment and specialized personnel to any place where they were needed. Not less than a dozen inhabited worlds in this sector alone owed the survival of their populations to the Med Service, and the number of those which couldn't have been colonized without Med Service help was legion.
Calhoun reread the briefing. Maya was one of four planets in this general area whose life systems seemed to have had a common origin, suggesting that the Arrhenius theory of space-traveling spores was true in some limited sense. A genus of ground-cover plants with motile stems and leaves and cannibalistic tendencies was considered strong evidence of common origin.
The planet had been colonized for two centuries now, and produced organic compounds of great value from indigenous plants, most of which were used in textile manufacture. There were no local endemic infections to which men were susceptible. A number of human-use crops were grown. Cereals, grasses and grains, however, could not be grown because of the native ground-cover motile-stem plants. All wheat and cereal food had to be imported, which fact severely limited Maya's population. There were about two million people on the planet, settled on a peninsula in the Yucatan Sea and a small area of mainland. Public-health surveys had shown a great many things about a great many subjects ... but there was no mention of anything to account for the failure of the spaceport to respond to arrival calls from space. Naturally!
The Med Ship drove on down, and the planet revolved beneath it.
As Maya's sunlit hemisphere enlarged, Calhoun kept the telescope's field wide. He saw cities, and vast areas of cleared land where native plants were grown as raw materials for the organics' manufacturies. He saw very little true chlorophyll green, though. Mayan foliage tended to a dark olive color.
* * * * *
At fifty miles he was sure that the city streets were empty even of ground-car traffic. There was no spaceship aground in the landing-grid. There were no ground-cars in motion on the splendid, multiple-lane highways.
At thirty miles altitude there were still no signals in the atmosphere, though when he tried amplitude-modulation reception he picked up static. But there was no normally modulated signal on the air at any frequency. At twenty miles—no. At fifteen miles, broadcast power was available, which proved that the landing-grid was working as usual, tapping the upper atmosphere for electric charges to furnish power for all the planet's needs.
From ten miles down to ground-touch, Calhoun was busy.
It is not too difficult to land a ship on rockets, with reasonably level ground to land on. But landing at a specific spot is something else. Calhoun
