Mission of Gravity

„Good point. I’ll see what can be done.” Lackland turned from the microphone to encounter several worried frowns. „What’s the matter? Can’t we make a photographic map as we did of the equatorial regions?”

„Certainly,” Rosten replied. „A map can be made, possibly with a lot of detail; — but it’s going to be difficult. At the equator a rocket could hold above a given point, at circular velocity, only six hundred miles from the surface — right at the i

„I hadn’t thought of that,” admitted Lackland. „We can do it, though; and I don’t see any ‘alternative in any case. I suppose Barle

„Right. Well launch one of the rockets and get to work.” Lackland gave the substance of this conversation to Barle

„I could either go on upstream, following the cliff around to the right, or leave the ship and the river and follow to the left. Since I don’t know which is best from the point of view of distance, well wait. I’d rather go upstream, of course; carrying food and radios will be no joke otherwise.”

„All right. How is your food situation? You said something about its being hard to get that far from the ocean.”

„It’s scarcer, but the place is no desert. We’ll get along for a time at least. If we ever have to go overland we may miss you and your gun, though. This crossbow has been nothing but a museum piece for nine tenths of the trip.” „Why do you keep the bow?”

„For just that reason — it’s a good museum piece, and museums pay good prices. No one at home has ever seen, or as far as I know even dreamed of, a weapon that works by throwing things. You couldn’t spare one of your guns, could you? It needn’t work, for’that purpose.”

Lackland laughed. „I’m afraid* not; we have only one. We don’t expect to need it, but I don’t see how we could explain giving it away.” Barle

It was also necessary to see to the food question; it was not, as he had told Lackland, really pressing, but more work with the nets was going to be necessary from now on. The river itself, now about two hundred yards wide, appeared to contain fish enough for their present needs, but the land was much less promising. Stony and bare, it ran a few yards from one bank of the stream to end abruptly against the foot of (he cliff; from the other, a series of low hills succeeded each other for mile after mile, presumably far beyond the distant horizon. The rock of the escarpment’s face was polished glass-smooth, as sometimes happens even on Earth to the rocks at the sliding edges of a fault. Climbing it, even on Earth, would have required the equipment and body weight of a fly (on Mesklin, the fly would have weighed too much). Vegetation was present, but not in any great amount, and in the first fifty days of their stay no member of the Bree’s crew saw any trace of land animal lif e. Occasionally someone thought he saw motion, but each time it turned out to be shadows cast by the whirling sun, now hidden from them only by its periodic trips beyond the cuff. They were so near the south pole that there was no visible change in the sun’s altitude during the day.

For the Earthmen, the time was a little more active. Four of the expedition, including Lackland, ma

As power was applied both to kill the moon’s orbital velocity and bring them out of Mesklin’s equatorial plane the picture changed. The ring showed for what it was, but even the fact that it also had two divisions did not make the system resemble that of Saturn. Mesklin’s flattening was far too great for it to resemble anything but itself — a polar diameter of less than twenty thousand miles compared to an equatorial one of some forty-eight thousand has to be seen to be appreciated. All the expedition members had seen it often enough now, but they still found it fascinating.

The fall from the satellite’s orbit gave the rocket a very high velocity, but, as Rosten had said, it was not high enough. Power had to be used in addition; and although the actual pass across the pole was made some thousands of miles above the surface, it was still necessary for the photographer to work rapidly. Three runs were actually made, each taking between two and three minutes for the photography and many more for the whipping journey around the planet. They made reasonably sure that the world was presenting a different face to the sun each time, so that the height of the cliff could be checked by shadow measurements on all sides; then, with the photographs already fixed and on one of the chart tables, the rocket spent more fuel swinging its hyperbola into a wide arc that intercepted Toorey, and killing speed so that too much acceleration would not be needed when they got there. They could afford the extra time consumed by such a maneuver; the mapping could proceed during the journey.

Results, as usual with things Mesklinite, were interesting if somewhat surprising. In diis case, the surprising fact was the size of the fragment of planetary crust that seemed to have been thrust upward en bloc. It was shaped rather like Greenland, some thirty-five hundred miles in length, with the point aimed almost at the sea from which the Bree had come. The river leading to it, however, looped widely around and actually contacted its edge at almost the opposite end, in the middle of the broad end of the wedge. Its height at the edges was incredibly uniform; shadow measurements suggested that it might be a trifle higher at the point end than at the Bree’s present position, but only slightly.

Except at one point. One picture, and one only, showed a blurring of the shadow that might be a gentler slope. It was also in the broad end of the wedge, perhaps eight hundred miles from where the ship now was. Still better, it was upstream — and the river continued to hug the base of the cliff. It looped outward at the point where the shadow break existed as tiiough detouring around the rubble pile of a collapsed slope, which was very promising indeed. It meant diat Barle

land part should not be overwhelmingly difficult. Lackland said so, and was answered with the suggestion that he make a more careful analysis of the surface over which his small friend would have to travel. This, however, he put off until after the landing, since there were better facilities at the base.

Once there, microscopes and densitometers in the hands of professional cartographers were a little less encouraging, for the plateau itself seemed rather rough. There was no evidence of rivers or any other specific cause for the break in the wall that Lackland had detected; but the break itself was amply confirmed. The densitometer indicated that the center of the region was lower than the rim, so that it was actually a gigantic shallow bowl; but its depth could not be determined accurately, since there were no distinct shadows across the i