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L01-030M

Sun Elevation: 23.59°

Distance: 1300.61km

This is the western part of the Korolev Basin Region. The northern rim of the South Pole-Aitken Basin is shown. It would be much more dramatic if the illumination were from the north, which is, of course, impossible. Icarus, De Vries, McK-ellar, and Bok are examples of craters that have a distinct central peak. The rim of Korolev has been eroded by subsequent bombardment, but the western edge of the rim appears to have formed across a previous crater. Because of the degree of erosion, Korolev has been assigned to an earlier Nectarian period, that is, slightly younger than Nectaris. Lacus Oblivionis and Rumford are dark in Clementine's images and probably have been invaded by lava.

Key: Korolev and craters to the west, north of SPA

Nectarian

Congreve, 57 km Icarus, 98 km Korolev Basin, 440 km Zhukovskiy, 81 km

Early Imbrium

Doppler, 1 1 0km Engelhardt, 43 km

Copernican

Crookes, 49 km

Crookes

L01-028M

Sun Elevation: 19.37°

Distance: 1305.28 km

The smooth parts of the floor of Korolev have been resurfaced in the Nectarian and Early Imbrian periods. Doppler is younger; it has impacted the southern rim of Korolev and thrown part of that rim, plus its own ejecta, onto the floor of the basin. The inner ring of Korolev (see Figure 7.4) is very clear in this photo. Some of the very sharply defined smaller craters may be secondaries from the Orientale Basin to the east-southeast.

Key: Craters to the east of Korolev, north of SPA

Pre-Nectarian Nectarian

Galois, 222 km Kibal'chich, 92 km

Paschen, 1 24km Mechnikov, 60km

Tsander, 1 81 km Sechenov, 62 km

Timiryazev, 53 km

Copernican

Vavilov, 96 km

L01-030H1, H2 (left from top) L01-036H1, H2 (right from top) Sun Elevation: ~22° Distance: ~1300 km

This photomosaic shows the southwest sector of the Korolev Basin, from its center to its rim (Kr). Its central floor is flooded with dark mare (ml), bounded by the raised inner ring (ir). Some mare material (m2) has also intruded into the western sector of the basin between the inner ring and the rim. This young surface is assigned to the Early Imbrian period and the mare in the center to the Nectarian period, later in that long period than Korolev itself, of course. Beyond the inner ring, the basin floor slopes upward to the rim cliffs.

Crookes D (CD, 41 km) has impacted the Korolev rim and broken down the rim cliffs. The ejecta blanket and rays (Cr) of Crookes have spread light material over Crookes D and onto the floor of Korolev. The eastern half of Crookes (49 km) is just southwest of Crookes D.

Chains of secondary craters (ch) radial to the 0rientale basin can be seen between the inner ring and the rim.

The southeast corner of the mosaic shows the circular rim of Korolev rising to a sharp maximum elevation and then sloping down into the ejecta blanket, with its hummocks. Some of the young craters on the inner rim appear elliptical because of the steep slope there. This is an illustration of the principle of superposition: the shape of an impact crater is added to the shape of the target surface. If the target surface is sloped, the crater will be slanted accordingly.

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i5 L01-030H3 (left) a L01-036H3 (right) Î Sun Elevation: ~22° Distance: ~1300 km

This photomosaic continues to the south from the one given before.

The northeast sector of the rim of the South Pole-Aitken Basin (SPA, 2500 km) dominates this picture. When this ancient basin was fresh, there were cliffs like those of Korolev. They have been worn away by over 3 billion years of subsequent impacts, including all of the period of the proposed great cataclysm discussed earlier. For example, Doppler (D, 110 km) has modified the SPA rim by its impact and ejecta. The high incidence of large craters inside the South Pole-Aitken Basin, relative to their frequency inside of Korolev, is further evidence of its great age.

The brightness of the area between Doppler and the South Pole-Aitken Basin is due to ejecta from Crooks to the northwest.

The sun elevation for this photo is lower than usual. As a result, the detail is exaggerated but more can be seen where the surface is nearly even. This area is in the northeast sector of the floor of Korolev. Mare has flooded and resurfaced this area of the basin floor, within the inner ring; evidence of individual flows can be seen. Most of the craters that were formed on top of the mare surface have had very little erosion. They show a rounded cross section, a sharply peaked rim, and a smooth ejecta blanket. The mare basalt here, like most, was probably exuded after the period of the proposed great cataclysm. There are many secondary craters, some chains of which are radial to 0ri-entale. Striations on the northern wall are probably due to 0rientale.

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L01-038H2

Sun Elevation: 6.36°

Distance: 1388.34 km

L01-038H2

Sun Elevation: 6.36°

Distance: 1388.34 km

The spectacular crater Korolev M (KM, 58 km) has a central peak that is almost perfectly formed. The mare that flooded its floor has hardly been disturbed but craters on its rim indicate that it is from the Nectarian period. The northern rim of this crater has impacted the inner ring of Korolev, probably raising a high sector of that northern rim, which later collapsed onto the floor in response to a small impact that must have come after the mare lava hardened. Other impacts have caused similar events at the southern rim. A catena (chain) of secondary craters from Orientale crosses the picture near the top.

In this chaotic area south of Korolev, we see the outer rim of Doppler (D, 110 km) superimposed on the outer rim of Galois Q (GQ, 132 km), which is superimposed on the outer rim of Korolev (top). Some loss of detail is a consequence of the low sun angle. There is a suggestion of a crater predating both Doppler and Galois Q in the lower half of the picture, a crater whose rim touches each of the other rims, but it may be just a coincidental pattern.

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