Lunar swirls as possible targets for the AMIE/SMART-1 mission

The nature of diffuse albedo anomalies on the lunar surface that look like swirls is one of most interesting mystery in current lunar studies. Unusual, light-colored surface markings were observed in Mare Marginis in results of the analysis of Apollo-8 photography and visual observation. Identical markings were distinguished in Mare Ingenii on the lunar far side and were associated with those in Mare Marginis. It was noted that the positioning of these two regions on the lunar globe was striking: the swirls of Mare Marginis location was diametrically opposed to the Mare Orientale, and the swirls of Mare Ingenii lied on opposite side of the Mare Imbrium. All swirl markings (with the only one exception - Reiner Gamma formation) lie on the far side of the Moon. Reiner Gamma swirl is relatively small formation. Its area is 3.3 x103 km^2. Swirl region in Mare Ingenii extends on the area equal to 50.2 x 103 km^2. The swirl area in Mare Marginis achieves 73.9 x 103 km^2. Of great interest is to compare the typical morphological features of the different swirl markings. The available Clementine images allow one to compare, for example, albedo features of the Reiner Gamma formation with albedo features of the swirl markings located in the area that is antipodal to the Crisium basin. The area includes a fragment that is located in the crater Gerasimovich itself and some small albedo formation to the North of the main structure. Feature named as bright "loop" is typical detail of the Reiner Gamma. The analogous detail of swirl it is possible to observe into crater Gerasimovich. It is needed to note that linear scale of the both features is the same. Other type of characteristic detail - "close loop" is shown as in Reiner Gamma swirl as in crater Gerasimovich swirl. The linear scale of these features is the same too. The presence of the characteristic details in the form of complex loops inside crater Gerasimovich swirl allows unambiguous classification of this albedo anomaly as a swirl of the same type as Reiner Gamma. Moreover, photometric and spectral properties of the swirl formations are very similar. Preliminary estimations of the swirl age show that Reiner Gamma formation and the swirl formation placed inside crater Gerasimovich are very young lunar features and they appeared about 107 years ago. Nature and origin of the swirl formations are open questions in lunar science. Investigation of them could be a good science objective for AMIE/SMART-1 mission.