After maintaining an enigmatic silence about their successful soft landing on the moon, the Russians finally answered some questions last week and gave Western scientists a chance to check their own interpretation of Luna 9's remarkable photographs.
At a 21-hr, news conference in Mos cow, top Soviet scientists disclosed that Luna 9's instrumented, picture-taking payload stood only 2 ft. high and weighed a mere 220 Ibs. The remaining bulk of the 3,428-lb. craft that the Russians fired into space consisted large ly of fuel and the retrorockets that slowed Luna 9's final descent. In addition, the payload was detached from its rocket engines just before impact and hurled to one side, well away from the area that was disturbed by the fiery blasts of the descending retrorockets.
Meteor Bombardment. The Russians confirmed that Luna 9 had found no dust on the moon. Instead, it hit a surface that consisted of hard, porous, volcanic soil formed from lava that had crumbled during billions of years of drastic temperature changes and bombardment by meteors and solar particles. Inhospitable as it is, such a surface could probably bear the weight of both heavy space vehicles and men. The major obstacle remaining before man can fly to the moon, concluded Soviet Academy of Sciences President Mstislav Keldysh, "is the problem of returning a cosmonaut to earth. I think it is easier to solve the problem of a relatively short stay on the moon than to solve the problem of recovery."
Western experts had speculated that the landing-site time had been picked so that Luna could begin operating near the start of a two-week period of lunar daylight. They figured it would have about 14 days of continuous sunshine to keep its solar batteries charged. Instead, the Russians explained, their intention was merely to land and operate Luna 9 during the early lunar morning-before surface temperatures could rise to their maximum of about 250° F. and damage delicate equipment. Thus their ship was equipped only with standard, unrechargeable batteries.
Explosive Expansion. While they assessed the Russian information, Western scientists continued to interpret Luna 9's pictures. London University Astronomer Gilbert Fiedler called attention to lines in some of the pictures that might be edges of an ancient lava flow; he agreed with the Russians and many American scientists that the porous surface resulted from the explosive expansion of gases in the lava as it emerged onto the moon's airless surface.
Though Luna 9 successfully disposed of the hypothetical thick layers of lunar dust, said University of Arizona Astronomer Gerard Kuiper, some parts of the moon could still present a hazard to landing spacecraft. Photographs from the U.S. Ranger 9 moon probe show that between 5% and 10% of the lunar surface is covered by depressions, apparently areas of thin crust that have sagged into caves or voids under the surface. Should a spacecraft land on such a crust, he believes, it might crash through into the cave below.
Luna 9's findings pleased space officials in Houston as well as in Moscow.
"We've got a rational surface," exulted Apollo Spacecraft Program Manager Joseph Shea, "and I think the hypothesis of an oddball surface has been put to bed. There are no fundamental problems standing between us and our standing on the moon."