If the appearance of our observer units and manned craft caused too violent reactions on the planet, the explorers would withdraw to their orbiting space vehicle and either wait for a lull or else start the long trip back home. Another interplanetary craft from the earth might take its place later to resume periodic surveys. In this way, a vast amount of information could be collected without once making contact with the strange race. If they seemed belligerent or uncivilized, we would probably end our survey and check on the next possibly inhabited planet. If we found they were highly civilized, we would undoubtedly attempt later contact. But it might take a long time, decades of observation and analysis, before we were ready for that final step. We might find a civilization not quite so advanced as ours. It might not yet have developed radio and television. We would then have no way of getting a detailed picture, learning the languages, or communicating with. the Martians. Analysis of their atmosphere might show a great hazard to earthlings, one making it impossible to land or requiring years of research to overcome. There might be other obstacles beyond our present understanding. This same procedure would apply to the rest of the solar-system planets and to more distant systems. Since Wolf 359 is the nearest star outside our system that is likely to have inhabited planets, one of these planets would probably be listed as the first to explore in far-distant space. It would be a tremendous undertaking, unless the speed of light can be exceeded in space. Since Wolf 359 is eight light-years from the earth, even if a space ship traveled at the theoretical maximum—just under 186,00 miles a second—it would take over sixteen years for the round trip. Detailed observation of the planet would add to this period. If we assume half that speed—which would still be an incredible attainment with our present knowledge—our space explorers would have to dedicate at least thirty-two years to the hazardous, lonely round trip. However, there has never been a lack of volunteers for grand undertakings in the history of man. It is quite possible that in our survey of the solar-system planets we would find some inhabited, but not advanced enough to be of interest to us. Periodically, we might make return visits to note their progress. Meantime, our astronomers would watch these planets, probably developing new, higher powered telescopes for the purpose, to detect any signs of unusual activity. Any tremendous explosion on a planet would immediately concern us. Such an explosion, on Mars, was reported by astronomers on January 16, 1950. The cause and general effects are still being debated. Sadao Saeki, the Japanese astronomer who first reported it at Osaka, believes it was of volcanic nature.