11. Thus, several techniques have been devised to reduce the fuel requirements of interplanetary travel . 12. Interplanetary travel , however, appears to come with a price tag.13. The station also would test interplanetary travel gear, including water-and air-recycling systems and space robots. 14. Its universe was limited to the solar system, and revolved heavily around interplanetary travel and terraforming. 15. A later version published in 1934 included details on interplanetary travel and applications of nuclear power. 16. No-I most certainly don't believe that interplanetary travel is easy . . . it's ridiculously difficult. 17. "' Interplanetary spaceflight "'or "'interplanetary travel "'is travel between planets, usually within a single planetary system. 18. Beginning in 1957, coinciding with the space race, Forner's attention turned to imagined scenes of interplanetary travel . 19. This fact is used in interplanetary travel . 20. A minimum-fuel Hohmann transfer orbit would take 146 days . See also our article on interplanetary travel .
