Octopus to fool prey by directing them towards the mouth, making them one of the few bioluminescent octopuses. Octopuses mainly move about by relatively slow crawling, with some swimming in a head-first position. Jet propulsion, or backwards swimming, is their fastest means of locomotion, followed by swimming and crawling. When in no hurry, they usually crawl on either solid or soft surfaces. Several arms are extended forwards, some of the suckers adhere to the substrate and the animal hauls itself forwards with its powerful arm muscles, while other arms may push rather than pull. As progress is made, other arms move
Spacecraft propulsion energy can be obtained from the gravity assist if rockets are used. Beam-powered propulsion is another method of propulsion without reaction mass. Beamed propulsion includes sails pushed by laser, microwave, or particle beams. There have been many ideas proposed for launch-assist mechanisms that have the potential of drastically reducing the cost of getting into orbit. Proposed non-rocket spacelaunch launch-assist mechanisms include: Studies generally show that conventional air-breathing engines, such as ramjets or turbojets are basically too heavy (have too low a thrust/weight ratio) to give any significant performance improvement when installed on a launch vehicle itself. However, launch vehicles can