The panspermia hypothesis eventually fell out of favor for a variety of reasons. Skeptics pointed out that microorganisms could not possibly survive the damage caused by ultraviolet radiation and cosmic rays while being propelled out of a solar system away from a star. Indeed, it was unclear how biological material could escape from a planet by natural processes in the first place. If unprotected, the molecules of life would quickly be destroyed by radiation near the ejecting planet. Furthermore, it was not clear how microorganisms, having made a journey across the huge distances of interstellar space, could have safely descended to the surface of the Earth or any other planet. Arrhenius himself argued that organisms caught inside meteorites would be subjected to incandescent* temperatures while entering the atmosphere of a terrestrial body. Such heat would destroy any life-forms lucky enough to have survived to this point.
The word " propelled" in the passage is closest in meaning to