Editing Panspermia (section)

=== Transport vessels ===
Bacterial spores and plant seeds are two common proposed vessels for panspermia. According to the theory, they could be encased in a meteorite and transported to another planet from their origin, subsequently descend through the atmosphere and populate the surface with life (see lithopanspermia below). This naturally requires that these spores and seeds have formed somewhere else, maybe even in space in the case of how panspermia deals with bacteria. Understanding of planetary formation theory and meteorites has led to the idea that some rocky bodies originating from undifferentiated parent bodies could be able to generate local conditions conducive to life.<ref name=":24"/> Hypothetically, internal heating from [[Radiogenic nuclide|radiogenic isotopes]] could melt ice to provide water as well as energy. In fact, some meteorites have been found to show signs of aqueous alteration which may indicate that this process has taken place.<ref name=":24"/> Given that there are such large numbers of these bodies found within the Solar System, an argument can be made that they each provide a potential site for life to develop. A collision occurring in the [[asteroid belt]] could alter the orbit of one such site, and eventually deliver it to Earth.

Plant seeds can be an alternative transport vessel. Some plants produce seeds that are resistant to the conditions of space,<ref name=":14"/> which have been shown to lie dormant in extreme cold, vacuum, and resist short wavelength UV radiation.<ref name=":14"/> They are not typically proposed to have originated on space, but on another planet. Theoretically, even if a plant is partially damaged during its travel in space, the pieces could still seed life in a sterile environment.<ref name=":14"/> Sterility of the environment is relevant because it is unclear if the novel plant could out-compete existing life forms. This idea is based on previous evidence showing that cellular reconstruction can occur from cytoplasms released from damaged algae.<ref name=":14"/> Furthermore, plant cells contain obligate [[endosymbiont]]s, which could be released into a new environment.

Though both plant seeds and bacterial spores have been proposed as potentially viable vehicles, their ability to not only survive in space for the required time, but also survive atmospheric entry is debated.

[[Space probe]]s may be a viable transport mechanism for interplanetary cross-pollination within the Solar System. Space agencies have implemented [[planetary protection]] procedures to reduce the risk of planetary contamination,<ref>{{cite web |date=July 30, 2000 |title=Studies Focus On Spacecraft Sterilization |url=http://www.aero.org/news/newsitems/sterilization073001.html |archive-url=https://web.archive.org/web/20060502194219/http://www.aero.org/news/newsitems/sterilization073001.html |archive-date=2006-05-02 |publisher=The Aerospace Corporation}}</ref><ref>{{cite web |date=22 May 2006 |title=Dry heat sterilisation process to high temperatures |url=http://www.esa.int/esaMI/Aurora/SEMBJG9ATME_0.html |archive-url=https://web.archive.org/web/20120201224127/http://www.esa.int/esaMI/Aurora/SEMBJG9ATME_0.html |archive-date=2012-02-01 |publisher=European Space Agency}}</ref> but microorganisms such as ''[[Tersicoccus phoenicis]]'' may be resistant to [[Cleanroom|spacecraft assembly cleaning]].<ref name="NAT-20140519" /><ref name="NASA-20131106" />