Editing Planetary engineering (section)

==Seeding==
[[File:Mars Hubble.jpg|thumb|NASA's Hubble Space Telescope took the picture of Mars on June 26, 2001, when Mars was approximately 68 million kilometers (43 million miles) from Earth — the closest Mars has ever been to Earth since 1988. Hubble can see details as small as 16 kilometers (10 miles) across. The colors have been carefully balanced to give a realistic view of Mars' hues as they might appear through a telescope. Especially striking is the large amount of seasonal dust storm activity seen in this image. One large storm system is churning high above the northern polar cap (top of image), and a smaller dust storm cloud can be seen nearby. Another large dust storm is spilling out of the giant Hellas impact basin in the Southern Hemisphere (lower right) exploration.<ref>{{cite journal |last1=Lopez-Arreguin |first1=A.J.R. |last2=Montenegro |first2=S. |title=Improving engineering models of terramechanics for planetary exploration |journal=Results in Engineering |date=September 2019 |volume=3 |page=100027 |doi=10.1016/j.rineng.2019.100027 |s2cid=202783328 |doi-access=free }}</ref>]]

=== Environmental considerations ===
Mars is the primary subject of discussion for seeding. Locations for seeding are chosen based on atmospheric temperature, air pressure, existence of harmful radiation, and availability of natural resources, such as water and other compounds essential to terrestrial life.<ref name="Todd">{{cite journal |last1=Todd |first1=Paul |title=Planetary biology and terraforming |journal=Gravitational and Space Biology |date=August 2006 |volume=19 |issue=2 |pages=79–85 |id={{Gale|A176373142}} |url=http://gravitationalandspaceresearch.org/index.php/journal/article/view/11 }}</ref>

=== Developing microorganisms for seeding ===
Natural or engineered microorganisms must be created or discovered that can withstand the harsh environments of Mars. The first organisms used must be able to survive exposure to ionizing radiation and the high concentration of {{CO2}} present in the Martian atmosphere.<ref name="Todd" /> Later organisms such as multicellular plants must be able to withstand the freezing temperatures, withstand high {{CO2}} levels, and produce significant amounts of {{chem2|O2}}.

Microorganisms provide significant advantages over non-biological mechanisms. They are self-replicating, negating the needs to either transport or manufacture large machinery to the surface of Mars. They can also perform complicated chemical reactions with little maintenance to realize planet-scale terraforming.<ref>{{cite journal |last1=Conde-Pueyo |first1=Nuria |last2=Vidiella |first2=Blai |last3=Sardanyés |first3=Josep |last4=Berdugo |first4=Miguel |last5=Maestre |first5=Fernando T. |last6=de Lorenzo |first6=Victor |last7=Solé |first7=Ricard |title=Synthetic Biology for Terraformation Lessons from Mars, Earth, and the Microbiome |journal=Life |date=9 February 2020 |volume=10 |issue=2 |page=14 |doi=10.3390/life10020014 |pmid=32050455 |pmc=7175242 |doi-access=free |bibcode=2020Life...10...14C }}</ref>