Editing Space colonization (section)

====Mercury====
Mercury is rich in metals and volatiles, as well as solar energy. However, Mercury is the [[Delta-v budget|most energy-consuming body on the Solar System]] to land for spacecraft launching from Earth, and astronauts there must contend with the extreme temperature differential and radiation.<ref name=":3" />{{Rp|page=|pages=311–314}}

[[File:TerraformedMercuryGlobe.jpg|thumb|upright=1.2|An artist's conception of a terraformed [[Mercury (planet)|Mercury]]]]
Once thought to be a volatile-depleted body like the Moon, Mercury is now known to be volatile-rich, surprisingly richer in volatiles than any other terrestrial body in the inner Solar System.<ref>{{Cite journal|last1=McCubbin|first1=Francis M.|last2=Riner|first2=Miriam A.|last3=Kaaden|first3=Kathleen E. Vander|last4=Burkemper|first4=Laura K.|date=2012|title=Is Mercury a volatile-rich planet?|journal=Geophysical Research Letters|language=en|volume=39|issue=9|pages=n/a|doi=10.1029/2012GL051711|bibcode=2012GeoRL..39.9202M|issn=1944-8007|doi-access=free}}</ref> The planet also receives six and a half times the solar flux as the Earth/Moon system,<ref name=Bolonkin>{{cite book |last=Bolonkin |first=Alexander A. |date=2015 |editor-last1=Badescu |editor-first1=Viorel |editor-last2=Zacny |editor-first2=Kris |title=Inner Solar System: Prospective Energy and Material Resources |publisher=Springer-Verlag |pages=407–419 |chapter=Chapter 19: Economic Development of Mercury: A Comparison with Mars Colonization |isbn=978-3-319-19568-1}}</ref> making solar energy an effective energy source; it could be harnessed through orbital solar arrays and beamed to the surface or exported to other planets.<ref name=UTMercury/>

Geologist Stephen Gillett suggested in 1996, that this could make Mercury an ideal place to build and launch [[solar sail]] spacecraft, which could launch as folded "chunks" by a [[mass driver]] from Mercury's surface. Once in space, the solar sails would deploy. Solar energy for the mass driver should be easy to produce, and solar sails near Mercury would have 6.5 times the thrust they do near Earth. This could make Mercury an ideal place to acquire materials useful in building hardware to send to (and terraform) Venus. Vast solar collectors could also be built on or near Mercury to produce power for large-scale engineering activities such as laser-pushed light sails to nearby star systems.<ref>{{cite book|first1=Stanley |last1=Schmidt |first2=Robert |last2=Zubrin |title=Islands in the Sky: Bold New Ideas for Colonizing Space |publisher=Wiley |date=1996 |pages=71–84 |isbn=978-0-471-13561-6 |url=https://books.google.com/books?id=YCV0QgAACAAJ|access-date=18 April 2025}}</ref>

As Mercury has essentially no axial tilt, crater floors near its poles lie in [[crater of eternal darkness|eternal darkness]], never seeing the Sun. They function as [[cold trap (astronomy)|cold traps]], trapping volatiles for geological periods. It is estimated that the poles of Mercury contain 10<sup>14</sup>–10<sup>15</sup>&nbsp;kg of water, likely covered by about 5.65×10<sup>9</sup> m<sup>3</sup> of hydrocarbons. This would make agriculture possible. It has been suggested that plant varieties could be developed to take advantage of the high light intensity and the long day of Mercury. The poles do not experience the significant day-night variations the rest of Mercury do, making them the best place on the planet to begin a colony.<ref name=Bolonkin/>

Another option is to live underground, where day-night variations would be damped enough that temperatures would stay roughly constant. There are indications that Mercury contains [[lava tube]]s, like the Moon and Mars, which would be suitable for this purpose.<ref name=UTMercury>{{cite web |url=https://www.universetoday.com/130109/how-do-we-colonize-mercury/ |title=How do we Colonize Mercury? |last=Williams |first=Matt |date=3 August 2016 |website=[[Universe Today]] |access-date=22 August 2021}}</ref> Underground temperatures in a ring around Mercury's poles can reach room temperature on Earth, 22±1&nbsp;°C; and this is achieved at depths starting from about 0.7&nbsp;m. This presence of volatiles and abundance of energy has led [[Alexander Bolonkin]] and James Shifflett to consider Mercury preferable to Mars for colonization.<ref name=Bolonkin/><ref>{{cite web |url=https://einstein-schrodinger.com/mercury_colony.html |title=A Mercury Colony? |last=Shifflett |first=James |date=n.d. |website=einstein-schrodinger.com |access-date=31 July 2021}}</ref>

Yet a third option could be to continually move to stay on the night side, as Mercury's 176-day-long day-night cycle means that the [[terminator (solar)|terminator]] travels very slowly.<ref name=UTMercury/>

Because Mercury is very dense, its surface gravity is 0.38g like Mars, even though it is a smaller planet.<ref name=Bolonkin/> This would be easier to adjust to than lunar gravity (0.16g), but presents advantages regarding lower escape velocity from Mercury than from Earth.<ref name=UTMercury/> Mercury's proximity gives it advantages over the asteroids and outer planets, and its low [[synodic period]] means that launch windows from Earth to Mercury are more frequent than those from Earth to Venus or Mars.<ref name=UTMercury/>

On the downside, a Mercury colony would require significant shielding from radiation and solar flares, and since Mercury is airless, decompression and temperature extremes would be constant risks.<ref name=UTMercury/>