Editing Space sunshade (section)

==== Lightweight solutions and "Space bubbles" ====
A more recent design has been proposed by Olivia Borgue and Andreas M. Hein in 2022, proposing a distributed sunshade with a mass on the order of 100,000 tons, composed of ultra-thin polymeric films and SiO2 nanotubes.<ref name=":1" /> The author estimated that launching such mass would require 399 yearly launches of a vehicle such as [[SpaceX Starship]] for 10 years.<ref name=":1" />

A 2022 concept by [[MIT Senseable City Lab]] proposes using thin-film structures ("space bubbles") manufactured in outer space to solve the problem of launching the required mass to space.<ref>{{Cite web |title=Space bubbles |url=https://senseable.mit.edu/space-bubbles/ |access-date=24 May 2023 |website=MIT Senseable City Lab}}</ref> MIT scientists led by [[Carlo Ratti]] believe deflecting 1.8 percent of solar radiation can fully reverse climate change. The full raft of inflatable bubbles would be roughly the size of Brazil and include a control system to regulate its distance from the Sun and optimise its effects.<ref name=":2">{{Cite web |date=2022-07-07 |title=Space Bubbles Could Be the Wild Idea We Need to Deflect Solar Radiation |url=https://www.popularmechanics.com/space/a40486004/space-bubbles-climate-change/ |access-date=2023-05-23 |website=Popular Mechanics |language=en-US}}</ref> The shell of the thin-film bubbles would be made of [[silicon]], tested in outer space-like conditions at a pressure of .0028 atm and at -50 degrees Celsius.<ref name=":2" /> They plan to investigate low vapor-pressure materials to rapidly inflate the bubbles, such as a silicon-based melt or a graphene-reinforced ionic liquid.<ref name=":2" />

In July 2022, a pair of researchers from [[MIT Senseable City Lab]], Olivia Borgue and Andreas M. Hein, have instead proposed integrating [[Nanotube|nanotubes]] made out of [[silicon dioxide]] into ultra-thin polymeric films (described as "space bubbles" in the media <ref name="Newcomb2022">{{Cite web |author=Tim Newcomb |date=7 July 2022 |title=Space Bubbles Could Be the Wild Idea We Need to Deflect Solar Radiation |url=https://www.popularmechanics.com/space/a40486004/space-bubbles-climate-change/ |archive-url=https://web.archive.org/web/20230401131841/https://www.popularmechanics.com/space/a40486004/space-bubbles-climate-change/ |archive-date=1 April 2023 |access-date=23 May 2023 |website=Popular Mechanics |language=en-US}}</ref>), whose semi-transparent nature would allow them to resist the pressure of [[solar wind]] at L1 point better than any alternative with the same weight. The use of these "bubbles" would limit the mass of a distributed sunshade roughly the size of [[Brazil]] to about 100,000 tons, much lower than the earlier proposals. However, it would still require between 399 and 899 yearly launches of a vehicle such as [[SpaceX Starship]] for a period of around 10 years, even though the production of the bubbles themselves would have to be done in space. The flights would not begin until research into production and maintenance of these bubbles is completed, which the authors estimate would require a minimum of 10–15 years. After that, the space shield may be large enough by 2050 to prevent crossing of the {{convert|2|C-change|F-change}} threshold.<ref name="Borgue2022">{{cite journal |last1=Borgue |first1=Olivia |last2=Hein |first2=Andreas M. |date=10 December 2022 |title=Transparent occulters: A nearly zero-radiation pressure sunshade to support climate change mitigation |journal=Acta Astronautica |volume=203 |issue=in press |pages=308–318 |doi=10.1016/j.actaastro.2022.12.006 |s2cid=254479656 |doi-access=free}}</ref><ref name="Newcomb2022" /><ref>{{Cite web |title=Space bubbles |url=https://senseable.mit.edu/space-bubbles/ |access-date=24 May 2023 |website=MIT Senseable City Lab}}</ref>

In 2023, three astronomers revisited the space dust concept, instead advocating for a lunar colony which would continuously mine the Moon in order to eject [[lunar dust]] into space on a trajectory where it would interfere with sunlight streaming towards the Earth. Ejections would have to be near-continuous, as since the dust would scatter in a matter of days, and about 10 million tons would have to be dug out and launched annually.<ref>{{cite journal |last1=Bromley |first1=Benjamin C. |last2=Khan |first2=Sameer H. |last3=Kenyon |first3=Scott J. |date=February 8, 2023 |title=Dust as a solar shield |journal=PLOS Climate |volume=2 |issue=2 |pages=e0000133 |doi=10.1371/journal.pclm.0000133 |doi-access=free}}</ref> The authors admit that they lack a background in either climate or rocket science, and the proposal may not be logistically feasible.<ref>{{Cite web |date=8 February 2023 |title=Space dust as Earth's sun shield |url=https://phys.org/news/2023-02-space-earth-sun-shield.html |access-date=2 July 2023 |website=[[Phys.org]] |language=en-US}}</ref>