Talk:Space sunshade

message: For the archived deletion debate for this article see Talk:Sunshade/delete -- Graham  ☺ | Talk 22:17, 17 Jul 2004 (UTC)
thread_title: Old talk

message: Shouldn't the article start with a definition ("A sunshade is ...")?  HistoryBA 00:46, 16 November 2005 (UTC)
thread_title:  Definition 

message: The present title is rather confusing since most folks would regard a sunshade as being another name for a parasol. I suggest moving the page to Space sunshade as being more descriptive. Bridgeplayer 15:51, 13 May 2007 (UTC)
replies: text: I'd agree with that - to me, a sunshade is something you put inside the car windscreen to stop it getting too hot. Although it would mean creating a disambig from the town, I think there ought to be a redirect from Soletta as well, given that that's the name Kim Stanley Robinson uses, which is where I suspect most people would have come across the concept —  iridescent (talk to me!) 19:27, 13 May 2007 (UTC)
thread_title:  Title 

message: The distances from earth used in this article appear to be incorrect. They place the objects inside the orbit of the moon.  The Sun-Earth L1 is about 150,000,000 km according to the Lagrangian_point article. This is my first post to a discussion section, so I hope I got it right. Jason3777 16:35, 19 May 2007 (UTC)
replies: text: Extremely good point - the 24000km in the article is below geostationary orbit let alone the L1 point. Angel's original paper talks about having it at 1.5 Gm (1.5 million km), don't know where the error crept in. Have corrected it —  iridescent (talk to me!) 16:59, 19 May 2007 (UTC)

text: 150,000,000 km distance to Earth-Sun L1 can't be right because Earth's semi-major axis is 149,598,261 km. According to http://orbitsimulator.com/formulas/LagrangePointFinder.html, ES-L1 is about 1,491,502 km distant from Earth's center of mass.Nydoc1 (talk) 02:13, 12 February 2013 (UTC)
thread_title:  Sun-Earth L1 Distances 

message: The article states that “In theory it would have a diameter of 210 kilometers.”  This diameter represents an area of 34,636 sq km.  The earth has a radius of 6,378.140 km [Peterson Field Guide₢ - Stars and Planets  p. 534, ] which represents a planar area of 127,802,093 sq km.  Even at L1 where I believe the radius required to eclipse the entire earth completely would be 6,316 km, this small of a radius (105 km) would require a lot of Sunshades to reduce the light from the sun by 2%, as shown in the picture.  I think the text needs to be updated to make clear that there would need to be many Sunshades of 210 km diameter to produce the 2% reduction in the sun’s light hitting the earth. Jason3777 21:55, 19 May 2007 (UTC)
replies: text: In fact the area to totally eclipse the Earth gets larger, not smaller, the closer you get to the sun -- since, surprise, the sun is somewhat larger. However, you certainly are correct — the radius should be more like 900km for 2% coverage, which is still a whole damn lot of mirrors. smurfix 17:37, 9 August 2007 (UTC)

text: Roger Angel's research paper mentions 100,000 km radius, which is - um - a slight difference. I'll guess the 210km figure is left over from the old Kim Stanley Robinson-style geostationary shade proposal —  iridescent (talk to me!) 22:32, 19 May 2007 (UTC)
thread_title:  Number of Sunshades required for 2% reduction 

message: http://en.wikipedia.org/w/index.php?title=Solar_shade&oldid=260927355 The edit after this killed a related article that contained numerous sources that could be used to shore up this piece. Hope this helps, MrZaiustalk 13:16, 27 January 2009 (UTC)
thread_title:  FYI - Sources available 

message: The one external link is completely unrelated to the topic of the article. That article discusses how launching sulfur particles into the atmosphere in order to mimic volcanic eruptions could cool the Earth, but cause drought. But it's attached to the bottom of this page, which is about a solar shield at L1. I think that external link should be removed, or at least moved to some other article where it is actually relevant. 150.182.161.253 (talk) 22:22, 5 April 2009 (UTC)
thread_title: Unrelated External Sources

message: This merge proposal makes a great deal of sense. 
The current Space sunshade article has three subsections, each describing a different implementation of this general idea.
But before we can do the merge, we need to be sure of two things:
* Does the current Space mirror (anti-global warming measure) article describe one of the three implementations in the Space sunshade article?  Or is it a fourth possible implementation?  Or is it sufficiently vague that it can apply to any of them?
* Do reliable sources prefer a specific term for this?  If there is, we should use that for the title of the article.  If there is not, we should pick the most descriptive and simple term.  I have always been uneasy using the term "sunshade" to refer to "a cloud of small spacecraft near the L1 point", since the term "sunshade" to my mind conveys a single object.  On the other hand, the term "space mirror" seems even more dubious, because not all of these implementations reflect the light:  some absorb light, and others refract it.
What does everyone think? — Lawrence King (talk) 03:59, 26 March 2012 (UTC)
replies: text: It's a fourth implementation as it uses mirrors rather than lenses, the light is reflected back rather than refracted. I'm not sure a merger is a good idea as it risks confusing the reader to discuss mirrors and lenses in the same article - unless it is done very carefully and the difference is explained clearly, if so it might be okay Robert Walker (talk)  —Preceding undated comment added 13:54, 26 March 2012 (UTC)
replies: text: Hi - I created Space mirror (anti-global warming measure). I have not responded up to now because I am honestly on the fence about this proposed merger. I created the article after noting persistent hijacking of the Space mirror DAB page, looking up what was referred to, and establishing that it was notable; but I do not have much education in the sciences, so this is the only science article I have started, and I don't feel very competent to judge whether they are in fact the same topic. The issue raised above by Robert Walker had occurred to me, but whereas this article uses scientific and technical sources, I wrote the other article from popular science and journalistic sources, and therefore the distinction may be partly an artefact of the differing terminologies and degrees of sophistication in the exposition. I do know the other article could use updating, and integration of specialist terminology that I'm not equipped to use. But I suspect I'm not a good judge of whether it merits its own article. I've asked friends for insights but not received any useful guidance. It looks as if by default it stays as it is, but I could be persuaded either way. Yngvadottir (talk) 21:05, 14 May 2012 (UTC)
thread_title:  Proposal to merge with [[Space mirror (anti-global warming measure)]] 

message: Hey, I was checking out the citations for this page, and I noticed that due to the fact that Nasa Earth Observatory no longer maintains its online Newsroom, the link for citation 7 is not usable. I searched for the article, by date and title, on their archives, which are linked to by the NASA page the link now goes to, but could not find it. If anyone else can provide help in finding this, it would be greatly appreciated. YoungScienceNerd (talk) 18:13, 8 May 2016 (UTC)
thread_title:  Defunct Source Link 

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thread_title:  External links modified 

message: The source seems to be a blog that doesn't cite any further sources. However, in a newspaper article Gregory Benford states in reply to a sunshield through many small flyers proposal: “This whole L1 idea is neat, but it’s going to cost trillions of dollars, we can’t do it right away, and it gets used to label the entire field of geoengineering as smoke and mirrors.” and continues to propose an aerosol solution (https://www.technologyreview.com/2007/02/13/130428/cooling-the-planet/).  — Preceding unsigned comment added by 2003:6:2190:A558:8824:7415:896E:A3F0 (talk) 16:30, 3 December 2020 (UTC)
thread_title:  The 10 billion estimate of Fresnel lenses is dubious 

message: This article should be considered a stub that only offers a tiny bit of information from a very limited POV. For instance, there is no mention of this NASA-sponsored 2006 paper  https://www.pnas.org/content/103/46/17184 that notes "In conclusion, it must be stressed that the value of the space sunshade is its potential to avert dangerous abrupt climate change found to be imminent or in progress. It would make no sense to plan on building and replenishing ever larger space sunshades to counter continuing and increasing use of fossil fuel. The same massive level of technology innovation and financial investment needed for the sunshade could, if also applied to renewable energy, surely yield better and permanent solutions. A number of technologies hold great promise, given appropriate investment (3)." -- Jibal (talk) 21:14, 9 July 2021 (UTC)
thread_title: stub

message: In the same paragraph, we read about 16 trillion disks, a mass of "about a gram", and that the total mass would be 20 million tonnes. These numbers still make sense but the style is questionable - using "about a gram" here to go on quoting a number which implies a mass of 1.25 g per disk.
A more serious issue occurs later on: 20 years contain about 7300 days. Thus, in 20 years with 100 tonnes launched per day, we would have launched 730000 tonnes. And that, according to the text, would be to low earth orbit - we need to get it to L1, and we need 20 million tonnes! Not even accounting for additional structure that might be necessary for deployment.
Icek~enwiki (talk) 18:39, 6 November 2021 (UTC)
thread_title:  Numbers should be consistent 

message: Would be interesting to know if studies from the previous years have been redone on the basis of the availability of Starship. Hektor (talk) 18:15, 20 October 2022 (UTC)
thread_title:  Starship 

message: The solar shield concept: Current status and future possibilities (Science Direct). Mooonswimmer 03:17, 13 February 2024 (UTC)
thread_title:  Relevant material