https://www.thedrive.com/the-war-zone/41787/rare-sight-of-two-supercarriers-docked-in-san-diego-with-their-decks-packed-with-aircraft
Bouncing off the Chinese stuff... did they really put 1.7 m mirror spysat in GEO, ground resolution 15 meters, to track down USN ships - under guise of remote sensing ? https://spacenews.com/china-launches-gaofen-13-observation-satellite-towards-geostationary-orbit/I wonder if the NRO / CIA / USAF had similar plans at some point in history. 1.7 m is very close from the MOL mirror 72-inch, 1.82 m. The closest I can think of was that tentative MOL mission with a 100% Navy crew.
Not an actual carrier, but a carrier-shaped (and sized! Unlike Iran's infamous mock-up) target in the middle of the desert: https://news.usni.org/2021/11/07/china-builds-missile-targets-shaped-like-u-s-aircraft-carrier-destroyers-in-remote-desert
Quote from: libra on 11/04/2021 10:11 amBouncing off the Chinese stuff... did they really put 1.7 m mirror spysat in GEO, ground resolution 15 meters, to track down USN ships - under guise of remote sensing ? https://spacenews.com/china-launches-gaofen-13-observation-satellite-towards-geostationary-orbit/I wonder if the NRO / CIA / USAF had similar plans at some point in history. 1.7 m is very close from the MOL mirror 72-inch, 1.82 m. The closest I can think of was that tentative MOL mission with a 100% Navy crew.I guess, re China, my question would be why would they need to nowadays ? The US might well have considered it in the 60s, but QUILL had demonstrated LEO radar of similar or better resolution in v early 60s, and PARCAE made passive electronic location of ships operational by late 70s from a "high LEO", so I doubt if it would have stayed a worthwhile mission. [Edit: iirc one of the QUILL declassified docs said Seasat equalled but did not better QUILL's resolution.]
Quote from: LittleBird on 11/05/2021 10:27 amQuote from: libra on 11/04/2021 10:11 amBouncing off the Chinese stuff... did they really put 1.7 m mirror spysat in GEO, ground resolution 15 meters, to track down USN ships - under guise of remote sensing ? https://spacenews.com/china-launches-gaofen-13-observation-satellite-towards-geostationary-orbit/I wonder if the NRO / CIA / USAF had similar plans at some point in history. 1.7 m is very close from the MOL mirror 72-inch, 1.82 m. The closest I can think of was that tentative MOL mission with a 100% Navy crew.I guess, re China, my question would be why would they need to nowadays ? The US might well have considered it in the 60s, but QUILL had demonstrated LEO radar of similar or better resolution in v early 60s, and PARCAE made passive electronic location of ships operational by late 70s from a "high LEO", so I doubt if it would have stayed a worthwhile mission. [Edit: iirc one of the QUILL declassified docs said Seasat equalled but did not better QUILL's resolution.]The advantage of GEO is continuous coverage, which you might need for targeting long-range missiles.
Quote from: Hobbes-22 on 11/11/2021 09:36 amQuote from: LittleBird on 11/05/2021 10:27 amQuote from: libra on 11/04/2021 10:11 amBouncing off the Chinese stuff... did they really put 1.7 m mirror spysat in GEO, ground resolution 15 meters, to track down USN ships - under guise of remote sensing ? https://spacenews.com/china-launches-gaofen-13-observation-satellite-towards-geostationary-orbit/I wonder if the NRO / CIA / USAF had similar plans at some point in history. 1.7 m is very close from the MOL mirror 72-inch, 1.82 m. The closest I can think of was that tentative MOL mission with a 100% Navy crew.I guess, re China, my question would be why would they need to nowadays ? The US might well have considered it in the 60s, but QUILL had demonstrated LEO radar of similar or better resolution in v early 60s, and PARCAE made passive electronic location of ships operational by late 70s from a "high LEO", so I doubt if it would have stayed a worthwhile mission. [Edit: iirc one of the QUILL declassified docs said Seasat equalled but did not better QUILL's resolution.]The advantage of GEO is continuous coverage, which you might need for targeting long-range missiles.Turns out I was wrong, there's plenty of interest in China in GEO observation of ships, both civil and military, e.g.https://www.mdpi.com/1424-8220/18/7/2007/htmandhttps://www.mdpi.com/1424-8220/21/22/7547/htmand references therein, as they say.
Great ! I was wondering why the average 2 m space or ground mirror couldn't do better than 100 m detail on the lunar surface. So I looked for how the maths work and found the formula is pretty basic. Formula right here by the great Phil Plait, of "Bad astronomy" fame. https://www.discovermagazine.com/the-sciences/moon-hoax-why-not-use-telescopes-to-look-at-the-landersBottom line - the ground resolution grows much, much slower than the mirror diameter, which is pretty irritating - but that's the laws of physics and optics, so do with them. It would take a 10 m+ diameter mirror to get below 100 m details of the lunar surface - so better to send LRO lunar probe instead. In the case of a MOL 1.82 m diameter mirror- looking at the Moon from LEO ( = 360 000 km, average) it wouldn't do better than a 150 m resolution - starring at Earth surface from GEO (= 36 000 km) ground resolution would be 15 meters. Plenty enough for 300 m long ships like aircraft carriers. Also just enough for very large aircraft like a 747.
I have to say that tracking aircraft carriers with GEO sats seems to make some sense. Even if the ground resolution sucks a little (25 ft to 50 ft average, according to the mirror size) US aircraft carriers are more than 1000 ft long, so even from 22 000 miles they should be pretty visible. And since GEO sats can "stare" at the same corner of the Earth for a very long time... including at the Pacific ocean...Let's suppose an optical spysat, mirror diameter 94-inch, ground resolution 40 ft (= 13 m) - staring at the Pacific Ocean. It should be able to get pretty decent pictures of a 1100 ft long Jerry Ford supercarrier. Note that it wouldn't be able to spot a 52 ft long F-35C on the deck, or merely as a blurred spot. https://en.wikipedia.org/wiki/USS_Gerald_R._FordDo you think the Chinese have such plan ? or is the idea flawed somewhere ?