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63

There is a very nice Myth Busters video about bouncing a laser off the Moon linked below. To answer your question, current work is done with an array of corner cube reflectors on the Moon roughly 50 x 50 cm in size. Pulsed lasers on Earth have traditionally been green frequency-doubled infrared Nd:YAG lasers, similar to the "classic" DPSS green laser ...


35

The University of Texas's McDonald Observatory performs laser measurements of the distance to the Moon using retroreflectors left by the Apollo astronauts. You can read all about it in the McDonald Laser Ranging page. Lots of technical details in this paper.


30

There are limits. For one, there's atmospheric effects that scatter light in visible wavelength spectrum. You might be able to penetrate clouds and haze easier in the lower end of the spectrum and towards the infrared wavelengths, and those might still be usable for facial recognition though. Another limit is aperture of optical equipment used to take ...


27

would the photography be good enough for facial recognition? Not yet. It's not even close. Facial recognition requires 50 to 100 pixels between the eyes, or on the order of 1 millimeter resolution. To see that kind of detail from a distance of 250 kilometers using blue-green light (500 nm) would require a lens or mirror that is 125 meters in diameter. Note: ...


13

There is a possibility of rainbows appearing naturally on other celestial bodies that have sufficient water vapor or a large number of water droplets in their atmospheres, or indeed gases or droplets of other molecules that are capable of acting upon the light from the Sun (or other sources) as tiny prisms and refract it to its visible components (different ...


10

It was, in the sense that all spacecraft have relationship to each other. Okay, beyond that, let's see how they are related. Wikipedia talks about the design of Hubble: Once the Space Telescope project had been given the go-ahead, work on the program was divided among many institutions. Marshall Space Flight Center (MSFC) was given responsibility for ...


9

From here: http://www.spacetelescope.org/about/faq/ How do you protect and clean the lens of the Hubble Space Telescope? Hubble doesn’t have a lens. Like all large telescopes, Hubble uses a curved mirror to focus starlight. This mirror is located deep inside the telescope, protected by its long tube-like structure. As there is no atmosphere around ...


8

The MAHLI camera of Curiosity may focus from infinity down to only 18.3 mm working distance. At minimal distance the resolution is 13.9 µm per pixel. It may image objects of some tens of meters in size down to only 22 by 17 mm. The Sherloc camera of the Mars 2020 Rover has a similar minimal object size of 23 by 15 mm. A microscope with a magnification of ...


8

The lubricant is a Braycote vacuum grease: Braycote 602-EF. There is good information on the Latching End Effector (LEE) lubrication task (the task that actually applies the grease to the Space Station Remote Manipulator System end effector mechanisms) in this paper: Extravehicular Activity Development of Unforeseen International Space Station Maintenance ...


6

This answer addresses the headline question, rather than the detailed content that suggests a connection between HST and a KH9. There may be a connection between the Hubble and a KH11. Refer here and here. These links identify the prime contractor as Lockheed in both cases and also suggest a rough gemoetric similarity based on an anecdote about the ...


6

In addition to the space weathering phenomenon described by ebv, optical surfaces can and do get dirtied by other mechanisms as well. In particular, outgassing from the rest of the spacecraft and produce various compounds that may recondense on lenses, especially if these surfaces are cooler than the rest of the spacecraft exterior, which they sometimes are ...


5

The winner (as of 2019) would be the ESA Herschel Space Observatory with a focal mirror of 3.5M/11.5ft (Image Source) Optical could include infrared, visible and ultraviolet, but not microwaves. Herschel covers both far infrared and microwaves (55–672 µm) and so doesn't show up on some lists of optical telescopes, but it counts as far as the current ...


4

Let's think about what stereo pictures give us scientifically rather than aesthetically. It's information about depth. How far something is away. Why scientifically? Because while bass players and astrophysicists like Brian May† can occasionally also be rich, they usually don't so many billions of dollars that they would need to count them on both hands to ...


4

The Closed Circuit TV (CCTV) cameras in the Space Shuttle Payload bay had optical zoom lenses. Zoom capability magnifies or reduces the size of objects in a camera's field of view by adjusting the focal length of the lens. The minimum focus for standard lenses is 3 feet, the maximum is infinity. (emphasis mine, reference) (personal photo of camera ...


4

The video camera on the Apollo LRV had zoom, used in the well-known Apollo 17 liftoff footage.


4

In this image of a Falcon 9 takeoff (CRS-14), you can see some transparency in the exhaust of the (much larger) Merlin 1D: I can make out the rear half of the engine bells through the exhaust (this is clearer in the much larger original of the photo, so click to enlarge). Now comparing to the Rocketlab photo, the structure of the exhaust is different, ...


4

D.A. Arnold "Optical and Infrared Transfer Function of the Lageos Retroreflector Array", 1978, NGR 09-015-002 (P179) confirms that they're for infrared measurements, and adds some interesting info: The infrared array carried by the Lageos satellite was designed to provide coverage from any direction of illumination with a minimum of interference between ...


3

The very structured nature of the features strongly suggests stray light. In fact, in-flight calibration has an example of this (ref. Figure 18). From the text: Also, when a bright object is located near to the corners of the NAC frame, a bright streak can be seen to extend diagonally across the field of view


3

I am not 100% sure but I think we are looking at the aperture cover. In the picture below I've pointed out what looks like hinges (top) and a latch (bottom). There's a cutaway of the scope here which does not show such a large obstruction. Source: https://dspace.mit.edu/bitstream/handle/1721.1/114747/Carlton%20Extended%20Abstract_Submitted_v2.pdf?sequence=...


3

Reading Wikipedia's KH-11 Kennen I found this ... "KH-11s are believed to resemble the Hubble Space Telescope in size and shape, as the satellites were shipped in similar containers. Their length is believed to be 19.5 meters, with a diameter of up to 3 meters.5,22 A NASA history of the Hubble,23 in discussing the reasons for switching from a 3-meter main ...


2

From the same site, an overview of the instrument, showing how the secondary is attached to the central tube and the primary: Here's a detail image looking down the tube, I think this shows the detectors (the blue rectangles inside the tube): And a photo of the fully-integrated instrument during final tests: There are some tantalizing hints of more ...


2

@BlakeWalsh started to figure out the answer here and finished here but declined the invitation to post the answer, so I'll finish by posting it by proxy. Why is gold "gold-colored"? Several answers (1, 2, 3) to the Physics SE question Why are most metals gray/silver? explain this, and I'll summarize as follows: In addition to the highly reflective ...


2

If I Recall Correctly, The gold (and silver) was an early version of dichroic optical filters. Thin films of gold and silver, when applied in a specific order, create "thin-film interference" which essentially become an optical bandpass filter. The gold would create the hi-pass, and silver would create the low-pass (I may have it backwards.) Modern ...


2

This is of course theory-craft since I'm sure if satellites do exist that can resolve your face, read a license plate, or make out the time on your watch or a phone number on your iphone, we (the public) would be the last to hear about it. I believe its worth noting that you can achieve the same with lower diameter lens simply because of how fast the ...


2

There doesn't seem to be a lot of discussion of actual optical lenses because they are mainly used on spy satellites. This is because the large, compound telephoto camera lenses can produce diffraction-limited images over a wider field of view than their long focal length mirror based telescope cousins used to take pictures of the stars. For instance this ...


2

Power. Could a spacecraft transform the energy beam to electric power for use onboard? Yes, a spacecraft can definitely turn a steady flux of light into electrical energy. A device that does exactly that is pictured below: Solar are more effective at some wavelengths than others, so the monochromatic light of a laser is especially useful for energy ...


1

The limitation of 10 cm or so here only applies for a single mirror. I don't know if it is possible but if you can fly two spy satellites in formation and combine the images using optical interferometry and given that the images from Earth are very bright- maybe, just maybe, they could improve on that? So, have to say, I don't know, rather than that it's ...


1

tl;dr: Yes, related! Assuming Wikipedia's discussion that the Hubble mirror was chosen to be 2.4 meters in diameter to use the same "technology" as that for the spy mirror, and assuming that actually took place, then definitely. (here and here and here and Wikipedia) Making a telescope mirror is hard, difficult, and exacting work. Making one that is not ...


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