Questions tagged [optical]

Questions involving optical components, such as lenses, filters, and mirrors

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Will future deep space optical communications “ground stations” actually be in space, or on the ground?

Deep space communications ground stations are on the ground because their transmit and receive electronics alone is bulky and heavy, not to mention their 34 and 70 meter dish antennas! But those ...
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3answers
6k views

Does it make any scientific sense that a comet coming to crush Earth would appear “sideways” from a telescope and on the sky (from Earth)? [closed]

In multiple different movies and fiction, there's the threat of a burning space comet heading for Earth, threatening to kill everyone and destroy the planet. One example is the animated Comet in ...
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403 views

First LED left on another planet⁺ by humans?

Light Emitting Diodes or LEDs are ubiquitous now, but I still remember riding my bike to Radio Shack and buying my first LED, checking the diagram on the back of the package, and getting a battery and ...
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29 views

What's happening with Laser Light Communications (company) now? What satellites will it communicate with?

The pair of Stack Exchange questions linked below are almost four years old. I still don't exactly understand how this will work, but here I'd like to ask if this company is still around and if it ...
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Is there any way that real stars would move like they do in the classic Windows 3.x screensaver if traveling through space at extreme speed?

In old versions of Windows, such as 3.1, there was this screensaver called "Starfield". It looked like this: However, in movies and TV series, it usually looks like ...
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1answer
143 views

Determine envelopes for the payloads?

I am a mechanical engineer who is trying to expand my domain knowledge in aerospace and am currently reading a book to increase my understanding of it. I am mostly interested in studying the design of ...
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3answers
12k views

Is pinging the Moon with a laser as shown on “The Big Bang Theory” possible?

In an episode of season 3 of The Big Bang Theory, the cast sends a laser pulse to the Moon. This seems to be a real thing: What Neil & Buzz left on the Moon (2004). My questions are: Could ...
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1answer
361 views

Why is there no microscope on the Mars 2020 rover?

Good magnification microscopes seem both light and cheap. As far as I could find out, there hasn't ever been one on any Mars rovers. The closest I could find is the Mars Hand Lens Imager (MAHLI) which ...
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2answers
370 views

How fast do optical surfaces get dirty or damaged in space?

These answers: (1, 2) to Do things get dirty in space? mention the Hubble Space Telescope but if I understand correctly refer to the outside of the telescope rather than its optical surfaces. Answers ...
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1answer
826 views

What is the “space grease” used to lubricate the ISS robotic arm? What are the material considerations for it?

Space.com's Spacesuit Gloves Contaminated During Friday's Historic Spacewalk quotes NASA astronaut Christina Koch (Wikipedia, NASA): "And so," she continued, "of course, a mechanical ...
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Why was the central obstruction in Galileo's Solid State Imager (SSI) so large? Was the secondary mirror flat?

According to Wikipedia's Galileo Solid State Imager (SSI) The SSI was an 800-by-800-pixel solid state camera consisting of an array of silicon sensors called a charge-coupled device (CCD). Galileo ...
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1answer
200 views

What's the largest optical lens put in space?

While star cameras and wide angle cameras in space are built from glass lenses, large aperture optical systems generally use reflective optics. For some large ones see answers to What's the largest ...
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1answer
468 views

What's the largest optical telescope mirror ever put in space?

As a follow-on question to What's the largest optical lens put in space? I'd like to ask about mirrors this time. Question: What's the largest optical telescope mirror ever put in space? Optical ...
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240 views

Why is the Aeolus space laser losing power so quickly?

The BBC News article Aeolus: Wind-mapping space laser is losing power says that Europe's Aeolus satellite was launched last year to gather data to improve weather forecasts, and its observations have ...
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1answer
59 views

How would 2 JWSTs make stereo pictures?

Could 2 JWST be launched in opposite directions to provide stereo vision? Would a stereo picture provide any benefit? https://space.stackexchange.com/a/35402/18879 Related: How will JWST manage ...
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2answers
221 views

Have optical zoom systems been used in space exploration?

Here, 'optical zoom' means an optical system that changes magnification (angle subtended per pixel). It would not mean for example switching from one camera to another on Hubble, or changing to ...
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213 views

How does the camera make the exhaust of the Electron's RP-1/LOX exhaust transparent?

In this 20-Nov-2018 Tweet from Rocket Labs XXX Peter Beck there is an image of the nine Rutherford engines of an Electron rocket burning. What is unusual is that the exhaust is luminescent but at the ...
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What are the space-based optical satellite sensors?

I was looking at a products page for Numerica Corp, and under their product MFAST it said (emphasis mine): Tracks objects in all regimes of space (e.g., LEO, MEO, HEO, GEO) using radar, ground-...
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645 views

How does the thin gold film in the glass of spacesuit helmets block thermal IR but transmit visible? What's the property?

Comments below this answer suggest that there is a thin gold coating on the glass of spacesuit helmets that blocks thermal IR (say roughly about 10 to 30 microns) but is mostly transparent to visible ...
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8k views

Was Hubble really related to spy satellites?

Around the launch of the Hubble Space Telescope, I remember comments in the media that the Hubble may be related to certain espionage satellites. The Hubble was designed and built around the time that ...
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1answer
89 views

What optical design is used by the GEDI's receiving telescope and how is the secondary held in place?

GEDI is a sophisticated LIDAR instrument now on its way to the ISS. Once installed, it will use powerful laser pulses (10 mJ, 242 Hz) from several lasers to map height in 3D, collecting multiple ...
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52 views

What would be the equivalent camera performance specification of Earth-imaging satellites, compared to consumer DLSRs?

In order to better understand what Earth imaging cameras are like (as seen in Google Earth) from the point of view of a photographer, I've asked the following. Consumer-grade cameras like DSLRs, ...
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181 views

Why do the LAGEOS' satellites have four germanium corner cube reflectors out of over 400?

When I was writing this answer about the LAGEOS satellites, I noticed that only four of the over four hundred corner reflectors are made of optical germanium rather than fused silica. Fused silica (...
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1answer
587 views

Accumulated environmental damage to Hubble main mirror

I'm interested in understanding what effect does long-term radiation and microdust exposure would do to the surface roughness of a high-precision mirror like the one on the Hubble. Since it has been ...
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5answers
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Is photography from a satellite good enough to make out a person on the ground?

When I first saw Google Maps satellite view many years ago, I remember being greatly impressed (and somewhat surprised) with the image quality, considering the photographs came from up there in space. ...
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208 views

How could the laser from Earth to a spacecraft be used other than to propel its light sail?

The Starshot Breakthrough Initiative, sponsored by Yuri Milner, now finances the attempt to use a huge laser on Earth to propell a tiny spacecraft to huge velocity. Not having to carry the energy for ...
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1answer
254 views

What are the “crossing beams of light” in the Cassini images taken during Enceladus plume flyby?

Whilst checking the latest images of the E-21 flyby returned by the Cassini probe, I've noticed that some of them show interesting optical phenomena that I'm not sure I can explain; For example, on ...
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1answer
1k views

Can you have a rainbow on any bodies in the solar system besides Earth?

We know from Flying on dense atmosphere planets & moons that many bodies in our solar system have sufficient atmosphere for at least the concept of flying to be considered. What about the ...
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291 views

What will the new Iranian satellites be imaging?

Iran is soon to launch two satellites which will reportedly take images "with a high degree of accuracy of less than 10 meters" (azernews). What will these satellites be imaging?