Questions tagged [optical]

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

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Interesting diffraction pattern on JWST composite false-color image released today (July 11) at Biden preview - how does this arise?

There was an earlier question on the diffraction pattern in the Mar 16 test image that was mainly explained by the hexagonal shape of the individual mirror segments. Today's image has similar ...
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8 votes
1 answer
268 views

JWST - pick-off mirrors?

In the documentation that I’ve been looking through recently, I occasionally come across references and diagrams to “pick-off” mirrors. For example, from this JWST user documentation article, there is ...
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2 votes
0 answers
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How to calculate laser link spot size

In the reseach paper " A laser link from lunar surface..." , chapter 2.1.3.: When employing, for example, 20 cm diameter apertures at the transmitter telescopes and considering a carrier ...
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2 votes
0 answers
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How is the maximum data rate of the Psyche mission's Deep Space Optical Communications (DSOC) system expected to scale with distance?

NASA's Mission Page Deep Space Optical Communications (DSOC) includes the following: Key DSOC technologies developed for the project include: a low-mass spacecraft disturbance isolation and pointing ...
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8 votes
1 answer
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Why aren't off-axis reflector telescopes more popular for space telescopes? Have there ever been any?

It seems that: The light gathering capabilities would be slightly better without the blocked aperture (clear aperture is a premium for fairing-limited space telescopes) The diffraction patterns from ...
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Are direct conversion optical receivers being looked at for future deep-space communication?

In this answer to Receiver and transmitter in RF/optic satellite communication: distance vs data rate v2 I explain that since the currently used photodiode-based photodetectors for optical ...
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3 votes
2 answers
174 views

What are the reasons for the specific operating wavelengths chosen for laser communication?

I am reading the book: Kaushal, H., Jain, V.K. and Kar, S., 2017, Free space optical communication, New Delhi: Springer India. The operating wavelengths for beacon and data transmission were discussed....
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Methods and techniques for correction for atmospheric effects

What are methods and pieces of hardware which can limit these effects? In one of the last my question, User Polar_Bear mentioned, but there are many methods and pieces of hardware which can limit ...
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0 votes
1 answer
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PAT (Pointing Acquisition, and Tracking) system in lasercom

After reading some articles and posting questions 1, 2 I think, the main challenges are PAT (Pointing Acquisition, and Tracking) system and operating environment. We must put the beam onto the ...
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4 votes
1 answer
362 views

Data rate in optical free space communication systems

Mynaric is one of the main suppliers of laser terminal for free space communication. In one of its latest publications I have read, they will increase the data rate of the last lasercom terminal up to ...
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4 votes
1 answer
226 views

There are only a few suppliers of optical terminals: what is the reason?

I am conducting research into optical free space communication and small/nano satellites in LEO. I have found only a few companies which supply lasercom (laser communication) terminals (transmitter/...
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0 votes
1 answer
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Beacon (PAT) in optical free space communication [closed]

Nanosatellite Optical Downlink Experiment (NODE) mission has 3 "signal":downlink, beacon uplink and RF. According to a description of the mission, the high-rate downlink and beacon uplink ...
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2 votes
0 answers
196 views

Biggest periscope camera that could fit inside a Starlink satellite; how thick are they?

If all Starlink satellites had phone tier cameras & simple scopes, could images processed by their super-resolution imaging network be competitive? is a cool question and to integrate a reasonable ...
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2 votes
1 answer
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Optic communication: day and night

Will launched time of a laser satellite teminal affect to transmission parameters, as data rate, power …? As I know , the main limitation of lasercom is a direct line-of-sight path exists between a ...
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4 votes
1 answer
130 views

Space based active optical sensors for maritime surveillance

I am designing a CubeSat. The size is yet to be decided as it is based on the sensor. The mission is maritime surveillance (illegal fishing). The payload should be capable of detecting the vessels. ...
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1 vote
1 answer
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Frequency/Spectrum regulation document for laser communication

For RF we have the frequency allocation table, where the RF spectrum is regulated. Optical has big bandwidth, there is a lot of frequency space. How do we regulate optical spectrum? I didnt find any ...
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1 vote
1 answer
183 views

Receiver and transmitter in RF/optic satellite communication: distance vs data rate v2

The first version of this question is here. I have read the article "Optical communications work best over relatively short distances in space." by Toyoshima, M., Leeb, W., Kunimori, H. and ...
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2 votes
1 answer
145 views

How are astronauts aboard the Tiangong space station keeping busy?

Per Wikipedia's Tiangong space station viewed today: Days in orbit: 3 months, 15 days (13 August 2021) Days occupied: 1 month, 27 days (13 August 2021) Currently it is just the single core ...
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4 votes
2 answers
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Has opalescence ever been observed on any solar system body besides Earth? Or at least from a sample from one?

New method for exoplanet detection based on iridescence? in Astronomy SE asks about observations of exoplanets, but here I'm asking about our own solar system bodies. Question: Has opalescence ever ...
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Has iridescence ever been observed on any solar system body besides Earth? Or at least from a sample from one?

New method for exoplanet detection based on iridescence? in Astronomy SE asks about observations of exoplanets, but here I'm asking about our own solar system bodies. Question: Has iridescence ever ...
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Why did some of the optical sensors of CYGNSS satellites suffer UV and radiation-induced loss of sensitivity? Was this unexpected? If so, why?

This answer to How fast do optical surfaces get dirty or damaged in space? says: ...On the CYGNSS spacecraft UV and radiation exposure lead to a marked loss of sensitivity on some of the optical ...
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-3 votes
2 answers
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Why does Unity look transparent?

The BBC's Virgin Galactic: Sir Richard Branson rockets to the edge of space includes the image below. Much of the Unity spacecraft appears (almost) transparent in this image; you can see the blue sky ...
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How big of a telescope will Psyche's deep space optical communications demonstrator use out at 5 AU?

NASA JPL News item says: The spacecraft's instrument payload includes three science instruments. The mission's magnetometer is designed to detect and measure the remnant magnetic field of the ...
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3 votes
1 answer
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Does Perseverance's SuperCam include a Martian meteorite? If so, why?

An automotive blog claims that There actually seems to be another Martian meteorite being sent to Mars, as part of the SuperCam calibration target. Shouldn’t we be keeping all the Mars rocks we have ...
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1 vote
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Has Made in Space any track record growing specialty crystals in microgravity before? ("Industrial Crystal Facility" to fly this year)

Ars Technica's There are an insane amount of cool space things happening in 2021 mentions: This year, Made in Space's "Industrial Crystal Facility" should also fly to space. This will serve ...
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1 vote
1 answer
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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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31 votes
3 answers
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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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6 votes
4 answers
730 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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3 votes
0 answers
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Are there any possible proxies for dust accumulation on the retroreflectors on the moon?

New York Times' How Do You Solve a Moon Mystery? Fire a Laser at It links to the new open access paper First two-way laser ranging to a lunar orbiter: infrared observations from the Grasse station to ...
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19 votes
3 answers
4k views

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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3 votes
1 answer
154 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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9 votes
1 answer
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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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5 votes
1 answer
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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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1 vote
1 answer
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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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5 votes
1 answer
514 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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5 votes
1 answer
328 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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13 votes
2 answers
554 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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9 votes
1 answer
420 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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1 vote
1 answer
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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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1 vote
2 answers
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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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5 votes
0 answers
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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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0 votes
2 answers
293 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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1 vote
1 answer
119 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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7 votes
2 answers
980 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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3 votes
0 answers
53 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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42 votes
3 answers
13k 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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4 votes
1 answer
230 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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7 votes
1 answer
222 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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13 votes
1 answer
314 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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15 votes
1 answer
664 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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