3 ms·
The main challenge is the earth to probe comms for distant probes, since the earth is often very close (in an angular sense) to the sun from the probes perspect
by londons_explore 2y ago
The main challenge is the earth to probe comms for distant probes, since the earth is often very close (in an angular sense) to the sun from the probes perspective, and the sun gives out a lot of black body radiation.
However, due to the shape of the black body radiation curve, the sun gives out relatively less microwave radiation than it does visible light, which might outweigh the advantages of more directionality given by using a laser.
- jjk166 2y agoFurther, we're good at building really big radio transceivers here on Earth, we don't have nearly the same technical experience with lasers of that scale.
- superposeur 2y agoOk what about using a maser instead of a laser?
- opwieurposiu 2y agoThe big dish antennas do use ruby masers, but not to transmit. The maser is used as the LNA on the receive side. Check out the picture on page 41 of the pdf, clearly this a flux capacitor, mislabeled to deceive us ;) https://descanso.jpl.nasa.gov/monograph/series10/03_Reid_chapt3.pdf https://descanso.jpl.nasa.gov/monograph/series10/03_Reid_cha... https://www.rfcafe.com/references/popular-electronics/amazing-maser-apr-1960-popular-electronics.htm https://www.rfcafe.com/references/popular-electronics/amazin...
- superposeur 2y agoCool use of maser for receive. Not having thought this through before, I see now that while a transmit maser may have efficiency advantages, it may not improve directionality relative to a standard parabolic radio transmitter. All methods of producing microwaves will have basically the same diffraction-limited gain for a given “aperture” (dish) size. That darn uncertainty principle! (However, an optical laser would still give way better directionality.)
- sebzim4500 2y agoPresumably though it would be useful to have a high bandwidth link back to earth even if we had to use conventional microwave transmitters to send data back. We want to download high resolution images/spectrographs whereas we only want to upload code/instructions.