
And that is the beginning of the Galactic Internet
Until the HoloNet is finally activated, that is.
Here's to millions of cat videos being transmitted all over the Solar System !
NASA hopes to launch a near-infrared laser transceiver to test a system that could one day be used to communicate with astronauts on Mars. The Deep Space Optical Communications (DSOC) experiment will head off into the void with Psyche, an asteroid-chasing probe that is scheduled to blast off on October 5. While they journey …
I wonder what the effective bitrate is, taking into account presumably LOTS of error correction and redundancy information. Still, it's pretty impressive. I wonder how the transceiver orbiting Mars keeps itself even aligned with Earth. There must be several times a day/month/year when it's impossible to use because other pesky objects like suns or moons get in the way
I wonder what the effective bitrate is
Article says 10-100 times over the current radio frequency technology. MRO can currently do a maximum of 5.2 Mbps via radio, so I guess we're talking 50-500Mbps with fricken' lasers.
Except NASA's poster says otherwise... Looks like 1 - 100Mbps from Mars distances.
https://www.lpi.usra.edu/opag/july2014/posters/9-DSOC_OPAG_Poster.pdf
Of course, this is an experiment so only time will tell what the actual reliable operational speed will be.
I wonder how the transceiver orbiting Mars keeps itself even aligned with Earth.
Well, it starts the same way as any other deep space communication... Radio transmissions are still a narrow beam, they're not just broadcasting out with an omni-directional antenna. They have to track the Earth with their instruments and orient themselves or antennas appropriately. Losing sight of the base station and having interruptions because of moons are the kind of things they already have to deal with... Not too many radio frequencies will go through hundreds or thousands of KMs of solid rock, ice, or iron.
Once it has the target roughly in sight, it locks onto the laser beacon & uplink signal from Earth to get a precise fix.
I would also have thought there is significantly more risk of a laser if the beam hit something. Unless the outputs are really silly RF is generally on dangerous if you are in the vicinity or the transmitter.
There is nothing mentioned about the power of the laser but it cannot be insignificant.
Light is also impacted by atmospheric conditions such as cloud. Now if the laser was at Cerro Paranal or Mauna Kea that mitigates some of that. I would also have thought that equipment on the space-end of the link would be heavier....
there is significantly more risk of a laser if the beam hit something. Unless the outputs are really silly RF is generally on dangerous if you are in the vicinity or the transmitter.
There's nothing particularly dangerous about lasers, except that the human eye can be easily damaged by very powerful lights. And this one is in the infrared range where that's even less of a concern. A laser would have to be insanely powerful to pose a danger to people all the way from Mars, so that's really not a concern at all.
As for real human health risks, visible light happens to be the dividing line between safety and danger, and this is below that... Lasers in the high UV spectrum, or RF at or above those frequencies, are classified as ionizing radiation. Here's a nice chart:
https://en.wikipedia.org/wiki/File:EM-spectrum.svg
There is nothing mentioned about the power of the laser but it cannot be insignificant.
It's just a 4 W, 1.55 µm laser. The low power requirements are one of the big benefits to NASA.
Light is also impacted by atmospheric conditions such as cloud. Now if the laser was at Cerro Paranal or Mauna Kea that mitigates some of that.
RF is impacted by atmospheric conditions as well. Moisture in the air / clouds absorb a lot of RF energy across much of the radio spectrum.
While it's not quite Mauna Kea, the receiver is the mountain-top Palomar Observatory in California.
"Except NASA's poster says otherwise... Looks like 1 - 100Mbps from Mars distances."
Worth remembering that "Mars distances" vary between ~34 to 250 million miles depending on orbital locations of Earth and Mars. Not to mention that big ball of uncontrolled fusion that sometime occludes the line of sight, eg from mid-November this year until early 2024.