4 ms·

> A group of researchers from NASA, MIT, and other institutions have achieved the fastest space-to-ground laser communication link yet, doubling the record they

> A group of researchers from NASA, MIT, and other institutions have achieved the fastest space-to-ground laser communication link yet, doubling the record they set last year . I'm guessing a returning astronaut with his or her pockets stuffed with SD cards is still faster and cheaper?

lettergram 3y ago
Hate to be dark, but the astronaut and SD card can also be lost on the trip back Not to mention 200Gbps is a lot of data, no way SD cards can match. Particularly as the stream can be constant
- senectus1 3y ago
  The term "Packet loss" is a bit grim in this scenario.
  - detuur 3y ago
    Maybe he just bumps into something and damages the SD cards. "Pocket loss", if you will.
    - patapong 3y ago
      Humans are also physically restrained from going certain places, such as crossing the barrier of a striking union.
  - jgtrosh 3y ago
    That's why they're encapsulated
- chakintosh 3y ago
  That and the risk of data corruption. Data transfer mitigates that by allowing you to simply retransfer the data in case it gets corrupted. You're also gonna have to copy the data from the drives/SD cards and the best transfer speeds they can do to your local computing machine would be in the order of 1Gbps max for SD Express and 7Gbps for an external NVME M.2 SSD. Now compare that to 200Gbps...
- ChrisMarshallNY 3y ago
  I've heard that radiation is hard on solid-state storage. Lot of that, out there, past our ionosphere.
rowanG077 3y ago
I doubt it. The largest capacity SD card I can find is 1 TB. Which weights around ~250 mg. With a data rate of 200GBps 25 1 TB SD cards are transmitted every second, 6.25 grams per second. From a quick google it takes astronauts anywhere from 4 hours to 3 days to get to the ISS so let's take the low number, 4 hours. 4 hours * 6.25 grams per second is 90 kilograms. I doubt anyone can just carry around 90 kilograms in their pockets. Let alone when going to space.
- deleted 3y ago
  [deleted]
- alexchamberlain 3y ago
  I think your calculations are off by a factor of 8 - network speeds are quoted in bits, rather than bytes. Apologies if I've misunderstood your comment though.
- jgtrosh 3y ago
  > 25 1 TB SD cards are transmitted every second, 6.25 grams per second. No, 1 Micro SD would be transmitted every 5s. Plus it's 200Gb/s = 25GB/s, so that's 250mg/40s. 4h × 6.25mg/s = 90g 3days × 6.25mg/s = 1.62kg Now with the max theoretical spec'd 128TB 2g SDUC cards, that's 101.25g for 3 days. Not too bad eh?
- tsimionescu 3y ago
  I think the correct calculation is that 1 TB SD card can hold 40s of 200Gbps traffic (1TB = 8Tb = 8000Gb; slightly more if these were actually TiB/Gib). So, 4h of 200Gbps traffic would be recorded on 4*60*60 / 40 = 360 cards. That would weigh 360 * 0.25g = 90g. Even with 3 days, that's 18*90g = 1620g = 1.62kg, well within rocket carrying capacity. However, arranging 360 SD cards by hand in the right order is much harder than relying on TCP SEQ numbers, though.
  - helsinkiandrew 3y ago
    Also, the satelites are not likely to be in geostationary orbit - so those 200Gbps are only being achieved for 5 minutes when they are in reception (possibly once or twice a day): > With data rates of 200 gigabits per second, a satellite could transmit more than 2 terabytes of data—roughly as much as 1,000 high-definition movies—in a single 5-minute pass over a ground station.
ppaattrriicckk 3y ago
Except you don't have astronauts going to the vast majority of the 1000s of satellites orbiting the planet. So apart from the 1-2 active space stations, where people go without having to do a full $100 million launch, I'd say laser transmission is a pretty good option for transferring data
thejosh 3y ago
And "semi"-realtime communication?
pnw 3y ago
Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway. -- Andrew S. Tanenbaum
- flangola7 3y ago
  I have a theory that alien civilizations don't even bother with long distance radio comms. It's far more efficient (and stealthy) to load up probes with hyper-dense storage and launch them at .99c than to be firing petawatt radio lasers all the time and hoping your recipient was able to listen in when it arrived.
dcow 3y ago
At 200Gb/s I think not. You have to factor in the round trip time for an astronaut and multiply that many seconds by 200 billion to get the total to compare against. At 25GB/s you’d fill up a 500GB SD card in 20 seconds.
- abwizz 3y ago
  more like 160 seconds. check you b's
  - Dylan16807 3y ago
    I think you read something wrong. 200 gigabits equals 25 gigabytes, and is five percent of a 500GB SD card.
    - abwizz 3y ago
      sure, my bad!
akira2501 3y ago
Move over sneakernet.. we've got rocketnet.

lettergram 3y ago

Hate to be dark, but the astronaut and SD card can also be lost on the trip back Not to mention 200Gbps is a lot of data, no way SD cards can match. Particularly as the stream can be constant

senectus1 3y ago
The term "Packet loss" is a bit grim in this scenario.
- detuur 3y ago
  Maybe he just bumps into something and damages the SD cards. "Pocket loss", if you will.
  - patapong 3y ago
    Humans are also physically restrained from going certain places, such as crossing the barrier of a striking union.
- jgtrosh 3y ago
  That's why they're encapsulated
chakintosh 3y ago
That and the risk of data corruption. Data transfer mitigates that by allowing you to simply retransfer the data in case it gets corrupted. You're also gonna have to copy the data from the drives/SD cards and the best transfer speeds they can do to your local computing machine would be in the order of 1Gbps max for SD Express and 7Gbps for an external NVME M.2 SSD. Now compare that to 200Gbps...
ChrisMarshallNY 3y ago
I've heard that radiation is hard on solid-state storage. Lot of that, out there, past our ionosphere.

rowanG077 3y ago

I doubt it. The largest capacity SD card I can find is 1 TB. Which weights around ~250 mg. With a data rate of 200GBps 25 1 TB SD cards are transmitted every second, 6.25 grams per second. From a quick google it takes astronauts anywhere from 4 hours to 3 days to get to the ISS so let's take the low number, 4 hours. 4 hours * 6.25 grams per second is 90 kilograms. I doubt anyone can just carry around 90 kilograms in their pockets. Let alone when going to space.

deleted 3y ago
[deleted]
alexchamberlain 3y ago
I think your calculations are off by a factor of 8 - network speeds are quoted in bits, rather than bytes. Apologies if I've misunderstood your comment though.
jgtrosh 3y ago
> 25 1 TB SD cards are transmitted every second, 6.25 grams per second. No, 1 Micro SD would be transmitted every 5s. Plus it's 200Gb/s = 25GB/s, so that's 250mg/40s. 4h × 6.25mg/s = 90g 3days × 6.25mg/s = 1.62kg Now with the max theoretical spec'd 128TB 2g SDUC cards, that's 101.25g for 3 days. Not too bad eh?
tsimionescu 3y ago
I think the correct calculation is that 1 TB SD card can hold 40s of 200Gbps traffic (1TB = 8Tb = 8000Gb; slightly more if these were actually TiB/Gib). So, 4h of 200Gbps traffic would be recorded on 4*60*60 / 40 = 360 cards. That would weigh 360 * 0.25g = 90g. Even with 3 days, that's 18*90g = 1620g = 1.62kg, well within rocket carrying capacity. However, arranging 360 SD cards by hand in the right order is much harder than relying on TCP SEQ numbers, though.
- helsinkiandrew 3y ago
  Also, the satelites are not likely to be in geostationary orbit - so those 200Gbps are only being achieved for 5 minutes when they are in reception (possibly once or twice a day): > With data rates of 200 gigabits per second, a satellite could transmit more than 2 terabytes of data—roughly as much as 1,000 high-definition movies—in a single 5-minute pass over a ground station.

ppaattrriicckk 3y ago

Except you don't have astronauts going to the vast majority of the 1000s of satellites orbiting the planet. So apart from the 1-2 active space stations, where people go without having to do a full $100 million launch, I'd say laser transmission is a pretty good option for transferring data

thejosh 3y ago

And "semi"-realtime communication?

pnw 3y ago

Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway. -- Andrew S. Tanenbaum

flangola7 3y ago
I have a theory that alien civilizations don't even bother with long distance radio comms. It's far more efficient (and stealthy) to load up probes with hyper-dense storage and launch them at .99c than to be firing petawatt radio lasers all the time and hoping your recipient was able to listen in when it arrived.

dcow 3y ago

At 200Gb/s I think not. You have to factor in the round trip time for an astronaut and multiply that many seconds by 200 billion to get the total to compare against. At 25GB/s you’d fill up a 500GB SD card in 20 seconds.

abwizz 3y ago
more like 160 seconds. check you b's
- Dylan16807 3y ago
  I think you read something wrong. 200 gigabits equals 25 gigabytes, and is five percent of a 500GB SD card.
  - abwizz 3y ago
    sure, my bad!

akira2501 3y ago

Move over sneakernet.. we've got rocketnet.