NASA's Psyche Hits 25 Mbps From 140 Miles Away (theregister.com) 62
Richard Speed reports via The Register: NASA's optical communications demonstration has hit 25 Mbps in a test transmitting engineering data back to Earth from 140 million miles (226 million kilometers) away. The payload is riding aboard the Psyche probe, which is headed for an asteroid of the same name. On December 11, when the spacecraft was 19 million miles (30 million kilometers) away, it reached 267 Mbps, which NASA described as "comparable to broadband internet download speeds."
However, as Psyche has continued on its trajectory, the distances have become greater, and the rate at which data can be transmitted and received has tumbled. At 140 million miles, the project's goal was to reach a lofty 1 Mbps. Instead, engineers managed to get 25 Mbps out of the demonstration. Earlier demonstrations tested the technology using preloaded data, such as a cat video. The latest experiment used a copy of engineering data also sent via Psyche's radio transmitter.
"We downlinked about 10 minutes of duplicated spacecraft data during a pass on April 8," said Meera Srinivasan, the project's operations lead at NASA's Jet Propulsion Laboratory (JPL) in Southern California. "Until then, we'd been sending test and diagnostic data in our downlinks from Psyche. This represents a significant milestone for the project by showing how optical communications can interface with a spacecraft's radio frequency comms system." The demonstrator is only along for the ride -- Psyche uses conventional radio technology for its mission. However, the demonstration does point to the potential for higher-bandwidth communications in future projects.
However, as Psyche has continued on its trajectory, the distances have become greater, and the rate at which data can be transmitted and received has tumbled. At 140 million miles, the project's goal was to reach a lofty 1 Mbps. Instead, engineers managed to get 25 Mbps out of the demonstration. Earlier demonstrations tested the technology using preloaded data, such as a cat video. The latest experiment used a copy of engineering data also sent via Psyche's radio transmitter.
"We downlinked about 10 minutes of duplicated spacecraft data during a pass on April 8," said Meera Srinivasan, the project's operations lead at NASA's Jet Propulsion Laboratory (JPL) in Southern California. "Until then, we'd been sending test and diagnostic data in our downlinks from Psyche. This represents a significant milestone for the project by showing how optical communications can interface with a spacecraft's radio frequency comms system." The demonstrator is only along for the ride -- Psyche uses conventional radio technology for its mission. However, the demonstration does point to the potential for higher-bandwidth communications in future projects.
140 miles (Score:5, Funny)
Re: 140 miles (Score:5, Funny)
It was an accomplishment in poor editing, that's for sure.
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You'd think this was an mdsolar hit piece!
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Dr. Evil had to be involved somehow.
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Re: 140 miles (Score:2)
And I'd like the data rate in Libraries of Congress per Second, please.
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That would be 44,800,000,000 rods, presumably of the inanimate carbon type.
Re:140 miles (Score:4, Insightful)
Just like you, at first I was not impressed.
And then I was, like, WOW, that's tight-beaming across nearly 1 AU at speeds better than home internet in some advanced countries.
Amazing
Re: 140 miles (Score:2)
I think he was talking about AU, not the US :-)
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I think there's a bunch of locations that qualify, so let's not fight about it :)
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Just like you, at first I was not impressed.
And then I was, like, WOW, that's tight-beaming across nearly 1 AU at speeds better than home internet in some advanced countries.
Amazing
25 Mbps over any distance would be a vast improvement in Australia... thank conservatives for killing the NBN.
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All hail the Australien government! My favorite youtube channel ;)
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This is probably an example of what Biblical text critics refer to as "haplography". It's common for copyists to omit words or phrases when their eye skips forward to another similar group of letters. In this case it's because "million" and "miles" both start "mil".
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C'mon. This is Slashdot, the "editors" are only here because they don't qualify as Walmart greeters.
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wow, so impressive.
They are long miles. Very long miles.
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That was a Gilligan's Island episode: a Mars probe inadvertently landed on the island, but NASA thought it reached Mars. Soon after being activated, the camera lens popped out and broke, preventing the castaways from sending an SOS.
The Professor baked a special glue to fix the lens, but Gilligan forgot to turn off the fire on the glue pot. Right when they got the lens to work, the pot exploded and blew glue & Gilligan's feather collection all over the crew and signs. NASA thought they were looking at "M
Title missing a word? (Score:1)
Shouldn't the title say 140 million miles? 140 miles seems a bit small-ish. ;-)
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No! That would make it much less funny.
25 Mbps From 140 Miles Away (Score:2)
I could do better than that.
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With a bunch of tapes on your back, running back and forth, sure. But can you do it using smoke signals?
Maybe NASA should become an ISP (Score:1)
Including all the hidden fees NASA will probably be cheaper than AT&T and 25Mpbs would be pretty decent.
Re: typo (Score:2)
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Re: typo (Score:1)
If the metric system is so intuitive, why did the article mention millions of km instead of simply referring to terameters?
Simply put, miles and km are both standards because of their relationships to the length of our legs.
Point source radiation (Score:2)
Re:Point source radiation (Score:5, Informative)
The law is inverse of the square only if your source is a point. A laser beam has a Gaussian profile with characteristics that depend on the medium and the resonator, so the law of propagation is different. And that's only the beginning.
Re:Point source radiation (Score:4, Informative)
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Yes. But in the case of a point source it ought to be a taugology, since a point source is devoid of structure by definition, and hence of any features that can prevent it from radiating isotropically.
For anything that is a physical source, your definition is better.
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In the far field (for distances much more than the Rayleigh length past the diffracted beam waist), lasers still look like inverse square. However, the effective antenna gain (and hence ERP) can be huge for a laser, which is why it works so well. The divergence angle of the diffraction cone can be microradians for a reasonable size exit optic. That corresponds, to an antenna gain of the order of 120 dB ( (10-6 radians)^2 ). Note I am intentionally ignoring extra factors of 4pi here, just for round num
Units! (Score:2)
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Not even units, but unit prefixes!
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While I do prefer metric, even I have to admit that miles is a unit.
Uh-oh. Oopsie. Possible editorial failure alert! (Score:3)
Hey guys, I could be on to something here. I think the title may be missing a "million". Could someone please confirm that for me?
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Confirmed snarkily in many comments... OP needs to edit their title.
What's The Ping Time? (Score:2)
Space porn must have low ping. NSA proclaims it.
BULLOCKS (Score:2)
Speed of light and vacuum of space means we can capture an optical laser signal aimed at earth.
The capacity of that laser doesn’t weaken in space so some quality of the packet scheme must be failing over distance since the earlier data rate validated reception quality at the receiving point or the transmitter power has fluctuated
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Wow, 140 miles! (Score:2)
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thanks captain obvious, only 2 hours and about a dozen comments about it late
And after demonstrating possible speeds... (Score:1)
FTFA linked by the TFA... (Score:2)
Bandwidths is good, but damn is it laggy (Score:2)
This ain't gonna work for FPS games... ping times of 25 minutes!
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This ain't gonna work for FPS games... ping times of 25 minutes!
More seriously, I wonder what sort of protocol they're using. I guess they could just use standard protocols, but with a freaking huge ACK window, but it seems more likely they'd use extensive FEC to reduce effective bit errors to extremely low rates, since NAKing and retransmitting corrupted packets would be incredibly slow. Or maybe that's okay. As long as they're only transmitting stored data which can be retransmitted a half hour later if needed, it might be fine to use simple error detection with retri
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NASA have been working on developing an "Interplanetary Internet [wikipedia.org]" set of protocols for decades now. I remember when Vint Cerf (one of the original designers of either TCP or IP) was hired as part of the project while everyone else was worrying about the Millennium Bug.
They seem to be using a "store and forward" protocol, with a recognition that physical and logical addressing are not necessarily going to be the same (or even similar) at both ends
You'll still need radio communication (Score:2)
Just a reminder, the margin of error for a laser to drift off target in a system failure is great enough that having radio as a backup is still needed. You'd at the very least need it to be able to send commands. In the meantime, when everything is working, this would be a huge boost in transmission rates.
It makes one feel small... (Score:1)