Earth Receives Laser-Beamed Message From 10 Million Miles Away

Rahul Rao reports via Space.com: On Nov. 14, NASA picked up a laser signal fired from an instrument that launched with the Psyche spacecraft, which is currently more than 10 million miles (16 million kilometers) from Earth and heading toward a mysterious metal asteroid. (The spacecraft is at more than 40 times the average distance of Earth's moon, and still voyaging afar.) The moment marked the first successful test of NASA's Deep Space Optical Communications (DSOC) system, a next-generation comms link that sends information not by radio waves but instead by laser light. It's part of a series of tests NASA is doing to speed up communications in deep space, on different missions. "Achieving first light is a tremendous achievement. The ground systems successfully detected the deep space laser photons from DSOC," Abi Biswas, the system's project technologist at NASA's Jet Propulsion Laboratory (JPL) in Southern California, said in an agency statement.

"And we were also able to send some data, meaning we were able to exchange 'bits of light' from and to deep space," Biswas added.

It did send some data

[Rosco P. Coltrane]

"And we were also able to send some data, meaning we were able to exchange 'bits of light' from and to deep space,"

Just getting the photons is one item of data in and of itself: it's a single bit that means "It works".

But the throughput and latency are still well below what's needed to get a "Hello World" using a modern browser, 15 layers of Javascript and a multitude of trackers and ads from Google, Microsoft, CloudFlare, Akamai, Facebook or Amazon. So it's not quite ready for prime-time yet: all it can do is useful stuff at the moment.

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[proctorg76]

Curious how sustainable using a 200-inch telescope as the ground-side reciever is going to be as well.

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[necro81]

Curious how sustainable using a 200-inch telescope as the ground-side reciever is going to be as well.

If you think 200-inch is big, just wait til you see the size of the telescopes of the Deep Space Network [wikipedia.org]!

Optical vs Radio, yeah, yeah, I know. I don't believe that a 200-inch telescope (Palomar) will be a strict requirement in the long term. I think it has more to do with the fact that it is 1) the largest optical telescope that, 2) they could get time on, and 3) is reasonably close to JPL, who's dev

Relay stations

[Okian Warrior]

Curious how sustainable using a 200-inch telescope as the ground-side reciever is going to be as well.

I see this more as a "proof of concept".

With our current launch capability I suspect the solution is to put a series of relay stations at various points in the solar system, such as the LaGrange points of some of the planets. The station would have record/retransmit capabilities and have a lot of power: solar at the inner planets, hefty nuclear further out.

This would allow for missions with less transmitting power. Instead of transmitting all the way back to Earth, you transmit to (for example) the relay at

Precision and Relativity

[Speare]

Yes, this is proof of concept stage. The key issue with the laser approach is not just power, but aiming precision. The better they columate the beam to focus the transmitted power, the better they need to aim the beam to actually hit the receiver. A deep space craft is only so large, and 200 inch telescopes are also a tiny target to hit at these distances. The mass curvature of space and the motion of objects need to be accounted for, as distance adds signal delay.

Jewish space lasers attack earth!

[iAmWaySmarterThanYou]

lol, sorry

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[Viol8]

Hilarious. Whats next in your comedy routine - some "jokes" about blacks or asians?

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[dknj]

Dave? Dave is that you?

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[Entrope]

(Shouting: "Dave?" Whispered "Yeah, Man, it's Dave.") Dave's not here!

Re: Jewish space lasers attack earth!

[HammerOn1024]

Dave's not here man!

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[iAmWaySmarterThanYou]

I see the no humor and politically unaware crowd is in the house tonight! Welcome! Those easily triggered by nuanced humor please take the special reserved seating we have for you in the taxi line out front.

It's people like you that modern comedians complain about.

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[iAmWaySmarterThanYou]

Yes, it is a US thing. This being a US site, it's fine you aren't familiar as a non-US but it is to be expected that Americans will post such things.

Ok, the explanation is that there have been any number of anti-Semitic conspiracies going back for ages. One of the more recent ones was space laser based mind control. Recently one of our less uh "stable" politicians tweeted a long rant about Jewish space lasers and a few other anti-Semitic conspiracy related nonsense. So, it was a small chuckle joke makin

All your base

[gosso920]

Are belong to us!

It wasn't the Psyche probe

[backslashdot]

It was aliens testing their sterilization laser.

Bandwidth not speed

[ghoul]

Light and Radio are both EM waves just different frequencies so as such they travel at the same speed - the speed of light. So how is using Lasers going to speed up deep space communication? Maybe they meant bandwidth. Though still fail to see how there is less interference in the visible light spectrum than in the radio spectrum.

Bandwidth = Speed

[Roger W Moore]

For communications, speed is measured as the time to send one bit of information because ultimately this determines how quickly you can send the information you have to transmit. The actual time-of-flight of the signal affects the latency which is how much later your recipient receives the information. Using light vs radio will not change the latency but it will absolutely increase the rate of transmission and hence the speed of communication.

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[Miles_O'Toole]

Thank you for an excellent, concise explanation.

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[HiThere]

I really do wonder about the frequency chosen, though. Optical light is often blocked by clouds. I think there are other bands that would yield better "seeing conditions". (But maybe there aren't any lasers in the appropriate frequencies?)

Re: Bandwidth = Speed

[beelsebob]

The idea I believe is that the receivers will be orbital, and relay data to the ground via RF.

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[RockDoctor]

Optical light is often blocked by clouds.

True, but probably irrelevant. I suspect the design target for this sort of technology would be a number (three?, more?) transmit/receive satellites on orbit (geostationary?) which link the space-based communication link to the ground stations - probably by better-established radio channels. Multiplex the radio links if you've got more (optical) bandwidth than one of your radio links can handle.

But to be honest, with rare exceptions, bandwidth hasn't generally been

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[timeOday]

Spacecraft have limited energy so the number of bytes you can transmit in a day is the number you can send with the energy budget you have. A laser focuses the energy on the recipient much better than RF which sprays it around in a wider angle.

"Speed" is not particularly synonymous with either bandwidth nor latency.

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[mbunch]

You get much more bandwith in the literal sense -- the visible light spectrum is ~300THz wide. By Shannon's theorem this means you can achieve a higher data rate even if the SNR stays the same.

Received from light or dark side of Earth

[JoeRobe]

I'm curious if the bits of data sent from earth were sent from an Earth-illuminated side or a dark side. Earth can be pretty bright in the near-IR, so if the spacecraft was able to detect photons from a bright earth, that's even more impressive (spectral filtering?, lock in amplifying?).

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[TheGratefulNet]

there is no dark side of the earth.

as a matter of fact, its all dark. /oblig

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[molarmass192]

I couldn't find out from the linked articles if they're using modulation or pulsed. I have to assume it's pulsed since space "detritus" would impact modulation more than pulses. The other thing that's puzzling is how diffraction is handled, the beam should be insanely wide at 10 million miles, even with special focusing lenses. Unless that's a feature, so you don't need to hit the bullseye while hurtling through space, but then that's hogging bandwidth from anything else in the same direction from the recei

The rage

[Suripat]

It enrages me that every news media tries to capitalize while writing the titles for this news. Every ducking media writes it as clickbait. Scum. Slashdot could at least be different.

Cryptic message

[AshFan]

"So long, and thanks for all the fish."