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NASA Testing Frickin' Laser Communications
itwbennett writes "The lunar laser communications demonstration will be part of the agency's Lunar Atmosphere and Dust Environment Explorer (LADEE) mission, which is scheduled to launch on Sept. 6. Here's how the system will work: When the satellite is in orbit around the moon and visible from Earth, one of three ground stations will shoot a laser towards its approximate location. The laser beam from Earth will scan a patch of sky and should illuminate the spacecraft at some point. When that happens, the spacecraft will begin transmitting its own laser towards the ground station and the two will lock on to each other. The technology should allow an upstream data rate, from the Earth to the spacecraft, of around 20Mbps and a much faster downstream rate of 622Mbps. That's roughly six times the speed that's currently possible with radio-based transmission, said Don Cornwell, mission manager for the lunar laser communications demonstration."
The latency will be absolute shit. Useless for most bandwidth-intensive internet applications. Imagine trying to play a game with twice the lag of a dialup modem. Not only that, but one cloud in the sky and it's game over, man.
Not reliable at all.
#fuckbeta #iamslashdot #dicemustdie
and no shark?!?
I hate you
As if laser communication would be something new...
NASA stands up and says, "Ignore the volunteers, put a robot there."
I remember leaving Olduvai Gorge, the first person to look past the rim of the canyon walls. For a moment, I was alone, and concerned. But I noticed the same crap happened along the rim as it did by the river. So I kept going outward, I noticed a lot more food on the Serengeti. I like it, I think I'll keep moving forward.
Then I realized how NASA is oriented; they are alone, and concerned. Only it's every day, and it never changes.
One of the weaknesses of the NASA science / PI driven culture is that engineering tests like this can take a very long time to fly, as they do not directly provide science and have no scientific community demanding them. Laser communications was proposed for testing on the space station (as a down-link site) in the 1980's, has made it close to getting into space several times, but every previous attempt to fly it was eventually canceled to save money. Now, finally, it will be tested (or, in NASA speak, achieve a TRL of 8).
As it is, numerous deep space missions are data limited, such as the Mars Reconnaissance Orbiter, which could take more pictures, if it could get the data back. Laser comms is badly needed, let's hope the LADEE test goes well and it can finally get deployed.
My moon satellites will all use FiOS to communicate with Earth.
It must have been something you assimilated. . . .
Long distance in space.
Careful, the roaming charges are killer.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
Using lasers for communications is not new. HAM Radio geeks have been experimenting with it for some time. The big problems seem to be maintaining the alignment of the laser, and atmospheric attenuation of the signal. That aside, the bandwidth of visible light signals will be awesome, compared to longer wavelengths.
âoeAny society that would give up a little liberty to gain a little security will deserve neither and lose both.
A modest suggestion - whenever you feel like someone has made a basic math error in their own field, or doesn't know basic facts about the technology in their own field, and they are a high-level professional in that field, say, a mission manager talking to the press, and you are not, you should consider the possibility that you might be the one who is mistaken.
Why is it asymmetric? Gravity?
*wink*
"If any question why we died, Tell them because our fathers lied."
The Terra satellite was also almost 5 tons in mass with 2.5 kW of power to work with in low Earth orbit. LADEE is a twentieth of the mass, with a tenth of the power budget, and in lunar orbit. The situations are different, and it is like you are complaining a 1000+ HP car is trivial because cargo ships do that all the time.
What happens on a cloudy day ?
Has NASA settled the question? I guess so. Upload rates are ALWAYS a fraction of download rates.
A satellite can be in any convenient orbit near earth to send/receive communication and then relay data to/from an earth station. The last hop can be radio or laser, whatever is most appropriate.
NASA currently has a set of eight satellites in orbit that do exactly this for radio signals, called TDRS. This program has been operational since 1983, and NASA is now working on the third generation of satellites.
Why is Snark Required?
But this is the Internet. You don't have to know anything about a subject, or even understand what someone's saying to remit some dopey argument because there's nothing worth watching on TV.
But this is Slashdot. So thanks for making the modest suggestion, even though that never seems to penetrate the cloud cover.
"You must try to forget all you have learned. You must begin to dream." -- Sherwood Anderson
A modest suggestion - whenever you feel like someone has made a basic math error in their own field, or doesn't know basic facts about the technology in their own field, and they are a high-level professional in that field, say, a mission manager talking to the press, and you are not, you should consider the possibility that you might be the one who is mistaken.
OTOH, the Terra press kit distributed by NASA includes the following statement:
The science data recorded onboard will be transmitted via Kuband at 150 Megabits per second.
Note to ACs: I usually delete AC replies without reading them. If you want to talk to me, log in.
And make it 9.99 a month and put everyone else out of business. Pretty please.
Makes sense. Thanks.
Note to ACs: I usually delete AC replies without reading them. If you want to talk to me, log in.
Wasn't the faulty "laser communications" device the plot motive used in the movie "Dark Star"?
"TALBY Before we get too far away, and our signals start to fade, I just wanted to tell you... you were my favorite."
Tracy Johnson
Old fashioned text games hosted below:
http://empire.openmpe.com/
BT