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NASA Creating Laser Communication System For Mars
techtribune writes "NASA is in the process of developing a new technology under project Laser Communications Relay Demonstration or LCRD which will allow them to provide faster means of communications from Mars. The Mars Reconnaissance Orbiter (MRO) currently can only send at speeds of around 6 Mbps or about like a DSL modem here on Earth. At this rate, it can take upwards to 90 minutes to transmit a single high resolution image to Earth from Mars. With the MRO outfitted with the new technology it would be able to transmit the same high resolution image back to Earth at over 100 Mbps and only taking about 5 minutes to do so."
Well then I would suspect that the orbit is dangerously low and the last message would likely read: "Ack!"
crazy dynamite monkey
Yeah, but the whole planet has to share 6 Mbps.
No. The issue here is not the latency. Latency is a problem (it is a major issue with the rovers. Trying to direct them where to go and then waiting to see if they run into problems is a big nuisance). But here the total problem is bandwith. The total bandwith is low, so it takes a very long time to send data from Mars to Earth. We get far more data on Mars than we can even send back to the Earth. Even with this new system that will still be the case but if it works it won't be nearly as bad. This will improve the total bandwith a lot.
Science images are NEVER EVER compressed in JPEG. In fact they probably don't even use the TIFF format either. Almost all science images in astronomy are done in the FITS format which I think was developed by NASA. This is because not only does the image need to be lossless raw data in order to be used for proper scientific measurements, but also much metadata must be included with the frame for some kinds of science observations.
Common metadata will include the position of the camera (where the orbiter was when the picture was taken), the camera's orientation (which way it was looking at the time), the exact time when the image was taken, the image exposure time, the camera's CCD temperature, whether on-chip binning has been carried out, the camera's readout noise, the camera's gain, etc. All of this information is necessary for some kinds of science and therefore NASA doesn't want to lose any of this information.
-Buck
Nice planning on the communication system. Nice to see good solid planning, development and R&D. It's what NASA is good at. They also design pretty good rockets, rockets that used to take us places. Now that we have a better network, lets build the SLS and quit relying vaporcraft to get us there. Let,s quit cutting funding, and make it a priority to travel to are causing a brai Mars. We put a human on the moon and can do it again. The SLS can get us there.. we still have the brain power to go to Mars, but our politicians and misguided and overly hopeful privatization plans.... Less than one tenth of one percent of our budget is spent on space... For all of you wanting to save money, if privatizing space makes sense, why not privatize our national security, epa, and social security?? We need a heavy lifter!
why would they want a probe orbiting Mars to communicate with sharks?
ELOI, ELOI, LAMA SABACHTHANI!?
. This is because not only does the image need to be lossless raw data in order to be used for proper scientific measurements, but also much metadata must be included with the frame for some kinds of science observations.
Pedantically speaking, TIFF also allows for arbitrary metadata. And all sorts of other bizarre crap. FITS is a much older format and part of the reason it is used is historical.
The main reason it is used is that it is a format specifically designed for archival use. It is a very simple format and one can easily write an image parser and writer from scratch which will happily accept and be accepted by most systems (so that ignores the more obscure non image options). I have done so.
NASA quite rightly expect FITS images to be readable in 100 years time. This is reasonable since you could probably write that parser in a couple of days without even having access to the spec. TIFF by comparison is not a simple file format.
t's also not a bad format. Lossless compression will get you at most 3x on a natural image with 8 bits per channel, but more like 1.5-2, and often is not worth the bother, especially as support for TIFF compression is somewhat spotty once it moves into more than 8 bits per channel.
one marginally irritating thing about FITS is that it is in column-major format (yay @ fortran) rather than row major, where as most capture hardware and other image formats are row-major. So, loaading/saving FITS images often requires a quadrupal for-loop (endian/channels/rows/cols) to rearrange the data.
But back on topic: 6mpbs over 400e6 km is amazing!
SJW n. One who posts facts.
eeek.
I expect that they use LDPCC, not Reed-Solomon error correction these days. Good LPCCCs get amazingly close to the shannon limit. Just crank down the rate a bit and watch the BER disappear.
GigE and greater also use LDPCC.
SJW n. One who posts facts.
Any possibility of licensing spectrum to the Russians, the Chinese, or other countries that want to send probes to Mars? Fractional T-1 to Mars in exchange for a Soyuz ride or something...
For all intensive purposes, "whom" is no longer a word. That begs the question, "who cares"?
Lose a bit here, a few dropped pixels there and you end up with the "Face On Mars."
I'd like us to get as much non-corrupted data as possible. Helps keep the kookie insane theory folks from getting any traction.
"Well, good luck finding a judge that doesn't run a bestiality site."
Your point is valid, except that the HIRISE imager on the MRO only produces images of 16.4Gb (2.05 GB) before compression, 5Gb (630MB) after compression in red, and 1/5 of that for blue/green channels. It's only a 3 channel device. The CTX camera is lower resolution with only a single channel. MARCI operates in 7 channels, but it's also low resolution.
The MCS spectrometer operates in 9 channels, but is very low resolution.
That leaves the CRISM spectrometer as the only imager on MRO with a large number of channels. It can image 50 or 544 channels depending upon the mode. But again, it's comparatively low resolution (~ 1/40 that of HIRISE, which means about 1/1600th as many pixels in a given area), which more than offsets the increase in number of channels.
make imaginary.friends COUNT=100 VISIBLE=false
Is this bi-directional? If I'm going to spend a year going out there I'm sure as hell going to download some "images" from earth!
LOLOMGWTFBBQ