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NASA Mars Science

NASA Creating Laser Communication System For Mars 104

Posted by samzenpus
from the mars-needs-lasers dept.
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."
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NASA Creating Laser Communication System For Mars

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  • by AndrewBuck (1120597) on Wednesday August 24, 2011 @06:33PM (#37197904)

    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 [wikipedia.org] 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

  • by serviscope_minor (664417) on Wednesday August 24, 2011 @07:02PM (#37198336) Journal

    . 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!

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