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Space Science

Landsat 7 Satellite Might Be Dead 35

Posted by timothy from the pings-go-unanswered dept.
Lord Satri writes "Landsat 7 ETM+ remote sensing satellite, probably the most important Earth Observation satellite, might be dead now. This would have very important repercussions on the remote sensing / space community."
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Landsat 7 Satellite Might Be Dead More

Landsat 7 Satellite Might Be Dead

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  • Software fix? (Score:3, Interesting)

    by DustMagnet ( 453493 ) on Wednesday June 11, 2003 @01:29PM (#6173057) Journal
    It looks to me like software fix would be possible, but the quality will be reduced. From this page [nasa.gov] it looks like a broken SLC would reduce the resolution of the image.

    The images must not look too bad, since it took them over a week to notice the problem.

    • Re:Software fix? (Score:3, Informative)

      by robslimo ( 587196 )
      Nope. The SLC physically modifies the imager's tracking, thereby modifying what is imaged. It keeps the imager from missing data in its desired, rectilinear image path.

      It is not a matter of diddling the image data to un-zig-zag it; without the SLC, the imager simply acquires the wrong data. Software *could* be utilized to interpolate and try to fill in the missing data at a lower resolution, but that would certainly leave a noticable zig-zag artifact of high-res diagonals filled between with lower res

      • Re:Software fix? (Score:2, Informative)

        by DustMagnet ( 453493 )
        I thought that's what I said, but I guess not. If you look at the picture I linked, you'll see what the data might look like with the SLC off. If you only used every other scan, you'd have parallel scans. The entire image would be at a lower resolution and the scan lines would not be orthogonal to the path of flight, but it might be better then nothing. I work with data far less regular than this (airborne LIDAR). The images we use from satellites always get resampled to fit our map projections anyway.
      • If we every get a shuttle back in the sky, maybe they can do a fly-by and have an astronaut give it a thump on the way by

        Couldn't we just launch a big boot into space to give it a kick? That seems to work for some of my servers (the kicking part - I haven't actually tried launching them into space)
    • It looks to me like software fix would be possible, but the quality will be reduced. From this page it looks like a broken SLC would reduce the resolution of the image.

      Holy cats! Combine that with my other post [slashdot.org], and you just might have something for the 'cordless shaver/vibrator' crowd for watching TV..

    • Software won't fix this. It suffered the same fate as CONTOUR. [uncoveror.com] Those images aren't even from Landsat 7. It's a cover up!

  • I know who did it. (Score:3, Funny)

    by davidhan ( 539718 ) on Wednesday June 11, 2003 @01:33PM (#6173092) Journal
    It must have been that high school computer club new project! Damn meddling kids...

  • "very important repercussions" ? (Score:4, Informative)

    by VisorGuy ( 548245 ) <inactive> on Wednesday June 11, 2003 @01:43PM (#6173206) Journal

    "This would have very important repercussions on the remote sensing / space community."

    From the website
    "For current multispectral imagery, please be aware that Landsat 5 TM, EO-1 Advanced Land Imager (ALI), and ASTER may provide useful data alternatives."

    Doesn't sound like total gloom and doom to me; but what do I know, I'm no asstronomer...

  • Reports of its death have been greatly exaggerated (Score:4, Informative)

    by Buran ( 150348 ) on Wednesday June 11, 2003 @05:45PM (#6175796)
    Note the phrase "The spacecraft itself appears to be in no danger..."

    Landsat 7 itself is still functioning. The Thematic Mapper is the instrument with the problem. These satellites contain other instruments on board which can be used to continue the mission.

    It's similar to how some of the instruments on board the Voyager spacecraft no longer function, but those that still work are returning useful data.

    • Re:Reports of its death have been greatly exaggera (Score:4, Informative)

      by dmadole ( 528015 ) on Wednesday June 11, 2003 @07:55PM (#6176766)

      These satellites contain other instruments on board which can be used to continue the mission.

      No it doesn't.

      As noted here [nasa.gov] and here [nasa.gov] and probably elsewhere, Landsat 7 contains only a single istrument -- the ETM (Enhanced Thematic Mapper).

      It's nothing like the Voyager spacecraft, which were multi-purpose and indeed contained many instruments. Landsat 7 was designed for exactly one specific function. If the ETM is badly broken, the whole satellite is pretty much a loss.

  • Oh, yeah, suuuuure it's "dead" (Score:5, Insightful)

    by stanwirth ( 621074 ) on Wednesday June 11, 2003 @09:47PM (#6177605)

    During the Reagan administration, when a high-resolution statellite instrument to measure the earth's geoid and topography was suddenly found to be extremely useful in locating submerged submarines (by way of their wakes) it, too, suddenly "went dead." I knew the guy at Lamont-Doherty Geophysical Lab who discovered how to recover the submarine wakes from these data. Funny how only the high-res instrument (the one that could detect submarine wakes) suddenly "went dead." The low-res instrument continued to return data. It was an open secret in the geophysical community that the high-res instrument didn't actually have a malfunction. Funny how the US won the cold war with a few years after that, too. Hrmmm.

    It was also the Reagan administration that privatised LandSat -- after spending billions of taxpayer's dollars to develop and deploy the LandSat satellites and do additional TM work from the space shuttle, suddenly all of the imagery was owned by a private company. And government-sponsored projects, instead of paying like $350.00 per scene, suddenly had to spend $3500.00 per scene. Double that to account for "University Overhead." What I want to know is, why, after paying for the development and deployment of this technology, do we (as taxpayers) then have to pay for it again when a project is formed to analyse these data? Didn't seem right at the time. Still doesn't seem right.

    But I honestly doubt the LandSat 7 TM instrument actually went dead. It was probably found to be returning data of military significance, and why bother with the political rigamarole with the scientific research community, not to mention the delay involved with classifying data -- when you can just claim the thing "went dead"? After all, who is going to make the trip to the thing itself to verify the claim that it "went dead"?

    • The US government already has 24 hours to review every image taken by US-owned spacecraft and decide whether or not to make them available based on national security concerns; there's no need to completely shut the thing down.
      • The US government already has 24 hours to review every image taken by US-owned spacecraft and decide whether or not to make them available based on national security concerns; there's no need to completely shut the thing down.

        Not to become a conspiracy nut myself, but there are a couple of big problems with this defense:

        One: There are a bazillion (I counted) satellites returning imagery, and probably not a bazillion folks to look over all the images before they're released -- especially not in a 24-hour

        • This is the perfect conspiracy theory: it's almost entirely plausible, almost impossible to refute, and we want to believe it!

          Reasonable suspicion based on past known behaviour does not a "conspiracy theory" make. Every time a remote sensing satellite goes black, it's worth wondering of what tactical or strategic value was the data. And to do this well, you need to know what image processing and multisensor fusion algorithms are currently being used, by both your own nation, and your nation's enemie

    • LandSat 7 resolution (Score:3, Insightful)

      by Valdrax ( 32670 )
      I'm chiming in in agreeance with the AC who says that you've never worked with LandSat 7 data. In my job as a developer for a company whose product line is used to analyze satellite and aerial photography, I regularly do. The LandSat 7 satellite has poor resolution for this sort of thing.

      The color bands only have a resolution of 30 meters per pixel width, with the exception of band 6 (the far infrared band) which only has a resolution of 60 meters per pixel width. The panchromatic band has a better reso

      • Actually, I worked on several image processing projects for the military, and we certainly did use LandSat data. And SPOT data (optical band) and SAR data (K band and X band mostly) as well as IR data.

        The advantage of LandSat data is the broad spectrum of data returned, not the resolution. As a consequence, LandSat data alone has little tactical use, but it has tremendous strategic value -- particularly when geolocated and registered with data in other bands, and in conjunction with other data. In on

        • Okay, I'll concede that you do work with and are actually familiar with the data formats and their uses. However, can you think of a good explanation for why LandSat 7 would go black instead the Hyperion instrument on the EO-1 satellite with its 220 band hyperspectral sensor and resolution matching that of LandSat 7? What about the ASTER sensor on the Terra satellite with its 9 bands of better/equivalent resolution data and its futher 5 bands of True IR at 90 m resolution?

          LandSat 7 is simply not as capab

          • LandSat 7 is simply not as capable of a sensor as some of the others out there. Shutting it down without shutting down better sensors is wasterful and strategically pointless.

            I'm not sure about that. For one thing, it's more plausible for an old satellite to "malfunction" than a new one. The other thing you need to consider is timing and coverage. Just because satellite A is better than B doesn't mean that it will be where you need the data at a particular time. No matter how you slice it, the da

  • Do not panic - ESA's Envisat is still rocking :-)

    http://envisat.esa.int/news/index.html

    Regards, Simon
  • One advantage of Landsat data is its synoptic coverage. Basically, the "camera" is always at the same place and shadows are the same.

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