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Landsat 7 Satellite Might Be Dead
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."
The images must not look too bad, since it took them over a week to notice the problem.
'SBEMAIL!' is better than a goat!!
It must have been that high school computer club new project! Damn meddling kids...
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...
This user account is inactive account replaced by the PDA
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.
i am a soviet space shuttle
These satellites contain other instruments on board which can be used to continue the mission.
No it doesn't.
As noted here and here 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.
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.
Energy: time to change the picture.
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 timeframe.
Two: The withholding of any particular image or set of images is an immediate sign that the image contained useful information.
Assuming this satellite's data was discovered to contain militarily (or commercially!) useful information, the only way to keep both the imagery and its location secret would be to make all imagery unavailable for some reason.
This is the perfect conspiracy theory: it's almost entirely plausible, almost impossible to refute, and we want to believe it!
On the other hand, I can get a pretty good aerial view of Downtown Baghdad any time I want it.
Stressed? Me? Of course not. Stress is what a rubber band feels before it breaks, silly.
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 resolution of 15 meters per pixel width. If you do the math, that means that the color bands have a resolution of about a 1/6 of a football field per pixel.
This is nothing compared to other satellites out there. Orbital Imaging owns a satellite called OrbView-3 that should be going up soon which has an 4-band multispectral sensor with 4 m resolution on each band and a panchromatic sensor with 1 m resolution. Digital globe has 2.44 m multispectral data and 61 cm panchromatic data for sale as their basic imagery for sale. Trust me, LandSat 7 one of the least likely sensors to be shut down for being just "too good."
Your conspiracy theory is silly. As noted by another poster, the government already reserves the right to pull all sensitive information from it. This is routine. There's no reason to declare the satellite to be an expensive piece of space junk when they've already got procedures for handling data of military significance.
(BTW, the LandSat fleet was taken back under the government's wing in 1992 after the costs for data became too onerous.)
If it's for-profit but free, you're not the customer -- you're the product (e.g., the Slashdot Beta's "audience").
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 data volume and coverage from A+B > the volume and coverage from A, unless the data from B is literally worse than useless.
Your "simple inductive logic" reminds me of an old joke: A mathematician, a physicist and an engineer ...
I know. That's why I identified formulating projections on the basis of past known events as inductive logic, rather than deductive logic. We're calculating probability density functions here, not proving that something is definitely so or not so.
By the way, can you give any substaniated examples of a satellite being shut down permanently when it was putting out data of military significance?
Yup! SeaSAT failed after 116 (or 106, or 99, depending on which source you believe) days of operation. The person doing the analysis showed me the pictures. I was just an undergraduate at the time. The high-res SAR data stopped coming through well before the low-res -- odd, considering the failure of the satellite was attributed to a massive power failure. The data were militarily significant for the better coverage of ocean floor topography than was practically feasible to gather with sonar -- again, coverage is key here, not resolution. Sonar gives you better resolution, satellite geoid and topography gives you better coverage, particularly in areas where it's difficult to conduct bathymetric surveys--around Novaya Zemlaya for example. Subsurface topography is the widely acknowledged military significance of these data. The person doing the analysis was specifically asked to decimate these data prior to publication-- remove the spikes. Sub holes, strategic canyons and particularly "anthropogenic time-dependent spikes in the sea surface topography". Sub wakes. He did it. I would have, too.
The later GeoSAT satellite data were held by the US Navy and not declassified until after the Cold War.
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.