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."

Comments

"very important repercussions" ?

[VisorGuy]

"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...

Re:Software fix?

[robslimo]

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 blurs.

It's hardware, man. 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.

Re:Software fix?

[DustMagnet]

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. I don't see this as any different.

Of course I don't know how Landsat 7's SLC works, or how it's broken. If they can't predict what the SLC is doing, then it's worthless to try to fix it in software.

I think you're wrong about the shuttle. I did some searches and Landsat 7 is orbiting at 438 miles. The shuttle's safe limit is 300 miles (design is 600 miles).

Reports of its death have been greatly exaggerated

[Buran]

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

[dmadole]

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.