February 7, 2007, HiRISE release Options

[Guest_AlexBlackwell_*]

February 7, 2007, HiRISE release

[Pavel]

My favorite is Slope Streaks in Acheron Fossae - that's quite a lot of "wet" stuff, not just a lone streak as we've seen before!

[ngunn]

I think these ones are supposed to be dry. I like the way some of them don't stop at the bottom of the slope - as if they each generate there own puff of wind which blows a little way out onto the plain.

[Guest_AlexBlackwell_*]

My favorite is Slope Streaks in Acheron Fossae - that's quite a lot of "wet" stuff, not just a lone streak as we've seen before!

As ngunn noted, the prevailing opinion is that these dark streaks are representative of dry dust avalanches. And imagery showing multitudes of streaks are by no means uncommon. See, for example, this MGS MOC image.

[Guest_Sunspot_*]

Make the most of these pictures:

http://www.jpl.nasa.gov/news/news.cfm?release=2007-013

In late November 2006, the spacecraft team operating the High Resolution Imaging Science Experiment camera on Mars Reconnaissance Orbiter noticed a significant increase in noise, such as bad pixels, in one of its 14 camera detector pairs. Another detector that developed the same problem soon after launch has worsened. Images from the spacecraft camera last month revealed the first signs of this problem in five other detectors.

[nprev]

Oh...<clink!!!!>

Still, seems like a work-around might save the day...looks like the prob is temp-dependent, which at least means that an optimal temp can be derived to assure the best data return. Had to do something sort of similar once with a NOAA oceanographic instrument, and we still got all our data.

I suspect that the root cause may well be the at the detector's electrical connections to the rest of the instrument, esp. if they're using something like socket ball-locks for critical board interfaces (the chip) instead of hard solder joins. Thermal expansion/contraction can play hell with the former, causing high-resistance pathways and consequent data dropouts.

[tuvas]

Make the most of these pictures:

http://www.jpl.nasa.gov/news/news.cfm?release=2007-013

In late November 2006, the spacecraft team operating the High Resolution Imaging Science Experiment camera on Mars Reconnaissance Orbiter noticed a significant increase in noise, such as bad pixels, in one of its 14 camera detector pairs. Another detector that developed the same problem soon after launch has worsened. Images from the spacecraft camera last month revealed the first signs of this problem in five other detectors.

It should be stressed that except for two of the CCDs, the problem is very minimal at the time, and even in the two, useful data can be obtained in all but 1 channel most of the time, and even in the 1 channel otherwise. It's not as bad as it would seem.

[mchan]

I suspect that the root cause may well be the at the detector's electrical connections to the rest of the instrument, esp. if they're using something like socket ball-locks for critical board interfaces (the chip) instead of hard solder joins. Thermal expansion/contraction can play hell with the former, causing high-resistance pathways and consequent data dropouts.

Possibly. There could be many causes of early life degradation, there is not a lot of public information on the symptoms and on the system / board design details that I am aware of to speculate. Given that sockets (in a generalization) can have reliability issues in high vibration and high thermal cycling environments, why would they be used in a production board that operates in the aforementioned conditions? Sockets in protos, yes, but I would not spec them for production unless there is a very good reason to.

[nprev]

I agree with you 100%, mchan. Still would really like to know if they did in fact use a solderless chip connection method (there does seem to be a trend towards using these in some circles for flight hardware, believe it or not) and IMHO it's very unwise indeed.