Colour and Stereo Surface Imaging System - CaSSIS


Flight Software, Telescope, and Rotation Mechanism

Here is an update of the flight software, telescope, rotation mechanism, and ...

Flight Software - FSW

The flight software is RUNNING. This was a real weird one. From the report....

"CaSSIS DPM hardware design causes a clock shift on the SDRAM clock line, causing double word memory access to fail in rare conditions at ambient temperature in the laboratory. The error occurred only on when writing two subsequent 32-bit words with bit 47 set and bit 15 cleared."


"The GR712RC allows to adjust the SDCLK delay in the purpose register. It can be used to advance the clock until it is within the required timing specifications related to the other SDRAM signal lines."

Double wow!! 

The above is the (very) short version. Once fixed the FSW ran stably for 13 hours! Great job from the hardware and software teams in Bern and Budapest. Thanks also to Gaisler (Sweden) for their support during de-bug.


Test review board is tomorrow afternoon. Delivery on Wednesday morning (22 July).

Rotation mechanism

We are fighting issues with the gearing. We have vastly improved the integration process but we still have issues with the coating being damaged during rotation. We are now lubricating the gears and the bearings with a space-qualified lubricant. There is a small worry about this stuff outgassing and getting onto the mirrors. But, we think this will not be sooooooo.... bad because the mirrors are quite well shielded from the mechanism. Getting this right is delaying us but it has to work well. We will know more later this week.


We will submit an abstract to AGU this week.