[time-nuts] OT - but of interest?

[Jim Lux]

On 4/27/13 9:40 AM, Gregory Muir wrote:
> On Fri, 26 Apr 2013 17:59:21 -0700, Jim Lux wrote:
>
>
>> Total dose will be very small (after all astronauts live in LEO)
>
>> So you'd worry about cosmic rays and single event effects.
>
> <snip>
>
>> They fly a lot of unmodified commercial equipment on ISS (and on
>> Shuttle, when we still flew it) and they typically have MTBF of a month
>> or so for the really soft parts.  Most stuff will last a year before it
>> dies.
>
> <snip>
>
> I'm curious if they ever have any problem with earth-based commercial component
> outgassing clouding the camera optics.
>

I suspect that on ISS, there's no precision imaging.  There's so much 
crud flying around station I doubt it would be worth trying.

Station is a unique environment. It's enormous  (>100 meters), it's mind 
bendingly complex (no single person understands it, there's thousands of 
people involved).  Another problem with doing any sort of precision 
imaging is that you probably don't know where your sensor is or where 
it's pointed with sufficient precision.  In absolute terms, you probably 
know where it is within about 100 meters (in Earth referenced 
coordinates) and where it's pointed within a few degrees. The structure 
moves and flexes a lot.  No spy satellite here..

We're doing a precision orbit determination experiment with a software 
GPS receiver over the next few months (it is the first civil L1/L2c/L5 
GPS receiver in orbit).  It's been challenging to find out information 
like Center of Mass position, where the other GPS receivers are, etc.
(complicated in part because half of station is measured in inches/feet, 
and the other half in meters)

I