[time-nuts] Space mission comes to an end becuase of a "computer time tagging" problem

DaveH info at blackmountainforge.com
Sun Sep 22 01:49:10 EDT 2013


There is a major problem with Radioisotope Thermoelectric Generators

Our stocks of Plutonium-238 are very low -- less than 40 pounds remain
available to NASA and this is all spoken for future missions.

We are restarting the manufacture and it is supposed to come online sometime
around 2017.

One gram of Plutonium-238 gives about 0.5 watts of deliverable electricity.
Half-life of 87.7 years. P-238 does not go KaBoom! -- you are thinking of
P-239.

http://en.wikipedia.org/wiki/Plutonium-238

http://www.space.com/20290-plutonium-spacecraft-nasa-fuel.html

http://www.wired.com/wiredscience/2013/09/plutonium-238-history-timeline/




> -----Original Message-----
> From: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] On Behalf Of Chris Albertson
> Sent: Saturday, September 21, 2013 20:34
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Space mission comes to an end 
> becuase of a "computer time tagging" problem
> 
> On Sat, Sep 21, 2013 at 6:40 PM, Hal Murray 
> <hmurray at megapathdsl.net> wrote:
> >
> 
> > What stops working when things get cold?
> >
> > On Mars, the solar cells are pointed in the right 
> direction.  Why doesn't it
> > recover when the sun comes back in the Spring?
> 
> They run out of power for running the battery heaters, then the
> battery freezes and fails.  The batteries get to such a low
> temperature that they are unable to be charged.  The rover was never
> designed so that it could move and operate under solar power.  It is
> really battery powered and uses the panel for charging.
> 
> This is the biggest reason the newest rover, "Curiosity" is powered by
> an RTG, not solar cells.  The RTG is powered by radioactive decay.
> The thing makes a lot of heat and should last 15 to 20 years. Likely
> longer than all the moving parts like motors and so on.
> -- 
> 
> Chris Albertson
> Redondo Beach, California
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