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

Bob Camp lists at rtty.us
Sat Sep 21 12:41:11 UTC 2013


Hi

I'd be a bit surprised if they were running anything as power hungry as an Rb all the time when a quartz based device would be smaller / lower power / lower volume. Of course they may have had mission requirements that drive them to a hydrogen maser ...

Bob

On Sep 21, 2013, at 5:30 AM, Rob Kimberley <robkimberley at btinternet.com> wrote:

> David,
> 
> The satellite has probably got a Rb as its clock (hopefully more than one).
> All I can imagine is that there has been a major clock failure of some sort,
> and everything is in free run and unable to sync up with ground.
> 
> Thoughts?
> 
> Rob
> 
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of David J Taylor
> Sent: 20 September 2013 17:51
> To: Time-nuts mailing list
> Subject: [time-nuts] Space mission comes to an end becuase of a "computer
> time tagging" problem
> 
> NASA's Deep Space Comet Hunter Mission Comes to an end
> 
> The news release includes this paragraph:
>    "After losing contact with the spacecraft last month, mission
> controllers spent several weeks trying to uplink commands to reactivate its
> onboard systems.  Although the exact cause of the loss is not known,
> analysis has uncovered a potential problem with computer time tagging that
> could have led to loss of control for Deep Impact's orientation.  That would
> then affect the positioning of its radio antennas, making communication
> difficult, as well as its solar arrays, which would in turn prevent the
> spacecraft from getting power and allow cold temperatures to ruin onboard
> equipment, essentially freezing its battery and propulsion systems."
> 
> Knowing the membership of this group, does anyone have more insight into
> what the "computer time tagging" problem might be?
> 
> Thanks,
> David
> --
> SatSignal Software - Quality software written to your requirements
> Web: http://www.satsignal.eu
> Email: david-taylor at blueyonder.co.uk 
> 
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