[time-nuts] Bicentennial GOES satellite clock

[jimlux]

On 8/12/18 6:36 PM, David I. Emery wrote:
> On Sun, Aug 12, 2018 at 07:48:52PM -0400, Bob kb8tq wrote:
>> Hi
>>
>> Well???. there???s also the solar flare that vaporizes the planet earth :)
>>
>> A flare big enough to take out all the sat systems would disrupt a lot more than just navigation.

> 
> 	But It is much more likely that orbits would be less accurately
> known for a while due to atmospheric heating and increased drag and
> maybe also due to disturbances in satellite orientation and power and
> thermal status during the event that could both change drag and perhaps
> even induce slight impulses if gas jets or similar means were required
> to recover the bird and make it stable again.   And the power and
> thermal perturbations in emergency mode shutdown configurations might
> well impact the on board clock performance and accuracy (even maybe just
> from the extra radiation as the magnetopause moved inside the satellite
> orbits in an extreme event).

GPS is up high enough that aerodrag isn't really a problem - if you're 
above 1500km, it's negligible, and they're up at 20,000km.
Solar wind pressure will push them around a bit, but not much.  I would 
think that if you did nothing, they'll be there for a very, very long time.

Their orbit is actually a quite high radiation zone (traversing the 
radiation belts as they pass through the polar region), compared to GEO.

So the GPS satellites are pretty robust to this kind of thing.