Re: [ntp:questions] OT: high-accuracy atomic clock to be attached outside of the International Space Station

2009-12-17 Thread Rick WIdmer
On 12/15/2009 2:02 PM, John Hasler wrote:
> Jan Ceuleers writes:
>> Secondly though, is the ISS able to receive GPS signals in order to
>> remove the need for its own high-accuracy clock?
>
> This appears to be a research-grade clock with epecially good long-term
> stability.
>
>> Assuming that the accuracy that results would still be good enough?
>
> I don't think GPS time would be adequate for the planned research.

This page has some info on the science.  Look in the lower right.

http://www.spaceflight.esa.int/users/downloads/factsheets/fs031_10_aces.pdf

One of them is "Absolute synchronization of ground clocks" to within 100ps.

Rick
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Re: [ntp:questions] OT: high-accuracy atomic clock to be attached outside of the International Space Station

2009-12-15 Thread John Hasler
Jan Ceuleers writes:
> Secondly though, is the ISS able to receive GPS signals in order to
> remove the need for its own high-accuracy clock?

This appears to be a research-grade clock with epecially good long-term
stability.

> Assuming that the accuracy that results would still be good enough?

I don't think GPS time would be adequate for the planned research.

> I'm asking because I wouldn't expect GPS/Galileo/GLONASS to have been
> designed with in-orbit receivers in mind.

GPS was.
-- 
John Hasler 
jhas...@newsguy.com
Dancing Horse Hill
Elmwood, WI USA

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Re: [ntp:questions] OT: high-accuracy atomic clock to be attached outside of the International Space Station

2009-12-15 Thread Jan Ceuleers
unruh wrote:
> They have high accuracy atomic clocks orbiting up there already (GPS,
> Galileo,...) What is significant about this?

Firstly, the linked press release talks about certain physics experiments which 
can presumably only be carried out in orbit and which require highly accurate 
clocks.

Secondly though, is the ISS able to receive GPS signals in order to remove the 
need for its own high-accuracy clock? Assuming that the accuracy that results 
would still be good enough? I'm asking because I wouldn't expect 
GPS/Galileo/GLONASS to have been designed with in-orbit receivers in mind.

Jan

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Re: [ntp:questions] OT: high-accuracy atomic clock to be attached outside of the International Space Station

2009-12-15 Thread unruh
On 2009-12-15, David J Taylor 
 wrote:
> ...an agreement that paves the way for the launch of a high-accuracy 
> atomic clock to be attached to the outside of the European Columbus 
> laboratory onboard the International Space Station (ISS).

They have high accuracy atomic clocks orbiting up there already (GPS,
Galileo,...) What is significant about this?

>
> See more:
>   http://www.esa.int/esaCP/SEMRDI9K73G_index_0.html
>
> David 
>

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[ntp:questions] OT: high-accuracy atomic clock to be attached outside of the International Space Station

2009-12-15 Thread David J Taylor
...an agreement that paves the way for the launch of a high-accuracy 
atomic clock to be attached to the outside of the European Columbus 
laboratory onboard the International Space Station (ISS).

See more:
  http://www.esa.int/esaCP/SEMRDI9K73G_index_0.html

David 

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