MSG-1 manoeuvre.


johnrigsec@...
 

All,

I had reported some time ago that MSG-1 would be drifted from its present
commissioning position of 10 deg. W to 3 deg. W (its operational position) by
late 2003 in preparation for the start of operational '0 deg. longitude services'
(replacing Meteosat-7's operational service) in early January.
It would then be renamed Meteosat-8.

I have just been informed by EUMETSAT that the drift is now likely to be the
second week of January 2004.
I understand imaging will continue whilst the satellite is drifted.

Registered EUMETCast users will be notified of developments.

Meteosat-7 will remain at 0 deg. longitude and continue WEFAX/HRI direct
dissemination till the end of 2005.

Regards,
John Tellick.


David J Taylor GM8ARV 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🇪🇺
 

I had reported some time ago that MSG-1 would be drifted from its
present commissioning position of 10 deg. W to 3 deg. W (its
operational position) by late 2003 in preparation for the start of
operational '0 deg. longitude services' (replacing Meteosat-7's
operational service) in early January.
It would then be renamed Meteosat-8.

I have just been informed by EUMETSAT that the drift is now likely
to be the second week of January 2004.
I understand imaging will continue whilst the satellite is drifted.
John,

Many thanks for that information - you are the first source, as ever!

One question: the imager will be kept running, so does that mean
that the axis of the satellite remains parallel with the earth's
axis? Does that mean there are separate 3D stabilsed small
thrusters which can perform this operation, without having to use
the main on-axis engine?

I'm showing my ignorance here, I realise!

Cheers,
David


Alan Sewards <alan.sewards@...>
 

David,
All modern satellites have three axis small thrusters for attitude
control. These are used for stationkeeping also. The satellite will have to
be reoriented when it arrives at its destination so it is just as efficient
to do it little by little on the way there.

Regards - Alan

----- Original Message -----
From: "David Taylor" <david-taylor@blueyonder.co.uk>
To: <MSG-1@yahoogroups.com>
Sent: Monday, December 08, 2003 7:16 PM
Subject: [MSG-1] Re: MSG-1 manoeuvre.


I had reported some time ago that MSG-1 would be drifted from its
present commissioning position of 10 deg. W to 3 deg. W (its
operational position) by late 2003 in preparation for the start of
operational '0 deg. longitude services' (replacing Meteosat-7's
operational service) in early January.
It would then be renamed Meteosat-8.

I have just been informed by EUMETSAT that the drift is now likely
to be the second week of January 2004.
I understand imaging will continue whilst the satellite is drifted.
John,

Many thanks for that information - you are the first source, as ever!

One question: the imager will be kept running, so does that mean
that the axis of the satellite remains parallel with the earth's
axis? Does that mean there are separate 3D stabilsed small
thrusters which can perform this operation, without having to use
the main on-axis engine?

I'm showing my ignorance here, I realise!

Cheers,
David



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Luca Bertagnolio <lucaberta@...>
 

Alan,

you're right, but my understanding of MSG-1 tells me that it is not a
three axis stabilized craft, but rather a spin stabilized spacecraft.

If I am correct, I am wondering what kind of wobble effect, or other
gyroscopic effect, will be observed during the thrusters firing
activity.

It seems strange to me though that they would risk any contamination
of the imager with the exhaust particles coming from the
thrusters... HST (a much more sophisticated imager, I admit) has a
big lens "cap" door which is/was closed during the Shuttle
maintenance missions.

In any case, keep those Tq software running during the maneuvre, it
could be fun!

Bye, Luca

--- In MSG-1@yahoogroups.com, "Alan Sewards" <alan.sewards@c...>
wrote:
David,
All modern satellites have three axis small thrusters for
attitude
control. These are used for stationkeeping also. The satellite will
have to
be reoriented when it arrives at its destination so it is just as
efficient
to do it little by little on the way there.


johnrigsec@...
 

In a message dated 08-12-03 18:36:43 GMT Standard Time,
david-taylor@blueyonder.co.uk writes:

John,

Many thanks for that information - you are the first source, as ever!

One question: the imager will be kept running, so does that mean
that the axis of the satellite remains parallel with the earth's
axis? Does that mean there are separate 3D stabilsed small
thrusters which can perform this operation, without having to use
the main on-axis engine?
David,

Very valid points and I don't know the answer - "but I know a man that does!"
I will get confirmation and further info.

I'm showing my ignorance here, I realise!<
Not at all David - you are held in the highest esteem!

Regards,
John.


johnrigsec@...
 

In a message dated 09-12-03 09:14:53 GMT Standard Time, lucaberta@yahoo.com
writes:

you're right, but my understanding of MSG-1 tells me that it is not a
three axis stabilized craft, but rather a spin stabilized spacecraft.
Hi Luca,

Yes, you are correct MSG-1 - indeed all the Meteosat craft are spin
stabilised.
Unlike the newer GOES which are three axis stabilised.

I am awaiting more information and confirmations from EUMETSAT on the drift.

Regards,
John Tellick.


johnrigsec@...
 

In a message dated 09-12-03 16:02:51 GMT Standard Time, Dave.Martin@manx.net
writes:

If it's a spin-stabilized bird, and not 3-axis stabilised, I wonder if the
simplest way to change orbital slot E - W might be to leave it spinning
totally undisturbed and just change the orbital period by slightly
raising/lowering the satellite's orbit ?
Dave,

That is my understanding of how the drift occurs - boost it to a higher orbit
- it goes one
way, boost it to a lower orbit it drifts in the other direction - in relation
to the Earth.

I believe that is how the Shuttle and ISS 'catch up' with one another.

Regards,
John Tellick.


Dave Martin <Dave.Martin@...>
 

If it's a spin-stabilized bird, and not 3-axis stabilised, I wonder if the
simplest way to change orbital slot E - W might be to leave it spinning
totally undisturbed and just change the orbital period by slightly
raising/lowering the satellite's orbit ?

Dave M

----- Original Message -----
From: Luca Bertagnolio
To: MSG-1@yahoogroups.com
Sent: Tuesday, December 09, 2003 9:13 AM
Subject: [MSG-1] Re: MSG-1 manoeuvre.


Alan,

you're right, but my understanding of MSG-1 tells me that it is not a
three axis stabilized craft, but rather a spin stabilized spacecraft.

If I am correct, I am wondering what kind of wobble effect, or other
gyroscopic effect, will be observed during the thrusters firing
activity.

It seems strange to me though that they would risk any contamination
of the imager with the exhaust particles coming from the
thrusters... HST (a much more sophisticated imager, I admit) has a
big lens "cap" door which is/was closed during the Shuttle
maintenance missions.

In any case, keep those Tq software running during the maneuvre, it
could be fun!

Bye, Luca


************************************************************************
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http://www.manx.net/solutions/mailplushome.asp
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Alan Sewards <alan.sewards@...>
 

Guys,
I did NOT say that MSG1 was 3 axis stabilized, but that it had thrusters
which were capable of producing thrust in the three axes which are used for
attitude control and stationkeeping.

Try the following link:
http://www.eumetsat.de/en/index.html?area=left7.html&body=/en/dps/dissemination.html&a=710&b=1&c=700&d=700&e=0

The following is an excerpt from the link's target:


Satellite Propulsion

The MSG propulsion system inherits the unified bi-propellant system
already proven on communication satellites and some scientific missions. It
includes:

a.. 4 propellant tanks providing a large storage capacity (up to 965
kg of propellant)
b.. 2 helium pressurant tanks
c.. 2 liquid fuelled apogee motors each giving 400 N thrust for
apogee manoeuvres in transfer/drift orbits
d.. 6 reaction-control thrusters for fine orbital manoeuvres,
attitude acquisition and maintenance
Satellite Attitude and Orbit Control System AOCS

The MSG AOCS is designed on a minimum-complexity basis. It takes full
advantage of the Meteosat experience, and the fact that the spinner concept
provides gyroscopic stability. The onboard real time operations provide:

a.. attitude sensor processing and spin rate determination
b.. attitude and orbit manoeuvre synchronization
c.. active nutation damping.
The sensors comprise Sun slit sensors, Earth horizon crossing sensors,
and accelerometers.



I hope that clears it up!

Best regards - Alan

----- Original Message -----
From: <johnrigsec@aol.com>
To: <MSG-1@yahoogroups.com>
Sent: Tuesday, December 09, 2003 3:35 PM
Subject: Re: [MSG-1] Re: MSG-1 manoeuvre.


In a message dated 09-12-03 09:14:53 GMT Standard Time,
lucaberta@yahoo.com
writes:

you're right, but my understanding of MSG-1 tells me that it is not a
three axis stabilized craft, but rather a spin stabilized spacecraft.
Hi Luca,

Yes, you are correct MSG-1 - indeed all the Meteosat craft are spin
stabilised.
Unlike the newer GOES which are three axis stabilised.

I am awaiting more information and confirmations from EUMETSAT on the
drift.

Regards,
John Tellick.






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Alan Sewards <alan.sewards@...>
 

Anything that causes a change in the velocity vector of the spacecraft will
have the effect of changing the orbit - that is how it is moved. You have to
cause the opposite change at the end of the manoevre to stop it continuing
to move (Newton!).

A nice method of changing attitude and doing gentle stationkeeping is
through the use of momentum wheels. The only problem with these is that the
bearings tend to pack up after some years in space, and they need the
momentum to be dumped from time to time through the use of the thrusters. I
suspect Hubble has momentum wheels as this gives gentle movement and no
thruster pollution possibilities.

Regards - Alan

----- Original Message -----
From: "Dave Martin" <Dave.Martin@manx.net>
To: <MSG-1@yahoogroups.com>
Sent: Tuesday, December 09, 2003 4:31 PM
Subject: [MSG-1] Re: MSG-1 manoeuvre.



If it's a spin-stabilized bird, and not 3-axis stabilised, I wonder if the
simplest way to change orbital slot E - W might be to leave it spinning
totally undisturbed and just change the orbital period by slightly
raising/lowering the satellite's orbit ?

Dave M

----- Original Message -----
From: Luca Bertagnolio
To: MSG-1@yahoogroups.com
Sent: Tuesday, December 09, 2003 9:13 AM
Subject: [MSG-1] Re: MSG-1 manoeuvre.


Alan,

you're right, but my understanding of MSG-1 tells me that it is not a
three axis stabilized craft, but rather a spin stabilized spacecraft.

If I am correct, I am wondering what kind of wobble effect, or other
gyroscopic effect, will be observed during the thrusters firing
activity.

It seems strange to me though that they would risk any contamination
of the imager with the exhaust particles coming from the
thrusters... HST (a much more sophisticated imager, I admit) has a
big lens "cap" door which is/was closed during the Shuttle
maintenance missions.

In any case, keep those Tq software running during the maneuvre, it
could be fun!

Bye, Luca


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