MON fuelling started

On Saturday 16/06/2012, the preparation for the MSG-3 fuelling started in EPCU S5B hall as planned. The first propellant to be injected is the MON (the oxidizer). The corresponding drum has been moved from the storage room to the S5B clean hall as seen above on the right hand side under the crane.
The completion of the preparatory activities were related to the final connection of pipes and tubes from the drum to the spacecraft (blue caps) via the kart (Fuelling Ground Support Equipment).

On Monday 18/06/2012 the MON fuelling started. This hazardous activity is performed by a specialised group of people (called "ergoliers" in French) who perform in SCAPE suits (Self Contained Atmospheric Protective Ensemble). Their activity is monitored from a remote room through video, radio and data links. The few pictures below are taken from the monitor screens the only place where the fuelling can be witnessed. This explains their poor quality.

There are two teams of two staffs operating in four hour shifts. A total of 601,5 kgs of MON will be injected in two tanks. This will be achieved by six injections of MON today and two others tomorrow 19/06/2012. During these active phases, to prevent any mistakes, each fueller check the work of his colleague, under the supervision of the remote control room.

Stabilisation phases are necessary between injections to make sure that propellant quantity is equally split between the two tanks. During these stabilisation phases, fuellers are requested to remain in the S5B Main Hall. In this phase, they may take a rest to recover from the extremely exhausting (physically and mentally) injection phase. Here below one of the fueller is in resting position for his head, the weight of the heavy helmet being particularly tiring.

The weight of the remaining propellant in the drum is measured by mean of a load cell (with a back up) and can be permanently read. The exact quantity of propellant injected into the spacecraft is calculated in real time by deducting what is read to the known total weight of the propellant in the drum.

Note: the MMH read on the TV monitor does not mean that MMH propellant is fuelled but it is the identification of the two cameras (Monitoring Main Hall :-)

MSG for dummies :-)

Note: This message is published as a living list of naive questions. It is of course not exhaustive of the MSG design.

A special thanks to Jean-Claude, Rolf and Francois for their support.

I - MSG PLATFORM DESIGN

What does "platform" means?

A spacecraft is normally made of two main elements; The platform which comprises all the support subsystems and the payload (SEVIRI and GERB for MSG) that will provide the mission data.
The MSG platform design comprises the following subsystems:

• Data Handling Subsystem (DHSS) + Software (SW)
• Electrical power Subsystem (EPS): 8 Solar Arrays, 2 Batteries, Power conditioning and distribution Units (PCU and PDU), and Pyrothechnic Release Unit (PRU)
• Attitude and Orbit Control Subsystem (AOCS). This comprises Control Electronic units (AOCE), Sun and Earth Sensor Units (SSU and ESU) and the passive nutation Dampers. The AOCS directly commands the UPS.
• Unified propulsion System (UPS). The UPS is a Bi-propellant system including the Liquid Apogee Motors (LAMs), the Reaction Control thrusters (RCTs), the pressurant and propellant tanks, all necessary valves, filters, pressure regulators and transducers and the Ultrasonic Gauge sensors (UGS)
• The Telemetry, Tracking and Command Subsystem (TT & C). This is supported by the Mission Communication Package (MCP) with all antennas and electronic units.
• The Thermal Control Subsystem (TCS), mainly insulation blanket (MLI) and optical sun reflectors (OSR). 
• The Structure Subsystem, mechanisms and Pyrotechnic devices

Where can I find a good description of the MSG-3 spacecraft platform functions?

About satellite architecture.

About Communications.

About propulsion: to be filled later

About  MSG facts and figures

Why MSG has a cylindrical shape?

Because the spacecraft is designed to rotate around its vertical axis during its mission at an angular speed of 100 rounds per minutes. The spinning increases the moment of inertia and therefore the gyroscopic stabilisation. It simplifies the the design of the attitude control sub-system compared to a 3 axis stabilised spacecrafts.

Why MSG is spinning and what are the general benefits of spinning satellites?

MSG rotation is 100 round per minute around its vertical inertial axis. It belongs then to the spin-stabilised satellite family. The main benefit is the attitude stabilisation by mean of the gyroscopic effect which makes the design of the attitude control much more simpler than a 3 axis stabilised spacecraft. The attitude stability is an essential parameter to get a sharp image by a “camera” at 36.000kms distance from Earth. At the time MSG programme was started in the seventies, the 3 axis technology was not able to meet the mission requirements. This new technology will appear on the third generation of Meteosat spacecraft (MTG) by end of the decade.

Why the SEVIRI solar array is slightly longer than the other ones?

 

There are eight solar panels mounted on MSG: one SEVIRI and seven "normal" panels. It is true that the SEVIRI Solar array (see above) is slightly bigger in size but the solar array surface covered by solar cells is the same for each panel. This oversize is made to compensate, with additional solar cells, the large SEVIRI aperture. As MSG is spinning the electrical current to be generated by the solar array in space should be the same for each solar array to prevent variations during the rotation.

What is the use of Earth and Sun Sensor Units  (ESU and SSU)  mounted on MSG?

 The Earth and Sun sensor units allow:

1. to determine the spacecraft attitude when  S/C, sun and earth  are not to close from  alignment (i.e. angle  between S/C earth direction and S/C sun direction  is above ca  15 deg and below ca  165 deg) 
2.   to measure the spacecraft spin rate (function done by the sun sensor unit only) 
3.   to elaborate a reference pulse used  a)  for synchronising the image taking by SEVIRI and GERB with the S/C rotation (ie to determine when the instrument is exactly facing the Earth), b) for synchronising the radial thrusters in order to deliver a radial force in a given direction (as the S/C is permanently spun) 
4. to synchronise the electronically despun antenna  (which counteract the S/C spin in order to ensure permanent pointing of this antenna towards the earth.

What is a despun antenna?

An Electronically Despun Antenna (EDA) is mounted on the top of the cylindrical MSG-3 spacecraft. The EDA purpose is to have the antenna continuously pointing at Earth whilst the spacecraft is rotating.

How MSG communicates with Earth?

This function is performed by the Mission Communication Package.
to be filled later

What are the propellants used on board MSG-3?

MSG propulsion is achieved by a classical bi-propellant system, i.e. the combustion of two components: a liquid fuel with a liquid oxidizer.

MSG system uses Monomethylhydrazine (MMH) as liquid fuel and Mixed Oxides of Nitrogen (MON) as liquid oxidizer.

Saftey again: the "sock" test

In few weeks, once fuelled, MSG-3 will be moved to the BAF (Batiment Assemblage Final/Final Assembly Building) where it will be mated on the Ariane 5 rocket. The few MSG-3 team members that will be authorised to operate in this building do have to follow a safety training. One of the practical tests is to train people to quickly escape from the top of this facility in case of danger.
As it can be seen on the picture below, the BAF, which accommodates the rocket is in fact a tower. The staff operating on the payload are working on the PFEI (PlateForme Elevatrice Inférieure) at the 9th level which is located in the upper part of this building. You may then take an external staircase, or even better:
are you ready for the big jump?

In case of alarm, the staff shall have to move quickly into a shelter located on the ground floor or even to leave the BAF. In both cases, if staff are operating on the PFEI, they imperatively need to use a (very) long "sock" to evacuate.
Posted signs indicate the way to follow... up to this closed door.

Then, you just open it to discover the sock in which you will have to jump in.
By walking on the grid, you get a shower, not to wake you up, but to decontaminate or put out your clothes in case of need.

Before jumping, have a look upstairs to make sure that nobody is already on its way. First, he/she may fall on your neck and second it is not sure that jams in socks have ever been tested...

Once on your way down, the speed can easily be regulated just by spreading elbows and/or knees. The trip from top to bottow will anyway last few seconds. So no time to be scared by local bugs that will be slightly surprised but for sure disturbed as the sock is fortunately extremely rarely used.

The training for the "sock" test  is performed in a dedicated tower in order not to disturbed operations in the BAF. In such a case members of fire brigade helps the trainees landing on the ground floor or those who may get stuck to get out...

In any case, Christian was ready to wake up fainting or shocked colleagues.

Finally everything went very well, all MSG-3 team members successfully passed the test and qualified for BAF operations.

A special thank you to Vincente (who took the picture), our training manager today, and the two firemen (members of the Paris Fire Brigade).

Observing the Spectacled Caiman

The Spectacled Caiman (Caïman à lunettes), can be observed at night. This is a traditional night excursion made at the Kaw swamp.
We embarked on a pirogue from the "floating camp" at 20:30 sharp in the complete dark. Our guide, Gilbert, had only a light halogen torch mounted on his head. He was standing at the rear side for piloting the pirogue. As the boat was moving, he was regularly sweeping the river bed from left to right and right to left with the beam of his lamp. The trick is that, in the complete dark, the eyes of the caiman strongly reflects the light when on the surface of the water. With such a technique we were able to approach a young caiman after 15 minutes. Great!
We continued our way for further observations. Then, after another evidence of the presence of a caiman, Gilbert re directed swiftly the pirogue in right direction without engine power to reach the targeted place. The boat slided silently in the complete dark toward the flooded bank while he was getting to the front. All passenger lights were switched off according to his instructions, but suddenly we just eared a noise as if  someone fell in the water...

Preparing for fuelling

...Cryogenic age has not spread over the Kourou river, or a new glaciation era has not suddenly hit French Guyana as it may be suggested by the picture below...

This is just the quiet Kocher river in Sindringen last January. A romantic place in the Baden-Württemberg near Lampoldshausen where the propellant drums for MSG were produced by ASTRIUM and were accepted by ESA and Thales before shipment by road and boat to Degrad de Cannes, the Cayenne harbour.
Two drums are needed to fuel MSG: one for MON, one for MMH plus two back up drums (i.e. four drums in total).
Here under is a representation of one of these highly securised containers.

The scale enables to reach the top of the drum for the leak detection measurements on the flanges, valves and manometers... these measurements are repeated at various steps of the transport to make sure that the drums are tight.

The fuelling (MON and MMH) will be done in EPCU S5B facility which has been already described in a previous message.
But...another operation will take place before the fuelling: The pressurisation of the Helium tank to 260 Bars (this operation will still be done in EPCU 5C). This inert gas will play the essential role in orbit to pressurise the MON and MMH tanks to about 13 bars in order that the different satellites manoeuvres required for the mission can be achieved. 85% of the propellant will be consumed within the first 2 weeks of the mission for the proper firing of the two Liquid Apogee Motors (LAM). With four Apogee Motor Firings (AMF), MSG-3 will move from the (elliptical) transfer orbit to its Geostationary position. The remaining 15% of propellant gas will be used for the usual orbit and attitude control manoeuvres performed by the thrusters during the 7 year nominal life time... and very likely more.
The Helium tank filling will be made using the Fill and Drain Valve (FDV), the last blue cap on the left, located just under the battery as showed on the picture below. The four other FDVs are used for testing only. Note that the Multi Layer Insulation (MLI) is not completely installed for permitting this filling operation.

As the filling is an hazardous operation (static and dynamic risks linked to pressurisation), two large  protective"walls" called blasting shields have been installed in the S5C clean room.

When the Helium pressurisation will be completed by mid of next week, the walls will be removed and MSG-3 will be transported to S5B for the fuelling.
By the way, all walls have eventually to be removed one day... or painted to tell their story!

Berlin, Postdamer Platz, June 6th 2010.

Note: The technical part of this message was proof read by Rolf our propellant expert 

Introducing EPCU S5B

If the schedule is met, MSG-3 is planned to move by end of May from EPCU S5C (where it is now tested) to S5B where it will be fuelled. The fuelling is for a satellite equivalent to go to a pump station for car. The difference being in the type of fuel to be delivered and the associated hazards linked to fuelling operations.
Hereunder is an external view on the EPCU S5B (fuelling) building at the CSG.

MSG propulsion, like many other spacecrafts and rockets, is achieved by a classical bi-propellant system, i.e. the combustion of two components: a liquid fuel with a liquid oxidizer.

For MSG-3 the fuel is the  Monomethylhydrazine (MMH) and Mixed Oxides of Nitrogen (MON) the oxidizer.
These two substances should NEVER EVER be in direct contact except in the combustion chamber of the rocket or satellite engines.Therefore, as showed by the picture below, the handling of these two substances follows physically separated routes: one on the right for the MON and another one on the left for the MMH.

At the moment, MSG "drums"containing these two propellants are still in a remote fuel farm (also called ZSE for Zone Stockage d'Ergol).
The S5B facility which has now been accepted for MSG-3 fuelling is now under preparation for performing this operation.

Inside S5B clean hall, Thales staff is validating a special device called DMRP  i.e. Dispositif Mobile de Remplissage et de Presurisation (Fill and Drain Cart). Note there is one cart for the MON and one other for the MMH.

The view below gives an idea of the area where the tank filling will be made. After a transfer from the airlock through the door into the clean hall with a crane, MSG-3 will be put in the middle on the fuelling stand. On the opposite side of the clean hall the MON and MMH rooms will accomodate drums. After being weighted, the MON drum will enter the clean hall the first. When the MON filling is completed, MMH filling will take place. In between decontamination operations is carried out in order to remove any residues of these (extremely) toxic substances inside the facility as well as in the filling material.

The fuelling stand on which MSG-3 will be installed for the fuelling

The propellant team will operate with SCAPE suits (a kind of diving suit) in 4 hour session shifts. The limitation is made by the battery of the radios. Before to don-off  their filling gear, operators have to take a shower. Facilities are foreseen just next to the filling hall.

Before and after the fuelling, the spacecraft is powered on, there fore a cooling device in necessary for the battery. The MICE used in S5C (see previous message), becomes an ICE (for Indoor Cooling Equipment) as it is built-in the facility and no longer a mobile device.

Once the fuelling is made, the SC will move to another area: the BAF (Batiment d'Assemblage Final or Final Assembly Building). At this moment the launch campaign turns into a new phase. The mating on the rocket is getting closer... but we shall let that open for further reporting :-)

Visit of the ELS

The Soyuz launch complex called ELS (for Ensemble de Lancement Soyuz) is one of the three active commercial launch pads at CSG together with the Vega launch pad and the ELA-3 (Ensemble de Lancement Ariane #3).  ELS was visited by the MSG teams on Monday 30/04/12.
The Soyuz rocket (family) is deeply related to the early age of the Soviet space adventure which started in the sixties. This is to date the most used launch vehicle in the world. Soyuz rockets are launched from Baikonur (Kazakhstan/Russia), Plesetsk (Russia) and, since 21 October 2011, from CSG ELS in Kourou French Guiana. The payload was then a pair of Galileo satellites. The main difference with a Soyuz rocket operated in Russia is that, at the CSG ELS, the payload is integrated vertically on the rocket whilst in Russia, the rocket and payload are assembled horizontally and then erected once on the launch pad. This difference may give a chance for MSG-4 to be launched on a Soyuz rocket in 2015. On the top of that, energy wise, the CSG quasi equatorial location benefits a lot for Soyuz GEO (geostationary) launches compared to the other Russian cosmodromes.

General view on the Soyuz launch pad.

Close up view on the arms supporting the Soyuz rocket.














View from top to bottom.

Bottom up view.

View on breeching (carneau).

Visit to Vega launch pad

The Vega rocket is the smallest launcher used by Arianespace. It is jointly developed by the Italian Space Agency and ESA and used for payloads ranging from 300 up 2500 kg. The VEGA maiden qualification flight took place on 13th February 2012.
MSG teams were invited to visit the launch pad which is now in preparation for the next flight planned for 2013.

Overall view on Vega launch pad complex: Assembly building (left), water tower (middle), four lightning rods and the thin white mast to which the rocket is connected via umbilical harnesses.






A view onto the assembly building (moving forth and back). It is rolled back few hours before the launch to prevent damages.

 A view inside the assembly building.












Note that during take off, stones were ripped off the concrete structure of the launch table by the flames of the P80 engine.  Few stones were projected meters away and have damaged the front door of the assembly building. One is still there to show the strength of these projections.

 A nice view on the empty launch pad.

The visitor gallery

As we already mentioned in this blog, the visitor gallery is a special place from where the activities performed on the spacecraft can be observed without entering the clean room. The gallery is accessible via a long corridor. On their way,  visitors attention will be attracted  by something very special. Walls are not decorated with mirrors, like in the Gallerie de Glaces (hall of mirrors),  but with posters of all the missions that where prepared and carried out at EPCU (Ensemble de Préparation Charge Utile)  facility.

The first poster in the raw, commemorates the ESA  ENVISAT mission launched from CSG on March 1st 2002.
When one walks slightly further, two posters remembering MSG-1 and MSG-2 launch campaigns (respectively launched on  28/08/02 and  21/12/05) can be observed:

 

Then, the entrance of the visitor gallery is on the right hand side just after the fire extinguisher.

If you have entered the visitor gallery room today, you would have seen  Jean-Claude (second from the left) giving a lecture on MSG-3 to the CSG new comers.The window enables to visualize the spacecraft and on-going activities in parallel to the explanations.

For the readers of this blog only :-), despite the red logo above, that is what the young audience could see from this window today:

... the continuation of the  Solar Array panels inspection while, in parallel, some electrical tests on the platform and on the payload were taking place.

The Meteosat heritage and future

METEOSAT is a European satellite programme that started in the seventies within the ESRO organisation (as shown by the handbook below dated October 1974).

A artist view of the Meteosat Operational Programme (MOP)

Credits EUMETSAT

 The first launch of  Meteosat-1  took place on 23rd of November 1977 and was followed by a series of seven spacecrafts. The mission was supported by an imager called MVIRI (for Meteosat Visible and Infra Red Imager). Note that Meteosat-7 launched on September 3rd 1997 is still working  to date!

The Meteosat programme was continued with Meteosat Second Generation (MSG) series. This new generation was bringing  significant improvements both on the platform and the Payload:

• SEVIRI Imager payload with 12 channels  enhanced imaging (3 chanels for MOP)
• Bi-propellant unified propulsion system (Powder booster for MOP)
• 600W power demand (200W for MOP)
• 1900kgs in Geo transfer orbit (720kgs for MOP)
• design compatibility with Ariane 5 (and Soyuz in Kourou to be confirmed)

An artist view of MSG (note the black aperture which is the opening for the SEVIRI imager)

Credits ESA

Four identical MSG spacecrafts were manufactured. Two are presently in orbit and the MSG-3 (Meteosat-10) will be launch  mid June 2012.

The fourth MSG spacecraft (Meteosat-11)  is foreseen to be launched in 2015 (to be confirmed) permitting the continuity of MSG service up to the the moment  the first spacecraft of the Meteosat Third Generation (MTG) programme will take over by the end of the decade. MTG is a programme of 6 Spacecrafts: 4 Imagers and 2 Sounders. One of the most significant technological breakthrough will be introduced by the 3 axes stabilised platform. This will enable to have a continuous view on Earth not interrupted by the spinning as it is the case at the moment with Meteosat and MSG spacecraft families. MTG should guarantee access to space-acquired meteorological data until at least the late 2030s.

An artist view of MTG-I and MTG-S

Credits ESA-P Carril