The Metop Satellite Metop Peter G

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The MetOp Satellite MetOp Peter G. Edwards, Bruno Berruti, Paul Blythe, Joerg Callies, Stefane Carlier, Cees Fransen, Rainer Krutsch, Alain-Robert Lefebvre, Marc Loiselet & Nico Stricker Directorate of Earth Observation Programmes, ESTEC, Noordwijk, The Netherlands

etOp-A is Europe's first polar-orbiting satellite dedicated to operational M meteorology. With its array of advanced instruments, it will provide data of unprecedented accuracy and resolution on temperature and humidity, wind speed and direction over the ocean, and ozone and other trace gases, making a huge contribution to global weather forecasting and climate monitoring. In addition, MetOp-A will observe land and ocean surfaces and its search-and- rescue service will help ships and aircraft in distress. Introduction MetOp-A is Europe’s first satellite dedicated to operational meteorology from polar orbit. It will balance the long-standing service provided by the Weather US since the first Tiros satellite in 1960. The US has provided the data from this evolving series free of charge to the Information world’s meteorological community. As early as 1967, Europe looked at contributing to this effort, but selected from Polar the geostationary satellite mission as the higher priority. This led to the development of the Meteosat series, which has Orbit been remarkably successful since 1977.

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AVHRR GRAS Antenna AMSU-A1

IASI

AMSU-A2

HIRS

GOME-2

MHS

ASCAT Antenna Farm Comparison of the schedule planned in 1998 (lighter colours) with the achieved schedule (solid colours). CDR: Critical Design Review. FAR: Flight Acceptance Review. PDR: Preliminary Design Review. QR: The MetOp Payload 23–90 GHz microwave sounder models. The AVHRR imager 25 x 25 km grid resolution. In Qualification Review to produce atmospheric supports this sounding mission addition, high-resolution wind The three satellites carry identical temperature profiles. It consists of for cloud detection. In addition to information can be generated payloads except that HIRS and two separate sounders (AMSU-A1 these operational sounding and over a 12.5 x 12.5 km grid. In 1992 plans were formulated to – a low-rate digital direct broadcast France, Germany, The Netherlands, S&R are not aboard MetOp-3. and AMSU-A2) to cover the imaging instruments, MetOp ASCAT can measure sea-ice type extend Europe’s contribution by using VHF service to replace the analogue Norway, Spain, Sweden, Switzerland, frequency range. Microwave carries the new-generation IASI and boundaries. Land surface AVHRR Advanced Very High measurements have the significant Infrared Atmospheric Sounding applications are an emerging using satellites in polar orbit. ESA’s Automatic Picture Transmission United Kingdom) and covering the Resolution Radiometer: a advantage of being much less Interferometer, a nadir-viewing area and will provide global soil MetOp-1 programme was approved in system, employing data-compression design and development of the first 6-channel visible/infrared affected by the presence of clouds Michelson interferometer moisture data for numerical 1998, followed shortly after by approval to ensure high-quality images; satellite as the space segment for EPS. imager with a pixel size of 1 km than infrared soundings. The operating at 3.6–15.5 micron. weather prediction. of the Eumetsat Polar System (EPS). – continuous onboard recording of the The EPS Programme is funding the square at nadir. Its data are AMSU-A pixel diameter is 48 km. used, inter alia, to identify The instrument is also flying on GOME-2 Global Ozone The GRAS Global navigation Eumetsat – the European Organisation global dataset to be dumped every building of two recurrent satellites, the clouds, generate cloud NOAA’s satellites. Monitoring Experiment: an satellite system Receiver for for the Exploitation of Meteorological orbit at a high-latitude ground station, launch of all three satellites, and the parameters, measure sea-surface improved version of the GOME Atmospheric Sounding uses Satellite – is charged with operating the with the ground system providing the design and construction of a ground temperature and derive MHS Microwave Humidity instrument on ERS-2. It monitors signals from the GPS system once the satellites are developed global processed data within 2.25 hr of segment to operate the satellites and vegetation conditions. AVHRR Sounder: a 5-channel, nadir- the ozone concentration and the constellation of satellites slicing has been the primary low-orbit viewing 90–190 GHz microwave components involved in ozone through the atmosphere to and launched by ESA. The joint system the measurements being made; process, archive and distribute the data imager for meteorology for more sounder provides atmospheric chemistry in the atmosphere. It produce atmospheric is the basis for an improved being – high pointing accuracy and orbital collected. EPS is designed for a total than 20 years, and also flies on humidity profiles. It is a measures the backscattered temperature and humidity offered to the world’s meteorological stability to ensure that data can be operational lifetime of 14 years. The NOAA’s satellites. technological advance on the ultraviolet-visible sunlight in four profiles, complementing the data organisations. It also satisfies specific geo-located without reference to EPS Programme is also making a previous-generation AMSU-B on bands between 240 nm and from the nadir-viewing scanning HIRS High-resolution Infra-Red the NOAA-K/L/M satellite 790 nm, at a spectral resolution sounding instruments. needs of the European and US ground-control points in imagery; financial and material contribution to Radiation Sounder: a 19-channel series. Nadir pixel size is about of 0.25–0.5 nm. It also monitors meteorological services. – selective encryption to meet the the ESA MetOp-1 Programme, infrared sounder measures 15 km. It is also carried by the the concentrations of trace gases Other payloads include: the SEM The notable improvements required commercial and data-denial needs of providing 36% of the € 746 million cost atmospheric temperature and NOAA-N and N’ satellites. such as bromine oxide, nitrogen Space Environment Monitor, from MetOp include: Eumetsat and the US Government, (current conditions). humidity profiles, with one visible dioxide and sulphur dioxide. which measures the charged channel for cloud identification. HIRS, AMSU-A and MHS particle environment; the A-DCS respectively. Accordingly, the ESA/Eumetsat Single Pixel diameter is about 10 km at together constitute the ATOVS ASCAT Advanced SCATterometer: Advanced Data Collection – new instruments (ASCAT, IASI, Space Segment Team was established to nadir. HIRS is also flying on Advanced TIROS Operational a C-band (5.3 GHz) dual-swath System, which collects data from GOME-2, GRAS) in addition to the Programme manage MetOp development via a joint NOAA’s satellites. Vertical Sounder suite, which (2 x 550 km) radar providing various meteorological and other existing suite on the NOAA satellites The ESA MetOp-1 Programme is an contract with the industrial Prime provide the operational sounding ocean wind speed and direction. platforms; and a S&R Search & AMSU-A Advanced Microwave data from low orbit for today’s It is an augmented version of the Rescue package for locating of the US National Oceanic & optional programme of the Agency, Contractor (EADS-Astrium, Toulouse, Sounding Unit: a 15-channel numerical weather prediction radar on ERS-1/2, with a distress beacons. Atmospheric Administration (AVHRR, subscribed to by 12 member states F). While this arrangement inevitably HIRS, AMSU-A1/A2, SEM); (Austria, Belgium, Denmark, Finland, led to increased bureaucracy, and could

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AVHRR GRAS Antenna AMSU-A1

IASI

AMSU-A2

HIRS

GOME-2

MHS

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have resulted in significant organisa- problems in the ground segment, pushed ment data processing and dissemination, contains all the science data, and the MetOp Main Features tional frustration and friction, most the first launch to mid-2006. Then three data archiving and retrieval facilities in limited subset of Low-Rate Picture Orbit: Sun-synchronous, near-circular, potentially contentious issues in practice attempts 17–19 July were scrubbed and Eumetsat’s central site in Darmstadt Transmission. Additionally, following 817 km altitude at ascending node; were addressed positively thanks to the the Soyuz launcher was returned to its repeat cycle 29 days (412 orbits); local (D), and a control and data acquisition storage in the solid state recorder, the constructive attitudes of the teams in factory for refurbishment. solar time 09:30 (descending node) station in Svalbard (N). Svalbard’s global data-set is transmitted to ESA and Eumetsat. Despite this, the financial impact Mission life: 5 years northerly position (78ºN) inside the ground through an X-band link. caused by this major delay have been Launcher: Soyuz ST-Fregat (also compatible Arctic Circle gives it the unique Challenges contained within reasonable bounds with Ariane-5) advantage of being within range of The Service Module MetOp carries 13 instruments provided thanks to a complex restructuring. This Size: 6.2m (high) by 3.4 x 3.4 m cross- MetOp on all 14 orbits each day. The SVM provides all the standard cooperatively by Eumetsat, ESA, allowed primary qualification of the section in launch configuration; service functions, including: NOAA and CNES. They vary from the design, including vibration, thermal 17.6 x 6.5 x 5.2 m with solar array and Satellite largely recurrent units (AVHRR, HIRS, vacuum and electromagnetic compati- antennas. deployed The satellite and its payload embody a – attitude and orbit control, to maintain Launch mass: 4093 kg, including 316 kg AMSU-A1/A2) developed within the bility tests, to be achieved in mid-2004 great deal of heritage from Spot, ERS accurate Earth-pointing for the various hydrazine in 4 tanks US Polar Orbiting Environmental using a payload module comprising a and Envisat, leading to significant cost operational modes, and to perform Attitude control: 3-axis stabilised by Satellite (POES) Programme to wholly mixture of Engineering Model and reaction wheels; orbit manoeuvres by savings in development and paving the orbit acquisition and maintenance; new instruments developed specifically flight-standard instruments. The hydrazine thrusters; pointing knowledge way to efficient exploitation of the data. – propulsion, for orbit and dedicated for MetOp (IASI, ASCAT, GRAS). The MetOp-1 satellite was then placed in 0.07º X-axis, 0.11º Y-axis, 0.15º Z-axis Further, most of the instruments are manoeuvres, and propellant storage; accommodation of such a diverse long-term storage and will be completed Data-handling: science data acquired as either fully recurrent units or have – power generation, through the solar payload, each with its very specific with its full flight payload for launch as CCSDS packets (the standard set by the operational precursors. The sole array, storage, conditioning and requirements and constraints, proved to MetOp-B around 2009–2010. Consultative Committee for Space Data exception is GRAS, and even this is the overall distribution; be a major challenge. Coordinating and Meanwhile, the MetOp-2 integration Systems); science data formatting and operational follow-on to an in-orbit – distribution of commands from the synchronising the delivery of the and test schedule matched the avail- multiplexing, encryption for selected experiment. ground and onboard, and collection instruments for three satellites and an ability of the first flight instruments. instruments; instrument and housekeeping The satellite is modular, consisting of of housekeeping telemetry data for data storage in solid-state recorder Engineering Model required significant MetOp-2’s assembly, integration and two largely independent modules, the transmission to ground through the (24 Gbit end-of-life) effort and flexibility. From the start, the verification was completed in mid-2005 Payload Module (PLM) and the Service S-band link; Communications: omnidirectional S-band development schedule for two major and the satellite was placed in short- coverage (uplink 2 kbit/s, downlink Module (SVM), and a deployable Solar – central software for telemetry genera- European instruments (IASI and term storage, awaiting call-up for the 4 kbit/s); instrument global data stream Array. tion, telecommand processing and GOME-2) lagged significantly behind first launch in 2006 as MetOp-A. That downlinked via X-band (70 Mbit/s); The PLM houses the instruments and various application functions, such MetOp’s timeline. MetOp development, gap was a consequence of delays accrued realtime broadcasting of instrument data their support systems. Instrument as thermal control, onboard which kicked off in early 1998, baselined in the complex Eumetsat ground system. with HRPT at 3.5 Mbit/s via L-band for sensors and antennas are mounted on surveillance and automatic command launch-readiness of the first satellite in Finally, the core modules of MetOp-3 all instruments, and LRPT 72 kbit/s the external panels, while most of the sequencing. MetOp and its Soyuz launch vehicle mid-2003. Late availability of instru- (Service Module, Payload Module and electronics are housed internally. ments, coupled with later development Solar Array) have also been completed The SVM is derived from the Envisat Changes and Problems and put into long-term storage, but and Spot-5 service modules. It consists power bus not available from the Large and complex satellites usually The Svalbard station in the far north of Norway provides contact with MetOp on every orbit without the full set of instruments. The of a box-like structure interfacing with SVM); encounter changes to the requirements missing instruments will be delivered the launch vehicle and the PLM. – power distribution: each unit or and technical and programmatic diffi- over the next 2-3 years and added before Subsystems provide standard support instrument is powered through a culties along the way. MetOp was no the call-up for launch, as MetOp-C, such as attitude and orbit control, switchable and protected line, provided exception in its 8 years of development. around 2014–2015. The satellite’s own electrical power (solar array) and data by specific PLM units; integration has also been deferred until management, including telemetry – command and control: a dedicated Launcher this time. generation and telecommand processing. data bus, based on the European On- The programme began on the basis of a MetOp-1 and MetOp-3 are stored as Board Data Handling Standard is dual launch on Ariane-5, but the lack of separate modules in enclosures purged The Payload Module used. The PLM computer receives available co-passengers compatible with with nitrogen. The Payload Modules Accommodating a large set of instru- commands from the SVM and MetOp’s very specific orbit meant that and critical elements of the Service ments was a major design driver for the interfaces with the European instru- an alternative had to be sought. Modules are reactivated annually to overall satellite and the PLM ments’ control units, the MHS Eventually, following a competitive assure longevity of important equipment. configuration, with many constraints adaptation unit and the NOAA process run by Eumetsat, the Starsem originating from the instruments’ fields interface unit for the US instruments; Soyuz-ST was selected. This required no System Overview of view, antenna patterns and thermal – handling of scientific data via modifications to the MetOp design, as EPS is devoted to operational meteor- radiators. The PLM also houses all of acquisition, formatting, encryption the Soyuz interfaces were fully ology and climate monitoring. It the avionics to ensure: and transmission to ground of consistent with the Ariane standard, and consists of the MetOp satellites, the core packetised data through the regional the launch environment (particularly ground segment of satellite command, – power regulation for the US instru- broadcast links: High-Rate Picture mechanical) was generally equivalent to, control and health monitoring, instruments (they need a 28 V regulated Transmission (HRPT), which or more benign than, Ariane-5.

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MetOp’s mission requirements call for As a result, all the valves on all use of the new-generation Soyuz-ST MetOp models were leak-tested at low with a Fregat upper stage. Soyuz temperature on a special rig. On modifications include a new fairing MetOp-A, valves leaking above 4ºC (the (similar to an Ariane-4 fairing), lowest qualification temperature, and mechanical adaptation and strengthen- the freezing point of hydrazine) were ing of Fregat, and a new digital avionics replaced with leak-tight valves. system for a more flexible launch A test representing the MetOp storage trajectory and sufficient stability time and the mission duration was margins to cope with the aerodynamics performed on two leaking valves to Brazing the cell connectors in MetOp-type batteries sometimes of the new fairing. Specifically for monitor any change over time. Gold-plating the GRAS antennas solved the corrosion problem MetOp, the thrust is offset from the created cracks (arrowed) Although it showed that the tempera- longitudinal axis for both stage-3 and ture at which leaks started increased Fregat to cater for the large offset of magnetic enclosure to reduce the with time, it confirmed there would not interfacing was a meticulous task that MetOp’s centre of mass. emissions from the interface harness be a problem under realistic conditions: took more time than expected. It All of these launcher modifications between the PLM and SVM. The with the hydrazine pressurised at 22 bar, included extensive testing with various were subjected to a rigorous qualification modifications were verified on MetOp-2, both valves remained leak-tight even at datasets from the real instrument. The campaign from late 2004 to May 2006. with additional ‘sniff’ checks made at abnormally low temperatures of around results of this complex test programme Baikonur to confirm the shielding on +5ºC. The operating conditions in flight have been used for correcting and fine- Electromagnetic and RF interference the final flight configuration. are always warmer than 11ºC in safe tuning the level-1b data-processing Avoiding electromagnetic and radio- mode and 25ºC during normal algorithms for the instrument. frequency (RF) interference between the Batteries operations. instruments and avionics was one of the Leaks in cells of MetOp-type nickel- It was also demonstrated that MetOp GRAS ASIC greatest design and verification cadmium batteries have been seen a few is rather insensitive to leaks. Early The GRAS receiver is built around an challenges. Two main concerns were times on Envisat, Spot/Helios and ATV. detection, isolating a leaking branch and Application-Specific Integrated Circuit evident from early on in the programme. They finally appeared on MetOp, but even disabling the entire thruster system (ASIC) known as ‘AGGA-2’ which The first was the necessary common affected only the ‘integration batteries’ are at the disposal of the operator performs most of the digital processing electrical grounding all elements despite used on the ground. The cause was (procedures are detailed in the flight of the GPS signals. This was developed their different design heritages. The found to be cracks in the ceramic operations manual) without major for another space application, but was second was the coexistence of powerful material isolating the cell connectors, impact on the mission. finally qualified within the MetOp radio transmitters on one side and from thermal/mechanical stress during programme. A significant number of extremely sensitive receivers in a large brazing to the battery cover. GRAS ground processing prototype problems were discovered during the frequency band (100 MHz up to Investigations to isolate the problems The GRAS ground processing prototype process, which led to the ASIC’s 200 GHz) on the other. and to develop and qualify improve- (GPP) was developed to validate the redesign as the AGGA-2A. The redesign The radio-compatibility campaign ments were exhaustive – taking more performance of the GRAS instrument and requalification took considerable was particularly demanding because of than 3 years. They were ultimately and its level-1b algorithms. It was a time, and risked MetOp’s schedule. the second point, with the high number successful, with no further leaks demanding task becasue the error Extra efforts in industry, coupled with of transmitters/receivers and the multi- occurring in the flight batteries delivered sources are numerous, depending on the workarounds for the satellite integration, Checking the radio emissions of MetOp in the anechoic chamber in Intespace. The satellite’s complex payload and many antennas made purpose antennas. This required early for MetOp. instrument and external sources such as avoided this. it difficult to avoid interference testing with a full-size satellite mock-up the GPS navigation satellite constella- to determine how they were coupling Thruster control valves tion, the atmosphere and ionosphere. A GRAS antenna metallisation However, some additional system after lift-off, versus 20 minutes for and, in some cases, to assist in finalising During the MetOp-A SVM thermal detailed error budget was compiled by The three GRAS antennas (one for analyses were necessary. The compati- Ariane) was necessary. the antenna design. tests, a leak of pressurising gas from a the instrument supplier, and had to be navigation and two for occultation bility of the propulsion system and In reality, however, the major effort MHS and GOME were modified after propellant flow-control valve was found confirmed using the GPP. measurements) initially had carbon- MetOp’s structural fatigue life with the resulting from this shift was in the it was discovered that their emissions at low temperature. A similar event To demonstrate this budget, a complete fibre structures finished with a layer of horizontal encapsulation, launcher additional preparation and planning were being picked up by the Combined occurred later on the MetOp-C SVM. It simulator environment was developed to aluminium. It transpired that the integration and ground transportation required for the launch campaign in Receive Antenna owing to the extreme was puzzling, because these valves have simulate the signals generated by the full combination can lead to corrosion – and imposed by Soyuz had to be assessed. Baikonur, ensuring the compatibility of sensitivity of the Search & Rescue a long and successful history in space, GPS satellite constellation. All the MetOp’s antennas shed flakes of Analysis of the random vibration levels the cosmodrome facilities with MetOp’s receiver. Later tests on MetOp-1 showed having been used on Eureca, XMM- errors can be added one by one, or all corroded aluminium. Instead, gold- generated by Soyuz (not required for final integration, test and encapsulation, the need for additional local GOME Newton and Integral without problems. together and with variable magnitude. plated antennas were qualified and Ariane) was carried out, and an analysis and preparing the logistics. MetOp-A shielding and improvement in the The cause was found to be a In view of the accuracy needed for remanufactured. (primarily thermal) of the extended and its support equipment for the electrical harness shielding of the SVM combination of thermal contraction GRAS, which is much greater than for a period required for MetOp injection launch campaign filled three Sun and Earth sensors. The testing also and creepage of the valve’s elastomeric standard GPS receiver, the verification GOME-2 improvements into the baseline orbit (some 70 minutes Antonov-124 heavy-lift cargo planes! confirmed the need for an electro- seal. of all the simulator modules and their Once in orbit, GOME-2 must be

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and the discharge threat was not a FAR to Launch: A Long Journey problem once the components were MetOp-A completed its Flight Accept- assembled in the units. Dedicated life ance Review (FAR) at EADS-Astrium tests on all the switching front-end units in Toulouse in July 2005. The go-ahead confirmed their flightworthiness. to prepare for launch in early summer The second issue was that radiation 2006 was then given. At the same time, tests showed the parts were highly remaining open items had to be taken susceptible to proton and heavy ions, care of, including retrofitting some causing a high rate of bit-flips. If this instruments, swapping some avionic happened in flight, ASCAT would be units and completing the investigations unavailable while it was reset. The of anomalies. ASCAT’s switching front-end ASIC The solar array is attached to MetOp during final reassembly at The flight-ready MetOp awaits encapsulation in its Soyuz fairing problem was solved by reprogramming Soyuz has seen more than 1700 Baikonur porosity and resultant moisture the switching logic, so that the antenna launches so far, with a reliability GOME’s diffraction gratings had to be recoated to prevent absorption of the coating, which switches were systematically reset at the exceeding 95%. It is the workhorse of absorption of moisture affected, at the sub-micron level, the start of each switching cycle. the Russian space programme and a key ported and installed at Baikonur, cleanroom. Reflecting the team’s hard geometry of the gratings. A slightly element for operating the International occupying some 500 m2 of the Payload work in preparation over the previous precisely calibrated by ‘observing’ a set modified coating process was developed ASCAT antenna deployment motors Space Station. Starsem has used it for 16 Processing Facility and the Upper months, MetOp, the Soyuz adapter, the of three light sources: a hollow cathode to produce stable coatings. Excessive wear of the motor brushes successful commercial launches. Composite Processing Facility (UCPF) Fregat upper stage and the intermediate lamp for spectral calibration, a tungsten The deficient gratings were stripped was found during life testing of the Starsem is a European-Russian partner- in the MIK 112 building, to perform the bay were stacked flawlessly in sequence. lamp for the broadband, and the Sun via and recoated, and GOME’s calibration ASCAT antenna deployment motor. ship created in 1996 by the key players final checks on the satellite and its On 8 July the team had the last chance a diffuser. On GOME-1 this diffuser was was successfully repeated. In parallel, The motors were tested in air, vacuum involved in the production and instruments. to wish good luck to MetOp before it an electrically-grounded aluminium the long-term stability of grating and under simulated orbital conditions. operation of Soyuz (EADS Space, Permission to ship was finally granted was slowly slid into the large fairing surface. Even though this type of samples is being carefully monitored. Following an unsuccessful search for a Arianespace, Roskosmos, TsSKB- in March 2006, at the end of the satellite during the horizontal encapsulation. diffuser adds only very small spectral better brush material, it was decided Progress). preparation activities in Europe and Following a 6-hour train transfer, the features to the incoming light (less than ASCAT switching front-end ASIC instead to replace the brushes close to Baikonur is the world’s largest space after the Launch and Operations fairing composite reached MIK40, a fraction of 1%), it still distorts This ASIC for the ASCAT scatter- flight. centre, spread over thousands of square Readiness Review confirmed the ground where the upper composite was mated GOME’s results. Instead, a ‘quasi- ometer includes both analogue and kilometres among the barren steppes of segment was ready. On 10 April the first with its Soyuz. volume diffuser’, which contributes only digital circuits that turned out to involve Conclusion Kazakhstan. Built in the mid-1950s as a of the Antonovs was on its way to A final short train ride brought the a tenth of the aluminium’s effects, was non-standard (and now obsolete) MetOp is one of the most complex strategic test site, it dispatched hundreds Baikonur, followed by the main flight vehicle to Pad 31 on 14 July where, after identified. Following lengthy qualifica- technology. Their production proved to satellites ever developed in Europe. It of launchers and missiles each year at its elements on 17 April and the final cargo the last countdown rehearsal, the launch tion, the original aluminium diffusers be very time-consuming, and then, in provides both continuity and major peak from around 65 pads. with the Solar Array on 20 April. was targeted for 22:28:10 local time were replaced by the new models in all addition to the delays caused by late advances in observational data for Organising the MetOp launch The launch campaign team, (16:28:10 UT) on 17 July. But faulty of the GOME-2 models. delivery of the components, two major meteorologists and Earth scientists. campaign was a complex task. Three representing the main participants in software checking the inertial platform’s issues were found during development. Despite significant delays in the fully loaded Antonov-124 cargo flights developing the satellite (ESA, Eumetsat, alignment stopped the countdown 1 h GOME gratings First, the technology was found to be deliveries of key instruments, and many were needed to transport all the flight Astrium, DutchSpace) and instruments 36 min before launch. On 18 July, the During calibration of GOME-2, the highly susceptible to electrostatic challenges along the way, the first and ground hardware from Toulouse to (NASA, CNES, ITT, Northrop- automated checkout routines proved optical efficiencies of channels 1 and 2 discharges, which destroyed many parts MetOp was launched from Baikonur in Baikonur. Its size meant that MetOp’s Grumman, Galileo Avionica), worked in unable to deal with the partially-fuelled were found to be lower than expected. It during assembly. Improvements in the July in time to meet Europe’s Service Module, Payload Module and Baikonur for 3.5 months. Averaging 55 launcher configuration, which had was soon established that the efficiencies ASIC’s design (causing further delays) commitment to the Initial Joint Polar Solar Array had to be transported people, this is the largest team involved resulted from investigations into the of their diffraction gratings had and in the soldering process did not System of meteorological satellites with separately, and then reassembled and so far in a Starsem launch campaign. previous abort. This led to an abort degraded. After deep analysis by the completely remove the risk. However, NOAA. This is thanks in no small part tested. A large quantity of electrical After arrival in Baikonur, 9 weeks 3 h 10 min before launch. On 19 July, it supplier, the cause was identified as the sufficient numbers could be produced, to the close cooperation between ESA, ground support equipment was trans- were required for the satellite’s final was within 185 sec when the ground Eumetsat, CNES, NOAA and NASA, assembly and checkout, achieved by system again stopped the clock, this time Over-worn brush on ASCAT’s antenna deployment motor (left, arrowed). Normal wear on a bedded-in brush (right) founded on the excellence of the ESA MetOp-A arrives at Baikonur mid-June. During this time, unplanned due to an operator error. Unfortunately, industry teams led by EADS-Astrium last-minute replacements of two US this meant that the Soyuz exceeded the for MetOp and Galileo-Avionica for instruments (AMSU-A1 and -A2) were maximum time it can be kept on the GOME-2. e made. They were urgently shipped from ground after fuelling, so it had to be the US following the discovery of returned to the factory for refurbish- problems affecting the MetOp-A ment. Meanwhile, the upper composite instruments. was demated and arrived back in in Detailed information on MetOp and its mission can be The satellite was fuelled in the second MIK 112 on 22 July, where the fairing found at www.esa.int/metop and in the new brochure half of June and finally, at the beginning was removed. Everything is being kept “MetOp: Monitoring the Weather from Polar Orbit” of July, MetOp-A was declared ready to ready awaiting the decision on a new (BR-261, available from ESA Publications) meet its Soyuz upper stage in the UCPF launch date. e

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