The ISO spacecraft being readied for launch, in Kourou, French Guiana
In June and July the spacecraft was subjected to the last System Functional Check in Toulouse (F), after some of its units had been brought back to full flight standard (transponder and solid-state recorder).
In parallel, the planned set of reviews of the mission elements took place: the Launcher and Ground-Segment Status Review on 29/30 June at Kennedy Space Center (KSC), followed on 11 July by the Flight Operations Review at Goddard Space Flight Center (GSFC). All of these reviews confirmed the general good health of the relevant components of the mission and identified further actions and areas for attention.
The Mission Flight-Readiness Review held at ESTEC (NL) in July drew together all of the results of the other reviews and highlighted a few problem areas on the spacecraft. Further investigations on all spacecraft flight-model reaction wheels had revealed that their assembly process needed to be improved in order to guarantee the lifetime needed for Soho. In addition, a thruster firing check had shown an anomalous 'vapour lock' behaviour under certain extreme conditions. The Pre-shipment Review on 27 July endorsed all plans to resolve these two problem areas.
The spacecraft and its equipment were airfreighted direct to Kennedy Space Center in Florida from Toulouse on 1 August. A few hours after the spacecraft's arrival and its storage in the assigned SAEF-2 facility, hurricane Erin struck the area, forcing an evacuation of the whole range.
After such an eventful start, the planned activities at KSC have run very smoothly, with the preparation of the last System Functional Test and its execution, and the last Ground Segment Compatibility Test with the Flight Operations Team commanding the spacecraft directly via an RF link from GSFC.
Meanwhile, the refurbishment of the reaction wheels has progressed at maximum speed and some minor modifications to the Attitude and Orbit Control (AOCS) subsystem have been identified and tested. These modifications will allow to the thrusters to be used outside the critical regimes.
The Atlas IIAS that will launch Soho (AC-121) arrived at KSC on 15 September and was erected on Pad 36B on 29 September.
A third simulation of experiment operations has also taken place at GSFC, resulting in further refinement of the interactions with the ground segment and the scientific data gathering process.
The ISO spacecraft being readied for launch, in Kourou, French Guiana
The ISO satellite and all associated equipment was transported in June by sea to the launch site at Kourou in French Guiana. The satellite subsystems and scientific instruments have since all been thoroughly tested and found to be in perfect order. ISO is now waiting its turn to be mated with the Ariane-44P launcher. The launch campaign will restart in early October, with a view to a launch early in November.
Preparations for the flight operations by ESOC and the flight control centre at Villafranca, near Madrid, Spain, are also in their final stages. Most efforts in the last two months before launch are geared to training, and performing simulations to prove flight-readiness.
The scientific community is eagerly awaiting the first results from ISO's first look into space.
The Structural Thermal Pyro Model (STPM) of the Huygens Probe was delivered to Jet Propulsion Laboratory (JPL) in July and has subsequently been integrated with the Cassini Orbiter's mechanical model, known as the Development Test Model (DTM). The STPM will remain with the DTM until late 1995, during which time a number of tests will be performed. A modal survey has already been conducted and has not shown any surprising results.
The Probe Engineering Model (EM) test programme was successfully completed on 15 August. The EM is now being stored at DASA, which is responsible for all Probe Assembly, Integration and Verification (AIV) activities. It will subsequently be delivered to JPL in April 1996.
Probe Flight Model AIV activities began on 7 August, when DASA received the flight internal structure and harness subsystems. The flight power-control subsystem has also been delivered and is now being integrated mechanically and electrically into the Probe. Delivery and integration of the flight subsystems will continue for another two months.
The system-level Critical Design Review is well underway. The review data package has been delivered to all participants and Review Panels have held preliminary meetings. The formal Critical Design Review Board will be held at ESTEC on 12 October.
Within the framework of the industrial Phase-B, the Prime Contractor, Alenia (I), has been progressing with the design concept for the spacecraft.
A configuration that accommodates the four instruments on the Payload Module and allows maximum re-use of the XMM Service Module design has been base-lined. Core features of the instrument design have also been settled, but a number of options will need further trade-offs. Special measures to support the payload development have been initiated by the Project, including the use of instrument data-processing electronic units of common design, parts procurement, and testing in coordinated facilities.
The Draft Arrangement between ESA and RKA concerning the provision of a Proton launcher in return for scientific observation time is under review by the Russian authorities.
Work has continued on mission and system definition in conjunction with the two industrial groups providing technical assistance to the Agency. The back-up launch options originally included in the mission options have been eliminated and the mission is now baselined for Comet Wirtanen, with a Mars and two Earth gravity assist manoeuvres. The choice of asteroid targets to be visited during the cruise phase is also being revised as the mission scenario is further optimised.
Responses to the Announcement of Opportunity for the scientific payload were received in August from a wide-ranging science community. The current system-design effort is geared towards accommodation of the payload. The selection process for the Orbiter's payload will be completed by the end of the year, in time for a recommendation to be made to the ESA Science Programme Committee in February 1996.
In parallel with the Orbiter payload selection process, the two Surface Science Package (SSP) groups are also going through the same process for the scientific payload for the Landers. This selection process will be completed during the autumn and the two proposals, complete with a recommended payload, are due on 1 December. The two SSPs will then be checked for interface compatibility and included as a part of the overall Rosetta payload selection recommendation.
A meeting was recently held between the two SSP groups, the Project and ESOC to discuss the near-comet navigation and Lander-release philosophies, both of which can have an influence the Orbiter's system design. In principle, it has been agreed to use common Lander-release mechanisms and Lander Orbiter communications systems, which greatly simplifies the system-design tasks.
The Scatterometer investigation campaign has been extended in order to achieve a better characterisation of the problem detected at switch-on. As a consequence, the commissioning of this instrument is still pending.
The performances of ERS-2's instruments are very good and comparable to those of ERS-1; all parameters are within specification and their evolution well within the established thresholds.
The calibration and validation activities for the SAR, RA and MWR instruments were successfully completed in September, confirming these instruments as able to ensure their nominal mission. The quality of the products obtained is the same as for ERS-1, facilitating both the current tandem operations and a smooth transition between satellites at a later date.
The commissioning of the new/enhanced GOME, ATSR-2 and PRARE instruments was completed in October, with product results of a very high level. These instruments are now operating normally and the scientific data is starting to be processed on the ground and is expected to be available to users from the beginning of 1996.
During the ERS-2 Commissioning Phase, ERS-1 has served as the nominal operational satellite, showing still very good performances, and it will continue to support the nominal mission scenario until the Scatterometer problem on ERS-2 can be fully resolved.
The tandem operations have already started with the systematic acquisition of the data streams from all available stations.
The ERS-2 Ground Segment has also been commissioned and is operational from October onwards.
The proposed further extension of EOPP from 1996 to 2001 has been discussed with the Delegations and subsequently revised.
The qualification model of the Polar Platform solar array during a recent deployment test at Fokker (NL)
Integration of the Payload Equipment Bay engineering model has started, and integration of the proto-flight Service Module will commence soon. The structure of the proto-flight payload carrier has been completed and is undergoing qualification static testing at CASA in Spain. Final negotiations with the Prime Contractor Matra Marconi Space (B) have been satisfactorily completed, and ESA signed the main development phase (Phase-C/D) contract on 24 July.
A major effort is now being focussed on the consolidation of the programme schedule, while on the technical side work is progressing towards the engineering-model unit test programme.
Critical design reviews at unit level are planned in the last quarter of 1995. The predicted overall payload mass is still a cause for concern and is being closely monitored.
Pending confirmation of the recommendations made at the Venice meeting of the Eumetsat Council Task Force regarding the composition of the Metop payload, a bridging phase was initiated in April to allow work to start on critical areas of Metop's design. This bridging-phase work has been performed by Prime Contractor Matra Marconi Space (F) with support from the Co-contractors DASA (D), Matra Marconi Space (B) and Alenia (I).
Following confirmation of the payload, the main Phase-B activities were initiated in July 1995, with a planned duration of one year.
The Metop spacecraft design has evolved somewhat compared with the Phase-A design through the addition of some further payload elements and by a proposed innovative dual-launch concept, the feasibility of which is currently being studied. In this scenario, Metop would share an Ariane-5 launch with a partner, such as Spot-5, which also requires a Sun-synchronous orbit, but with different local hour requirements. Among other issues being studied is Ariane's ability to accomplish the associated local-hour shift.
Currently, the design has progressed to the point where a configuration that is compatible with a range of launch opportunities has been developed. Other topics investigated have included a detailed assessment of structural materials, command and control architecture and compatibility with new telemetry and telecommand standards. The Preliminary Design Review for Metop is foreseen for December, at which point the requirements on equipment will be known to the extent necessary for the selection of subcontractors for the remainder of Phase-B to be commenced.
Meetings of the Potential Participants in the main development phase (Phase-C/D) have taken place throughout this study phase and will continue. ESA and Eumetsat have prepared a joint Programme Proposal for the development of Metop-1 and -2, and the elements of Metop-3 which can be defined today, as well as the requisite ground infrastructure and the overall EPS programme.
A joint meeting of the Eumetsat Council and the Earth Observation Programme Board is foreseen in October to discuss the Metop Programme.
The operational service is presently being provided by Meteosat-5, with Meteosat-4 and, recently, Meteosat-6 on standby.
Software has been developed and tested by ESOC to compensate for the anomalous behaviour of the Water Vapour and Infrared channels of Meteosat-6, and the commis-sioning of the spacecraft was declared complete at the end of July. The spacecraft has since been handed over to Eumetsat.
The launch date for the remaining spacecraft being built for Eumetsat by ESA under the Meteosat Transitional Programme has been rescheduled to June 1997. All sub-systems except the radiometer and the apogee boost motor have already been delivered to the Prime Contractor, Aerospatiale (F).
A proposal for the procurement of further spacecraft models, MSG-2 and MSG-3, was submitted to Eumetsat in September.
The MSG System Baseline Design Review is planned for October.
At the Space Station Control Board (SSCB) held in Houston in early June, an updated Assembly Sequence was baselined. Apart from a shift in the launch date for the COF, only detailed refinements not affecting ESA were introduced into the sequence. The launch dates for the Russian Service Module (DMS-R), the Russian Science Power Platform (ERA) and the first flight of the MPLM (ECLS) remained unchanged.
An ESA/NASA Joint Programme Review, co-chaired by the NASA and ESA ISSA Programme Managers took place at ESTEC at the end of June.
In the context of the Laboratory Support Equipment early-delivery items, following authorisation of the Phase-B activities for the 80 deg freezer several meetings were held at NASA with the main objective of finalising the interfaces with the MPLM and agreeing upon the official Interface Control Documentation.
Activities concerning the Microgravity Glovebox have focused mainly on the preparation of the mock-up and documentation needed for the Preliminary Crew Review, and preparation of the Safety Data Package.
Proposals for the design (Phase-B) of the Hexapod were received from two industrial consortia. A contract was successfully concluded and the full go-ahead for Phase-B activities was given by ESA in July.
A plan for the running of ESA ground-based facilities in Russia (at ZPK and in ZUP) after the completion of the Euromir-95 mission has been established. This will ensure the reinforcement of the relationships with Star City.
Cosmonauts at work during the Euromir 95 mission (photo: Thomas Reiter, ESA astronaut)
One Training Engineer from the European Astronaut Centre will be temporarily assigned to the NASA Training Division at Johnson Space Center in Houston, for a period of two years. In the meantime, he will provide training support to ESA astronaut Pedro Duque, who is Alternate Payload Specialist for the LMS-1 Mission in 1996.
The proposal for the continuation of the European Microgravity Research Programme (EMIR-1) has been approved by the Microgravity Programme Board. The Declaration for this continuation, to be known as the EMIR-2 Programme, was opened for subscription on 1 August and will be closed on 31 December 1995.
The proposal for Microgravity Multi-User Facilities on the Space Station, known as the MFC Programme, has been finalised and will be submitted to Delegations as part of the preparatory documentation for the ESA Council Meeting at Ministerial Level, to be held in Toulouse in mid-October.
The Euromir 95 mission began on 3 September with the launch of the ESA astronaut Thomas Reiter on board a Soyuz capsule. The mission, which will last for 4.5 months, includes physiological and materials-science experiments, as well as some radiation measurement studies. A total of twenty-five microgravity experiments will be flown, weighing a total of 350 kg at launch. With the exception of some minor deviations, the mission is proceeding very well and valuable experiment data have already been acquired.
The next Spacelab flight carrying a ESA microgravity payload will be the USML-2 mission, scheduled for launch at the end of September. It will carry the Advanced Glove Box, to used for both fluid-physics and materials-science experiments, and two units of the Advanced Protein Crystallisation Facility (APCF), with which 15 protein-crystallisation experiments will be conducted.
A flight of the largest available sounding rocket yielding 14 min of free-fall conditions is planned in November. This 'Maxus' rocket, which will reach an altitude of approximately 800 km, will carry five fluid- physics and three biological experiments.
Preparations for microgravity experiments to be flown in 1996 are also proceeding well. The flights foreseen are: two flights of Biorack on the Shuttle-to-Mir mission (March and December); the flight of a diffusion experiment on the Space Shuttle (January); participation in the LMS Spacelab mission (June) and in the Russian retrievable unmanned-carrier Foton 11 mission (autumn). In addition, ESA microgravity experiments will be flown on the Swedish 'Maser' and German 'Texus' sounding rockets.
ESA Bulletin Nr. 84.