The Huygens flight Probe, with back cover removed
In-orbit operations of ESA's Infrared Space Observatory (ISO) satellite continue to run extremely smoothly. Very efficient schedules containing an average of 45 highly-graded observations per day are routinely carried out. Many scientific papers have been published with ISO results and more are in preparation. As examples of ISO results on objects in our own solar system, ISO's infrared camera (ISOCAM) has been used to take images of the comets Hale-Bopp and Wirtanen, the latter being the target of ESA's Rosetta mission.
ISO's pointing system has been fine-tuned after a series of investigations, including some in-orbit tests with the satellite. The absolute pointing accuracy has been increased to around 2 arcseconds (cf. specification of 12 arcsecs) and a further improvement to the 1 arcsec level is expected. Operations with the Long Wavelength Spectrometer (LWS) were suspended on 28 November as a precautionary measure following a number of anomalies in the operation of its interchange wheel - which carries the two Fabry-Perots and an aperture for the grating mode. Detailed investigations were made on the existing telemetry from the in-orbit instrument, as well as tests on the flight spare model. The in-orbit malfunctions were attributed to changes in the distribution of the low-temperature lubricant in the ball races of the wheel assembly, leading to a loss of torque margin in the drive mechanism. The way in which the wheel is operated was changed so as to restore this margin and LWS observations were successfully resumed on 31 January. This change has no effect on the scientific operation or performance of the instrument.
The peer review of the second round of proposals for ISO observing time was completed in November. Recommendations were made for a total of about 1900 hours of time, spread over 330 proposals. About 6% of the time is for solar system studies, 32% for stellar and circumstellar observations, 21% for the interstellar medium, 28% for extragalactic systems and 13% for cosmology. In the period from December to March, successful proposers provided full details of their observations and some have already been carried out by ISO.
Detailed planning is underway for a station-keeping manoeuvre to be executed on 14 May. At the same time, a second direct measurement of the remaining liquid helium will be made in order to provide a more precise estimate of when ISO's helium will be exhausted. The current prediction of December 1997 is about 6 months longer than specified. This extended lifetime means that, in September, ISO will suffer eclipses with durations of up to 2 hrs 40 mins, about twice the design value. Special operational restrictions will be imposed during this period.
The Huygens flight Probe, with back cover removed
Integrated System Testing and Software Verification Testing - the on-line interface testing with the ESOC ground network - were the last major system-level tests to be carried out on the flight-model Probe in Europe. All such tests were successful and so just a few minor unit and subsystem tests and adjustments remained to be performed before the Probe is finally readied for shipment to Kennedy Space Center for launch preparations.
The Probe Flight Acceptance Review (FAR) activities have been intense, starting with an industry presentation of the Probe testing status to ESA, including the co-chairmen of the FAR Board, and delivery of the FAR data package, in January. The findings to date all point to a satisfactory conclusion to the Review, with flight Probe acceptance scheduled for 26 March. The Probe is due to be shipped to the launch site on 1 April 1997.
Critical Design Reviews at equipment level were successfully completed during the last quarter and the team is currently delivering the equipment items to the prime contractor Dornier (D) for the integration of the electrical, structural and thermal models of the spacecraft. In parallel, assembly of the structural and thermal models has started with the integration of the reaction-control elements onto the service-module structure at BPD (I).
Significant progress has also been made on the X-ray optics. The flight mirror modules numbers one and two were delivered as planned in January and February 1997 by Media Lario (I). Optical and environmental testing of the first mirror module, conducted at CSL (B), has been completed and has confirmed the very good performance expectations. This model will now be X-ray tested in the PANTER facility (D), while the second module will in turn start its test campaign at CSL. All three structural/thermal models of the mirror modules have been completely tested and handed over to Dornier for spacecraft integration.
Optical testing of the X-ray instruments at the Max-Planck Institute conducted during the last quarter of 1996 using the mirror qualification model and engineering models of the detectors and gratings has been completed. The structural, thermal and engineering models of the instruments are being delivered to Dornier for spacecraft integration, and preparations are well underway for the calibration campaign for the X-ray instruments together with the flight mirror modules at the PANTER facility.
The user- and software-requirement documentation for the major elements of the ground segment have been finalised and the next milestone will be the completion of the architectural design.
XMM's orbit is currently being redefined to make the best possible use of the Ariane-5 launch vehicle's revised capabilities.
Following the kick-off of the spacecraft's main development phase (Phase-C/D), the industrial team has proceeded with the detailed design activities. In parallel, negotiations have been held with the majority of the subcontractors to reach fixed-price agreements. Special emphasis has been placed on those payload items required early in the development cycle, ground-support equipment simulating the spacecraft, and the spacecraft data-processing electronic units.
The Instrument Baseline Design Review has been held. Instrument-specific issues were raised, but generally speaking payload definition has progressed satisfactorily and should allow the freezing of the interfaces to the spacecraft during the spacecraft review in May.
Further progress was made with the Russian Space Agency (RKA) regarding the provision of a Proton launcher in exchange for scientific data. A detailed analysis is currently being carried out to determine the precise implications for the spacecraft of a Proton launch and the appropriate sharing of tasks associated with the launcher and the spacecraft. The results of this study will facilitate the proper definition of the interface documentation and, subsequently, the signature of the Memorandum of Understanding.
Further progress was also made with NASA on the provision of ground stations. Although the planned changes to the antenna network may have implications for Integral, a generic ground-station performance specification has been jointly established which will serve as a baseline for finding a suitable scenario.
Satellite
The Artemis structural model has successfully completed
its mechanical environmental test programme at qualification
levels. In early February, with the support of NASDA hardware
and personnel, an interface test with the Japanese HIIA
launcher adapter was performed at ESTEC (NL). The structural
model is presently being transported to Madrid, where micro-
vibration testing in the CASA facilities will complete the
qualification of the spacecraft secondary structure and where
hardware inspection after the environmental testing will take
place.
The formal engineering-model test campaign is now starting with the Integrated System Test. This will be followed by the EMC/ESD test.
The thermal preparation of the flight-model structural panels has been completed and they are now available for unit integration at the Alenia AIT facility in Rome (I).
Flight-model spacecraft primary structure assembly is continuing with the integration of the propulsion equipment, harness, associated thermal-control hardware and test instrumentation. Once the fully assembled propulsion subsystem has been tested, the Artemis flight model will be delivered to Alenia Spazio (I).
Silex LEO terminal
The Silex Low Earth Orbit terminal has successfully
completed its environmental test programme and has been
delivered to SPOT for integration and satellite-level testing.
Future programmes
During the last quarter, the final contract commitments
were made for the EOPP first extension programme. Although
work initiated within that programme will continue until well
into 1998, no further activities can be started until agreed
by the Participating States or until subscriptions to the new
slice have reached 80%. In particular, this financial problem
is delaying the initiation of the Earth Explorer and Earth
Watch programmes.
Campaigns
All data acquisition from the 1996 campaigns has been
successfully completed. Analysis of the data from the last
three campaigns is still in progress. In particular, the data
from the INDREX campaign have now been released by the
Indonesian authorities and have been made available to the
investigators.
Envisat's service module in the Large Space Simulator at ESTEC
The Polar Platform/Envisat-1 mission is the most challenging ESA has ever undertaken in the Earth-observation domain. It will not only provide continuity with space- acquired ocean, land and ice data from ERS-1 and ERS-2, but will also gather information on atmospheric constituents and Earth-surface features that will be invaluable for future environmental research and applications.
The instrument payload is a combination of six ESA- developed instruments (EDIs) and three Announcement of Opportunity Instruments (AOIs).
Envisat-1 is planned to be launched by an Ariane-5 in mid- 1999 into a Sun-synchronous, near-polar orbit in which it will circle our planet some 14 times per day. The mission is expected to provide continuous global data for at least five years.
Envisat-1 system
Envisat-1 in the ESTEC test facilities (HYDRA)
The Envisat Mission System (EMS) Critical Design Review (CDR) took place in February, involving programme participants via their experts in DOSTAG, the providers of Announcement of Opportunity Instruments (AOIs), and the Processing and Archiving Centres (PACs), as well as the key representatives of the Instrument Science Advisory Groups (SAGs). The Executive is confident that the mission objectives can be met, subject to confirmation by the EMS-CDR.
The activities of the Data Policy Working Group are progressing. The preliminary results have permitted the preparation of the Announcement of Opportunity for scientific data exploitation and pilot projects to be initiated. Preparation of the High-Level Operations Plan (HLOP) is also being initiated.
Polar Platform
The structural-model satellite activities have continued
with axial vibration testing using the HYDRA facility at ESTEC
(NL). The vibration tests are currently being completed with
lateral-axes testing on the Multi-Shaker at ESTEC.
The engineering-model Payload Module system-level integration has progressed well at Matra Marconi Space (UK). Five engineering models/simulators of the instruments have been successfully integrated on the engineering-model Polar Platform, namely: the AATSR engineering model, the GOMOS breadboard, the MIPAS reduced engineering model, the RA-2 engineering model, and the SCIAMACHY simplified engineering model. The small number of problems encountered has confirmed the good engineering of the Polar Platform/ instrument interfaces. Activities are currently being adjusted to accommodate a delay in the deliveries of MERIS and ASAR engineering models.
The flight-model Payload Equipment Bay (PEB) is under integration at DASA/DSS. The Service Module successfully under- went thermal-balance/thermal-vacuum testing in the Large Space Simulator (LSS) at ESTEC (NL) in December. The final Service Module acceptance tests will now be carried out at Matra Marconi Space (F) prior to the Module's delivery to Matra Marconi Space (UK) in April 1997.
The Polar Platform Critical Design Review is being conducted simultaneously in the framework of the Envisat Mission System CDR.
Envisat-1 payload
Development of the Envisat payload instruments has passed
a further milestone with the delivery of the RA-2 engineering
model in December. Together with the MTSR, MIPAS, SCIAMACHY
and GOMOS engineering models delivered earlier, five
instruments have now been successfully integrated onto the
engineering-model Polar Platform. All of them were integrated
without major problems, with the use of standardised elements
in the instrument design (the Remote Bus Interface) and
unified Electrical Ground Support Equipment (EGSE) proving to
be a valid and cost-effective engineering approach.
The results of the test campaign on the Polar Platform structural model, which is now almost complete, have generally confirmed the validity of the instrument mechanical design. In particular, adequate design margins have been demonstrated for the MERIS instrument and the ASAR antenna, which have been causes of concern in the past. For the GOMOS instrument, local reinforcement of the structure may still be required.
Work is also well in hand on the instrument flight models, for which all subsystems and equipment items are in manufacture and testing. Several flight-model units have already been delivered and integration of the flight-model instruments has started.
Integration of the first MERIS flight-model camera is nearly complete, and the MIPAS interferometer mechanisms have been fully tested and delivered to the instrument prime contractor. Integration of the AATSR, MWR and RA-2 instruments is also well advanced.
Envisat-1 ground segment
The Flight Operations Segment (FOS) Critical Design Review
was concluded successfully at the end of December. With the
recent delivery of the RA-2/MWR, MERIS and AATSR ESL
documentation, all Payload Data Segment (PDS) operational
processor developments have been kicked-off, except that for
SCIAMACHY which is planned to start later in 1997.
The PDS Detailed Design Review for version V-1 is going on in parallel with the Envisat Mission System Critical Design Review.
The Statement of Work for the PAC contracts is under final review. The kick-off of the PAC development activities is foreseen for April/May 1997 for those PACs that already have approved national financing for the development phase.
The SEVIRI (Scanning Enhanced Visible and Infrared Imager) telescope and scan assembly has been re-designed, the telescope has undergone a preliminary design review, and its engineering-model and mechanical/thermal-model equipment manufacture has been released to industry. The Preliminary Design Review (PDR) for the scan assembly is currently in progress. The SEVIRI scheduling remains on a critical path.
The development of MSG-1 and the procurement of MSG-2/3 are on schedule, with engineering and thermal/mechanical model production in progress at equipment and subsystem level. The launch of MSG-1 remains on schedule for October 2000, with MSG-2 to be launched in 2002 and MSG-3 to go into storage in 2003.
The approval within ESA and Eumetsat of the combined EPS/Metop programme was significantly advanced by the opening for voting of the EPS Resolution by the Eumetsat Council in December. The opening for subscription of the ESA Metop-1 Declaration by the Agency's Director-General, also in December, and the approval at the March meeting of the Eumetsat Council of a bridging phase for the space segment also reflected the strong support that exists in Europe for this programme.
The Agency's Industrial Policy Committee (IPC), meeting in January, approved the release of the Metop Phase-C/D Request for Quotation (RFQ) to industry. Preparation of this documentation is well advanced and ESA and Eumetsat, in the framework of their future joint responsibility for the Metop programme, intend to release it to industry at the end of March.
The next major step in the programme's approval will be the outcome of the ESA Member States' subscriptions and their agreement on how to proceed as far as advanced Phase-C/D industrial activities are concerned. An early start to these activities is essential to preserve the validity of the programme's cost and schedule envelopes. Industrial activities are 'on-hold' in the interim, awaiting the results of these deliberations.
The Meteosat Transition Programme (MTP) spacecraft has been fully integrated and all of the major environmental tests have been completed. The ground-system validation tests have also been successfully performed. In order to achieve a July launch, a replanning exercise is in preparation which may bring forward the start of the launch campaign by at least a month.
The MTP spacecraft will be the last of the Meteosat Operational Programme (MOP) design to be launched. Once launched, it will be operated by Eumetsat to provide the regular weather pictures over Europe which are currently being provided by Meteosat-5, with Meteosat-6 as the in-orbit spare. Both of these spacecraft were provided under ESA spacecraft supply contracts.
The overwhelming attendance (over 700 participants) at the Third ERS Scientific Symposium, held in Florence on 17-21 March, reflected the fact that ERS-1 and ERS-2 data are now being actively utilised by a multitude of scientists and engineers working in a very broad range of disciplines. An increased emphasis on applications in the field of geophysical research since the last symposium was apparent. In particular, the newly emerging areas of disaster monitoring and hazard analysis attracted much attention and show interesting potential. Other highlights were the results reported from the 'tandem mission' of ERS-1 and ERS-2 providing SAR- interferometry, and the first very encouraging results from the new GOME instrument on ERS-2.
ERS-2 has continued to provide high-quality data combined with good data availability. ERS-1 is presently in hibernation mode and the periodic checkouts show that its performance levels remain high and it is therefore readily available for backup purposes.
There was a 36 hour interruption in ERS-2's service during the reporting period, due to a gyro failure that provoked a de-pointing of the satellite. The payload was automatically switched-off for safety reasons. After a careful analysis and subsequent recovery actions, however, service was resumed with the same high standard as before this anomaly. The exact cause of the failure is still being analysed with a view to reinforcing the onboard attitude-control algorithms to avoid such problems in the future.
The budget for the extension of ERS Phase-El will be presented to the Agency's Administrative and Finance Committee (AFC) in April, by which time subscriptions are expected to have reached an appropriate level.
Columbus Orbital Facility (COF)
Consolidation of the industrial consortium to reflect the
final levels of contributions to the Programme has almost been
completed with, in particular, the transfer of some equipment
responsibilities from US to Member State countries being
achieved. The project technical baseline (top-level
specifications and plans) has been approved by the Agency, and
the planning baseline is nearing finalisation. Agreement has
been reached with NASA on the launch of the COF by the NSTS
Orbiter, and a barter arrangement has also been agreed to
offset this launch by a package of deliverable items from
European industry to NASA, including two outfitted Nodes, a
range of freezers and sustaining engineering support for some
of the Early Deliverable Items (notably the Glovebox, MELFI
Freezer and the Software Verification Facility). Discussions
between NASA and the Russian Space Agency on the initial
flights in the ISS Assembly Sequence will potentially have
some effect on the overall launch schedule of the ISS in
general, possibly including that of the COF.
Automated Transfer Vehicle (ATV)
After the Procurement Proposal for Phase-C/D was approved
by the Agency's Industrial Policy Committee (IPC) in
September, a price estimate for that phase was submitted by
the prime contractor, Aerospatiale, to ESA in November but
proved to be far above the announced ESA target. Subsequently,
a task force on Phase-C/D costs was set up between ESA and
Aerospatiale and it identified substantial price-reduction
possibilities. The Request for Quotation (RFQ) for Phase-C/D
was then formally released to Aerospatiale on 19 March.
The first flight demonstration in the ATV Rendezvous Predevelopment Programme (ARP) took place in November 1996 (on STS-80) with the onboard GPS experiment in combination with the Orpheus SPAS programme from Germany. The GPS equipment worked satisfactorily and the flight-test results are currently being processed by Matra Marconi Space. Preparations for Flight Demonstration No.2 (GPS and Rendezvous Sensors onboard STS-84) are now in progress.
Crew Rescue Vehicle/Crew Transfer Vehicle
(CRV/CTV)
Signature of the Phase-B CTV study contract, to evaluate a
capsule-type vehicle, took place in mid-September 1996 with a
European Economic Interest Grouping (EEIG) made up of
Aerospatiale, MAN Technologie and Alenia Spazio. A 90-day
joint ESA/NASA study on possible cooperation on a lifting-body
CRV/CTV derived from the NASAX-38 demonstration programme was
completed. This was followed in early December by a
reorientation of the Phase-B study after the Manned Space
Programme Board had approved a first set of activities with
respect to ESA/NASA cooperation until April/May 1997.
Activities related to a capsule CTV were still performed in
parallel as planned, and an Intermediate Requirements Review
will take place in the first half of April. As far as the
lifting-body studies are concerned, definition of a common
core (e.g. shape) between a NASA-led CRV and a European-led
CTV is in progress and concepts for cooperative scenarios are
under discussion between the Agencies.
Atmospheric Re-entry Demonstrator
The ARD qualification tests have been completed.
Validation of the launch sequence is about to start.
Preparation of the acceptance test procedures and facilities
has been initiated, as well as that for the storage needed
until Ariane flight 503.
Data Management System for the Russian Service
Module (DMS-R)
The first Software Integration Facility has been delivered
to Moscow and is being used intensively by the Russians to
generate Service Module application software. A full EGSE Test
Facility and the first engineering models of the DMS-R onboard
computers are being prepared for delivery in March 1997. The
potential Service Module launch delay will not have an impact
on the ESA delivery milestones, but will require increased
engineering support from Europe to cover the prolongation.
European Robotic Arm (ERA)
The change in launch vehicle (from the baselined use of a
Russian launcher to that of the STS Orbiter) has continued to
be a primary concern for the project. Mass problems associated
with the Science and Power Platform (SPP) on which ERA is
installed during launch necessitated a radical change to the
launch configuration at the end of 1996, with attendant
feasibility concerns. These have now largely been solved and
the associated changes are being incorporated into the ERA
design.
Due to persistent problems with the availability of a working ADA compiler for the THOR processor, it has now been decided to abandon this approach for the ERA onboard computer and to use the SPARC ERC-32 chip-based processor board instead, in common with the DMS-R project. The Man/Machine Interfaces have been reviewed by Russian experts and representatives of the ISS crew office. Both Russian cosmonauts and ISS astronauts contributed significantly to the review, which has put the ERA MMI designs on a more secure footing.
The ERA geometric model has been completed and is awaiting delivery to Russia, pending incorporation of late modifications which are expected due to the changes caused by the new launch configuration.
Laboratory Support Equipment
Signature of the MELFI (Minus Eighty Degree Celsius
Laboratory Freezer) took place on 14 January (see Bulletin
89, page 129). In the MSG (Microgravity Science Glovebox)
arena, preparation for the Preliminary Design Review
continued, as well as the negotiation of the Phase-C/D
contract.
The procurement of the Hexapod Phase-B development model continued to progress. Tests performed on each of the six linear actuators showed the performance of all six legs to be compliant with the design specifications.
Utilisation
The Proceedings of the Space Station Utilisation Symposium held in Darmstadt (D) at the end of September were made available to the Space Station User Community in December (as ESA Special Publication SP-385, available from ESA Publications Division).
Further to the Agreement reached with NASA concerning the early opportunities on Space Station for Europe, in December the 'ESA Announcement of Opportunity for Externally Mounted Payloads during the Early Space Station Utilisation Period' was issued to some 6000 addressees in all ESA Member States, together with the 'ESA Life-Sciences Research Announcement'. Publication of these AOs (by ESA Publications Division as SP-1201 and SP-1210, respectively, in hard copy and on the World Wide Web) has to be seen as marking the real start of Space Station utilisation preparation.
The European Utilisation Board (EUB) had discussed the principles of user access to the International Space Station and reviewed the documentation to accompany the above AOs. The Space Station User Panel, at its meeting in November 1996, had issued recommendations with regard to payload selection, ISS access rules, interactive operations, and multinational research
ESA Bulletin Nr. 90.