ERS-1 one year after! status and perspectives of the ERS programme

0273—i 177~3$24.00 Copyright ©1993 COSPAR Adv. Space Res. Vol. 13, No. 5, pp. (5)5—(5)1 8, 1995 Printed inGreat Britain. All rights reserved. ERS-1 ONE YEAR AFFER! STATUS AND PERSPECTIVES OF THE ERS PROGRAMME G. Duchossois* and M. Fea** * ESA/HQ, 8—10 rue Mario Nikis, 75738 Paris Cedex 15, France ESA/ESRIN, Via G. Galilei C. P. 64, 00044 Frascati, Italy ** INT~DUCTION The first European R~tote Sensing Satellite ERS-1 was launched by the European Space Agency (ESA) on 17 July 1991 and successfully injected into a quasi-polar sun-synchronous orbit at a mean altitude of 780 I<ht. ERS-1 is the forerunner of ncdem Earth Obeervation missions and its advanced payload catprises active and passive micrc%.,ave instruments and an infrared radiateter (Ref. 1). In order to properly serve the large variety of scientific and operational users, a very cctnplex ground segment has been bout based on many ESA and national facilities distriboted around the world. During the initial carfnissioning period very intense work has been concentrated in the verification activities. One year after the launch many facilities and products have been calibrated and validated, and are routinely operational, although the highest degree of autanation ained at for the ground segment is not yet fully ~i~l~nted. The initial user expectation for the distribotion of ERS-1 data was challenged by the canpiexity of the above task. And even if ERS-1 is by definition a pre-operational mission, the preliminary results achieved by the scientist and by operational people are already outstanding and confirming that the ERS-1 mission objectives can be met. ERS-l PAYLOAD The ERS-1 spacecraft is catiposed of a service platform, derived frau the S~T-1satellite, and a payload, which includes (Fig. 1): the foll~ingESA funded pre-operational instrumentation - an Active MicrcMave Instrument (AMI), ca’nprising a Synthetic Aperture Radar (S~R), which can be operated in Image MDde (SAR), or in Wave Made (WAVE), and a Wind Scatterar~ter (WIND SCAT) [WINDand WAVE can be operated siimiltaneously] - a Radar Altflreter (RA) a Laser Retroreflector device (LRR) and two Announceient of Opportunity instruments (5)5 (5)6 G. Duchossois and M. Fea a Precise Range and Range Rate Equi~rent (PRARE), fran Germany - an Along-Track Scanning Radianeter and Microwave Sounder (1~TSR), fran United Kingdan. - ERS-l MISSION OBJECTIVES AND MAIN ACHIEVEMENTS The initial mission objectives for ERS-1 in the early 1980’s were to develop a rat~te sensing satellite system as an european contribution to increasing the scientific understanding of global ocean processes, rr~nitoringof polar regions, all-weather imaging of land at regional scale, contributing to the World Climatology Research Prograrrrre, developing and praroting technological capabilities of european industry as well as econanic and catrrercial applications. One year after launch, the major achievements can be surra~narizedas follows: implexentation of the Orbit Scenario as planned very stable orbit configuration, with alircst 6000 orbits canpieted (on 7 Septar~ber),with the ground track maintained within +1 km and with the spacecraft already in the fourth 35—day repeat cycle (well into the Multidisciplinary Phase) Platform and Payload (except PRARE and ATSR 3.7 inn channel) performing up to specification or better and showing a high degree of stability core system operational routine global coverage of Low Bit Rate data systematic regional coverage of SAR High Rate image data routine dissemination of Fast Delivery products regular distribution of Off-line products absolute calibration of SAR data validation of n~stFast Delivery and Baseline products issue of the main documentation initial results also fran new and not envisaged applications (eg. interferanetry). - - - Obviously, as any ca-nplex system ERS-1 has also suffered sane problem areas. At the level of payload, a fatal failure of PRARE occurred few days after normal operations at the end of July 1991; in addition, the ATSR 3.7 pm channel data flow stopped on 27 May 1992 and no recover was possible until now. Other problems were understood and circumvented. At ground segment level, the integration effort for the caiplex multinational distributed ground segment required more resources and time than expected. Also, it has to be noted that the very successful start of ERS-1 created a very high initial expectation in the user carrnunity. It is important to stress here that what has been built for ERS-1 is in most cases a long-term investment. SPACE SEG~IENTOPERATIONS The ERS-1 Orbit Scenario has been implemented to extrEnely accurate injection into orbit by the listing the manouvres between phases, and taking achieved one year after launch, the current orbit Mission Phase Launch A Carinissioning - date as planned, after the ARIANE-4 launcher. Without into account what has been scenario is as follows: T~ine 17 July 1991 26.07.91 10.12.91 — Repeat 3-day (5)7 ERS-1 One Year After 28.12.91 30.03.92 04.04.92 12.04.92 14.04.92 15.12.93 01.01.94 31.03.94 05.04.94 onwards B First Ice Roll—Tilt Mode campaign C Multidisciplinary D Second Ice E Geodetic — 3—day 35—day 35—day 3—day 176-day — — — - — — - The ERS-1 payload is performing extrEnely well, except for the failures of PHARE and the 3,7 pm channel of ATSR. Until now, the on-board chains activated after the launch are still the ones being operated, so that the redundancy has not been used yet and it is still fully available. Furthermore, to date both tape recorders are working naninally and they are used alternatively every three months. The two X-band links to ground are also naninal and stable, and the third tube has not been used yet. The availability of the platform has been 99%, except for the period mid July-early Septanber 1992, when the availability was reduced to sai~85% for investigations. The performance of the ERS-1 Payload can be s~rnarizedas follows: AMI Phase (cycle) Data Outage (days) Availability (%) (over N days) A (1—47) 2.52 98.13 (135) B (48—81) 2.98 97.04 (101) C (83—84) 0.93 98.15 (53) C (85) 4.81 85.95 (35) During the Phase C, the AMI BAR in Image Mode is used: 60% on average 80% when ALL ground stations are available out of 12 min x 501 orbits capability per each cycle; operations over sea or ocean are planned only on request. Therefore, no on-board energy problem for SAR is experienced to date! PA Phase (cycle) Data Outage (days) Availability (%) (over N days) Phase (cycle) IR Data Outage (days*) MW Data Outage (days*) IR Availability (%) MW Availability (%) A (1—47) 1.55 98.85 (135) A (1—43) 0.34 0.34 99.75 99.75 B (48—81) 4.76 95.28 (101) B (48—81) 1.27 1.27 98.75 98.75 C (83—84) 2.77 94.45 (53) C (83—84) 0.46 0.46 99.07 99.07 C (85) 2.22 93.67 (35) C (85) 6.84 2.02 80.44 94.23 ~oth Operations until 27 May 1992, when Channel 3.7 pin data flow suddenly stopped. Despite many att~npts, no recovery has been possible to date. All other channels are working naninally. * it does not include IRR decontamination operations (5)8 G. Duchossois and M. Fea GR)UND SE(~ENTOPERATIONS (up to end August 1992) The develo~nentand integration of the ERS-1 ground segment has been a major challenge for ESA and its national partners. Running routinely this very canplex assembly of distributed facilities owned by different agencies is also a very challenging task. After a long and stepped phasing in period, most facilities are carrying out regular operations. The ESRIN ERS-1 Central Facility (EECF) manages most of the ground segment operations and provides the users with the gateway to the system services (Ref. 2). EECF routine operations started before launch with the ERS-1 Order Desk and the Product Control Service in Spring 1991, respectively to handle the data requirements of the Principal Investigators and to prepare the quality assessment operations. The Mission Planner carinenced in August 1991 when the first Payload Exploitation Plan expressing the user requirEtents for BAR operations was sent to the ~4CC for integration into the overall satellite operation plan; the detailed plan sent back fran M~4CCwas used to generate the first Global Activity Plan. The GAP is used to generate the operating schedules for the ground facilities, and provides visibility on future payload operations to the users. The ERS-l Help Desk became operational at the end of January 1992, after the signature of the agreement between ESA and the ERS Consortium (Eurimage, Radarsat International, Spot Image) for the distribution of ERS-1 products. The EECF user services canprise the link operations between EECF and the various ground segment and user facilities, including the distribution of Fast Delivery products. The Mission Management & Control centre (~CC) is fully operational in performing the routine spacecraft control and car~andingthrough the remotely controlled Kiruna-Saimijärvi ground station, and in running the mission planning system. Pranpt intervention is made and necessary action are taken in case of ananalies: this has permitted in most instances the circumvention of problems and the quick restoration of operations. Through the M~4CC-EECF link, Payload Exploitation Plans are regularly received fran ESRIN and assimilated to generate the overall detailed mission operations plans. The latter are used for creating the daily satellite operation schedule, and are sent back to EECF for the scheduling of the other ground segment operations. Many ERS-1 Ground Receiving Stations are operational to date: ESA Network HR+LIBR LBR National (HR) Foreign (HR) Kiruna-Salmijärvi, Etncino, Maspalanas Gatineau, Prince Albert Gatineau, 0 ‘Higgins, Prince Albert, Transo, West Freugh Aussaguel has been operated until 31 March 1992 on an experimental basis (routine acquisitions during the First Ice Phase) Alice Springs, Cotopaxi, Cuiaba’, Fairbanks (ASF), Hatoyarna, Hyderabad, Kumamoto, Syowa Campaigns in Antarctica: O ‘Higgins Syowa 20 Sep 10 Jan 1 Jul — 15 Oct 1991 15 Mar 1992 (with few short interruptions for VLBI) 30 Jul 1992 21 23 Oct 1991, 28 Oct 10 Dec 1991 20 31 Jan 1992, 1 Mar 31 Mar 1992 1 Aug 1992 onwards (05:00—15:00 IJIt only) — — — — ERS-1 One Year After (5)9 Other ground stations are being built or upgraded to the ERS-1 standard: National (HR) Foreign (HR) Transportable (Germany) Bangkok, Hobart, Taiwan, Parepare Plans are being discussed for sate other ground stations: Beijing, Malta, South Africa, Saudi Arabia. The performance of the ESA facilities, operational since launch, has been very satisfactory, both in data acquisition and in Fast Delivery product generation. In the first part of 1992 the following has been achieved: ESA HR NEIWJRK PERR)M’4ANCE (Jan SAR Acquisition (%) BAR FD On—line (%) - Jul 1992) Kiruna 99.6 97.4 Maspalanas 98.0 96.9 Fucino 97. 6 96.1 T(Y~AL 98.7 96.9 National and foreign ground stations have been phased in during the initial part of the Cannissioning Phase. All together and including the frames acquired in overlap by more than one station, a huge number of BAR scenes will be acquired by ESA and national/foreign stations by November 1992: ALL GE~DUND STATIONS Phase A 112,123 Phase B 85,024 RIM 2,862 Phase C 145,957 ‘BEAL 345,966 equivalent in size to sane 7 times the extension of the Earth surface! Unlike the BAR HR (Image mode) tel~netry data, the data generated by the LBR instruments, i.e. BAR in Wave Made, Wind Scatterareter, Radar Altimeter and Along-Track Scanning Radiareter, are stored on the on-board recorders around the globe and dumped to an ESA LER ground station once every orbit, thereby ensuring the global mission. The performance of the ESA LBR facilities in LBR data acquisition and FD product generation is summarized as follows: ESA LBR NFIW)RK PERPO~~4ANCE Phase C Kiruna Gatineau 100 97.3 Acquisition Maspalanas ‘BY~AL 99.1 Prince Albert 99.1 Kiruna Gatineau Maspalanas ‘ItYI~AL 84.4 89.8 94.3 93.7 96.5 95.2 85.9 94.5 90.5 86.5 91.7 94.1 99.2 Jan-Jul 1992 SCAT FD On—line HA FD On—line WAVE Fl) On—line Note: to date Prince Albert LBR data are Fl) processed off-line at Gatineau to caiplete the dataset for final archiving at F-PAF The ERS-1 Fast Delivery Distribution ccmrmrenced after the PD products were carefully verified and consequently the distribution list was increased in few successive steps. JASR 13:5-B (5)10 G. Duchossois and M. Fea The SAR PD products started to be distributed through the Broadband Data Distribution Network (BDDN) making use of the EUTELSAT system to few Baltic centres in support to ice projects. The generation and distribution of similar products by the Alaska BAR Facility and the Transo station to their authorized users started also in 1991. The BDDN service covers now the whole Europe. The LBR data, injected into the meteorological network through the nodes in Rare and Bracknell, were firstly addressed only to saie centres which participated to the verification and validation process. At the end of October 1991, all european LBR Naninated Centres started receiving the PD products. After the signature of the NOAA/ESA Memorandum of Understanding, the dissemination of LBR Fl) products to USA and Canada was activated. The actual performance of the ERS-1 Fast Delivery Distribution system is shown below: BAR (U116, UILR) upon request LBR (TJRA, UWI, UWA) routine through GrS 1992 Feb Mar % success 88 96 average delay fran sensing: Apr 87 2 h 40 mm up to 20.08.92 ‘BY~AL 3745 May 82 Jul 94 Jun 95 When evaluating the performance of the LBR system, it has to be noted that the overall performance depends on various cariponents (satellite, ground station, ESA and meteorological links), such that the success rate includes also the performance of elements external to the ESA ERS-l Prograrrine. The four Processing and Archiving Facilities operations caimnenced at different t:imes, since their development has been flnpl~rented as a joint long-term venture between ESA and national Agencies. To date not all the PAP el~tents are fully operational, on the one hand because of objectives difficulties and on the other hand because off-line precision products require a more demanding validation and in same cases a long lead tine for accumulating the necessary temporal data series. Nevertheless, in terms of raw data archiving the PAFs are catching up and the following tel~retrydata have been archived on various media (High Density Digital Tapes HDD~ or Optical Disks OD) after quality control and cataloguing: BAR UK-PAP D-PAF I-PAP (Kiruna, N/F stations [Thorn-E~ni]) (O’Higgins, N/F stations [others]) (Fucino, Maspalanas) 36,953 scenes 17,428 scenes 1,715 scenes LBR F-PAP & UK-PAP (back-log being recovered) (3 orbits per optical disk) > 2,200 OD’s To date, the following ERS-l Data Products have been or are being validated and made available for the users fran the ground stations and the PAFs (Ref. 3): ERS-1 One Year After (5)11 ESA FACILITIES products validated and available BAR Wave Orbi ALT SCAT RAW, UWA, PRL, URA, UWI, U116, UILR, FDC, PRI, SLC, GEC, GIN FDC PRC FDC, OPRO2, WDR PDC products under validation ALT Q/L SSH, WDR ATSR Baseline products N/F STATIONS validated: Gatineau, Prince Albert, ASF, Transo, Aussaguel, Cotopaxi, Cuiaba’ India and Japan have been authorized to distribute on a experinental basis. The delivery of ERS-1 products has increasingly progressed, and at the end of August 1992 the situation was as follows: BAR P~)DUCI’RF~UESTS Carrrercial Orders for ESA Facilities Pilot Project Principal Investigators Others (cal/val, QA, test, background) 207 233 1,682 2,593 ‘BYrAL requested 4,715 products delivered % requests satisfied 4,068 86.3 r.BR (ALT, SCAT) DELIVERY delivered routinely to interested P1 ‘S since January 1992 (re-processing of products before 5 Nov 91 started) ALT.OPRO2 (*) August 1991 data delivered Sept-Oct 1991 almost ready ALT.WDR (*) 24—31 Aug 1991 delivered to 13 P1’s FDC (ALT.URA, WSC.UWI) The generation and delivery of other data, like ATSR products, will start as soon as the products are validated. SCME EARLY RESULTS In the meanwhile, quality assessment and calibration and validation activities lead to inportant results. For the first tine, the a~eolute calibration of an spaceborne BAR data was achieved. In-flight antenna pattern were retrieved fruit the Amnazonian Rain Forest responses, and since 15 Sept~nber 1992 the ESA SAR.PRI products are fully calibrated: the in-flight antenna pattern are applied, and the calibration constant is given. This allows to give, for the first tine for a spaceborne BAR, the absolute value of the back-scattering coefficient Sigma Naught witht (*) products validated in July 1992 (5)12 a) b) G. Duchossois and M. Fea a radiciietric stability a radianetric accuracy = = = 0.37 dB 0.31 dB (mean) 0.74 dB (max) (Radiatetric stability is the normalised standard deviation of radar echoes fran a number of identical points or distributed targets with stable radar cross-sections, assuming that the system is operating within the dynamic range and that a linear calibration drift correction is performed on the data. Radiametric accuracy is the nonnalised difference between the actual and the measured target radar cross-section). In addition. the great stability of the ERS-1 orbit has allowed novel applications to be identified and studied. One of them is the use of BAR canplex data for interferanetric work. EBA has established the ERS-1_FRINGE Working Group in January 1992. Its activity has led already to the generation of a Digital Elevation Model (height noise estimated to be 5 m) with 2-8 Aug 91 datasets (Gennargentu, Sardinia) to daronstrate the technique. Currently, the evaluation of D~ quality for selected sites is in progress. The capability of ERS-1 to detect small rrovarents (-1 an) was achieved (Bonn experiment, March 1992), and the evaluation of the sensitivity to small terrain novanent is in progress over different areas. ESA supports the Group’s activities by coordinating them, and scheduling acquisition, processing and distribution of data. Certainly, in the danain of operations and applications a lot of expectation derives fran the canplanentarity of the Earth Observation satellite missions. Nowadays several opportunities exist already: - ERS-1, SPOT and LANDSAT in multi-spectrum imaging ERS—1, ALMAZ and JERS-1 in BAR imaging ERS-1 and ~OPEX-~SEI~ in radar altimetry the last two being an absolute and very exciting space “premiere”! Sane very preliminary results have confirmed the great potential of the ERS-1 data, and additional pranising reports are expected at the ERS-1 Symposium to be held in Cannes on 4-6 November 1992. MEDIUM AND LONG TE~ PERSPECTIVES ERS-1 is the forerunner of a serie of modem and advanced remote sensing systans and is paving the way to the Earth Observation missions of the year 2000. The need of ensuring long-term continuity to the ERS-1 data has been well perceived by EBA and its Delegates Bodies, such that ERS-2 has been approved and the satellite is being built for a launch in December 1994 or January 1995. ERS-2 is quasi-identical to ERS-1. In fact it will carry on board an improved version of ATSR and a new atmospheric instrument, the Global Ozone Monitoring F~uiprent (G~4E): - - the flrproved version of the ATSR includes three additional channels in the visible part of the e .m. spectrum for vegetation monitoring the new experimental instrumrent ~XMEis a spectraneter working in the ultraviolet/visible band (250-790 Nm), using differential absorption and backscatter techniques. It will measure a range of trace constituents in the troposphere and in the stratosphere, with the following target molecules ERS-1 One Year After Global Coverage (5)13 Partial Coverage or occasional observations Constituents Constituents 03 NO (above 40 ~n) NO2 H2O 02/04 BrO SO2 HCII) OC1O ClO N03 plus aerosols and polar stratospheric clouds (PSC5) It is worth Imentioning here that an intense activity is being carried out between ESA and its }‘~nber States, in close cooperation with ESA’ 5 international partners and user catinunities, in order to prepare the EBA Earth Observation long-term progranrme to be presented in November to the Ministerial meeting in Granada. The progranue is aimed at establishing the strategy which will bring ESA activities into the years 2000 and focuses on four basic objectives: a) b) c) d) monitoring of the earth’s environment on various scales, fruit local through regional to global monitoring and mnanagament of the earth’ s resources, both renewable and non-renewable continuation of the services provided to the worldwide operational meteorological catinunity contribution to the understanding of the structure and dynamics of the earth’s crust and interior. Several satellite missions support the above strategy: ERS-l and ERS-2 POEM-i programr~re (series of polar missions), canprising ~VISAT-1 for launch in 1998 - ~ItP-1 - MEIOP-2 - for launch in 2000 POEM Follow-on progrante, canprising ENVISAT-2 for launch in 2003 for launch in 2005 M~T~X)SAT Second Generation, for launch in 1999/2000 ARIS’ItYTELES Solid Earth mission, for launch not later than 1998 (solar cycle minimum) The mission objectives and the planned payload of the future ESA Earth Observation missions can be surtinarized as follows: ENVISAT-1 continuation and enchancanent of the ERS missions as contribution to environmental studies, notably in the areas of atnospheric chemistry and marine biology ESA funded core payload: BAR GCK)S MERIS MIPAS HA-2 - Advanced Synthetic Aperture Radar Global Ozone Monitoring by Occultation of Stars MEdium Resolution Imaging Spectraneter Michelson Interferareter for Passive Atmospheric Sounding Radar Altimeter-2 (including a microwave sounder) (5)14 G. Duchossois and M. Fea instrurments provided by national progrartines: AATSR PRAREE SCARAB SCIAMACHY - Advanced Along-Track Scanning Radianeter Precise Range And Range-rate Equipitent Extended version SCAnner for RAdiation Budget Scanning Imaging Atmospheric Spectraneter for Atmospheric Chartography ME’IOP-1: for operational neteorology as contribution to climate monitoring and operational climatology in the future; the mission will be carried out in the framework of an agreanent to be concluded with EUMF~TBAT. core payload for operational meteorology: VIRSR Visible and InfraRed Scanning Radianeter IRIS Infra-Red Temperature Sounder MIS Microwave Tenperature Sounder MHS Microwave }~.nniditySounder DCS Data Collection System IASI Infrared Atmospheric Sounding Interferaneter - proposed payloads for climatology monitoring: MIMR Multifrequency Imaging Microwave Radiareter - ASCAT AATSR GCME SCARAB - Advanced wind SCATterateter Advanced Along-Track Scanning Radiareter Global Ozone Monitoring Instrument SCAnner for RAdiation Budget Both ENVIBAT-i and I~’IOP-iwill make use of the COLUMBUS polar platform and will be equipped to work with the Data Relay Satellite (DRS) system. POEM Follow-on progrartine, as a preparation to: ENVISAT-2 with develo~rentof new advanced instrumentation (e.g. lidar, multifrequency BARs, high resolution thermal infra-red radiareter) MEaOP-2 in cooperation with EUMETSAT METEOSAT Second Generation (MSG), follow-on of present METEOSAT Operational Progranue, to be inplemented in cooperation with EUMETSAT, with the following objectives: — higher spatial and spectral resolution VIS/IR imaging higher temporal resolution (more frequent imaging) air mass analysis data collection and dissemination inclusion of scientific package and/or Search & Rescue (optional) The Study phase should start in 1993/1994 ARIS’ItYTELES mission in low Earth orbit focussing on gravity and magnetic fields, in cooperation with NASA, as contributions to science and applications in: - geodesy and orbit mechanics mapping, surveying and exploration — geodynamics - - physics of the Earth’s interior oceanography climate (sea level monitoring) high atmosphere (density variations at 200 and at 500 Km altitude). ERS-1 OneYear After (5)15 Obviously, the developnent of the above progrannes requires that a major effort is made on the development of the related ground segilent, in particular for ENVISAT-i, effort which is based on the experience gained with ERS-1 and ERS-2 and takes into account the availability of DRS. Also, a major progress is foreseen in the capability for both operations and data manag~rentby the ESA, national entities and data users carrnunities. In this context, a key role is played by the international cooperation. Strong partnerships are being developed in Europe with EUMETSPIT and the European Econanic Cairnunity to ensure that Europe’ s needs in Earth Observation data are net. Here, an important elanent is the establishment of the european carponent of the global environmrent data network. Close cooperation with the USA (NASA and NOAA), Canada and Japan is also being actively pursued through exchange of instrurrentation and data, making the end of the century very challenging and at the same time very pranising for the Earth Observation fran space. ~CES 1. 2. 3. ERS—i System ESA SP-ii46, ESTEC, Noordwijk (NL), 1992 ERS-1 User Handbook ESA SP-i148, ESTEC, Noordwijk (NL), 1992 ESA ERS—1 Product Specification EBA SP-1l49, ESTEC, Noordwijk (NL), 1992 - - - St~RYTABLES ERS-1 PAYLOAD: Surrrrer 1992 outages 26—27 19—23 9—10 23—24 Jun Jul Aug Aug 92 92 92 92 In stand-by due to a PDU ananaly In stand-by due to investigtions In stand-by due to investigtions Switched down in stand-by Problem successfully circumvented ERS-1 SAR HIS’IORY (up to 31 August 1992) 27 27 4 5 Jul Jul Sep Sep 91 91 91 91 15 Oct 91 11—12 Dec 91 12 Dec 91 11 Jan 92 23 Mar-3 May 4—13 Apr 92 14 Apr 92 July 1992 since 1 Sep 92 Initial operation check First BAR Image acquired and processed Activation of EBA transponders in Flevoland (NL) ESA transponder gain adjusted by 6 dB Calibration constant K for ESA products fixed (same until to date (BAR high radiaretric stability)) Preliminary values of calibration coefficient available for EBA Verification Mode Processor Roll-Tilt Mode operational test EBA transponders re-calibrated at ESTEC Activation of ESA transponders in Zeeland (NL) Progressive re-calibration at ESTEC and re-deployment in Flevoland of the ESA transponders Roll-Tilt Mode campaign Re-activation of EBA transponders in Flevoland (NL) BAR radiaretric accuracy and stability over one year confinred within specifications In-orbit antenna pattern applied to all ESA BAR. FRI products E~-1SCATP HIS!IORY (up to 31 August 1992) 27 Jul 91 Initial operation check (G~JD-2airborne n~x~el used) G. Duchossois and M. Fea (5)16 15 Sep 91 19 Sep 91 29 Oct 91 4 Nov 91 10 Dec 91 15 Jan 92 1 Mar 92 30 Apr 92 10 Jun 92 17 Jul 92 Rene’ 91 Geophysical Campaign started Scaling 1.3 dB for all beams (Transponders) 1st Mid beam correction (Rain Forest) Transponders tuning End of Engineering Calibration 1st Fore/Aft beam correction (Rain Forest) Rene’ -91 Geophysical Campaign canpleted Sampling correction (29.42 29.942 kHz) Last Antenna Pattern Tuning (sigma naught OK) 2nd correction for all beams (Rain Forest + Transponders) Rene ‘-91 Workshop: Q4DD-3 selected CMDD-3 spaceborne model implemented in all ESA stations An~iguityRai~valcorrected (WIND interface). -> In parallel: Jan — 15 Apr 92 Definition of the new model Q>~IJD-3 ERS-1 ALT HISWRY (up to 31 August 1992) 25 Jul 91 1 Aug 91 17 Sep 91 Initial operation check Calibration carrpaign started Calibration campaign canpleted (external calibration: -19.2 an 5 an bias) routine dissemination of ALT PD (URA) started PD processing tuned, loss-of-track algorithm improved Tracker parameters tuned (more agile tracker) production of Quick Look Sea Surface Height (PD PRL averaged per 35-d cycle) started. -~ 24 Nov 91 Dec 91 20 Jan 92 14 Apr 92 Phase C operational Mode (per cycle): Over oceans Over Ice Polar Caps and Land + always in Ocean Mode Ice and Ocean Mode alternated. ERS-1 ATSR HIS’IORY (up to 31 August 1992) 26 Jul 91 1 Aug 91. up to 14 Sep 91 8 Oct 91 20—22 19—23 7—11 27 27 May-4 4-16 since 27 Nov Dec Apr May Jun Jun May 91 91 92 92 92 92 92 Initial operation check Microwave Sounder (~S) switch-on and operating in naninal mode Infrared Radianeter (IRR) switch-on Ccnmisioning activities, care in usinq science data IRR pixel selection map:IRR science data not to be used during the period 14:37:24 andl9:28:48 UTc IRR decontamination cycle IRR decontamination cycle IRR decontamination cycle IRR 3.7 pm channel data flow stopped IRR 1.6 and 3.7 pm channel data not available Switched on various modes for investigations IRR 3.7 pm channel data not available ERS-1 PRARE HISWRY (up to 31 August 1992) 24 Jul 91 25 Jul 91 26 Jul 91 Equipment switch-on First telemetry over Stuttgart Data frames & range codes acquired at Stuttgart ERS-1 One Year After (5)17 29 Jul 91 09:36 10:52 29 1 1 since 1 Synchronisation of on-board clock Synchronisation of range code and correct expansion of up-link carrnands Jul 91 12:54 Autariatic equipl~ntswitch-down Aug 91 Cairnanding trials unsuccessful Equipment switch-off Aug 91 Aug 91 Equipment OFF ESA ERS-l PI~JDUC~S Product Annotated Raw Data Fast Delivery Image Fast Delivery Image Copy Single Look Canplex Image Precision Image Ellipsoid Geocoded Image Terrain Geocoded Image Wave Annotated Raw Data Wave Fast Delivery Product Wave Fast Delivery Product Copy Wave Intermediate Product Copy Wave Canplex Imagette Wave Detected Imagette Spectrum Wave Imagette Precise Spectrum Wind Scatterareter Fast Delivery Product Wind Scatterareter Fast Delivery Product Copy Scatterateter Extracted Wind Copy Dealiased off-line Wind Fields Altimeter Annotated Raw Data Alti.rreter Fast Delivery Product Altirreter Fast Delivery Product Copy Off-line Intermediate Product Ocean Product, with Preliminary Orbit with Precise Orbit Altimeter Wave data record Altimeter Wave Foundation Product Sea Surface Height Sea Surface Height Quick Looks Sea Surface Topography Oceanic Geoid Preliminary Orbit Precise Orbit ~S-1 Gravity Model First Generation BAR BAR BAR BAR BAR SAR BAR BAR SAR SAR BAR SAR BAR BAR Code ERS—1.SAR.RAW ERS—1 BAR. U116 ERS—1.SAR.FDC ERS—1. SAR. SLC ERS—1 BAR. FRI ERS—1.BAR.GEC ERS—1.BAR.~I’C ERS—1 S~1. RAW ERS—1 S~’I,f.UWA . . . . ~S—1 S~N.FDC ERS—1 S~1.IPC ERS-1 S*1.CIT ERS-1 S~.DIS ERS—1 S~1.IFS . . . . . ERS—1 .WSC .UWI ~S—1 .WSC FDC ERS—1 .WSC. IWC ~S—1 .WSC .WNF . ERS-1.ALT.RAW ~S-1 .ALT.URA ~S-1 .ALT PDC ERS-1 .ALT OIP ERS-1 .ALT.OPRO1 ERS-1 .ALT OPRO2 . . . ERS-1 .ALT.WAP ERS-1 .ALT .WDR ERS-1 .ALT. SSH ERS-1 .ALT. SSI~L ERS-1 .ALT ~OP ERS-l .ALT OGE ERS-1 ORB.PRL ERS-1.ORB.PRC ERS-1.ORB.Ea~tl . . . Under validation: ATSR ATSR ATSR ATSR ATSR Infrared Brighthess Temperature Microwave Brighthess Tenperature Sea Surface Temperature Precise Sea Surface Tarperature Water Vapour, Liquid Water Content JASR 13:5-C ERS—1 .I4TS. IBT ERS—1 .ATS .MBT ERS-1 .ATS SST ERS—1 .ATS .PST ERS—1 .ATS .VLC . G.Duc ho sso is zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFE and M. Fea (S)18 SAR Ante nna _. -~ ATSR- ’ MIc ro w o ve So und e r ATSR - Infro -re d Ra d io m e te r La se r Re tro -re fle c to rs Fig ure 1 The EM-1 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIH instrum e nts.