0273—i177~3$24.00Copyright ©1993COSPAR

Adv. SpaceRes. Vol. 13,No. 5, pp. (5)5—(5)18, 1995PrintedinGreatBritain. All rightsreserved.

ERS-1 ONE YEAR AFFER! STATUS ANDPERSPECTIVES OF THE ERS PROGRAMME

G. Duchossois*and M. Fea**

* ESA/HQ,8—10 rueMario Nikis, 75738Paris Cedex15, France** ESA/ESRIN, Via G. Galilei C. P. 64, 00044Frascati,Italy

INT~DUCTION

The first European R~tote Sensing Satellite ERS-1 was launched by theEuropeanSpaceAgency (ESA) on 17 July 1991 and successfully injected into aquasi-polarsun-synchronous orbit at a mean altitude of 780 I<ht. ERS-1 is theforerunner of ncdem Earth Obeervation missions and its advancedpayloadcatprises active andpassive micrc%.,ave instruments and an infrared radiateter(Ref. 1). In order to properly serve the large variety of scientific andoperational users, a very cctnplexground segment has beenbout based on manyESA and national facilities distriboted around the world.

During the initial carfnissioning period very intense work has beenconcentratedin the verification activities. One year after the launch manyfacilities and products have been calibrated andvalidated, and are routinelyoperational, although the highest degree of autanation ained at for theground segment is not yet fully ~i~l~nted.

The initial user expectation for the distribotion of ERS-1 data waschallenged by the canpiexity of the above task. And even if ERS-1 is bydefinition a pre-operationalmission, the preliminary results achievedby thescientist and by operational people are already outstanding and confirmingthat the ERS-1 mission objectives can be met.

ERS-l PAYLOAD

The ERS-1 spacecraft is catiposed of a service platform, derived frau theS~T-1 satellite, and a payload, which includes (Fig. 1):

the foll~ing ESA funded pre-operational instrumentation

- an Active MicrcMave Instrument (AMI), ca’nprising

a Synthetic Aperture Radar (S~R), which can be operatedin Image MDde (SAR), orin Wave Made (WAVE), and

a Wind Scatterar~ter (WIND SCAT)[WINDand WAVEcan be operated siimiltaneously]

- a Radar Altflreter (RA)- a Laser Retroreflector device (LRR)

and two Announceientof Opportunity instruments

(5)5

(5)6 G. Duchossoisand M. Fea

- a PreciseRange and RangeRate Equi~rent(PRARE), fran Germany

- an Along-Track ScanningRadianeterand Microwave Sounder (1~TSR),f ranUnited Kingdan.

ERS-l MISSION OBJECTIVES AND MAIN ACHIEVEMENTS

The initial mission objectives for ERS-1 in the early 1980’s were to developa rat~tesensing satellite systemas an european contribution to increasingthe scientific understandingof global ocean processes, rr~nitoring of polarregions, all-weather imaging of land at regional scale, contributing to theWorld Climatology Research Prograrrrre,developing and praroting technologicalcapabilities of european industry as well as econanic and catrrercialapplications.

One year after launch, the major achievementscan 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 maintainedwithin +1 km and with thespacecraft already in the fourth 35—day repeat cycle (well into theMultidisciplinary Phase)

- Platform and Payload (except PRARE and ATSR 3.7 inn channel) performingup to specification or better and showing a high degreeof stability

- core systemoperational- routine global coverageof Low Bit Rate data- systematicregional coverageof 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 andBaseline products- issue of the main documentation- initial results also fran new and not envisaged applications (eg.

interferanetry).

Obviously, as any ca-nplexsystem ERS-1 has also suffered saneproblem areas.At the level of payload, a fatal failure of PRARE occurred few days afternormal operations at the end of July 1991; in addition, the ATSR 3.7 pmchannel data flow stopped on 27 May 1992 and no recover was possible untilnow. Other problems were understood and circumvented. At ground segmentlevel, the integration effort for the caiplex multinational distributedground segment required more resources and time than expected. Also, it hasto be noted that the very successful start of ERS-1 created a very highinitial expectationin the user carrnunity.

It is important to stress here that what has been built for ERS-1 is in most

casesa long-term investment.

SPACE SEG~IENTOPERATIONS

The ERS-1 Orbit Scenario has been implementedto date as planned, after theextrEnely accurate injection into orbit by the ARIANE-4 launcher. Withoutlisting the manouvres between phases, and taking into account what has beenachievedone year after launch, the current orbit scenario is as follows:

Mission Phase T~ine Repeat

Launch 17 July 199126.07.91— 10.12.91A - Carinissioning 3-day

ERS-1OneYearAfter (5)7

B — First Ice 28.12.91 — 30.03.92 3—dayRoll—Tilt Mode campaign 04.04.92 — 12.04.92 35—dayC — Multidisciplinary 14.04.92 - 15.12.93 35—dayD — Second Ice 01.01.94 — 31.03.94 3—dayE - Geodetic 05.04.94 onwards 176-day

The ERS-1 payload is performing extrEnely well, except for the failures ofPHARE and the 3,7 pm channel of ATSR. Until now, the on-board chainsactivated after the launch are still the ones being operated, so that theredundancy has not been used yet and it is still fully available.Furthermore, to date both tape recorders are working naninally and they areused alternatively every three months. The two X-band links to ground arealso naninal and stable, and the third tube has not been used yet.

The availability of the platform has been 99%, except for the period midJuly-early Septanber1992, when the availability was reduced to sai~ 85% forinvestigations.

The performance of the ERS-1 Payload can be s~rnarized as follows:

AMI

Phase (cycle) A (1—47) B (48—81) C (83—84) C (85)

Data Outage (days) 2.52 2.98 0.93 4.81Availability (%) 98.13 97.04 98.15 85.95

(over N days) (135) (101) (53) (35)

During the Phase C, the AMI BAR in Image Mode is used:

60% on average80% when ALL ground stations are available

out of 12 min x 501 orbits capability per each cycle; operations over sea orocean are plannedonly on request.Therefore, no on-board energy problem for SAR is experiencedto date!

PA

Phase (cycle) A (1—47) B (48—81) C (83—84) C (85)

Data Outage (days) 1.55 4.76 2.77 2.22Availability (%) 98.85 95.28 94.45 93.67

(over N days) (135) (101) (53) (35)

Phase (cycle) A (1—43) B (48—81) C (83—84) C (85)IR Data Outage (days*) 0.34 1.27 0.46 6.84MWData Outage (days*) 0.34 1.27 0.46 2.02IR Availability (%) 99.75 98.75 99.07 80.44MWAvailability (%) 99.75 98.75 99.07 94.23

~oth Operations until 27 May 1992, when Channel 3.7 pin data flow suddenlystopped. Despite many att~npts, no recovery has been possible to date. Allother channels are working naninally.

* it does not include IRR decontamination operations

(5)8 G.DuchossoisandM. Fea

GR)UND SE(~ENTOPERATIONS (up to end August 1992)

The develo~nentand integration of the ERS-1 ground segment has been a majorchallenge for ESA and its national partners. Running routinely this verycanplex assemblyof distributed facilities owned by different agencies isalso 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) managesmost of the ground segmentoperationsand provides the users with the gateway to the system services(Ref. 2). EECF routine operations startedbefore launch with the ERS-1 OrderDesk and the Product Control Service in Spring 1991, respectively to handlethe data requirements of the Principal Investigators and to prepare thequality assessment operations. The Mission Planner carinenced in August 1991when the first Payload Exploitation Plan expressingthe user requirEtents forBAR operations was sent to the ~4CC for integration into the overallsatellite operation plan; the detailed plan sent back f ran M~4CCwas used togenerate the first Global Activity Plan. The GAP is used to generate theoperating schedules for the ground facilities, and provides visibility onfuture payload operations to the users. The ERS-l Help Desk becameoperational at the end of January 1992, after the signature of the agreementbetween ESA and the ERS Consortium (Eurimage, Radarsat International, SpotImage) for the distribution of ERS-1 products. The EECF user servicescanprise the link operations between EECF and the various ground segment anduser facilities, including the distribution of Fast Delivery products.

The Mission Management & Control centre (~CC) is fully operational inperforming the routine spacecraft control and car~anding through the remotelycontrolled Kiruna-Saimijärvi ground station, and in running the missionplanning system. Pranpt intervention is made and necessary action are takenin case of ananalies: this has permitted in most instancesthe circumventionof problems and the quick restoration of operations. Through the M~4CC-EECFlink, Payload Exploitation Plans are regularly received fran ESRIN andassimilated to generate the overall detailed mission operations plans. Thelatter are used for creating the daily satellite operation schedule, and aresent 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 Kiruna-Salmijärvi, Etncino, MaspalanasLBR Gatineau, Prince Albert

National (HR) Gatineau, 0 ‘Higgins, Prince Albert, Transo,West FreughAussaguelhas been operated until 31 March 1992on an experimental basis (routine acquisitionsduring the First Ice Phase)

Foreign (HR) Alice Springs, Cotopaxi, Cuiaba’, Fairbanks(ASF), Hatoyarna, Hyderabad, Kumamoto, Syowa

Campaigns in Antarctica:

O‘Higgins 20 Sep - 15 Oct 199110 Jan - 15 Mar 1992 (with few short interruptions for VLBI)1 Jul — 30 Jul 1992

Syowa 21 — 23 Oct 1991, 28 Oct — 10 Dec 199120 — 31 Jan 1992, 1 Mar — 31 Mar 19921 Aug 1992 onwards (05:00—15:00 IJIt only)

ERS-1OneYear After (5)9

Other ground stations are being built or upgradedto the ERS-1 standard:

National (HR) Transportable (Germany)Foreign (HR) Bangkok, Hobart, Taiwan, Parepare

Plansare being discussed for sate other ground stations:

Beijing, Malta, SouthAfrica, Saudi Arabia.

The performance of the ESA facilities, operational since launch, has beenvery satisfactory, both in data acquisition and in Fast Delivery productgeneration. In the first part of 1992 the following hasbeen achieved:

ESA HR NEIWJRK PERR)M’4ANCE (Jan - Jul 1992)

Kiruna Fucino Maspalanas T(Y~ALSAR Acquisition (%) 99.6 97. 6 98.0 98.7BAR FD On—line (%) 97.4 96.1 96.9 96.9

National and foreign ground stations have been phased in during the initialpart of the Cannissioning Phase. All together and including the framesacquired in overlap by more than one station, a huge number of BAR sceneswill be acquired by ESA and national/foreign stations by November 1992:

ALL GE~DUNDSTATIONS

PhaseA PhaseB RIM PhaseC ‘BEAL112,123 85,024 2,862 145,957 345,966

equivalent in size to sane7 times the extension of the Earth surface!

Unlike the BAR HR (Image mode) tel~netrydata, the data generatedby the LBRinstruments, i.e. BAR in Wave Made, Wind Scatterareter, Radar Altimeter andAlong-Track ScanningRadiareter, are storedon the on-board recorders aroundthe globe and dumped to an ESA LER ground station once every orbit, therebyensuringthe global mission.The performance of the ESA LBR facilities in LBR data acquisition and FDproduct generation is summarized as follows:

ESA LBR NFIW)RK PERPO~~4ANCE

PhaseCKiruna Gatineau Maspalanas Prince ‘BY~AL

AlbertAcquisition 100 97.3 99.1 99.1 99.2

Jan-Jul 1992Kiruna Gatineau Maspalanas ‘ItYI~AL

SCAT FD On—line 84.4 93.7 85.9 86.5HA FD On—line 89.8 96.5 94.5 91.7WAVE Fl) On—line 94.3 95.2 90.5 94.1

Note: to date Prince Albert LBR data are Fl) processed off-line at Gatineauto caiplete the datasetfor final archiving at F-PAF

The ERS-1 Fast Delivery Distribution ccmrmrenced after the PD products werecarefully verified and consequentlythe distribution list was increased infew successive steps.

JASR 13:5-B

(5)10 G. DuchossoisandM. Fea

The SAR PD products started to be distributed through the Broadband DataDistribution Network (BDDN) making use of the EUTELSAT system to few Balticcentres in support to ice projects. The generation and distribution ofsimilar products by the Alaska BAR Facility and the Transo station to theirauthorized users started also in 1991. The BDDN service covers now the wholeEurope.

The LBR data, injected into the meteorological network through the nodes inRare and Bracknell, were firstly addressed only to saie centres whichparticipated to the verification and validation process. At the end ofOctober 1991, all europeanLBR Naninated Centres started receiving the PDproducts. After the signature of the NOAA/ESA Memorandum of Understanding,the dissemination of LBR Fl) products to USA and Canadawas activated. Theactual performance of the ERS-1 Fast Delivery Distribution system is shownbelow:

BAR (U116, UILR) upon request up to 20.08.92‘BY~AL 3745

LBR (TJRA, UWI, UWA) routine through GrS

When evaluating the performance of the LBR system, it has to be noted thatthe overall performance depends on various cariponents (satellite, groundstation, ESA and meteorological links), such that the success rate includesalso the performance of elements external to the ESA ERS-l Prograrrine.

The four Processing and Archiving Facilities operations caimnenced atdifferent t:imes, since their development has been flnpl~rented as a jointlong-term venture between ESA and national Agencies. To date not all the PAPel~tents are fully operational, on the one hand because of objectivesdifficulties and on the other hand because off-line precision productsrequire a more demanding validation and in same cases a long lead tine foraccumulating the necessary temporal data series.

Nevertheless, in terms of raw data archiving the PAFs are catching up and thefollowing tel~retry data have been archived on various media (High DensityDigital Tapes HDD~or Optical Disks OD) after quality control andcataloguing:

BAR

(Kiruna, N/F stations [Thorn-E~ni])(O’Higgins, N/F stations [others])(Fucino, Maspalanas)

LBR

F-PAP & UK-PAP (back-log being recovered)(3 orbits per optical disk)

To date, the following ERS-l Data Productshave been or are being validatedand made available for the users fran the ground stations and the PAFs (Ref.3):

1992 Feb Mar Apr May Jun Jul% success 88 96 87 82 95 94average delay fran sensing: 2 h 40 mm

UK-PAPD-PAFI-PAP

36,953 scenes17,428 scenes

1,715 scenes

> 2,200 OD’s

ERS-1OneYearAfter (5)11

ESA FACILITIESproducts validated and available

BAR RAW, U116, UILR, FDC, PRI, SLC, GEC, GINWave UWA, FDCOrbi PRL, PRCALT URA, FDC, OPRO2, WDRSCAT UWI, PDC

productsunder validationALT Q/L SSH, WDRATSR Baseline products

Gatineau, Prince Albert, ASF, Transo, Aussaguel, Cotopaxi,Cuiaba’India and Japan have been authorized to distribute on aexperinentalbasis.

The delivery of ERS-1products has increasingly progressed, and at the end of

August 1992 the situation was as follows:

BAR P~)DUCI’RF~UESTS

Carrrercial Orders for ESA FacilitiesPilot ProjectPrincipal InvestigatorsOthers (cal/val, QA, test, background)

‘BYrAL requested 4,715

products delivered 4,068

% requests satisfied 86.3

r.BR (ALT, SCAT) DELIVERY

FDC (ALT.URA, WSC.UWI) delivered routinely to interestedP1 ‘S since January1992

(re-processing of products before 5 Nov 91 started)August 1991 data deliveredSept-Oct 1991 almost ready24—31 Aug 1991 delivered to 13 P1’s

The generationand delivery of other data, like ATSR products, will start assoon as the products are validated.

SCME EARLY RESULTS

In the meanwhile, quality assessment and calibration and validationactivities lead to inportant results. For the first tine, the a~eolutecalibration of an spaceborneBAR data was achieved. In-flight antennapatternwere retrieved fruit the Amnazonian Rain Forest responses, and since 15Sept~nber1992 the ESA SAR.PRI products are fully calibrated: the in-flightantennapattern are applied, and the calibration constant is given. Thisallows to give, for the first tine for a spaceborne BAR, the absolute valueof the back-scattering coefficient Sigma Naught witht

N/F STATIONSvalidated:

207233

1,6822,593

ALT.OPRO2 (*)

ALT.WDR (*)

(*) productsvalidated in July 1992

(5)12 G. Duchossoisand M. Fea

a) a radiciietric stability = 0.37 dBb) a radianetric accuracy = 0.31 dB (mean)

= 0.74 dB (max)

(Radiatetric stability is the normalised standard deviation of radar echoesfran a number of identical points or distributed targets with stable radarcross-sections, assuming that the system is operating within the dynamicrange and that a linear calibration drift correction is performed on thedata. Radiametric accuracy is the nonnalised difference between the actualand the measuredtarget radar cross-section).

In addition. the great stability of the ERS-1 orbit has allowed novelapplications to be identified and studied. One of them is the use of BARcanplex data for interferanetric work. EBA has established the ERS-1_FRINGEWorking Group in January1992. Its activity has led already to the generationof a Digital Elevation Model (height noise estimatedto be 5 m) with 2-8 Aug91 datasets (Gennargentu,Sardinia) to daronstrate the technique. Currently,the evaluation of D~ quality for selected sites is in progress. Thecapability of ERS-1 to detect small rrovarents (-1 an) was achieved (Bonnexperiment, March 1992), and the evaluation of the sensitivity to smallterrain novanent is in progress over different areas. ESA supports theGroup’s activities by coordinating them, and scheduling acquisition,processing and distribution of data.

Certainly, in the danainof operations and applications a lot of expectationderives 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 verypreliminary results have confirmed the great potential of the ERS-1 data, andadditional pranising reports are expected at the ERS-1 Symposium to be heldin Canneson 4-6 November 1992.

MEDIUM AND LONG TE~PERSPECTIVES

ERS-1 is the forerunner of a serie of modem and advancedremote sensingsystansand is paving the way to the Earth Observation missions of the year2000. The needof ensuring long-term continuity to the ERS-1 data has beenwell perceived by EBA and its Delegates Bodies, such that ERS-2 has beenapproved and the satellite is being built for a launch in December 1994 orJanuary1995.

ERS-2 is quasi-identical to ERS-1. In fact it will carry on board an improvedversion of ATSR and a new atmospheric instrument, the Global Ozone MonitoringF~uiprent(G~4E):

- the flrproved version of the ATSR includes three additional channelsinthe visible part of the e.m. spectrum for vegetation monitoring

- the new experimental instrumrent ~XMEis a spectraneterworking in theultraviolet/visible band (250-790Nm), using differential absorption andbackscattertechniques. It will measurea range of trace constituents inthe troposphere and in the stratosphere, with the following targetmolecules

ERS-1OneYearAfter (5)13

Global Coverage Partial Coverage oroccasionalobservations

Constituents Constituents

03 SO2NO (above 40 ~n) HCII)

NO2 OC1OH2O ClO

02/04 N03BrO

plus aerosolsandpolar stratospheric clouds (PSC5)

It is worth Imentioning here that an intense activity is being carried outbetween ESA and its }‘~nber States, in close cooperation with ESA’ 5

international partners and user catinunities, in order to prepare the EBAEarth Observation long-term progranrme to be presented in November to theMinisterial meeting in Granada. The progranue is aimed at establishing thestrategy which will bring ESA activities into the years 2000 and focuses onfour basic objectives:

a) monitoring of the earth’s environment on various scales, fruit localthrough regional to global

b) monitoring and mnanagamentof the earth’ s resources, both renewable andnon-renewable

c) continuation of the services provided to the worldwide operationalmeteorological catinunity

d) contribution to the understandingof the structure and dynamics of theearth’s crust and interior.

Severalsatellite 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 for launch in 2000

- POEM Follow-on progrante,canprisingENVISAT-2 for launch in 2003MEIOP-2 for launch in 2005

- M~T~X)SATSecondGeneration, 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 EarthObservation missions can be surtinarized as follows:

ENVISAT-1 continuation and enchancanentof the ERS missions ascontribution to environmental studies, notably in the areasof atnosphericchemistry and marine biology

ESA funded core payload:

BAR - AdvancedSynthetic Aperture RadarGCK)S - Global Ozone Monitoring by Occultation of StarsMERIS - MEdium Resolution Imaging SpectraneterMIPAS - Michelson Interferareter for Passive Atmospheric SoundingHA-2 - Radar Altimeter-2 (including a microwave sounder)

(5)14 G. Duchossoisand M. Fea

instrurmentsprovided by national progrartines:

AATSR - AdvancedAlong-Track ScanningRadianeterPRAREE - Precise Range And Range-rate Equipitent ExtendedversionSCARAB - SCAnner for RAdiation BudgetSCIAMACHY - Scanning Imaging Atmospheric Spectraneter for Atmospheric

Chartography

ME’IOP-1: for operational neteorology as contribution to climate monitoringand operational climatology in the future; the mission will be carried outin the framework of an agreanent to be concluded with EUMF~TBAT.

core payload for operational meteorology:VIRSR - Visible and InfraRed Scanning RadianeterIRIS - Infra-Red Temperature SounderMIS - Microwave Tenperature SounderMHS - Microwave }~.nnidity SounderDCS - Data Collection SystemIASI - Infrared Atmospheric Sounding Interferaneter

proposedpayloads for climatology monitoring:MIMR - Multifrequency Imaging Microwave RadiareterASCAT - Advanced wind SCATterateterAATSR - AdvancedAlong-Track Scanning RadiareterGCME - Global Ozone Monitoring InstrumentSCARAB - SCAnner for RAdiation Budget

Both ENVIBAT-i and I~’IOP-i will make use of the COLUMBUSpolar platformand will be equippedto work with the Data Relay Satellite (DRS) system.

POEMFollow-on progrartine, as a preparation to:

ENVISAT-2 with develo~rent of new advanced instrumentation (e.g. lidar,multifrequency BARs, high resolution thermal infra-red radiareter)MEaOP-2 in cooperation with EUMETSAT

METEOSATSecondGeneration (MSG), follow-on of present METEOSATOperational 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 magneticfields, in cooperationwith NASA, as contributions to science andapplications 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 OneYearAfter (5)15

Obviously, the developnent of the above progrannes requires that a majoreffort is made on the development of the related ground segilent, inparticular for ENVISAT-i, effort which is basedon the experiencegainedwithERS-1 andERS-2 and takes into account the availability of DRS. Also, a majorprogress is foreseen in the capability for both operations and datamanag~rentby the ESA, national entities anddata users carrnunities.

In this context, a key role is played by the international cooperation.Strong partnerships are being developed in Europe with EUMETSPIT and theEuropean Econanic Cairnunity to ensure that Europe’ s needs in EarthObservationdataare net. Here, an important elanent is the establishment ofthe european carponent of the global environmrent data network. Closecooperationwith the USA (NASA and NOAA), Canada and Japan is also beingactively pursuedthroughexchangeof instrurrentationand data, making the endof the centuryvery challengingand at the sametime very pranising for theEarth Observationfran space.

~CES

1. ERS—i System- ESA SP-ii46, ESTEC, Noordwijk (NL), 19922. ERS-1 User Handbook- ESA SP-i148, ESTEC, Noordwijk (NL), 19923. ESA ERS—1 ProductSpecification - EBA SP-1l49, ESTEC, Noordwijk (NL),

1992

St~RYTABLES

ERS-1 PAYLOAD: Surrrrer 1992 outages

26—27 Jun 9219—23 Jul 92

9—10 Aug 9223—24 Aug 92

In stand-by due to a PDU ananalyIn stand-by due to investigtionsIn stand-by due to investigtionsSwitcheddown in stand-byProblem successfully circumvented

ERS-1 SAR HIS’IORY (up to 31 August 1992)

27 Jul 9127 Jul 91

4 Sep91

5 Sep91

15 Oct 91

11—12 Dec 9112 Dec 9111 Jan 92

23 Mar-3 May

4—13 Apr 9214 Apr 92July 1992

since 1 Sep 92

Initial operation checkFirst BAR Image acquiredand processedActivation of EBA transpondersin Flevoland (NL)ESA transponder gainadjusted by 6 dBCalibration constant K for ESA products fixed (sameuntil to date (BAR high radiaretric stability))Preliminary values of calibration coefficientavailable for EBA Verification Mode ProcessorRoll-Tilt Mode operational testEBA transpondersre-calibrated at ESTECActivation of ESA transponders in Zeeland (NL)Progressive re-calibration at ESTEC andre-deployment in Flevoland of the ESA transpondersRoll-Tilt Mode campaignRe-activation of EBA transpondersin Flevoland (NL)BAR radiaretric accuracy and stability over one yearconfinred within specificationsIn-orbit antennapattern applied to all ESA BAR. FRIproducts

E~-1SCATP HIS!IORY (up to 31 August 1992)

27 Jul 91 Initial operation check (G~JD-2airborne n~x~elused)

(5)16 G. DuchossoisandM. Fea

15 Sep 9119 Sep 91

29 Oct 914 Nov 91

10 Dec 9115 Jan 921 Mar 92

30 Apr 92

10 Jun 92

17 Jul 92

In parallel:

Jan — 15 Apr 92

Rene’ 91 Geophysical Campaign startedScaling 1.3 dB for all beams (Transponders)1st Mid beam correction (Rain Forest)TransponderstuningEnd of Engineering Calibration1st Fore/Aft beamcorrection (Rain Forest)Rene’-91 Geophysical CampaigncanpletedSampling correction (29.42 -> 29.942 kHz)Last AntennaPattern Tuning (sigma naught OK)2nd correction for all beams (Rain Forest +

Transponders)Rene‘-91 Workshop: Q4DD-3 selectedCMDD-3 spacebornemodel implementedin all ESAstationsAn~iguity Rai~val corrected (WIND interface).

Definition of the new model Q>~IJD-3

Initial operation checkCalibration carrpaignstartedCalibration campaigncanpleted(external calibration: -19.2 an -~ 5 an bias)routine dissemination of ALT PD (URA) startedPD processing tuned, loss-of-track algorithmimprovedTracker parameters tuned (more agile tracker)production of Quick Look Sea Surface Height (PD +

PRL averaged per 35-d cycle) started.

PhaseC operationalMode (per cycle):Over oceansOver Ice Polar Caps and Land

always in Ocean ModeIce 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 Nov 9119—23 Dec 91

7—11 Apr 9227 May 92

27 May-4 Jun 924-16 Jun 92

since 27 May 92

Initial operation checkMicrowave Sounder (~S)switch-on and operating

in naninal modeInfrared Radianeter (IRR) switch-onCcnmisioningactivities, care in usinq science dataIRR pixel selection map:IRR science data notto be used during the period 14:37:24 andl9:28:48 UTcIRR decontamination cycleIRR decontamination cycleIRR decontamination cycleIRR 3.7 pm channel data flow stoppedIRR 1.6 and 3.7 pm channel data not availableSwitched on various modes for investigationsIRR 3.7 pm channel data not available

Equipment switch-onFirst telemetry over StuttgartData frames & range codes acquiredat Stuttgart

ERS-1 ALT HISWRY (up to 31 August 1992)

25 Jul 911 Aug 91

17 Sep 91

24 Nov 91Dec 91

20 Jan 9214 Apr 92

ERS-1 PRARE HISWRY (up to 31 August 1992)

24 Jul 9125 Jul 9126 Jul 91

ERS-1OneYear After (5)17

29 Jul 91 09:36 Synchronisationof on-boardclock10:52 Synchronisation of range codeand correct

expansionof up-link carrnands91 12:54 Autariatic equipl~ntswitch-down91 Cairnandingtrials unsuccessful91 Equipment switch-off91 EquipmentOFF

ESA ERS-l PI~JDUC~S

Product Code

BAR AnnotatedRaw DataBAR Fast Delivery ImageBAR Fast Delivery Image CopyBAR Single Look CanplexImageBAR Precision ImageSAR Ellipsoid Geocoded ImageBAR Terrain GeocodedImageBAR Wave AnnotatedRaw DataSAR Wave Fast Delivery ProductSARWave Fast Delivery Product CopyBAR Wave Intermediate Product CopySAR Wave Canplex ImagetteBARWave DetectedImagette SpectrumBARWave Imagette Precise SpectrumWind Scatterareter Fast Delivery ProductWind Scatterareter Fast Delivery Product CopyScatterateter ExtractedWind CopyDealiasedoff-line Wind FieldsAltimeter Annotated Raw DataAlti.rreter Fast Delivery ProductAltirreter Fast Delivery Product CopyOff-line Intermediate ProductOcean Product, with Preliminary Orbit

with Precise OrbitAltimeter Wave data recordAltimeter Wave Foundation ProductSea Surface HeightSeaSurfaceHeight Quick LooksSea Surface TopographyOceanic GeoidPreliminary OrbitPrecise Orbit~S-1 Gravity Model First Generation

Under validation:

Infrared Brighthess TemperatureMicrowave Brighthess TenperatureSea SurfaceTemperaturePrecise Sea Surface TarperatureWater Vapour, Liquid Water Content

ERS—1.SAR.RAWERS—1. BAR. U116ERS—1.SAR.FDCERS—1.SAR.SLCERS—1. BAR. FRIERS—1.BAR.GECERS—1.BAR.~I’CERS—1. S~1.RAWERS—1. S~’I,f. UWA~S—1. S~N.FDCERS—1. S~1.IPCERS-1. S*1. CITERS-1. S~.DISERS—1. S~1.IFSERS—1.WSC.UWI~S—1.WSC. FDCERS—1.WSC.IWC~S—1.WSC.WNFERS-1.ALT.RAW~S-1 .ALT.URA~S-1 .ALT . PDCERS-1.ALT . OIPERS-1.ALT.OPRO1ERS-1.ALT . OPRO2ERS-1.ALT.WAPERS-1.ALT .WDRERS-1.ALT. SSHERS-1.ALT. SSI~LERS-1.ALT . ~OPERS-l.ALT . OGEERS-1. ORB.PRLERS-1.ORB.PRCERS-1.ORB.Ea~tl

ERS—1.I4TS.IBTERS—1.ATS.MBTERS-1.ATS . SSTERS—1.ATS.PSTERS—1.ATS.VLC

29 Jul1 Aug1 Aug

since 1 Aug

ATSRATSRATSRATSRATSR

JASR 13:5-C

(S)18 G. Duchossois and M. Fea

SAR Antenna

_. -~ ATSR- MIcrowove Sounder

’ ATSR - Infro-red Radiometer

Laser Retro-reflectors

Figure 1 The EM-1 instruments.