The Atmospheric Monitoring System of the JEM-EUSO Space Mission

1.6 MB·English

by  M. D. Rodriguez Frias

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The Atmospheric Monitoring System of the JEM-EUSO Space Mission
M. D. Rodríguez Frías1,2, S. Toscano2, E. Bozzo2, L. del Peral1,2,a, A. Neronov2, and S. Wada3 for the JEM-EUSO
Collaboration.
1SPace&AStroparticle(SPAS)Group,UAH,Madrid,Spain.
2ISDC,AstronomyDept.UniversityofGeneva,Versoix,Switzerland.
5
3RIKENAdvancedScienceInstitute,Japan.
1
0
2
Abstract.AnAtmosphericMonitoringSystem(AMS)isamandatoryandkeydeviceofaspace-basedmission

n which aims to detect Ultra-High Energy Cosmic Rays (UHECR) and Extremely-High Energy Cosmic Rays
a (EHECR)fromSpace. JEM-EUSOhasadedicatedatmosphericmonitoringsystemthatplaysafundamental
J
role in our understanding of the atmospheric conditions in the Field of View (FoV) of the telescope. Our

0 AMSconsistsofaverychallengingspaceinfraredcameraandaLIDARdevice,thatarebeingfullydesigned
2 with space qualification to fulfil the scientific requirements of this space mission. The AMS will provide

informationofthecloudcoverintheFoVofJEM-EUSO,aswellasmeasurementsofthecloudtopaltitudes
]
M with an accuracy of 500 m and the optical depth profile of the atmosphere transmittance in the direction of
eachairshowerwithanaccuracyof0.15degreeandaresolutionof500m. Thiswillensurethattheenergy
I of the primary UHECR and the depth of maximum development of the EAS ( Extensive Air Shower) are
.
h measuredwithanaccuracybetterthan30%primaryenergyand120g/cm2 depthofmaximumdevelopment
p forEASoccurringeitherinclearskyorwiththeEASdepthofmaximumdevelopmentaboveopticallythick
-
cloudlayers.MoreoveraverynovelradiometricretrievaltechniqueconsideringtheLIDARshotsascalibration
o
r points, thatseemstobethemostpromisingretrievalalgorithmisunderdevelopmenttoinfertheCloudTop
t Height(CTH)ofallkindofclouds,thickandthincloudsintheFoVoftheJEM-EUSOspacetelescope.
s
a
[

1 1 Introduction beingfullydesignedunderspacequalificationtofulfilthe
v
scientificrequirementsofthisspacemission.
1
2 Cosmic Ray Physics is one of the fundamental key is-
8 sues and an essential pillar of Astroparticle Physics that 2 The Atmospheric Monitoring system
4 aims, in a unique way, to address many fundamental
0 Tofullymonitortheatmosphereandtoretrievethecloud
questions of the non-thermal Universe in the Astroparti-
1. cle Physics domain. The huge physics potential of this coverageandcloudtopheightintheJEM-EUSOFoV,an
0 AtmosphericMonitoringSystem(AMS)isforeseeninthe
field can be achieved by an upgrade of the performances
5 telescope. TheAMS[2]iscrucialtoestimatetheeffective
of current ground-based experiments and pioneer space-
1
UHECR&EHECRexposureofthetelescopeandforthe
: based missions, as the JEM-EUSO space telescope [1].
v proper analysis of the UHECR & EHECR events under
The JEM-EUSO space mission is the Extreme-Universe
i cloudyconditions[3],[4].
X Space Observatory (EUSO) which will be located at the
TheAMSofJEM-EUSOwillinclude:
r Exposure Facility of the Japanese Experiment Module
a (JEM/EF) on the International Space Station (ISS) and 1. abi-spectralInfrared(IR)camera;
looking downward the atmosphere will allow a full-sky
2. aLIghtDetectionAndRanging(LIDAR)device;
monitoringcapabilitytowatchforUltra-HighEnergyCos-
mic Rays (UHECR) and Extremely High Energy Cos-
3. globalatmosphericmodelsgeneratedfromtheanal-
micRays(EHECR).AnAtmosphericMonitoringSystem
ysis of all available meteorological data by global
(AMS)ismandatoryandakeyelementofaSpace-based
weather services such as the National Centers
mission which aims to detect Ultra-High Energy Cosmic
for Environmental Predictions (NCEP), the Global
Rays(UHECR).JEM-EUSOhasadedicatedatmospheric ModelingandAssimilationOffice(GMAO)andthe
monitoringsystemthatplaysafundamentalroleinourun-
EuropeanCentreforMedium-RangeWeatherFore-
derstanding of the atmospheric conditions in the FoV of
casts(ECMWF)[5].
the main telescope. The JEM-EUSO AMS consists of a
bi-spectral infrared camera and a LIDAR device that are 4. the slow mode data of JEM-EUSO, the monitoring
of the pixel signal rate every 3.5 s for the observa-
ae-mail:[email protected] tion of Transient Luminous Events (TLEs), which
AtmoheadConferenceseries
will give additional information on cloud distribu- thecoldspotoftheopticsthatallowsamultispectralsnap-
tionandtheintensityofthenightskyairglow. shot camera without a dedicated filter wheel mechanism
is foreseen. This is a very “smart” solution that leads to
TheJEM-EUSOtelescopewillobservetheEASdevelop- have a more reliable baseline and to reduce the costs of
mentonlyduringnighttime.TheIRcamerawillcoverthe acomplicatedfilterwheelmechanismintendedforSpace
entireFoVofthetelescopeinordertodetectthepresence applications. The only drawback of this solution is that,
ofcloudsandtoobtainthecloudcoverandthecloudtop in order to overcome the use of half of available area of
altitude. TheLIDARwillbeshotinsomepre-definedpo- thedetectorforeachspectralband,theIR-Cameraimages
sition around the location of triggered EAS events. The acquisition time has to be faster to avoid gaps during the
LIDAR will be used to measure the clouds altitude and ISSorbitwiththeimpactontherestricteddatabudgetal-
optical depth as well as the optical depth vertical profile locatedforanISSmission.
oftheatmospherealongthesedirectionswitharangeac-
curacyof375minnadir. TheIRcameraandtheLIDAR
havebeendesignedtoworkinacomplementaryway.
3 The Infrared Camera
TheIRCamera(Fig.1)onboardJEM-EUSOwillconsist
ofarefractiveopticsmadeofgermaniumandanuncooled
µbolometer array detector. The FoV of the IR Camera is
48◦, totally matching the FoV of the main JEM-EUSO
telescope. The angular resolution, which corresponds to
onepixel,isabout0.1◦. Atemperature-controlledshutter
inthecameraandblackbodiesareusedtocalibrateback- Figure 2. Preliminary Design Scheme of the Optical Unit As-
ground noise and gains of the detector to achieve an ab- sembly.
solute temperature accuracy of ∼ 3 K. Therefore, the IR
Camera takes images continuously every 17 s while the
ISSmoves1/4oftheFoVoftheJEM-EUSOtelescope.
Figure3. SchemeoftheCalibrationunitAssemblypreliminary
Figure1.IRCameraPreliminaryDesignModelization designwiththetwoBlackBodiesBB1&BB2andthestepper
motor
Abrightnesstemperaturemeasurement,intendedfora
single band infrared camera configuration, may not pro- ThepreliminarydesignoftheIRCamera[6]canbedi-
vide the required radiometric accuracy without the use videdintothreemainblocks:theTelescopeAssembly,the
ofexternalinformationforatmosphericeffectscorrection. Calibration Unit and the Electronic Assembly. The main
Therefore a multispectral approach has been selected as function of the Telescope Assembly is to acquire the in-
baseline of the Infrared Camera of JEM-EUSO [6]. The frared radiation by means of an uncooled microbolome-
delailedanddedicatedretrievalalgorithmforthecloudtop terandtoconvertitintodigitalcounts. Adedicatedopti-
heightparameterthatfulfillthescientificandtechnicalre- caldesignhasbeendevelopedaswell,withahugeangu-
quierementsoftheInfraredCameraofJEM-EUSOcanbe larfieldtocomplywiththewideFoVoftheJEM-EUSO
foundintheseProceedings[4]. Inthepreliminarydesign main telescope (Fig. 2). To assure the high demanding
of the IR-Camera a bi-spectral design with two filters in accuracy,adedicatedon-boardcalibrationsystemisfore-
Proceedingsofthe2ndAtmoheadConference,May19-21,2014.Padova(Italy)
seen(Fig.3).Moreover,thisSystemPreliminaryDesignis drivingboardblock. Thecontrollingboardblockiscom-
complementedbyachallengingMechanicalandThermal posedoftheelectronicsboardinwhichwillrunthecom-
design to secure that the IR-Camera will be completely municationprotocol,usingaRS422typeas“telemetryand
isolated(Fig.4). command"bus. Thiscontrollingboardisalsoinchargeof
thecompressionalgorithmusedfortheimagespreviously
captured by the optics to be sent to the Main Instrument.
AssessmentoftheVHDLcodeoccupationhasbeenmade
giving as a result that at least a RTAX2000S FPGA from
Actel is needed to implement the compression algorithm
andthecommunicationsprotocol. TheDrivingBoardwill
be composed of the board which contains the driver for
the motor and the switches acquisition. Both functional-
ities will be managed by a small FPGA which runs the
controlalgorithmanddrivestheactuator. Occupationas-
sessment has been performed, giving as a result that the
RTSX72-SUFPGAfromActelissuitableforthisdesign.
In addition, a motor will be connected to drivers through
relays. Theserelayswillisolatethemotorfromelectron-
ics when stands off. Otherwise, some currents from non-
activewindingcouldbedriventothenon-activeelectron-
ics. Drivingboardwillprovidepowertotheheaters(32.2
Figure 4. Heaters & Temperature Sensors Distribution in the Ωresistancewithanominalpowerdissipationof1.69W)
System Preliminary Design of the Infrared Camera of JEM-
placedincalibrationunitbymeansofa1HzPulseWidth
EUSO.
Modulation(PWM)lineof15V.
Meanwhile, the Electronic Assembly provides mech- A full characterization and calibration of the Bread
anisms to process and transmit the obtained images, the Board Model (BBM) for the Infrared Camera of the
electrical system, the thermal control and to secure the EUSO-Balloon pathfinder led by CNES [7] was per-
communicationwiththeplatformcomputer.TheElectron- formed on April 2014 at the Instituto de Astrofisica de
icsAssemblywillbecommunicatedwiththeMainInstru- Canarias (IAC, Tenerife). Moreover this dedicated bi-
ment(apartfromthepowerinputbuses)bymeansofthree spectral and waterproof Infrared Camera was flown with
main links: a Data link, a Command link, and Synchro- EUSO-BALLOON first flight on August 24, 2014 from
nizationlines. Inaddition, theElectronicsAssemblywill Timmins(Canada)(Fig.6).
provide discrete telemetries to the Main Instrument. Re-
gardingtheFrontEndElectronics(FEE),theywillbealso
communicated through serial links, synchronization lines
andpowergeneratedintheElectronicsAssemblytosup-
plytheFEE(Fig.5).
Figure6.Dedicatedbi-spectralandwaterproofInfraredCamera
fortheEUSO-BALLOON(CNES)pathfinder.
4 The LIDAR
Figure5.FEEoverviewoftheInfraredCamera.
ThetaskoftheLIDARistolocalizeopticallythinclouds
Moreover,theInterfaceControlUnit(ICU)canbesep- and aerosol layers and to provide measurements of the
arated into 2 blocks: the controlling board block and the scattering and absortion properties of the atmosphere in
AtmoheadConferenceseries
theregionoftheEASdevelopmentandbetweentheEAS tiveMicro-Electro-MechanicalSystems(MEMS)technol-
andtheJEM-EUSOtelescope. ogyhasbeenselectedbytheUniGetodevelopthetilting
mirror [8]. This mechanism will use magnetic forces to
4.1 LIDARdesign
The LIDAR is composed of a transmission and a receiv-
ingsystem.ThetransmissionsystemcomprisesaNd:YAG
laser and a pointing mechanism (PM) to steer the laser
beam in the direction of the triggered EAS events. As
thelaserbackscatteredsignalwillbereceivedbackbythe
JEM-EUSO telescope (working as the LIDAR receiver),
thelaseroperationalwavelengthwaschosentobethethird
harmonicoftheNd:YAGlaser,atλ=355nm.Thelaseris
beingdevelopedatRIKEN(Japan)andwillbepartofthe
JAXA (Japanese Space Agency) contribution to the Mis-
sion. The PM is under development at the University of
Geneva,inclosecollaborationwithCSEM1(Switzerland).
In the current JEM-EUSO design, the light of the
pumpingdiodesisguidedtothelaserheadthroughanop-
ticalfibre. ThePMisconceivedtohaveasteeringmirror
withtwoangulardegreesoffreedomandamaximaltilting
Figure8. CADmodeloftheMEMSmirror(notinscale,view
angleof±15◦, neededtomovethelaserbeamanywhere fromthebottomside). Themirrorissquezedbetweentwosup-
within the JEM-EUSO FoV. The LIDAR system will be portstructures. Itisholdthroughsiliconbeamersthatallowtilt-
integrated into the JEM-EUSO telescope. A preliminary ingmovementswhentheleverslocatedonthebottomsupport-
schemeoftheplacementofthedifferentelementsisshown ingstructureareforcedintheXandYdirectionbythemagnetic
inFig.7. Asummaryofthespecificationsneededforthe forces generated by two magnets and the coils controlled by a
entiresystemisreportedinTab.1. dedicatedelectronicboard. Thecoilsarenotsketched. Thetwo
magnetsarenotvisible,butlocatedatthebottomoftheactuation
points.
achieve the steering pointing function. A CAD design of
the device has been already prepared and is presented in
Fig.8. Itconsistsofasandwichoftwosupportingstruc-
turesthatallowatip-tiltmovementofthemirrorsqueezed
inbetween. Thelowersupportingstructurecanbeforced
in the X and Y directions independently by levers con-
nected to it. The ends of these levers are connected to
guidedmagnetsthatareactuatedintheXandYdirections
bycoils.Thecoilswillbecontrolledthroughanelectronic
control board, that is also in charge to receive the trigger
forpossibleEASeventsandtranslatethisintomirrorde-
Figure7.SchematicLIDARplacementontheJEM-EUSOtele-
scope. The laser head and the pointing mirror will be placed placements. Themirrorpositioniscontrolledatanytime
close to the front lens of the telescope, while the pump diodes through a high precision positional sensor and the auxil-
andthecontrolelectronicsforthemirrorswillbeplacedonthe iaryopticalsystem. Boththelaserandthebeamusedfor
focalsurface. the positional sensor will be facing the front side of the
mirror,assketchedinFig.9. ThedevelopmentofthePM
at the UniGe is currently in phase B1. This phase is ex-
The LIDAR is expected to receive on average a new
pectedtobecompletdattheendof2014andencompasses
trigger on possible EAS events roughly every ∼10 s. In
thecompletedesignofanElegantBreadBoard(EBB,see
thetimebetweentwoconsecutivetriggers,thePMshould
Fig.10),whosescopeistodemonstratetheachievementof
beabletodecodetheinformationonthelocationofthelast
thecriticalPMfunctionalities.TheEBBcomprisesacom-
triggeredeventwithinthetelescopeFoV,re-pointthelaser
mercial version of the laser operating at the same wave-
beamin thisdirection, andshoot5 lasershots coveringa
lenghtoftheJEM-EUSORIKENlaser,anopticalsystem
sufficientlywideregionaroundtheEASposition. Theef-
withapositionencoder,theMEMSmirrorprototype,and
fective time available to the pointing system to steer the
thecontrolelectronics.TheEBBwillbeimplementeddur-
laserbeamisthustypicallyoffewtenthsofseconds,thus
ing phase B2 and it is expected that a fully operational
requiringalightweightmirrorwithlimitedinertiatoopti-
modelwillbeavailableattheendof2015. Aqualification
mizetheoperationsofthePM.Forthisreason,theinnova-
and flight model of the JEM-EUSO PM are planned for
1www.csem.ch >2016(projectphaseC/D).
Proceedingsofthe2ndAtmoheadConference,May19-21,2014.Padova(Italy)
backscattered signal detected by the JEM-EUSO tele-
scope.
Altitude [km]
25 20 15 10 5
U] 1000
T Clear sky
e/G 800 Cloud: top = 7 km, τ = 1
h
p 600
al [
n 400
g
si
d 200
e
v
ei 0
c
e
RR)2080
Figure9.Representationofthelaserandpositioncontrolbeam, o (S 67
facingthefrontsideoftheMEMSmirror. ati 5
ng r 43
atteri 021
Sc 11250 1300 1350 1400
Time after shot [µsec]
Figure11. Top: LIDARbackscatteredsignalinclearsky(blue)
andinthepresenceofanopticallythick(τ=1)cloud(red)asa
functionoftime.Bottom:Scatteringratio(SR).
Thetoppanelshowsthesignalincaseofclearatmo-
sphere(bluecircles)andinpresenceofthecloud(redtri-
angles) as a function of the time after shooting the laser
Figure 10. CAD model of the LIDAR PM EBB. In the figure
and the altitude. The presence of a cloud at ∼ 7 km will
we show the housing, the commercial version of the laser that
be clearly detected by the LIDAR as an increase of the
willbeusedfortheEBB,theopticalsystemsupportingthepo-
backscattered signal coming from that region. The bot-
sitionalsensor, thememsmirror, andtheelectronicboard. All
tom panel shows the so-called LIDAR Scattering Ratio
componentsarerepresentedinscale(theMEMSmirrorisabout
3×3mmlarge). Theredbeamrepresentsthelaserbeam,while (SR), the ratio between the backscattered signal detected
the green one is the beam used to measure the position of the in the real condition and a reference profile which repre-
MEMSmirrorthroughthepositionalsensorandthesupporting sentsthebackscatteredsignalinclearatmosphere. Fitting
opticalsystem. the SR in the region below the cloud allows for the mea-
surement of the optical depth simply using the formula
τ=−log(SR)/2.
Table1.SpecificationfortheJEM-EUSOLIDAR.
Once the cloud is detected and its optical depth de-
termined,thecloud-affectedEASprofilecanbecorrected
Parameter Specification
usingtheformula:
Wavelength 355nm
Signal =Signal (exp−τ). (1)
RepetitionRate 1Hz cloud clear
Pulsewidth 15ns Fig.12showsthephotonsarrivaltimeinGTU2 atthede-
Pulseenergy 20mJ/pulse tectorfocalplaneforashowergeneratedbyaUHEproton
Beamdivergence 0.2mrad withE =1020 eVandθ =60◦. Thebluehistogramrepre-
Receiver JEM-EUSOtelescope sentstheprofileoftheshowerdevelopinginaclearatmo-
Detector MAPMT(JEM-EUSO) sphere,characterisedbythepresenceofthe“groundmark"
Rangeresolution(nadir) 375m at∼60GTU.ThisfeatureisduetoCherenkovphotonshit-
Steeringofoutputbeam ±30◦fromvertical tingthegroundandreflectedbacktotheJEM-EUSOfocal
Mass 14kg surface.Theredhistogramshowstheprofileoftheshower
Dimension 450×350×250mm crossingthesameopticallythickcloudshotbytheLIDAR
Power <20W andlocatedatanaltitudeof∼7km. Asinthecaseofthe
LIDAR,thepresenceofthecloudmodifiestheEAStime
profile, with the appearance of a new feature (the “cloud
4.2 Simulationsanddataanalysis mark")at∼28GTU,andthegroundmarkvanishing. Af-
terthecorrectionisdoneusingtheLIDARmeasurementit
Simulations[9]havebeencarriedoutinordertostudythe ispossibletoretrievethecorrectprofile(blackpoints)and
capability of the system in retrieving the physical prop- almostentirelyrecoverthegroundmarkfeature.
erties of atmospheric features such as clouds or aerosol 2TheGateTimeUnit,orGTU,isthetimeunitofthedetectorfocal
layers. Fig. 11 shows an example of the simulated laser surface;1GTUcorrespondsto2.5µsec.
AtmoheadConferenceseries
Homage to the Discovery of Cosmic Rays. Nova Sci-
Shower in clear sky Reconstructed profile encePublishers,NewYork,ISBN:978-1-62618-998-0,
Shower in cloud (top = 7 km, τ = 1)
Inc,Pg201-212(2013).
70 [2] Rodríguez Frías, M. D. et al. for the JEM-EUSO
cloud mark Collaboration. The Atmospheric Monitoring System
60
of the JEM-EUSO Space Mission. Proc. International
phe]50 Symposium on Future Directions in UHECR Physics,
gnal [40 The European Physical Journal, Vol 53, 10005-pg1-
d si 7, http://dx.doi.org/10.1051/epjconf/20135310005,
e
ect30 ground (2013).
et mark
D20 TheJEM-EUSOCollaboration(correspondingauthors
S. Toscano, J. A. Morales de los Rios, A. Neronov,
10
M. D. Rodríguez Frías & S. Wada). The Atmospheric
00 10 20 30 40 50 60 70 Monitoring System of the JEM-EUSO instrument.
GTU [=2.5 µsec] Experimental Astronomy 37, DOI 10.1007/s10686-
014-9378-1(2014).
Figure12. Reconstructedtimeprofile(blackpoints)of1020eV [3] Sáez-Cano,G.,Shinozaki,K.,delPeral,L.,Bertaina,
EAStogetherwiththeclearatmosphere(blue)andcloudaffected M. and Rodríguez Frías, M.D. for the JEM-EUSO
(red)profiles.Errorbarsarestatisticalonly. Collaboration.Observationofextensiveairshowersin
cloudy conditions by the JEM-EUSO Space Mission.
AdvanceinSpaceResearch,53,1536-1543(2014).
5 Conclusions [4] Sáez-Cano, G., Morales de los Rios, J. A., del Peral,
L., Neronov, A., Wada, S. and Rodríguez Frías, M.D.
TheInfraredCameraandLIDARoftheJEM-EUSOSpace fortheJEM-EUSOCollaboration.Thinandthickcloud
Mission are under fully design, prototyping and devel- topheightretrievalalgorithmwiththeInfraredCamera
opment under responsability of Japan, Switzerland and andLIDARofJEM-EUSO.TheseProcc.
Spain. Presently both devices are under Preliminary De- [5] http://www.ncep.noaa.gov/;
signPhaseandspacequalificationoftheInfraredCamera http://gmao.gsfc.nasa.gov/;http://www.ecmwf.int/
and the LIDAR are foreseen to accomplish for the scien- [6] Rodríguez Frías, M. D. et al. for the JEM-EUSO
tificandtechnicalspecificationsoftheJEM-EUSOSpace Collaboration. Towards the Preliminary Design Re-
Mission. view of the Infrared Camera of the JEM-EUSO Space
Mission. Proc. of 33rd International Cosmic Ray
Conference (ICRC), Rio de Janeiro, Brazil (2013),
Acknowledgements
arXiv:1307.7071v1[astro-ph.IM]
The JEM-EUSO team at the University of Geneva ac- TheJEM-EUSOCollaboration(correspondingauthors
knowledgessupportfromtheSwissSpaceOfficethrough J. A. Morales de los Rios & M. D. Rodríguez Frías).
a dedicated PRODEX program. This work is sup- The Atmospheric Monitoring System of the JEM-
portedbytheSpanishGovernmentMICINN&MINECO EUSO instrument. Experimental Astronomy 37, DOI
under the Space Program: projects AYA2009-06037- 10.1007/s10686-014-9402-5(2014).
E/AYA, AYA-ESP 2010-19082, AYA-ESP 2011-29489- [7] VonBallmoos,P.,etal.Aballoon-borneprototypefor
C03,AYA-ESP2012-39115-C03,AYA-ESP2013-47816- demonstratingtheconceptofJEM-EUSO.Advancein
C4, MINECO/FEDER-UNAH13-4E-2741, CSD2009- SpaceResearch53,1544-1560(2014).
00064(ConsoliderMULTIDARK)andbyComunidadde Morales de los Ríos, J. A., Joven, E., del Peral, L.,
Madrid under projects S2009/ESP-1496 & S2013/ICE- Reyes, M., Licandro, J., and Rodríguez Frías, M. D..
2822. M. D. Rodriguez Frias acknowledge International TheInfraredCameraPrototypeCharacterizationforthe
VisitorGrantfromtheSwissNationalScienceFoundation JEM-EUSO Space Mission. Nuclear Instruments and
(SNSF). MethodsNIMA,749,74-83,ISSN0168-9002(2014).
[8] D. Bayat, “Large Hybrid High Preci-
sion MEMS Mirrors”, PhD Thesis, 2012
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