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The Bepicolombo Spacecraft, Its Mission to Mercury and Its Thermal 5Erik Cation 1Oger ) 6Ikson Anc Markus Schekkke Irbus #S &Mb' %Riecrichshaeen &Ermany

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The Bepicolombo Spacecraft, Its Mission to Mercury and Its Thermal 5Erik Cation 1Oger ) 6Ikson Anc Markus Schekkke Irbus #S &Mb' %Riecrichshaeen &Ermany The BepiColombo Spacecraft, its Mission to Mercury and its Thermal 5erik cation 1oger ) 6iKson anC Markus ScheKkKe irbus #S &mb' %rieCrichshaEen &ermany !eOi"oKombo is a Ioint $S ) 7 mission to OKace 2 sOacecraEt in orbits arounC Mercury Airbus DS is prime contractor for the European industrial part From Launch to Mercury Orbit Functional Breakdown Mission Objectives 3hD main sciDntij c obIDctiUDs oE thD !DOi "oKombo mission to MDrcurX comOrisD thD inUDstigation oE thD origin anC DUoKution oE a OKanDt cKosD to thD OarDnt star anC a comOrDhDnsiUD stuCX oE thD OKanDt itsDKE 3his ViKK bD achiDUDC bX OKacing tVo sOacD craEt in CiEEDrDnt OoKar orbits arounC MDrcurX !y courtesy oE ) 7 The )aOanese MMO Mercury The $uroOean MPO Mercury PKanetary Orbiter carries Magnetos Oheric Orbiter carries 11 instruments some Vith muKtiOKe sensors instruments Vith a totaK oE 11 sensors Spacecraft Driving Requirements MPO continuously nadir pointing: • Nadir pointing provides maximum science return with continuous MMO spins when free Ļ ying, therefore planet observation needs shading during the 3-axis stabilised cruise phase: • Causes sun illumination of “all” spacecraft faces • A sunshade and interface structure are required ¨Solution needed to provide a heat rejection radiator ¨a separate module is needed 3hD M"2 Mercury ComOosite SOacecraEt consists oE 4 oOtimiseC moCuKes MPO l is oOtimiseC Eor its oOerationaK mission Deceleration of 7 km/s needed to reach the innermost planet • PerEorms commanC anC controK Eor M"2 Mercury: • PerEorms aOOroach OroOuKsion anC Mercury orbit KoVering • Planetary gravity assists are used to provide braking and 4.4 km/s braking is provided by electric propulsion MMO (requiring 10 kW power) • 2Oins Curing its oOerationaK mission Launch Operations and Control Requirements: ¨a separate module is needed • (s OassiUe Curing cruise • rianD $" into DscaOD orbit • Communication delays: maximum one-way signal time 14 minutes MOSIF MMO Sun2hieKC anC InterFace Structure Interplanetary Cruise Phase • Solar conjunctions of 20 days in cruise and 7 days in • 3hermaK Orotection Eor the MMO • 1 W $arth 2 W 5Dnus anC W MDrcurX graUitX assist manoDuUrDs Mercury orbit – no ground contact possible • MechanicaK anC eKectricaK interEaces Eor the MMO • $KDctric ProOuKsion Eor braking bDtVDDn graUitX assists shortDns transEDr • Temperature control by maintenance of safe attitude • M3M sDOaration on 1 11 202 aEtDr 1 orbits arounC thD sun (especially of solar arrays) MTM Mercury TransEer MoCuKe Operational orbits around Mercury can only be inertially ĺ xed • ProUiCes braking by means oE eKectric OroOuKsion ¨ Mercury Approach Phase polar orbit of 0° inclination chosen: • ProUiCes oUeraKK OoVer source Curing cruise • -aUigation bDEorD caOturD thDn orbit KoVDring • Orbit offset to manage thermal environment. • "hemicaK OroOuKsion Eor naUigation anC O"S • %rDD graUitX caOturD on 01 01 2024 MPO: 480 km x 1,500 km, MMO: 590 km x 11,640 km • 1000 ms manoDuUrDs ODrEormDC bX MPO • Apoherm towards sun at perihelion to constrain planet Subsystem and Hardware • MMO sDOaration in MMO orbit IR load to 5200 W/m2 (5400 W/m2 at aphelion) • MO2(% sDOaration Implications • #DscDnt to MPO orbit The CriUing rePuirements haUe imOacts beyonC the mechanicaK Module Attachment and Separation anC thermaK systems Communications System M"S conj guration anC seOarations aEter years oE cruise • 7 anC *a banCs Eor 10 &bityr science Cata anC 77 • The centraK structure oE the M"S at Kaunch is comOoseC oE mo 7*a *a*a ranging CuKe structures IoineC by inter moCuKe eKements IM' Inter • ntennas oE titanium to surUiUe thermaK enUironment MoCuKe Har CVare l incK 2 W 2 eKectricaK connections • 4 Ooint attachments at MTM MPO anC MPO MOSI% interEaces Power System emOKoyeC to enabKe minimisa tion oE Oarasitic heat inOut once in • SoKar rrays oOerating at 10¦" TemOerature KimiteC by tiKting Mercury orbit OaneKs unCer O"S controK to ¦ Erom sun The IM' eKements Oass through the #T" DeOKoyabKe ThermaK • 1 OS1s on MPO SoKar rray CoUer Erames to connect the structures Eter seOaration the MLI Ciscs oE the AOCS (AttitudeControl) #T"s are CeOKoyeC to thermaKKy cKose • "ontroK oE sOacecraEt anC soKar array attituCes in an the aOertures in the main MLI enUironment Vhere 10 seconC CeKay can cause oUerheating • "aters Eor OhysicaK conj gurations Thermal Environment Boundary Conditions due to Mercury’s proximity to the Sun: Data Management • Solar intensity varying between 6,300 W/m2 and 14,500 W/m2 • %"$ %aiKure "ontroK $Kectronics ensures continueC O"S (> 10 solar constants), plus IR >5,200 W/m2 saEe oOeration Curing reboot oE main comOuter • %irst sOacecraEt Vith netVork aOOKication oE SOaceVire interEaces Eor science Cata Electric Propulsion System DTC MPO to MTM • 4 W 14 m- T ion thrusters oOerateC singKy or in Oairs MPO Mercury Orbit Phase IMH attachment • -ominaK mission 1 $arth year l 2024 • $WtenCeC mission 1 $arth year Eoreseen Launch mass 4120 kg MPO mass on orbit 1240 kg Thermal Design for the severe thermal environment Thermal 5erik cation Programme The MPO unCergoes a k iO oUer manoeuUre tVice Oer Mercury MOSIF – including MPO l ight model year in orCer to OroUiCe a singKe raCiator surEace Eor heat reIection MLI comOrises a singKe -eWteK outer Kayer Vith CimOKeC titanium then Kayers seOarateC by gKass sOacers %reeKy suOOorteC oUer Kengths The LSS Large SOace SimuKator at $ST$" is being useC to test anC • 'eatOiOes are embeCCeC in the ePuiOment mounting OaneKs anC oE uO to 2 m UeriEy each moCuKe the raCiator OaneK to transEer anC Cistribute heat • The LSS Vas moCij eC anC has suOOorteC !eOi"oKombo since • LouUres in Eront oE the raCiator rek ect the OKanet inErareC raCiation MTM SeOtember 2010 Vhen the MMO thermaK moCeK Vas testeC VhiKst aKKoVing the raCiator a UieV to sOace contains embeCCeC anC surEace heatOiOes anC uses MLI CeriUeC n intensity oE soKar constants is achieUabKe at 2 m • The entire MPO boCy is coUereC Vith high temOerature ML( Erom the MPO Cesign • The MOSI% MMO Vere successEuKKy testeC thereaEter CeUeKoOeC Eor !eOi"oKombo in orCer to combat temOerature anC • The MPO STM EoKKoVeC a year Kater shoVing notabKe CeUiations Erom restrict heat inOut into the boCy the OreCicteC OerEormance reUieV oE the CetaiKeC Cesign anC the Outer heat shieKC comOrises 2 Kayers oE -eWteK ceramic cKoth MLI construction Vas OerEormeC EoKKoVeC by 11 aKuminium Kayers 2 aKuminiseC 4OiKeW Kayers • In autumn 2012 a Karge scaKe test 2 W m samOKes Uerij eC the anC 10 aKuminiseC MyKar Kayers in Oackets comOKete imOroUeC MLI Cesign Eor the MPO k ight moCeK the MLI • The MTM STM Vas successEuKKy testeC in sOring 201 its P%M test The -eWteK Kayers reach 0¦" is stiKK to come • The EuKKy ePuiOOeC MPO P%M Vas testeC in -oUember 2014 This conj rmeC the imOroUeC OerEormance oE the thermaK Cesign anC aKso the correct Eunctioning oE the eKectricaK systems oUer the mission temOerature ranges MPO high temperature MLI k Wation MPO PFM - thermal testing in LSS MOSIF + MMO – thermal test models in LSS 4th Lunar anC PKanetary Science "onEerence The 6ooCKanCs TW The BepiColombo Spacecraft, its Mission to Mercury and its Thermal Verification 46th Lunar and Planetary Science Conference, The Woodlands, March 2015 The BepiColombo Spacecraft, its Mission to Mercury and its Thermal Verification. Roger J. Wilson1 and Markus Schelkle1, 1 Airbus Defence and Space, Friedrichshafen, Germany ([email protected]) Abstract The spacecraft and subsystem designs are strong- BepiColombo is an interdisciplinary mission per- ly driven by the severe demands of the thermal envi- formed in a partnership between ESA (European ronment experienced at Mercury (whilst the same Space Agency) and JAXA (Japan Aerospace Explo- solar intensities are also experienced during cruise) ration Agency). The mission aims to place 2 space- and by the staging necessary to evolve the mechani- craft in complementary orbits around Mercury and cal/electrical configuration from the 4-module com- perform scientific investigations of the planet. The posite at launch to the two free-flying orbiters. BepiColombo scientific results will add to the Equipment not required in Mercury orbit is ejected knowledge already gained from the Mariner 10 fly- before capture into orbit around the planet. Due to the bys and the Messenger in-situ measurements. nature of the MPO mission (in a low, inertial, polar JAXA provides the MMO (Mercury Magneto- orbit) all external equipments are of bespoke high- spheric Orbiter), whilst Airbus Defence and Space is temperature design. prime contractor for ESA, providing the MPO (Mer- cury Planetary Orbiter) and all other spacecraft hard- ware. The scientific payload is provided by national agencies. This paper provides an overview of the mission (including its trajectory to Mercury), spacecraft de- sign (in particular its staging characteristics) and the specific solutions implemented in the spacecraft subsystems to meet the peculiar BepiColombo needs. It further addresses the thermal testing performed to verify the ability of the spacecraft and its equipments to survive the harsh thermal environments experi- enced during the cruise phase and in Mercury orbit. Introduction Mercury is the innermost planet of the solar sys- tem, is therefore difficult to reach and until now has been visited by only two spacecraft. Mariner 10 flew- by Mercury in March 1974, September 1974 and March 1975 and Messenger has been in orbit around Mercury since March 2011. The BepiColombo mission will be the first Euro- pean mission to Mercury. It was named after the Italian scientist Giuseppe “Bepi” Colombo (1929 – Figure 1: The Mercury Composite Spacecraft 1984), who proposed the trajectory of Mariner 10, Whilst addressing the above topics in more detail, and discovered the planet’s 3:2 spin-orbit resonance. this paper also pays particular attention to the verifi- The BepiColombo mission will place the Europe- cation of the thermal control performance. In total, 8 an MPO (Mercury Planetary Orbiter) and the Japa- module sized tests will be performed (starting in nese MMO (Mercury Magnetospheric Orbiter) in low autumn 2010 with the MMO under JAXA responsi- polar orbits around Mercury.
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