1、Preliminary Design of the eXTP Satellite Institute of Spacecraft System Engineering , CAST Hong Bin Mar 22th , 2017 , Beijing,1. General Description 2. Design Evolution 3. Basic Parameters 4. Preliminary Design 5. Programme Schedule 6. Problems 7. Conclusions,Outlines,General Description,eXTP , the
2、enhanced X-ray Timing and Polarimetry mission, is a science mission designed to study the state of matter under extreme conditions of density , gravity , and magnetism. Its the next generation of the X-ray detected telescope after HXMT in China.,HXMT,eXTP,2007 The conception of XTP was put forward b
3、y IHEP; 2008-2012 An advanced research of the XTP was carried out by ISSE; 2013-2014 Completed the system analysis and achieved the missions basic parameters . The first step design of the XTP was finished; 2015-2016 With the LAD and WFM adding into the XTP and the parameters of SFA new orbit；new pa
4、yload；So we update the design of the eXTP satellite.,2. Design Evolution,3. Basic Parameters,LM-7 launch vehicle ，has a big fairing with diameter of 4200mm a total height of 10300 mm， has maximum capacity for 550km circular orbit at 0 deg. inclination is 4500kg.,4. Preliminary Design,Launch Vehicle,
5、Telemetry and Control system,The TC system applies the international USB system . Low tilt angle communication is achieved through utilizing relay satellites or building new TC station.,Satellite ground application system,Data receiving is achieved by stations at Sanya. Or using the ground station a
6、t Malindi (3S Kenya), built by Italian (LOFT team).,The X axis point to the specific objects in the inertial space ； The sun vector is controlled in XOZ plane and in a obtuse angle with the +Z axis； The sun vector will perpendicular to the solar array by rotate it； According to the users observation
7、 plan to carry out attitude maneuver，aiming at the burst objects to carry on the observation.,4. Preliminary Design,Observation ModePointing Observation,Objects,4. Preliminary Design,Flight Procedure,Burst source,Objects,Configuration,Stowed in fairing,On orbit,4. Preliminary Design,4. Preliminary D
8、esign,Configuration,Service module(SVM): the SVM includes all units required to control and operate the S/C platform. The WFM and GRM are accommodated in the SVM, too. LAD Assembly(LADA): the LADA consists of LAD panel(#1#4), LAD sunshields, deployment mechanisms. The LADA are accomodated on either
9、sides of the SVM. Mirror Assembly Module(MAM): the MAM is located inside the telescope tube , contains the SFA & PFA mirror module and star trackers，with the associated supporting platform. Telescope Tube(TT): the TT allows to maintain the SFA&PFA at the required distance from the focal planes. Foca
10、l Plane Assembly (FPA) : the FPA hosts the 13 focal plane cameras, including thermal control hardware.,Configuration,4. Preliminary Design,4. Preliminary Design,Hosts all platform subsystems;-four tanks-six reaction wheels-two star trackers-four sun acquisition senors-three gyroscopes Support the LA
11、D，WFM and GRM; Downside of SVM is the interface of the launch vehicle; Inside the SVM theres a contamination cover , its also the sun-shield of the WFM.,Service module(SVM) :,4. Preliminary Design,SFA and PFA are accomodated in the mirror platform. Conceived as independent unit. Can be later integra
12、ted into the telescope support structure. Kinematic mounts :Minimising the impact of mechanical and thermal-elastic loads onto the optics alignment.,Mirror Assembly(MA) :,LAD Assembly,4. Preliminary Design,Two wings (each wings two panels or one panel（TBD）); LAD support platform use the hign thermal
13、 conductivity material for the structure; The deployment mechanisms perform the connection between LAD panel and satellite, withstand the launch loads in the stowed condition; On orbit, the DM releases the panel reliably, and then performs the deployment of the LAD payloads, with the automatic latch
14、ing at the end of its travel; After the latching, the DM maintains the angular position and assure the stiffness.,10 modules each panel 1973(L)1212(B)132(H),20 modules each panel（TBD） 2384(L)1973(B)132(H),4. Preliminary Design,Maintain the required focal length; Support the solar array and ka-antenn
15、a; Provide the catching interface for on-orbit servicing(TBD); The ICU of the focal detectors are accomodated on top of the TT;,Telescope Tube(TT) :,4. Preliminary Design,Hosts the 13 focal plane cameras; With the sun-shield to protect the detectors from the suns; The shape is designed to minimize t
16、he envelope dimesions and fit the fairing;,Focal Plane Assembly(FPA) :,4. Preliminary Design,TCS: Mirror assembly thermal design,The insulating washers(fiberglass) are used to limit the conductive heat transfer between the MA and MSP. The MA are covered by 15-layer MIL to insulate heat radiation of
17、SVM. The external surface of TT is used for radiator of the MA.,SFA: 202,PFA: 202,4. Preliminary Design,TCS: SDD thermal design,The FPA is connected to the TT by insulating washers, to limit the conductive heat transfer between the SDD and FPSP. The SDD are covered by 10-layer MIL. The SDD heat diss
18、ipation are firstly collected by the ethane loop heat pipe, then the collected heat dissipation is refrigerated by the pulse-tube refrigerator(5W180K ,power 120W). Finally, the hot junction heat dissipation of refrigerator is transmitted to the individual radiator by the ethane heat pipe.,SFA-SDD *1
19、1：-110-80 ,Ethane loop heat pipe,Radiator,Pulse-tube Cryocooler,4. Preliminary Design,TCS- LAD thermal design,Extensile sun-shield is used for the LAD, to insulate heat radiation from the sun. The inside of the sunshield, covered by 15-layer MIL to insulate heat radiation. The LAD heat dissipation(5
20、.4W*40=216W) is radiated by itself. Electric heaters(50W power) are applied in LAD for maintaining the -20 lower limit.,extensile sunshield,LAD:-20-10,Phase A:2017.012017.12, international coordination, feasibility design2017.08, Subsystem interface definition document (IDS) 2017.10, Subsystem requi
21、rements document2017.12, System feasibility design Phase B:2018.012018.12, Preliminary design2018.09, Subsystem preliminary design 2018.12, System preliminary design Phase C:2019.012021.12, System critical design2019.01 SM delivery(30% for special test(TBD)2019.12 EM delivery2020.12 SM and TM delive
22、ry2021.06 QM completed Phase D:2022.012024.06, Flight model and launch2022.06 FM delivery Phase E:2025.012035.10, Science observation,5. Programme Schedule,21,5. Programme Schedule,Payload equipment requirements,LAD Assembly,6. Problems,The following key requirements should be confirmed: Panels:The
23、interface between panel structure and sun-shield, DM, module, PBEE.The requirements for strength, stiffness, alignment, thermo-stability, material, connection style.The technical flow about the delivery, assembly, test(How? Where?). LAD sun-shield:The requirements for materials, frequency, weight, t
24、hermal control.Interface of the HDRM. Deployment Mechanisms: The interface between DM and the panels.Requirements for Frequency, Accuracy, Drive torque, Thermo-stability, Weight.AIT process and items.,WFM,6. Problems,The requirements for installation accuracy, consistency of direction (for one pair)
25、 Can you accept the state that FoV is blocked or change the point angle(decide by the LAD panels and sunshield)？ The URF could meet the launch loads and on-orbit thermal environment？ If CAST responsibility for the design of WFM support structure: Can you adjust the position of the three URF？(Insuffi
26、cient Operation Space) Can you redesign the position of the electrical connector？(Insufficient Operation Space for 3 pairs),7. Conclusions,We have updated the design of eXTP satellites, which could meet the requirement of the science; Something should be confirmed to help us understanding the design and requirements of the science.,Thanks for your attention！,探索宇宙奥秘 造福人类社会,
