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  • Small satellite conference 2007

    Tokyo Tech’s

    Technology Demonstration

    Satellite

    ““TSUBAMETSUBAME””

    Junichi Nishida, Yoshihiro TsubukuJunichi Nishida, Yoshihiro Tsubuku

    LSS (Lab. for Space Systems) Tokyo Institute of Technology, Japan

  • Small satellite conference 2007

    IntroductionIntroduction CubeSat Project (10cm cubed picoCubeSat Project (10cm cubed pico--satellite)satellite)

    Tokyo Tech 2Tokyo Tech 2ndnd satellite projectsatellite project

    CuteCute--1.71.7

    20042004~~

    2003.6

    2007~2007~

    The 1st cubesat, CUTE-I launch

    CUTE-I

    Cute-1.7+APD

    Tokyo Tech 4th satellite projectTokyo Tech 4th satellite project

    TSUBAMETSUBAME has started !!has started !! Cute-1.7+APD II

    -Acquisition of satellite bus technologies

    -Has been operated more than 4 years !

    �Cute-1.7+APD Launched on February 2006

    �Had been operated for about a month

    �Cute-1.7+APD II will be launched in 2007

    �Applying some modifications to the 1st design

    -Trying new design methodology

  • Small satellite conference 2007

    ContentsContents

    �Satellite overview

    �Mission �Overview

    �Science mission

    �Engineering mission

    �General System overview �Specifications

    �Subsystems

    �Launch vehicle

    �Conclusion

  • Small satellite conference 2007

    ““TSUBAMETSUBAME”” overviewoverview

    • Polarized X-ray observation by using high-speed

    attitude maneuver with CMGs

    Mission

    Development Guidelines

    • Student-leading system design

    • Promptly conduct high-technology

    demonstration on orbit

    Overview of TSUBAME

    TSUBAME means TSUBAME means ・・・・・・・・・・・・・・・・・・・・・・・・””SwallowSwallow”” in Japanesein Japanese

  • Small satellite conference 2007

    Mission overviewMission overview

    Polarized X-ray observation by using high-speed attitude maneuver with CMG

    2. Detection, Position determination

    3. High-speed attitude

    maneuver

    4. Start observation

    within 10 seconds

    1. Burst Occurrence

  • Small satellite conference 2007

    time

    luminosity

    ~10 sec

    What are GRBs ?What are GRBs ? � Largest / brightest explosions at distant

    Universe.

    Where & When ?Where & When ? � Impossible to predict…

    � Prompt decay within ~ 1min !

    Mysteries ?Mysteries ? � Production mechanism and origin

    of GRBs yet to be understood…

    Science GoalScience Goal

    Astronomical observation of Polarized XAstronomical observation of Polarized X--rays and rays and γγ--rays rays

    from from GammaGamma--Ray Bursts (GRBs).Ray Bursts (GRBs).

  • Small satellite conference 2007

    Why XWhy X--ray Polarimetry Awaited ?ray Polarimetry Awaited ?

    But X-ray polarimetry is very difficult…

    � X-rays / γ-rays are detected as quantums, not as waves. � No sensitive X-ray polarimeter has been available.

    Crab pulsar

    /chandra.harvard.edu/photo/

    Artist's impression of a GRB

    By past observation methods,

    we couldn’t solve the mysteries of GRBs.

    � Production mechanism and origin

    of relativistic jets from central engine. � Magnetic field geometry near the

    black hole.

    Focus on XFocus on X--ray / ray / γγγγγγγγ--ray polarimetry.ray polarimetry.

    X-ray polarimetry directly probes…

  • Small satellite conference 2007

    Mission InstrumentsMission Instruments

    (1) Wide-field Burst Monitor (WBM) � Detection of GRBs by monitoring a half of the sky.

    � Localization of GRBs with ∆θ ~10 deg accuracy. � Comparing counts in 5 “Scintillation” detectors.

    (2) Hard X-ray Compton Polarimeter (HXCP) � Use Compton-scat. Technique.

    � Energy range: 30-100 keV � FOV: ~ 100 deg2

    � Effective area: ~ 72 cm2

    HXCP

    WBM

  • Small satellite conference 2007

    Design of Hard XDesign of Hard X--ray Polarimeterray Polarimeter

    � We have investigated an optimum design of HXCP with Monte Carlo Simulation.

    Multi-Anode Photo

    Multiplier Tube

    (MAPMT)

    CsI Scintillator [Absorber]

    Plastic Scintillator [Scatterer]

    6 cm

    Avalanche

    Photo Diode (APD)

    Horizontally polarized direction

    Photo-Absorption !

    Compton-Scattering !

    Photo-Absorption !

    Compton-Scattering !

    Passive Shield

    Vertically polarized direction

  • Small satellite conference 2007

    High Speed Attitude ManeuverHigh Speed Attitude Maneuver

    �Slewing 90°within 10s �Torque requirement :

    more than 60mNm �Lifetime : more than 1 year �As small and light as possible

    Basic of CMGs

    TSUBAME mounts four single gimbal CMGs

    Requirements

    Solution

    CMG (Control Moment Gyro)CMG (Control Moment Gyro) is selected after careful investigation

  • Small satellite conference 2007

    CMG unit for space useCMG unit for space use

    �Developing a CMG unit which can be used in the orbit �Small size �Shield type �Low power consumption

    �Under development with Japanese company, Tamagawa Seiki

    Test model of CMG unit Planned CMG size and configuration

  • Small satellite conference 2007

    SimulationSimulation

    Attitude angular (quaternion)

    Angular velocity

    -0.2

    -0.18

    -0.16

    -0.14

    -0.12

    -0.1

    -0.08

    -0.06

    -0.04

    -0.02

    0

    0.02

    0 2 4 6 8 10 12 14

    Time [sec]

    A n g u le

    r V

    e lo

    c it y [ ra

    d /s

    ] .

    -1

    -0.75

    -0.5

    -0.25

    0

    0.25

    0.5

    0.75

    1

    0 2 4 6 8 10 12 14 Time [sec]

    Q u at

    er n io

    n

    Acceleration of wheels Burst occurrence

    Attitude maneuver Start observation

    10 seconds

    Reliable algorithm is required for prompt attitude maneuver with singular point avoidance

  • Small satellite conference 2007

    Engineering experimentEngineering experiment

    �A daughter satellite is released �Communications and measurement of tether formation flight dynamics �Recovering and docking the daughter satellite by controlling the tether

    Parent satellite Daughter satellite

    Cute-1.7+APD

    Tether deployment mission

    Ex. Tether Formation Flight

  • Small satellite conference 2007

    General System OverviewGeneral System Overview

    �Spec. of the satellite �Size : 50cm x 50cm x 40cm

    �Weight : 40kg

    �Designed lifetime : 1 year

    �Orbit : Sun-synchronous orbit

    �Altitude : 800km

    �Inclination : 98.6 deg.

    �Subsystems �Structure, Electrical Power

    �Command and Data Handling, Attitude Determination and Control

  • Small satellite conference 2007

    • Deploy two solar cell paddles

    • Three series and three parallel cells

    Electrical Power , StructureElectrical Power , Structure

    • Requirement from subsystem – Two solar cell paddles

    – CMG, Polarization detector

    subsystem Power(W)

    AD&C 27.27 C&DH 3 Comm 8.56

    Structure 8 Mission(GRB) 9.73

    Electrical Power Structure

    On-Orbit

    Daylight

    On-Orbit

    Eclipse Power(W) 14.67 21.67 31.53 30.53 39.56

    Telemetry

    Initial

    Attitude

    Control

    Paddle

    Deploy

    ment

    Occurrence of GRB

    Table. Power of subsystems

    Table. Power consumption of each mission sequence

    Paddle deployment

    Components allocation

  • Small satellite conference 2007

    C&DH, ADCSC&DH, ADCS

    Magnetic sensor HMR300

    Gyro sensor GYROCUBE 3A

    • Estimated data volume • Hardware

    - COTS based high performance MPU - SDRAM

    • Radiation tolerant design

    • Attitude sensors - Sun sensor : side planes - Gyro sensor : 3 axis - Magnetic sensor : 3 axis

    • Attitude determination algorithms - QUEST, REQUEST, Extended Kalman Filter

    • Actuator - Magnetic torquer : 3 axis - Control Moment Gyros

    •Orbit determination - GPS

    Medium sun sensor

    bit/sec Mbyte/day

    Mission data 200 2.09

    Attitude data 1065 10.6

    HK data 58 0.89

    Table. Handling Data (Observation)

  • Small satellite conference 2007

    Launch vehicleLaunch vehicle

    JAXA (Japan Aerospace

    Exploration Agency) provides piggyback launch opportunities

    using H-IIA rocket TSUBAME satellite is

    nominated (Priority A) for launch

    in 2009 (planned)

    H-IIA Rocket Launch

  • Small satellite conference 2007

    ConclusionConclusion

    • Mission

    – X-ray polarimetry of Gamma-ray bursts

    – High speed attitude maneuver using CMGs

    • Conceptual design

    – Specifications

    – Subsystems

    We are now developing TSUBAME satellite by stude