tokyo tech’s technology demonstration...

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


IntroductionIntroductionCubeSat 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


ContentsContents

�Satellite overview

�Mission�Overview

�Science mission

�Engineering mission

�General System overview�Specifications

�Subsystems

�Launch vehicle

�Conclusion


““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


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


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).


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…


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


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


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


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


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]

Angule

r V

elo

city [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 14Time [sec]

Quat

ernio

n

Acceleration of wheels Burst occurrence

Attitude maneuver Start observation

10 seconds

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


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


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


• 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

EclipsePower(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


C&DH, ADCSC&DH, ADCS

Magnetic sensorHMR300

Gyro sensorGYROCUBE 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)


Launch vehicleLaunch vehicle

JAXA (Japan Aerospace

Exploration Agency) provides piggyback launch opportunities

using H-IIA rocketTSUBAME satellite is

nominated (Priority A) for launch

in 2009 (planned)

H-IIA Rocket Launch


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 student leadership for 2009 launch.


• LSS webpage:

http://lss.mes.titech.ac.jp

• Contact:

- engineering

[email protected]

-science

[email protected]

Thank you very much!

Any Questions?

Cute-1.7 + APDand its separation mechanism

TSUBAME

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