PETSAT Projectwith PETSAT Project team

A Novel Satellite Concept “Panel Extension Satellite (PETSAT) ” Consisting

of Plug-in, Modular, Functional Panels

PETSAT Project

Shinichi Nakasuka and Hironori SaharaUniversity of Tokyo, Japan

Yoshiki SugawaraAoyama Gakuin University, Japan

Kanichi Koyama, Takanori Okada, Hideaki Kikuchi, and Chisato Kobayashi

SOHLA

PETSAT Project

Plug-in of Panels having different functions deal with variety of mission requirements just like a “Lego Block”

→ Mass production of panels lead to low cost/high reliability→ Plug-in makes system level test simple and less time consuming→ Open architecture to allow participation of new companies → Extending panels makes it possible to use small satellite as “large sat”

PETSAT(Panel ExTension SATellite)Mission panel 1

Mission panel 2

Attitude Control panel 1

Attitude Control panel 2

Attitude Control panel 3

Communication panel 1

CPU panelBattery panelCommunicationpanel 2

extension

PETSAT Project

Before Separation（Launch Locked）

PETSAT Project

Important Considerations• How to distribute various satellite functions into

different functional panels• Design of standard interfaces between panels in

four aspects:– Mechanical– Electrical– Information– Thermal

• Standardization of components– Standard panel structure for different functional panels– Equipment should be installed into flat, standard panels

• Fault tolerance and graceful degradation

PETSAT Project

(1) Architectural Study

PETSAT Project

PETSAT Project

Function Distribution into PanelsHow to distribute OBC, memory, attitude control, power, communication, etc, into (how many) different panels

• Each panel has “Common compo.” + “Special compo.”– Inter-panel communication controller is indispensable– How about solar cell, battery, CPU ?– Each panel is powered by components in each panel ?

• Easy plug-in of any quantity of panels should be possible– Distributed architecture like “Personal Computer on Internet”

• Fault tolerance required including panel interface failure– Tolerant against electric or information line failures– Graceful degradation and reconfiguration capability

• Should deal with variety of mission requirements by changing types and quantity of panels– Ex) Two communication panels should have double capacity

PETSAT Project

PETSAT Project

Overall Architecture of Functional Panels• Types of Functional Panels：

– (1)OBC+memory (2)communication(COMM-P) (3)attitude control(ACS-P) (4)thruster(PROP-P) (5)battery (6)mission panel (MISN-P)

• Common components to be implemented on each panel:– Power control module including solar cells/battery – Information module：inter-panel communication and in-panel

information management • Other important considerations:

– Power demands and generations are not balanced in each panel(e.g., Mission, communication panels require lots of power)→Real time power distribution between panels is indispensable

– Many CPU exists including local CPUs and main OBC →System management by multi-CPUs

PETSAT Project

PETSAT Project

Common Components

Interpanel comm.

Solar Cell

Small Battery

Local CPU

Other panels

Other panels

Power

PETSAT System Configuration

Tx/Rx・Antenna

Comm. Panel

Large Battery

Battery Panel

Actuator

Sensor

Control Panel

MemoryMissionSystem

Mission PanelOBC Panel

OBC

Memory

PETSAT Project

OBC Panel

Comm. Panel

Battery Panel

Control Panel

Mission Panel One Panel

PETSAT Project

Requirements as to Four Interfaces• Mechanical Interface

– Reliable folding/extension in space environment– Low shock extension and latch in several angles

• Electrical Interface– Self-supply within each panel in principle– Autonomous power re-distribution between panels

• Information Interface– Plug-In simplicity and system extensibility – Fault tolerance in distributed agent architecture

• Thermal Interface– Suppress temperature difference between/within

panels

PETSAT Project

PETSAT Project

(2) Design of Each Subsystem

PETSAT Project

PETSAT Project

(1) Structure: stowed and deployed configuration

PETSAT Project

Deployment Sequence should be controlled

PETSAT Project

Standard Panel Structure

Model 1(FY16) Model 2(FY17) Model 3(FY18)weight@space (3kg@2ℓ) (0.7kg@4.5ℓ)

Cost65.6Hz

Thermal pass

(1.0kg@4.5ℓ)

1st Frequency 400Hz 137.5HzThermal. cond.

FY16： FY17： FY18：Press

1.5mm thickness

PETSAT Project

Equipment weight ratioBase-unit BASE-U

SAPHING-M

PROP-CONTIG-CONT

THRTNKSUP

PROPELLANT 0.5kg 6.7%Panel structure PNL 1.0kg 13.3%

8%Solar cell plate

0.6kg0.6kg0.3kg

0.2kg0.4kg0.4kg1.5kg2.0kg

8%inter-panel hinge 4%

2.7%5.3%5.3%

7.5kg

Propulsion module

20%26.7%

total

Packing Components into PanelsExp) PROP panel

CUBE-P COMM-P ACS-P MISN-P

350 mm one side

Base Unit Bay

Local Unit Bay

PETSAT Project

1) Cutting wire of launch rock triggered by signal from rocket

3) Cutting nylon wire to deploy panels sequentially triggered by bus-panel or timer

Release and Deployment Sequence

2) Release from Rocket

PETSAT Project

(2) Power System1. Distributed power system

to realize high reliability2. Consisting of Solar cell, BCR, PDM3. Compact standard platform

Independent power system for each panelThe battery output line is connected between panels to obtain redundancy(12.6v)Independent PDM for each panel (for 5v,12v)Minimum inter-panel connection

Panel Module 3

Panel Module 2

Panel Module 1

Panel Module n

PDM+5V+12VVOLT

REG

PDM+5V+12VVOLT

REG

PDM+5V+12VVOLT

REG

SeparationRelay

PDM+5V+12VVOLT

REGActivation

Switch

SeparationRelay

SeparationRelay

SeparationRelay

BCR

BCR

BCR

BCR

PETSAT Project

(3) Information System: Concept

HCAN1HCAN2

… …

CPU1 CPU2

COMPO1

COMPO2

COMPO3

CPU1 CPU2

COMPO1

COMPO2

COMPO3

CPU1 CPU2

COMPO1

COMPO2

COMPO3

Panel #1 Panel #2 Panel #3

Comparator

I2C

- Two Layered

PETSAT ProjectPCM（パネルコントロールマネージャ）

CPUI（CPU統合器）

PWR（電力制御モジュール）

PANELBASEunit

INFO-U

PCM

CPUI

PCM

CAN(Inter-panel)I2C

(Intra-panel)

I2CCAN CAN@750[kbps]

I2CMemory Bus

PWR(Power Control Module)

Local Component

Memory Bus

Information Management System

PETSAT Project

Common Information Unit (INFO-U）

CAN bus500 [kbps] (debug)700 [kbps] (release)

EEPROMMax 512 [kB]

External bus selection to isolate failed bus

Bus selection

Arbitration FUnctionInter-panel Comm.

Data storage/telemetry data

ArbitrationIntra-panel Comm.

I2C bus100 [kbps] --- 400 [kbps]

DIPSW3 x 8bit

Panel ID／Mode change

Power control for local components

SCI bus56.4 [kbps]

Intra-panel comm.

GPIOLocal components power

control and monitoring

CompareReliability

Redundancy of CPUs

MeasurementsADC / 8ch8ch x 12 bit

PETSAT Project

(4) Thermal Interface• Orbits (thermal environment) usually cannot

be decided until the last moment

• Suppress inter-panel and intra-panel temperature difference under as little level as possible

• Preparation of design freedoms for thermal control to be used to deal with variety of missions and orbits

PETSAT Project

(3) SOHLA-2

- In-orbit Demonstration Model -

PETSAT Project

PETSAT ProjectSOHLA-2 Configuration

Launch will be in 2008 - 2009

PROP

ACS

BOOM

COMM

MISN

CUBE

LF Antenna for Lighting Observation Gravity Gradient

Boom

Earth

- Gravity gradient stability- Maximum solar power in

worst case- Importance of each panel

PETSAT Project

Overview of SOHLA-2• Mission: Test and demonstration of PETSAT

technologies and lightning observation experiment• Bus panel: as similar as possible to University of

Tokyo’s CubeSat “XI-IV” and “XI-V”• Attitude control panel: 3-axis gyros, sun sensor

magnetic torquers• Communication panel: S-band, max 256kbps.• Propulsion panel: mono-/bi- propellant using H2O2,

Isp=60/120s, F=100mN/1N• Mission panel: Three channel LF receiver, 5m

antenna

PETSAT Project

Direction Estimation

Data Storage and Preprocessing

Ground Observation System

Wide band Antenn+Filter+Amp

A/D Converter

Signal Processing

５ｍ

５ｍ

Satellite Observation System

Difference of arriving RF phases has information about the relative direction of the RF source

Location of lightning

Mission: Lightning Observation

Research by Prof. Kawasaki, Osaka University

PETSAT Project

2 9 4 . 5 2 9 5 . 0 2 9 5 . 5 2 9 6 . 0 2 9 6 . 5

- 0 . 0 0 0 4

- 0 . 0 0 0 2

0 . 0 0 0 0

0 . 0 0 0 2

0 . 0 0 0 4

0 . 0 0 0 6

E-F

ield

[V/m

]

T i m e [ μ s e c ]

衛 星 観 測

0 . 0 0 . 5 1 . 0 1 . 5 2 . 0 2 . 5

E-F

ield

T i m e [ μ s e c ]

地 上 観 測

VHF Radiation from LightningObserved at Ground

Observed at Satellite

PETSAT Project

ADC board

AMP board

< RF Performance >- 30MHz～100MHz- 45dB

1st model will beDemonstrated onSOHLA-1/BMW(2008.8 launch)

< ADC Performance >

- 200MHz，7-bit，

- 16kpts，100 pulse

Configuration of Interferometer

BPF

ADC

FPGA

BPF

ADC

FPGA

BPF

ADC

FPGA

200MHz

memory memory memory

Trigger detect

DSP RAM FLASH

IIC I/F

AMP AMP AMP

FLASH

PETSAT Project

University of Tokyo’s CubeSat Project “XI”

XI-IV (Launched in 2003.6) XI-V (Launched in 2005.10)

PETSAT Project

Bus panel (heritage from CubeSat “XI-IV”)

Thermo Sensors

CUBE-ModulePower

Com1Main

Com2

Battery

Solar Cell

DCDC

DCDCOBC

ROM TX TNC

RX TNC

CW Gen

TX

RX

CWCharge Circuit

OBC

RX TNC

uSWFlight PinFlight Pin

PWR5V

TLMTLM

CMD

TLM

DCDC

OBC

PWR5V

Info.Power

BASE-Module

POWER UNIT

I/F CPU

INFO UNITInfo.

PETSAT Project

Design Policies of Propulsion for Microsatellite

• We set the following 6 policies for the propulsion:– SAFETY FIRST, but DECENT PERFORMANCE– MODERATE PRICE due to STANDARDIZATION– also, GOOD HANDLEABILITY and REDUNDANCY

In order to keep the policies,performance degradation is tolerated to some extent.

• We started development of the propulsion as follows:– Mono-Propellant

• Hydrogen Peroxide solution (< 60 wt%)• High-performance catalysts used.

– Bi-Propellant• Flammable fuel such as Ethanol• Oxygen derived from decomposition

of Hydrogen Peroxide.

• Propulsion System for common use ofboth of Mono- and Bi-Propellant desired.

Conventional

Promising

PETSAT Project

Propulsion System for Microsatellite• Configuration should be simplified to be installed into small capacity.• Effective Commercial-Off-The-Shelf (COTS) is adopted.

• We conducted captive tests of Mono- and Bi-Propellant,and attained 60 and 120 seconds of specific impulse, respectively.

Mono-Propellant:Isp=40~60sec100mN-class thrust

Bi-Propellant:Isp=120~150sec1N-class thrust

PETSAT Project

Propulsion System for Microsatellite• Now we are manufacturing a Flight-Model of the Propulsion.• Demonstration will be conducted by using SOHLA-2 microsatellite in

2008 or 2009, and BOTH operations of Mono- and Bi-Propellant are made possible.

PETSAT Project

2003 04 05 06 07 08 09

CubeSat XI-IV’03/6

CubeSat XI-V ‘05/10(Sister-Sat with XI-IV launched with SSETI-EXPRESS)

PRISM(Remotesensing) ‘08

PETSAT(PanelSatellite) ’08-‘09

Nano-JASMINE(AstrometrySatellite） ’08-‘09

PETSAT and University of Tokyo’s Nano-Satellite Projects

30 m Ground Resolution

Multi-purpose4 km Ground Resolution

Development Launch

Space Science

PETSAT Project

PETSAT for Small Industries• Development under way by SOHLA (group of

small industries), Univ.of Tokyo, Aoyama-gakuin, Osaka Univ. and Doshisya Univ.

• Fusion of technological competence in small industries with system design/analysis capability of universities

• Contribution to technological and management training for non-space engineers and young students

PETSAT Project

PAF to be hard-attached to the rocket

Wire

Rocking using volt

Launch Rock Mechanism

PETSAT Project

Items Values CommentsOVERALLWeight < 50kg

Size (stowed) 350x350x500 mm

Size (deployed) 350x50x1400 mm (Antenna length is 5m)

Size (one panel) 350x350x50 mm350x350x100 mm

(four panels)(mission panel)

BUS FUNCTION PANEL (BUS-P)Configuration Same system as CubeSat “XI” Space proven for over

3 yearsCommunication Uplink: (FM)

145MH 1200bpsDownlink: (FM,CW)437MHz 1200bps437MHz CW

Amateur Frequency Band

LOCAL CPU PIC16F877

PETSAT Project

Items Values CommentsATTITUDE CONTROL PANEL (ACS-P)Sensors Magnetometer

3-axis mechanical gyros6 sun sensors

Accuracy is roughly 0.5°

Actuators Magnetic TorquerReaction Wheel (TBD)

Local CPU H8/3694F (Renesas)THRUSTER PANEL (PROP-P)Fuel Ethanol (C2H5OH) can be othersOxidizer H2O2 (stabilizer included) middle-level

concentration (<60%) Thrust 500 mN / 1 N For mono / bi-

propellantTotal ΔV 50sec / 120sec mono- / bi-Local CPU H8/3694F (Renesas) (Hitachi)