Transcript PowerPoint プレゼンテーション

26th ISTS @Hamamatsu [2008-f-17]
ISAS/JAXA Small Scientific Satellite Series
Program with Flexible and Reusable Bus Design
T. Nakagawa (ISAS/JAXA)
S. Sakai (ISAS/JAXA)
ISAS/JAXA small scientific
satellite series
• The Institute of Space and Astronautical Science, Japan Aerospace Exploration
Agency (ISAS/JAXA) has recently started to develop a series of small scientific
satellites, and has a plan to launch three to five minisats (300-400 kg) per five
years.
• The series aims at ‘cheaper and faster realization of unique space experiments’
as a complementary program of mainstream medium-class scientific satellites.
• In order to shorten the period of
satellite development with low
cost, it is considered to be
reasonable to employ standard bus
architecture, where the bus and
payloads are clearly separated in a
modular manner.
The mission payloads are on
the roof of the bus system.
- The modular configuration is attained
in exchange of resources like mass.
S.Sakai: ISAS/JAXA Small Scientific Satellite Series Program with Flexible and Reusable Bus Design
Mission payload
Standard bus
2
Working Groups for small
scientific satellites
Scientific missions:
TOPS
Tele-observation of planetary plasma
FFAST
X-ray observation w/ formation flight
PPM-Sat
Precise positioning w/ GPS occultation
CAST
Gamma-ray burst observation
DPF
Gravity wave observation
DIOS
X-ray observation (dark baryons)
ELMOS
Seismic Electromagnetism
ERG
Plasma observation in Geospace
POLARIS
X-ray polarization observation
First flight (2012)
Engineering missions:
Tether
Tether technology demonstration
SPS
Solar power generation
SLIM
Lunar lander
Venus balloon
Venus balloon
MAGSAIL
Pure magneto-sail
EGG
Gas-balloon re-entry
S.Sakai: ISAS/JAXA Small Scientific Satellite Series Program with Flexible and Reusable Bus Design
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This presentation
• The missions for small scientific satellites have various kinds of requirements:
- three-axis/spin-stabilized attitude control,
- a wide range of power (50 to 300 W),
- a variety of orbit (LEO, SSO, HEO, etc),
...
-> A traditional rigid standard bus will be unable to satisfy the
diversity of mission requirements.
• In this presentation, several concepts to enhance flexibility of the standard bus
are introduced:
- Layers of standardization
- Semi-custom-made bus system
- Tradeoff between integration and modularization
S.Sakai: ISAS/JAXA Small Scientific Satellite Series Program with Flexible and Reusable Bus Design
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Layers of standardization
• Specifications of most conventional standard buses are strictly regulated for a
particular mission in the whole system/subsystem of satellites.
(e.g., communication satellites on GEO)
- Effectiveness of the rigid standardization depends on the number of satellites with the
particular mission.
scientific satellites with a wide
variety of requirements
• Traditionally, medium-class scientific satellites in ISAS/JAXA were dedicatedly
developed in order to satisfy various requirements and pursue resource-optimal
design, so that fruitful achievements would be brought.
- Optimization
of satellite-by-satellite consumes relatively large cost and long
development time.
-> ‘layers of standardization’ concept
S.Sakai: ISAS/JAXA Small Scientific Satellite Series Program with Flexible and Reusable Bus Design
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Layers of standardization
[Cont’d]
The Layer (IV): Configuration
- Similar to the conventional rigid standard buses
- Possible to omit mechanical/thermal model tests
- Applicable to most scientific observation missions
by adding selectable or alternative options
The Layer (III): Instruments
- Advantageous for engineering missions where
the satellite configuration itself is hard to be
standardized (e.g., the small lunar lander with a
large-scale propulsion system)
- Valuable concerning economics of bundling order
The Layer (II): Interfaces
- Essential for higher levels of standardization
The Layer (I): Design Methods
- Standard method of modeling satellites
-> reuse of GSE software, etc
SpaceWire as standard data network
• Promising technology because of high
speed, simplicity, and testability
• RMAP (Remote Memory Access Protocol)
over SpaceWire is a powerful method,
which enables one component to read
and write directly from memory and
registers of another component over the
network.
S.Sakai: ISAS/JAXA Small Scientific Satellite Series Program with Flexible and Reusable Bus Design
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Semi-custom-made bus system
• Consideration of the bus specifications
using a requirement matrix
- Three categories:
Core, alternative option, and selectable option
• The alternative and selectable options are
crucial for the flexible standard bus to
realize diverse missions with time- and
cost-saving strategies.
Ready-made
standard bus
Semi-custom-made bus system
For small scientific satellites
full-custom-made
medium-class scientific satellites
• The idea is similar to Product Line or Product Platform engineering in
development of commercial products.
- The capability of adding or replacing options is based on recent progress in technology
of modular design and Plug and Play.
- A tradeoff between the number of options and effectiveness of the standardization
should be carefully investigated.
S.Sakai: ISAS/JAXA Small Scientific Satellite Series Program with Flexible and Reusable Bus Design
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Semi-custom-made bus system
[Cont’d]
Selectable options
• solar array drive assembly (SADA)
• GPS receiver
• X-band transmitter
• monopropellant propulsion system
• design for EMC (Electro-Magnetic
Compatibility)
Alternative options
• number of solar panels
(one, two, or three panels per wing)
• capacity of Li-ion batteries (35Ah/50Ah)
• accuracy of attitude sensors such as a
star tracker and an inertial reference
unit (corresponding to requirements)
• size of reaction wheels (corresponding
to requirements of perturbation
immunity)
Note: Nominal specifications are underlined.
S.Sakai: ISAS/JAXA Small Scientific Satellite Series Program with Flexible and Reusable Bus Design
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Tradeoff between integration
and modularization
Cost analysis says that present satellite
cost has strong correlation with the
number of onboard components.
-> Common functions which belong to
different components have to be
integrated into a single component.
What is important is to standardize
interfaces between modules.
The integrated architecture is intrinsically appropriate
for small satellites because it will consume less
resources such as mass, size, and electric power.
-> The standard interfaces will facilitate
change of architecture from integration
to modularization, and vice versa.
The integrated architecture, however, has
latent difficulties in testability and reusability.
-> Modularization is attempted in the next step.
The modular architecture seems preferable in many cases, if
a resource budget including cost allows it.
Conventional
Integration
Modularization
S.Sakai: ISAS/JAXA Small Scientific Satellite Series Program with Flexible and Reusable Bus Design
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Tradeoff between integration
and modularization [Cont’d]
DreamCubeSAt
SMU (Satellite Management Unit)
ACFS
SAP1
unregulated
50 voltage
NEA
×4ch
SAP1
64bit CPU (MIPS) +
PROM/EEPROM/RAM
64bit CPU (MIPS) +
PROM/EEPROM/RAM
Mission × 2ch
APR
DRU
S-TRP1、S-TRP2
WDE1～WDE4
STT-E, IRU
SA
DA
2
ODC
SPS
DC/DC
converter
SAP2
Space
Packet
only on
NW
AC-NW
Li-ion
BAT
35AH
Mission Payload
DR
(2Gbytes)
SpW
Router
(12port)
SpW
Router
(12port)
SAP2
NEA
×4ch
DHFS
SMOS(RealTimeOS)
PCU
SA
DA
1
TCFS
DH-NW
ADC/M
UX
(Temp)
TCIM
(ON/OF
)
STT
-E
STT-S
from Temp. Sensors
(64ch max)
ACIM(STT)
To WDE1～WDE4、STT-E、IRU Power ON/OFF
ACIM
SADA Driver
各Heater
(24ch max)
RCS
Valve
Module 2
Heater Driver
×3ch
(MW)
(Sensor)
ADC/M
UX
TCIM
(TLM/C
MD)
S-ＴRP1
SDIP1
S-ＴRP2
SDIP2
S-SW
S-ANT1
S-ANT2
S-ANT3
Valve Driver
RCS
Heater
PRE
Thruster
Driver
STT
MTQ Driver
IRU
GFD
SPS
TNK
Valve
Module 1
ACIM
(STT)
ACIM
S-HYB
S-RTM(S-band Routing module)
DRU(Drive Unit)
MTQ-Z
PFD
WDE1
WDE2
WDE3
WDE4
FLT
LV
MTQ-Y
1
2
3
3N thruster
4
ＲＷ1～
RW4
RD TLM
SA SEP
The functional integration
isData
considerably
pursued.
Handling Network(DH-N/W)
100Mbps×n max
CSAS1
CSAS2
MTQ-X
Analog TLM
(32ch max)
Avionics Control Network (AC-N/W)
50V Primary Power from PCU
NIC (Network Interface Circuit)
System block diagram of the standard bus for small scientific satellites
(baseline)
S.Sakai: ISAS/JAXA Small Scientific Satellite Series Program with Flexible and Reusable Bus Design
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Tradeoff between integration
and modularization [Cont’d]
DreamCubeSAt
SMU (Satellite Management Unit)
SAP1
unregulated
50 voltage
NEA
×4ch
DRU
S-TRP1、S-TRP2
WDE1～WDE4
STT-E, IRU
SA
DA
2
ODC
SPS
SAP2
Li-ion
BAT
35AH
STT
-E
STT-S
ACIM(STT)
SpW
Router
(14port)
DC/DC
converter
Space
Packet
only on
NW
SpW
Router
(14port)
SAP2
NEA
×4ch
DR
(2Gbytes)
64bit CPU (MIPS) +
PROM/EEPROM/RAM
64bit CPU (MIPS) +
PROM/EEPROM/RAM
Mission × 2ch
APR
DHFS
SMOS(RealTimeOS)
PCU
SA
DA
1
TCFS
TCIM
(ON
/OFF)
TCIM
(TLM
/CMD)
μHCE
AC-NW
S-RTM(S-band Routing module)
RD TLM
SA SEP
S-ＴRP1
SDIP1
S-ＴRP2
SDIP2
S-SW
S-HYB
ACFS
SAP1
Mission Payload
DH-NW
S-ANT1
S-ANT2
S-ANT3
System block diagram of the standard bus
for small scientific satellites (modification)
RCS
Valve
Module 2
PRE
μHCE
GFD
Valve
Module 1
μHCE
MTQ-Z
TNK
WDE1
WDE2
WDE3
WDE4
STT
PFD
FLT
IRU
MTQ-Y
LV
1
2
MTQ-X
3
3N thruster
4
ＲＷ1～
RW4
SPS
CSAS2
CSAS1
Now studying to modify the
architecture to more
modular one so as to
enhance testability and
reusability
Data Handling Network(DH-N/W)
100Mbps×n max
Avionics Control Network (AC-N/W)
50V Primary Power from PCU
NIC (Network Interface Circuit)
ACIM (Avionics Control Interface Module)
S.Sakai: ISAS/JAXA Small Scientific Satellite Series Program with Flexible and Reusable Bus Design
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“Semi-order-made” approach
[e.g. AOCS]
 So, now “semi-order-made” approach is considered.
 Example: what is the appropriate attitude & orbit
control system (AOCS) configuration to implement
this concept.
 IRU
 Type-A (Fine, larger, expensive)
 Type-B (Coarse, small, cheaper)
 Reaction Wheel
Um… IRU should be Type-B for
 ….
my mission…
Example of “semi-ordermade” approach
 To achieve this concept, one important thing is to distinguish
and separate the AOCS into two categories:
 one which is independent of the AOCS components
selection, and
S.Sakai: ISAS/JAXA
Smalldependent
Scientific Satellite Series
with Flexible and Reusable Bus Design
 ones
onProgram
components.
New Architecture for AOCS Data
Interface
Conventional ISAS approach
For slightly difference
component configuration…
• Monolithic AOCS computer unit.
+ Effective to minimize weight, size, number of parts, …
– Component change affect wide area in the unit.
S.Sakai: ISAS/JAXA Small Scientific Satellite Series Program with Flexible and Reusable Bus Design
New Architecture for AOCS Data
Interface [Cont’d]
New approach
• Distributed AOCS computer unit.
+ Minimize the are influenced by the component change.
S.Sakai:
Smalletc.
Scientific
Program with Flexible and Reusable Bus Design
– ISAS/JAXA
Weight
areSatellite
not Series
minimum.
New Architecture for AOCS Data
Interface [Cont’d]
• In this novel approach, function to interface each component
is distributed in the individual ACIM (attitude control interface
module), not implemented in the computer unit.
• Thus the connection between ACIMs and the computer unit
should behaves just like local bus.
• Then, what is the appropriate data interface for this purpose?
• “SpaceWire” is assumed to be a solution, because of
-
Speed,
Simplicity,
Open standard,
…
S.Sakai: ISAS/JAXA Small Scientific Satellite Series Program with Flexible and Reusable Bus Design
Architecture for ground test
equipments
For software development & test,
flight operation simulation, etc.
For static closed loop test, etc.
S.Sakai: ISAS/JAXA Small Scientific Satellite Series Program with Flexible and Reusable Bus Design
Conclusion
• A standard bus system for the ISAS/JAXA’s new series of small scientific
satellites has been presented. Some ideas and concepts to enhance flexibility of
the bus system have been shown.
• The TOPS project which is the first satellite of the series will proceed to the
Phase B soon.
• On and after the second flight, the development time will be no more than two
years from determination of mission interfaces to the launch including
integration tests.
• As the estimated cost is worldwide competitive, the standard bus has potential
to be applied to earth observation or disaster monitoring missions in the future.
Thank you very much for your attention.
S.Sakai: ISAS/JAXA Small Scientific Satellite Series Program with Flexible and Reusable Bus Design
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