MISSION DESIGN

Hotel Fort Canning, Singapore
October 7 – 8, 2015
Mission Design and Operation for
a Micro-Deep-Space Explore: PROCYON
Yoshihide Sugimoto
LSAS Tec Co., Ltd
Acknowledgement
Asso. Prof. Dr. Ryu Funase
Project manager
Department of Aeronautics and Astronautics Engineering,
The University of Tokyo
Asso. Prof. Dr. Yasuhiro Kawakatsu
Coordinator in JAXA (Development)
Institute of Space and Astroautical Science (ISAS)/
Japan Aerospace Exploration Agency (JAXA)
Assistant Prof. Dr. Atsushi Tomiki
Coordinator in JAXA (Operation)
ISAS/ JAXA
Oct. 7-8, 2015
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INTRODUCTION
Art by Sean McNaughton, National Geographic Staff; Samuel Velasco, 5W Infographics
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INTRODUCTION
Q: How many people want to have their “own” spacecraft?
Many !
Q: How many of them do have it?
Very little…
Q: Why ??
Not enough time…
Not enough people (talent)…
Not enough money…
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INTRODUCTION
Cost of Deep-Space Missions
Total cost ($)
10
?
5
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PROCYON
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INTRODUCTION
What’s PROCYON
<Main mission>
Demonstrate 50 kg class micro-spacecraft bus system for deep-space
missions
•
•
Power, thermal, deep-space communication, and attitude and orbit control
Orbital maneuvering by a miniature ion engine propulsion system
<Advanced mission>
•
•
•
•
X-band communication using GaN power amplifier
Deep-space navigation by relative VLBI technique
Optical navigation combined with classical RF navigation
Proximate flyby to an asteroid
<Science payload>
•
•
Rotatable optical telescope for proximate asteroid flyby
Lyman Alpha Imaging Camera
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INTRODUCTION
The Journey to Asteroid
< High-velocity Proximate Asteroid Flyby >
Asteroid arrival
(2016-05)
control sight direction
Sun
order of dozens km
Earth gravity assist
(2015-12-3)
Launch (2014-12-3)
Oct. 7-8, 2015
Flyby in a very close distance and
take proximate image of the objective
asteroid using 1-axis rotatable telescope
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INTRODUCTION
The Journey to Asteroid
Movie !
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INTRODUCTION
Spacecraft Specification
Structure
Power
AOCS
Size
0.55m x 0.55m x 0.67m + 4 SAPs (Solar Array Panels)
Weight
<70kg (wet)
SAP
Triple Junction GaAs, >240W(1AU,qs=0,BOL)
BAT
Li-ion, 5.3Ahr
Actuator
4 Reaction Wheels (RW), 3-axis Fiber Optic Gyro (FOG)
Sensor
Star Tracker (STT), Non-spin Sun Aspect Sensor (NSAS)
Telescope (for optical navigation relative to the asteroid)
Propulsion
Performance
<0.002[deg/s], ~0.01[deg] (pointing stability)
RCS
Xenon cold gas jet thrusters x8, ~22mN thrust, 24s Isp
Ion propulsion Xenon microwave discharge ion propulsion system
0.3 mN thrust, 1000s Isp, ~400m/s DV capability (for 65kg s/c)
Propellant
Communication Frequency
Antenna
2.5 kg Xenon (shared by RCS and ion propulsion)
X-band (for deep space mission)
HGA x1, MGA x1, LGA x2 (for uplink), LGA x2 (for downlink)
Output power >15 W (RF output), >30% (GaN XSSPA)
Payload
Oct. 7-8, 2015
Weight
~10kg (asteroid observation camera + Lyman alpha imager)
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INTRODUCTION
Development
Year
Month
9
▲
2013
10
11
2014
12
1
2
3
4
5
6
7
9
10
11
12
▲
Launch approval
Start of S/C Development
Conceptual study &
System design
(05/2013~)
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S/C Delivery
▲
Launch
(Dec. 3)
EM/STM test
FM (component)fabrication
FM integration & test
Schedule
•
•
•
Thermal Vacuum test
Vibration/Shock test
“Table sat” test
EM: Engineering Model
STM: Structure and Thermal Model
FM: Flight Model
•
•
•
•
•
I/F test
Ion thruster test
Thermal Vacuum test
Vibration test
Separation shock test
Very small team (20~30 staffs and students at one place) enabled
quick decision making for quick development
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INTRODUCTION
Development – How’s this mission possible!?
 Minimizing newly development elements and maximizing current
existing technology and equipment
 Inherit the “HODOYOSHI” project’s*1 technical know-how that
enables realistic performance and reliability
 Aggressively utilize the software and hardware from commercial
companies
 Conduct small parts integration test in prior to total integration test in
order to make schedule compact and safe
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MISSION DESIGN
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MISSION DESIGN
Design Flow
1. Initial condition
Launch condition (separation epoch
and state vector) are given for each
launch window of the main mission
2. Asteroid selection
Location and epoch are evaluated for
entire asteroid catalogue (more than
600,000) and ranked based on the
mission requirements
3. Low-thrust trajectory
design
Design mission trajectory and
maneuver planning using low-thrust
optimization technique
4. Mission analysis
Evaluate mission requirements and
constraints for each potential
trajectory
Nominal trajectory
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MISSION DESIGN
Initial condition and Asteroid search
Launch hyperbola
1-yr after launch
• There are two cases for the Earth gravity assist (EGA), 1-year or 2-year
• Depending on the EGA case, the mission has two different set of asteroid candidates
• In both cases, we have only 1-3 target asteroids which satisfies the mission
requirements
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MISSION DESIGN
Initial condition and Asteroid search
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MISSION DESIGN
Low-Thrust Trajectory Design
• Developed two identical trajectory optimizer
• GALLOP (Gravity Assist Low-thrust Local Optimization Program)
Simple model
Preliminary mission design
• jTOP
Full-model
Precise nominal trajectory design
Equation of motion is simple but to prove the accuracy
of the solution is difficult
Use STK Astrogator to check our final state and initial state
(from the final state backward)
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MISSION DESIGN
Mission Trajectory
Sun-Earth fixed rotating
reference frame
Heliocentric J2000 ecliptic coordinate frame
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MISSION DESIGN
Mission Trajectory
Summary of trajectory design
Launch
Earth gravity assist
Asteroid arrival
2014/12/3 06:24:21.561 UTC
2015/12/3 20:55:30.474 UTC
2016/5/12 18:35:13.199 UTC
Start IES maneuvering
Finish IES maneuvering
(Total maneuver duration)
2015/1/25 16:35:20.771 UTC
2015/6/15 11:21:54.243 UTC
（3400-hour）
Sun distance
0.911 - 1.118 AU
Maximum Earth distance
0.451 AU
The nominal trajectory is an Earth gravity assisted trajectory
Use STK CAT to evaluate the flyby hyperbola
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MISSION OPERATION
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MISSION OPERATION
Nominal operation strategy
 S/C Communication
 S/C Health check
Command &
Telemetry
Command
planning
Navigation
 Short/ long term operation planning
 Simulation and evaluation
 Command build
Operation
assignment
 Time shift of ground station
assignment
Oct. 7-8, 2015
 Orbit determination
 Orbit prediction
 Antenna tracking plan
Orbit analysis
 Maneuver assessment
 Access calculation
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MISSION OPERATION
Structure
Ground station
USC34 (UDSC6)
Operation Center
@ISAS/JAXA
Propulsion
Commander
Oct. 7-8, 2015
Power
Thermal
Attitude
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etc…
GNC
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MISSION OPERATION
Launch – Critical Operation
 Launch at 2014-12-3 4:23 UTC from Tanegashima Space enter
 Obtain 1st voice at 6:30 UTC
Friendly support of signal acquisition by
Warkworth (NZ) ground facility!
The tracking antenna prediction was
generated by STK access calculation
 Obtain first telemetry at 10:12 UTC
 Start checking-out each devices
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MISSION OPERATION
Current Status
 Main bus system is working good!





Attitude is three-axis stabilized!
Success continuous IES maneuvering!
Obtained image by mission and science payload!
Relative navigation by using VLBI technique is on going!
Every mounted devices are confirmed their designed performance!
 Due to unexpected engine malfunction, we had to gave up asteroid
flyby…




Small-force analysis
Telescope operation
Science payload operation
Guidance by RCS
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MISSION OPERATION
Current Status
0.01
Launch 2014-12-3 6:24:21 UTC
to the Sun
Launch 2014-12-3 6:24:21 UTC
0.005
0
0
Planned trajectory
Y-axis (AU)
-0.005
Y-axis (AU)
-0.1
-0.01
Achieved orbit
@2015-3-8
-0.015
-0.02
Achieved orbit
@2014-12-3
-0.025
-0.2
-0.03
-0.035
-0.04
-0.03
-0.3
-0.02
-0.01
0
0.01
0.02
0.03
X-axis (AU)
We are here!
Magnified view of a black dash rectangle
-0.4
Asteroid arrival
2016-5-12
-0.5
-0.3
-0.2
-0.1
Asteroid DP107 orbit
0
0.1
0.2
0.3
X-axis (AU)
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Summary
• PROCYON is a joint mission between The University of Tokyo and
JAXA
• The micro-deep-space system is proved in real space
• The low-cost development has been done by inheriting past Earth
satellite know-how and using as much as current existing commercial
devices and software
• Priceless students’ effort!
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Summary of STK Contributions
1. Evaluation tool to verify the in-house developed
trajectory designer: Astrogator
2. Conjunction analysis at the Earth gravity assist: CAT
3. Tracking antenna prediction for the first acquisition:
STK
4. Long term and daily operation planning: STK
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Artwork of PROCYON Earth Gravity Assist ©JAXA
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ミッションの意義
• 50kg級超小型深宇宙探査機バスの実証
• 地上局との通信、軌道決定、軌道制御まで行える深宇宙探査機を50kg級という非常に小さ
い規模で実現すること（世界初の試み）により、将来的にさまざまな深宇宙ミッション機会
(※1)の高頻度な利用と柔軟な探査ミッション構成が可能になる。
• 将来の活用例
•
•
①将来の中・大型探査機に向けて、開発リスクの高い技術の研究を超小型探査機を用いて実施する。（超近
接・高速フライバイ観測技術の実験は、この役割を想定したもの）
②大型の深宇宙輸送機に搭載されて現地（小惑星等）で活動するような、ミッションに特化した超小型機
※1 このクラスの重量であれば、イプシロン単独打ち上げ、
クラスタ打ち上げ、キックステージを利用したGTOミッションへの相乗り、
など多様な打ち上げ機会が今後期待できる
• 深宇宙探査技術の実証
• GaN高効率X帯アンプの実証…探査機の小型・軽量化に資する省電力化技術
• 高精度VLBI航法の実証
…深宇宙での編隊飛行ミッション等の実現に資する高精度軌道決定技術
• 小惑星の超近接・高速フライバイ観測…フライバイ（マルチフライバイ）探査における訪問天
体数と観測の質（分解能）の両立を可能とする技術
• サイエンス観測
• ジオコロナ（地球コロナ）観測…アポロ16号以来42年ぶりとなるジオコロナの全球撮像を実施。
地球周回衛星からは観測できない高高度の水素大気分布と磁気嵐の関係を明らかにする。
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PROCYON at a glance
Solar Array Paddle
(SAP)
X-band High gain antenna
1.5 m
Cold Gas Jet
Thruster (CGJ)
X-band Low gain antenna (LGA)
for uplink
1.5 m
+Z
X-band LGA for
downlink
CGJ
+Y
CGJ
Telescope
+X
X-band middle
gain antenna 0.55
(MGA)
CGJ
m
Miniature ion
engine
Science payload
(LAICA)
Star tracker
Sun censor
X-band LGA for
downlink
Wight ~65 kg
+Y +Z
X-band LGA for
uplink
+X
CGJ
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System block diagram and development team
(System：UT, ISAS)
AOCS: UT, ISAS
(Thermal design：UT, ISAS, Hokkaido Univ.)
Propulsion: UT, ISAS
(Ground station：ISAS)
AOCS
Thermal control
HTR(xN)
FOG
STT
SS(x5)
Mission:
UT, Meisei Univ.
MIPS
+XeCGJ
RW(x4)
PDU
TELE
CAM
HRM(x4)
MIR
EPS
SAP(x4)
OBC
(Data Handling)
PCU
BAT
XSW3
LGA
XSW1
XDIP
XSW2
XTRP
XTX
BPF
XSSPA
Communication:
ISAS
XSW4
Power I/F
Data I/F
XRX
BPF
LGA
XSW5
LAICA
SAP deployment mechanism:
Nihon Univ.
DHS:
Tokyo Science Univ.
IMG PROC
MGA
Mission
LGA
LGA
HGA
Science Instr.:
Rikkyo Univ.
Communication
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Organization
The University of Tokyo
Collaboration
Project manager：Associate professor
Ryu Funase
• Manage spacecraft development
ISAS
ISAS
PIC：Associate professor
Yasuhiro Kawakatsu
• Communication subsystem
• Support spacecraft development
• Support mechanical tests
Component developper
・ The University of Tokyo
・ Hokkaido University
・ Tokyo University of Science
・ Meisei University
・ Rikkyo University
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Micro-communication unit for deep-space
communication
はやぶさ等の深宇宙探査機と互換性のある深宇宙用の超小型X帯通信系を開発．
世界初のGaNを用いた高効率アンプの実証，VLBI軌道決定のさらなる高精度化を目指
したチャープDOR方式の実験等の最先端技術の実証を狙う．
X帯低利得アンテナ
（アップリンク用）
PROCYON搭載通信系の仕様
項目
通信周波数帯
アップリンク周波数
ダウンリンク周波数
送信出力
コマンドビットレート
テレメトリビットレート
軌道決定
地上局
仕様
Xバンド
7.1 [GHz]
8.4 [GHz]
最大15 W以上
15.625, 125, 1000bps
8 bps 〜32 kbps
R&RR
DDOR（Delta VLBI）
臼田局，内之浦局，
その他海外協力局
X帯高利得アンテナ
X帯低利得アンテナ
（ダウンリンク用）
X帯中利得アンテナ
X帯低利得アンテナ
（アップリンク用）
X帯低利得アンテナ
（ダウンリンク用） 32
イオンスラスタ・コールドガスジェット統合推進系
姿勢制御用（リアクションホイールアンローディング）＋軌道制御用（高加速度）のコールドガスジェット系と
軌道制御用（低加速度，高比推力）の電気推進を統合した，キセノンベースの統合推進系
項目
値
探査機総重量[kg]
約65kg
キセノン搭載燃料重量[kg]
2.5
MIPS（小型イオン推進システム）比推力[s]
1000
MIPS（小型イオン推進システム）推力[N]
300×10-6
コールドガスジェット比推力[s]
24.5
コールドガスジェット推力[N]
22×10-3
コールドガスジェット
イオンスラスタ
ほどよし衛星搭載の小型イオン推進システム
”MIPS”
作動中のイオンスラスタ
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ミッション系（小惑星撮像ミッション）
• 超近接・高速フライバイ撮影を実現するための撮像システム
– 小型衛星に搭載可能な小さな口径の望遠鏡でも
小惑星接近時の光学航法に必要とされる角度分解能を実現
– 望遠鏡の一部（駆動部）の回転角を画像フィードバックに基づいて
オンボードで制御することにより，高速視線変更を実現
口径50mm,焦点距離150mmと小型ながら，
12等級まで観測可能な光学系
光学系
駆動鏡の回転による高速視線変更
→最接近前後も小惑星を追尾観測可能
望遠鏡光軸周りの回転角を制御可能な駆動部
34
ジオコロナ観測装置 LAICA
（Lyman Alpha Imaging CAmera)
ジオコロナ(地球コロナ)
地球周辺13万kmまで広がる水素大気発
光。アポロ16号(1972年4月)が初めて撮像し
たが感度不足のため3万km程度まで。以降、
全球分布の撮像は行われていない。
近年になって注目されている
・高高度分布の非対称性(大気散逸過程を反映)
・高高度分布変動と磁気嵐の関係
を、42年ぶりのジオコロナ全球撮像によって明らかにする。
[Carruthers et al., 1976]
・真空紫外線領域にある水素ライマンα線(121.6nm)用の特殊
な望遠鏡と検出器で構成
・立教大学内で望遠鏡部の設計・組立・性能試験を実施
・超小型衛星に搭載可能な大きさ・質量で要求感度を達成
LAICA FM
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