SLIM ProjectPress Kit▶ Table of Contents
Importance of pinpoint landing
Mission Objectives of SLIM
Success Criteria
Equipment for a Lightweight Spacecraft
Launch Vehicle and Trajectory
Landing Sequence
Vision-based Navigation
Missions on the Lunar Surface
Landing Site
“Two-step Landing”
Development History of SLIM
Pictures at the Launch Site
Role of SLIM in the JAXA Exploration
Reference Information
Related Organizations
Abbreviations

ー 3p
ー 5p
ー 6p
ー 7-12p
ー 13p
ー 14p
ー 15-16p
ー 17p
ー 18p
ー 19p
ー 20p
ー 21p
ー 22p
ー 23p
ー 24p
ー 25p
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▶ Importance of Pinpoint Landing

Fresh, excavated crater with a white appearance,reaching a certain depth.

Candidate of landingsite（Rover-based exploration toreach the target is assumed）

North100m
Rocks of a
exploration
target1km diameter© NASA / LRO

Candidate landing sites

As a result of the high-resolution lunar
observation data brought in abundantly by
the lunar orbiters “Kaguya” and “LRO,”
current lunar exploration missions involve
discussions focused on individual rocks
within specific images. In order to conduct
such “in situ observations” for individualrocks, it is necessary to land the spacecraft
precisely on a nearby flat terrain.
The left figure is an example of a landing
point that is scientifically interesting. (Notethat this is not the landing site for SLIM).
While this example considers using a lunar
rover to reach the exploration target,
traversing steep slopes and rough terrain
still poses a high difficulty level. Therefore,
it is important to achieve pinpoint landingfor effective exploration in the future.

（These are different from SLIM landing site)3▶ Importance of Pinpoint Landing

400km square area inthe south pole region

Red squares show areas with 300 days of sunlightthroughout the year.

Areas in the lunar polar regions withlong periods of daylight

Moreover, it is said that the favorable locations
allowing sustainable water resource explorationin polar regions (such as areas highly exposed
to sunlight), are limited to a very narrow area.
On the other hand, there are no previous
instances of pinpoint landing on celestial bodies
with significant gravity such as the Moon.
This is why "SLIM“ , a mission involving a small
lunar lander to demonstrate pinpoint landing
technology, is being carried out by ISAS/JAXA.

[Related Information]•The landing accuracy of conventional lunar landers is several orsometimes a dozen kilometers.

•Hayabusa" and "Hayabusa2" achieved precise touchdown, but thedynamics are completely different since the gravity of asteroids issignificantly lower than that of the moon and the earth. （ Spacecraft
can approach slowly and rise again if necessary. ）Lunar landing demonstration spacecraft: SLIM4

▶ Mission Objectives of SLIM
SLIM （Smart Lander for Investigating Moon） is a JAXA project aiming
to contribute to future lunar and planetary exploration by achieving
the following two objectives.

Objective A

Demonstration of high-precision landing technology
on the moon•

Aimed landing accuracy of 100m compared to several kilometers to tens ofkilometers of conventional lunar landers.

•Key technology includes “Vision-based navigation" and “Navigation, guidance andcontrol"

Objective B

Realization of a lightweight lunar and planetary probe
system to allow more frequent lunar and planetary
exploration missions•Small, lightweight, and high-performance chemical propulsion system•Weight reduction of core elements in most spacecrafts such as computers andpower supply systems
5▶ Success Criteria

Success criteria of SLIM project are defined as follows.
DegreeMinimum

Criteria
Realize a soft landing on the Moon with a small and lightweight spacecraft.
Accomplish the following two items.
•
By conducting an actual lunar landing descent, verify the vision-basednavigation, which is essential for high-precision landing•Develop a lightweight spacecraft system and check its operation in orbit

FullAchieve high-precision landing within 100m accuracy.
The navigation system and the guidance rules operate normally, and theachievement of landing accuracy is confirmed by telemetry data after landing.

Extra

Continue activities on the lunar surface for a certain period of time until sunset.
Carry out missions that operate on the lunar surface to obtain knowledge for lunar
and planetary surface exploration in the future.

6▶ SLIM Configuration• Mass： 200kg（Dry） / 700-730kg（Wet）• Size: 2.4m x 1.7m x 2.7m
S-band antennaThin film solar cell

Rocket connecting
ring

TankNavigation
Camera(CAM-MZ)

Navigation
Camera(CAM-PX)
Small prove(LEV)

Landing radar

22N-Thruster (12 unit)
Main engine (2unit)
Shock absorber(Contact points to Lunar surface)

SLIM has adopted a fuel and oxidizer integrated tank to reduce weight. Thiscylindrical tank is also used as the structure base.
7▶ Equipment for a Lightweight Spacecraft

２2N Thruster (THR)

RCSA
small-thrust
bipropellant
thruster with a thrust of 20 N. It
consists of 12 units, and the
combination of thrusters andvarious thrust patterns generates
translational and rotational forces,
assisting attitude control, orbit
maneuvering, and precise landing.

推進系
Propulsion system
IHI AEROSPACE Co., Ltd.

Mitsubishi Heavy Industries, Ltd.
KYOCERA Corporation

Main Engine (OME)Tank

A bi-propellant 500 N-class thruster used
for orbital control and velocity regulation
during lunar landing. It incorporates adomestically developed ceramic combustion
chamber,enabling
anunprecedented
combination of "wide thrust range andpulse operation" not found elsewhere in theworld.
Itshighperformance
also
contributes to the overall mass reduction ofthe propulsion system.

This tank stores the propellant andoxidizer used in OME-THR. It is also
used as the structure base of SLIM,
making a significant contribution totheoverallmassreduction.
Additionally, a lightweight diaphragm
made of newly developed PTFE is usedon the oxidizer side.
Mitsubishi Heavy Industries, Ltd.
Chukoh Chemical Industries, Ltd.

8▶ Equipment for a Lightweight Spacecraft

Landing Radar

ISC
統合化制御系
Integrated spacecraft control system

Mitsubishi Electric Corporation
MITSUBISHI ELECTRIC
DEFENSE AND SPACE TECHNOLOGIESCORPORATION

Mitsubishi Electric Corporation
MEISEI ELECTRIC CO., LTD.

A sensor used to measure thealtitude and velocity towards thelunar surface during the verticaldescent phase. It emits microwave
pulses toward the lunar surface andmeasures the round-trip time andDoppler frequency. It features
multiple modes with different pulse
widths and can be used in a range ofseveral kilometers to tens of metersin altitude.

Laser Range Finder(LRF)

Navigation Camera (CAM)

An optical wave sensor used tomeasure the altitude above thelunar surface just before landing. It
receives the modulated laser lightreflected from the lunar surface andcalculates the distance based on its
phase. It is characterized by its
compactness
andlightweight
qualities
throughfunctional
distribution with SMU.

A compact and lightweight camera
used to image the lunar surface duringthelandingphase.
It
cansimultaneously output uncompressed
images for vision-based navigationand compressed images for downlinks.
Two cameras are installed in different
orientations and are used during thepowered descent and vertical descentphases, respectively.

MEISEI ELECTRIC CO., LTD.

9▶ Equipment for a Lightweight Spacecraft

Integrated computer（SMU）

ISC
統合化制御系
Integrated spacecraft control systemMitsubishi Electric Corporation

An integrated computer that performs
all computational functions to control
SLIM. One of its distinctive features
is that the calculations for both thedata processing system and thenavigation and guidance control
system are handled by a single MPU
within the SMU. Image processing forvision-basednavigation
isalsoperformed on the FPGA within theSMU.

S-Band Transponder（STRX）
This S-band transceiver is used tocommunicate with the ground station
by SLIM. It incorporates advanced
design features such as digitalization
using FPGA and direct transmission
signal output through high-speed D/Aconversion, achieving a compact andlightweight design.

COM
通信系
Communication system
Mitsubishi Electric Corporation

10▶ Equipment for a Lightweight Spacecraft

Lithium-Ion Cell Module（LICM）

EPS
電源系
Electrical power system

The Furukawa Battery Co., Ltd.
Technosolver Corporation
SANKYO MANUFACTURING
CO., LTD

Integrated Power Control Unit
（IPCU）

Mitsubishi Electric Corporation
MITSUBISHI ELECTRIC
DEFENSE AND SPACE TECHNOLOGIESCORPORATIONThe IPCU is an innovative power control
device that consolidates various functions
including battery charging and discharging,regulation of solar power generation,
power distribution, and control functionsfor thruster valve operation and heatercontrol, which were previously handled byseparate components. By implementing
digital control for these operations, theIPCU achieves a significant enhancementin functionality and lightweight design
compared to conventional analog control
devices.

Toachieve
miniaturization
andlightweight design, SLIM utilizes SUS
laminate battery cells with an outercasing made of SUS (Stainless Steel).
Two sets of cells are securely bound by
CFRP(CarbonFiber
Reinforced
Plastic) plates to withstand vibrations,
impacts during launch, and charging/discharging in vacuum environment.

Thin Film Solar Cell
SLIM incorporates lightweight andhighly efficient thin-film triplejunction solar cell sheets to achieve
lightweight design. Leveraging theirflexibility, they are installed oncertain curved surfaces as well. In
addition, for simplified processes,
we have adopted an attachment
method using Velcro.
Sharp Corporation11▶ Equipment for a Lightweight Spacecraft

Shock Absorber (ABS)

ABS
衝撃吸収系
Shock-absorbing system

KOIWAI Co., Ltd.
JAMPT CORPORATION
Technosolver Corporation
ORBITAL ENGINEERING INC.

SLIM
isequippedwithamechanism to absorb the impactduringlanding
atits
five
touchdown legs. The structurefeatures an aluminum latticepattern designed to absorb shocks
efficientlywith
3D
printingtechnology.

Multi-Band Camera(MBC)
Lunar excursion vehicle(LEV)
Laser Retro-reflector Array(LRA)

PLD
月面活動系
Payload mission system
MEISEI ELECTRIC CO., LTD.
(MBC)

The Multi-Band Spectral Camera (MBC) is
responsible
forinvestigating
thecomposition of the surrounding rocks afterlanding. By utilizing this instrument, we
aim to obtain clues that could lead tounraveling the mysteries of Moon’s
formation. In addition, the SLIM mission
also includes a small probe called the Lunar
Exploration Vehicle (LEV), which separates
from the main spacecraft just before
landing and performs photo imaging.
Furthermore, the mission incorporates areflector (LRA) provided by NASA for
precise measurement purposes.

12▶ Launch Vehicle and Orbit

The planned launch method is the “H-2A rideshare”, where it will be launchedsimultaneously with the scientific satellite “X-Ray Imaging and Spectroscopy
Mission(XRISM)” also currently under development by ISAS. The launch is scheduled
for August 2023 or later.
SLIM will use its own propulsion
systemtoperform
trajectoryadjustments toward the Moon.
Therefore, it adopts a trajectory
design that minimizes propellant
consumption. As a result, it willtake several months to reach theMoon.

・Arrival in lunar orbit
3 to 4 months after launch
・Lunar orbit
1 month・Landing descent
4 to 6 months after launch(5) Lunar orbit insertion(1) Adjustment of Lunar transfer orbit conditions
through apogee altitude.

(2) Lunar transfer orbit insertion13▶ Landing Sequence
The landing sequence of SLIM will be conducted as follows:
1. Initiate the landing descent from lunar orbit and perform precise vision-basednavigation to accurately estimate its own position. Utilizing navigation, guidanceand control, it will approach the target location above the lunar surface.
2. From above the target location, precise measurements of altitude and terrainrelative velocity will be conducted using the landing radar, which will beintegrated into the navigation and guidance system.
3. During the final approach, autonomous image-based obstacle detection andavoidance will be employed to ensure a safe landing, avoiding hazardous rocks
and other obstacles.

Powereddescent

Pre‐landing lunar orbit
An elliptical orbit with dimensions
approximately 15 x 600km
Altitude: 15km

Altitude:
7km

Verticaldecent© JAXA

Landing sequence during powered descent14▶ Vision-based Navigation

SLIM will achieve pinpoint landing by measuring and correcting its own
position by “vision-based navigation."

1.

Vision-based navigation systemprocesses the captured images
to identify “crater positions.”(Creator identification)

2.

From a broad map encompassingthe spacecraft’s location, thesystem identifies locations thatmatchthecrater
patterns
composed of multiple crater
positions. (Crater Matching)15▶ Vision-based Navigation

To achieve "vision-based navigation," processing time is a crucial factor.
The current space-grade CPUs have only about 1/100th of the capability
compared to those used on the ground. Therefore, we have developed
image processing algorithms specifically designed for space-grade FPGAs,
enabling vision-based navigation to be accomplished within a few
seconds.

REALTIME

Image captured byhandheld camera

Camera imaging position
identified through “Visionbased navigation” system

ISAS/JAXA Exhibition demonstration (2018)16▶ Mission on the Lunar Surface
After a successful landing, our mission aims to unravel the origins of the Moon
through composition analysis of rocks estimated to be derived from the lunar mantle
using a “multi band spectral camera."To achieve this, it is essential to landin the vicinity of the targeted crater,
enabling precise observations that canonly be accomplished through pinpoint
landing. This observation is included inone of the “extra success” criteria.

gimballaunch rock for
FOV rotation
mechanismlaunch rock forfocus mechanism

Placement of MBC

Furthermore, SLIMprobes equippedfeatures:•••is loadedwith thewith twofollowing

Mission status monitoring after landing
Imaging of the landing scene from anexternal perspective (still images)
Independent communication system fordirect communication with Earth

Small probe ejection (left)
Small probes on Lunar surface (right)
17▶ Landing Site
As a suitable location for spectroscopic camera observations and fordemonstrating landing technologies, we have selected a site neighboring
the SHIOLI crater near the "Sea of Nectar" as the landing target site.
•Landing targets that can provide new insights through spectroscopic
camera observations are limited to a very specific region on the lunar
surface. Therefore, conducting such observations requires "pinpointlanding" capability to be in place.

•Consequently, landing on the “slopes” near the crater became
necessary.

ሺെ13.3, 25.2ሻ

ሺെ13.3, 25.2ሻ

出典:NASA/LRO
SLIM landing site
(Left: Position on the Moon, Right: Expanded view)

The area, located in a low-altitude
region known as the “Sea of Nectar”,
have relatively constant slope of 15
degrees or less. （13.3degS／25.2degE）

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▶ “Two-step Landing”
Because the landing site is located near a crater, the surrounding area issloped to approximately 15 degrees. Therefore, the method of landing
safely on such a slope becomes important.
As science and exploration objectives become more sophisticated, landing
on such sloping area will be increasingly required in the future.
Especially for the case of a SLIM-scale spacecraft, the "two-step landing
method", in which the main landing gear first touches the ground and thenrotates forward to stabilize, has shown excellent reliable landing results
through simulation.

(1) Hovering(2) Forwardinclination(3) Main leg (4) Front leg
touchdown touchdown(5) Stabilization

Landing simulation for SLIM

19▶ Development History of SLIM
The development history of the SLIM project can be summarized as follows.
It originated from the SELENE-B project around the year 2003, and sincethen, it has been under continuous design study up to the present day.

2002SELENE-B plan

2012

SLIM Project Proposed

2016

System Definition Review

2016

Project Transition Review

2018Preliminarily Design Review

2019

Critical Design Review

202３

Post Qualification-test Review©Mitsubishi Electric Corporation

System test for flight model

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▶ Pictures at the Launch Site

21▶ Role of SLIM in JAXA Exploration"SLIM" is a technology demonstrator, and the expertise gained in precision
landing and other technologies will be inherited by future missions such as
the Martian Moon eXploration (MMX) and lunar polar missions.

22▶ Reference Information
We have refurbished the models (MTM, TTM) used for thermal vacuum and mechanical environmental testingand put them on display at the Sagamihara Campus!

©三菱電機
©三菱電機

©三菱電機

©三菱電機

SLIM Project website
https://www.isas.jaxa.jp/home/slim/SLIM/index.html

SLIM on Twitter@SLIM_JAXA

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▶ Related organizations
JAXA, and numerous universities and institutions, have been actively
engaged in researching and developing various technologies toachieve the SLIM mission.

* 配置については順不同

24▶ Abbreviations

略称
AANT

名称（英語）RAV Altimeter ANTenna

名称（日本語）
着陸レーダ高度測定用アンテナ

略称
PLD

名称（英語）
PayLoaD mission system

月面活動系

ADM

Apolune Descending Maneuver遠月点降下マヌーバ

BAT

BATtery

バッテリ（二次電池セルモジュール）

CAM
COM

navigation CAMera
COMmunication system

航法カメラ
通信系

PT
RAV
RCS

Pressure Transducer
Radio Altimeter and Velocity meter
Reaction Control System

圧力センサ
着陸レーダ
推進系

CSS

Coarse Sun Sensor

粗太陽センサREU
SABS

Rav Electorical Unit
Shock ABSorber

着陸レーダ電気ユニット
衝撃吸収材

DSN

Deep Space Network

深宇宙用追跡ネットワーク

EPS
FLT

Electrical Power System
FiLTer

電源系
フィルタ

SANT
SAP

S-band ANTenna
Solar Array Panel

Sバンドアンテナ
太陽電池パネル（薄膜太陽電池シート）

GFD

Gas Fill and Drain valve

ガス系注排弁

SDIP
SHYB

S-band DIPlexer
S-band HYBrid

Sバンドダイプレクサ
Sバンドハイブリッド

GN

Ground Network

追跡ネットワーク

IMUINT

Inertial Messurement Unit
INTegration hardware

慣性基準装置
計装系

SLIM
SMU

Smart Lander for Investigating Moon
System Management Unit

小型月着陸実証機SLIM
統合化計算機SSW
STR

S-band SWitch
STRucture system

Sバンドスイッチ
構造系

STRX
STT

S-band TRansponder
STar Tracker

Sバンドトランスポンダ
スタートラッカ

SWB
TCS

lunar SWing-By
Thermal Control System

月スイングバイ
熱制御系

THR
TLI

THRusterTrans-Lunar Injection

補助スラスタ
月遷移軌道投入

TNK
TOR

fuel TaNK
Trim ORifice

推進薬タンクトリムオリフィス

UDSC
USC

Usuda Deep Space Center
Uchinoura Space Center

臼田局
内之浦局

IPCU

Integrated Power Control Unit

電力制御分配器

ISC

Integrated Spacecraft Control system

統合化制御系LEV

Lunar Excursion Vehicle

小型プローブLOI
LRA

Lunar Orbit Insertion
Laser Retro-reflector Array

月周回軌道投入
リフレクタ（NASA JPL)

LRF

Laser Range Finder

レーザレンジファインダ

LRO

Lunar Reconnaissance Orbiter

ルナー・リコネサンス・オービター

MBC
NPV

Multi-Band Camera
Non-Pyro valve

分光カメラ
ノンパイロ弁

OME

Orbit Maneuvering Engine

メインスラスタ

PAM

Period Adjustment Maneuver

周期調整マヌーバ

PD
PDM

Powered Descent
Perilune Descending Maneuver

動力降下
近月点降下マヌーバ

PFD

Propellant Fill and Drain valve

液系注排弁

VANT
RAV Velocity meter ANTenna
XRISM X-Ray Imaging and Spectroscopy Mission

名称（日本語）

着陸レーダ速度測定用アンテナ
X線分光撮像衛星25

From the era of “Landing where we can”
to “Landing where we want.”

Just a little more until launch!
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