The Science Scenario of the SELENE-2 Mission

Manabu Kato, Kohtaro Matsumoto, Tatsuaki Okada, Satoshi Tanaka, and Science Working Group for Post- SELENE Project

Japan Aerospace Exploration AgencyISAS & ISTA

SELENE-2 Science group is studying:Science goals in lunar scienceCandidate mission and instrumentsCandidate target areaLander-rover designGeophysical study for lunar deep interior using probes

Key questions in lunar science:

(1) Bulk composition of whole moon, and internal structure such as core radius for origin and evolution of the Moon,

(2) Origin of dichotomy, differentiation of magma ocean, and tectonic style for evolution of lunar crust and mantle, and

(3) History of lunar environment such as solar activity and meteoroid impact flux.

・1990 /1/ 24 Launch (M3S-II Rocket）・Orbit Maneuver by Lunar/Solar Gravity Assist Technology of Lunar Orbit Insertion・Technology of Orbit Determination・1993 /4/ 11 Impact on Lunar Surface

JAXA’s Activities in Lunar Exploration

Past

Hiten/Hagoromo

In Development

Lunar-A

SELENE

Under Study

SELENE-2

Technology demonstrationPenetrator mission

Surface remote-sensing

Landing, in-situ observation

SELENE Series Lunar Exploration

• SELENE-1 was defined as a lunar mission for the science of the Moon and demonstration of technology for future exploration of the Moon and planets.

・ Science WG for next lunar mission concluded:

SELENE-2 and after must be landing missions. Candidate mission targets:

1. Geological survey using a science rover.2. Internal structure study using multi-penetrators

(Lunar-B).3. Celestial study using small telescope.4. Sample return for dating and geochemical studies.

Ｕsing improved, long-lived penetrators and/or lander,install seismological network for study of lunar internal structure

Investigation of lunar orbital motion by observing polar stars using a celestial telescope

In-situ observation of typical geological features using intelligent rover(s)

Candidate Areas:1. Central peak-type craters

for study of deep crust materials and crater formation

2. Thin crust layer crater such as South Pole Aitken basin for study of mantle materials. ⇔ Moonrise

3. Typical highlands of far-side for highland rock study.

4. Polar regions for exploration of topologically interest area.

Bussey et al. 2005

Lunar North Pole

Central Peak Craters

Tsiolkovsky Crater Clementine UV/VIS ( Pieters & Tompkins (1999))

Gassendi crater

Central peaks: petrologicalinformation of deep crust.Reflectance studies show high contents of

anorthosite in c.p. of both basin and highland areas. (e.g. Tompkins & Pieters(1999))

Remote sensing observation by SELENEIn-situ observation by SELENE-2

CraterCentral Peak

- Multi-band Spectroimager- Gamma-ray Spectrometer- Abrasion・polishing- Sample collection & storage

Geological Analysis Package- Spectromicroscope-X-ray spectro/diffractmeter- Abrasion*polishing

Telescopic imaging spectrometer

- Observation of outcrops in central peak- Temporal surface treatments of samples-In-situ analysis of rocks and soil, major and radioactive elements

-Detailed observations and analyses of rock -samples collected by the rover- Telescopic observations of landing area- Sample transportation from rover to lander

High-resolution imaging of central peak and surroundings

Earth orRelay Sat.

XX--BandBandCMDCMD：：1kbps1kbpsTLM:TLM:≧≧2kbps2kbps

S-BandCMD：1kbpsTLM:≧40kbps(LGA) [256kbps(MGA) ]

Broadband: 2Mbps(max)Only Visible-Time

128MB128MB

1GB1GB

128MB128MB

Lander-rover cooperationPayload (including Rover) - 100kg

Pre.Amp.

Φ1.5inch

22--D CCDD CCD

ElectronicsElectronics

XRTXRT

samplesample

XRF, XRD Geophysical

Study Probe

Current Status of Lunar-A

Lunar-A Project has been reviewed by an external review board in JAXA.

Suggestions for improvement were made:1. Assurance of robustness on communication

link between Penetrator and S/C, including the data acquisition during deployment phase.

2. Addition of CPU reset circuit for possiblemalfunction at the impact.

Improvements suggested to the penetrator may take about 3 years, including multiple qualification tests.

Geophysical Study of Lunar Internal Structure:

MantleMantle←←Earth

Thin surface layer Crust

Metal core ?

Th concentration region of lunar surface （Joliff et al.,1998）

◎◎Layer structure study of lunar interiorLayer structure study of lunar interior-- Average density and thickness of lunar Average density and thickness of lunar crustcrust

-- Vertical structure of lunar mantleVertical structure of lunar mantle- Melting feature of lower mantle

- Core density and size◎◎ Heterogeneity study of lunar interior Heterogeneity study of lunar interior structure structure

-- Horizontal distribution of crust Horizontal distribution of crust thicknessthickness

-- Horizontal structure of lunar mantleHorizontal structure of lunar mantle

××

××

××

××Deep moonquake

Seismological observation since Apollo Seismological observation since Apollo missionmissionHeat flow observationHeat flow observationInstallation of wideInstallation of wide--band seismometer band seismometer by by landerlanderEmployment of Employment of penetratorspenetrators carrying carrying short period seismometershort period seismometer

Free oscillationFree oscillation and body wave exited by large moonquake

Detection of Lunar Free Oscillation by LongDetection of Lunar Free Oscillation by Long--period Seismic Recordperiod Seismic Record

Global Survey of Planetary Body InteriorGlobal Survey of Planetary Body Interior

r

( ) ( ) mlr

mlln YrVYrUS 1: ∇+e

( ) rm

lln YrWT e×∇1:

100 S

290 S

101 S

1020 S r

Spheroidal mode

Troidal mode

Free Oscillation Modes:

l = 10, m = 0 l = 10, m = 5

l = 10, m = 10 l = 10, m = 15

Vertical layer contribution to each mode

Technical Development of Long-period Seismometer and Setting Technology

・Carry-on system・Autonomous drilling system

・Alignment・Telecommunication・Operation

Carry-on drilling system on lander

Carry-on long-period seismometerAutonomous drilling and installation of seismometer in subsurfaceAutonomous 3-axis alignment

Bore-holeTypeseismometer

LUNARLUNAR--AA

Body waveSurface wave

FreeOscillation

Earth’s tide

(dig

it/c

m)

(dig

it/c

m)

Frequency characteristics of seismometer

Requirement

Frequency、Hz

STS-1

Autonomous Drilling System

エアバッグを伸縮させて打ちこみ時の反力を支持する案

Air-bag support

Tunnel Boring Machine Mole

Using motor torque

3-axis Alignment Gimbals

Gimbals mechanism onboard Lunar-A penetrator

Heritage of Lunar-A alignment system

Autonomous Gimbals using lunar gravityLight weight and compact

mechanismReduction of shock resistance from

Lunar-A system

The science working group studies;Science mission scenarios,Sampling processes such as crush, polish,abrasion, manipulation under low gravity,In-situ analyses of collected samples by spectrometry of X-ray, Gamma-ray, UV/VISSurvival technology over two-weeks nightsGeophysical probe development; seismometer, heat flow probe, ..

The engineering study working group studies;Pin-point soft landing technology:Navigation, guidance, and hazard avoidance of landerRover technology:Autonomous operation, telecommunication,..Setting mechanism of geophysical probes