The Science Scenario of the SELENE-2 Mission

Transcription

1 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 Agency ISAS & ISTA SELENE-2 Science group is studying: Science goals in lunar science Candidate mission and instruments Candidate target area Lander-rover design Geophysical study for lunar deep interior using probes

2 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.

3 JAXA s Activities in Lunar Exploration Hiten/Hagoromo Technology demonstration 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 Past Lunar-A Penetrator mission SELENE Surface remote-sensing In Development SELENE-2 Landing, in-situ observation Under Study

4 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.

5 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

6 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. Lunar North Pole Bussey et al. 2005

7 Central Peak Craters Tsiolkovsky Crater Clementine UV/VIS ( Pieters & Tompkins (1999)) Central peaks: petrological information of deep crust. Reflectance studies show high contents of anorthosite in c.p. of both basin and highland areas. (e.g. Tompkins & Pieters (1999)) Gassendi crater Remote sensing observation by SELENE In-situ observation by SELENE-2

8 Lander-rover cooperation Payload (including Rover) - 100kg Crater Central Peak X-Band CMD:1kbps TLM: 2kbps Earth or Relay Sat. Broadband: 2Mbps(max) Only Visible-Time S-Band CMD:1kbps TLM: 40kbps(LGA) [256kbps(MGA) ] High-resolution imaging of central peak and surroundings Telescopic imaging spectrometer 128MB 1GB 128MB Φ1.5inch Pre.Amp. - Multi-band Spectroimager - Gamma-ray Spectrometer - Abrasion polishing - Sample collection & storage Geological Analysis Package - Spectromicroscope -X-ray spectro/diffractmeter - Abrasion*polishing - Observation of outcrops in central peak - Temporal surface treatments of samples -In-situ analysis of rocks and soil, major and radioactive elements XRF, XRD sample 2-D D CCD Electronics XRT -Detailed observations and analyses of rock -samples collected by the rover - Telescopic observations of landing area - Sample transportation from rover to lander Geophysical Study Probe

9 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 possible malfunction at the impact. Improvements suggested to the penetrator may take about 3 years, including multiple qualification tests.

10 Geophysical Study of Lunar Internal Structure: Seismological observation since Apollo mission Heat flow observation Installation of wide-band seismometer by lander Employment of penetrators carrying short period seismometer Layer structure study of lunar interior - Average density and thickness of lunar crust - Vertical structure of lunar mantle - Melting feature of lower mantle - Core density and size Heterogeneity study of lunar interior structure - Horizontal distribution of crust thickness - Horizontal structure of lunar mantle Th concentration region of lunar surface (Joliff et al.,1998) Thin surface layer Earth Deep moonquake Metal core? Mantle Free oscillation and body wave exited by large moonquake Crust

11 Global Survey of Planetary Body Interior Detection of Lunar Free Oscillation by Long-period Seismic Record Free Oscillation Modes: Vertical layer contribution to each mode l = 10, m = 0 l = 10, m = 5 0 S 10 r 1S S r 10 0 S 29 l = 10, m = 10 l = 10, m = 15 () m () m r Y e + V r Y n Sl : U l r 1 Spheroidal mode n T l : W () r Y m e 1 l r Troidal mode l

12 Technical Development of Long-period Seismometer and Setting Technology Carry-on long-period seismometer Autonomous drilling and installation of seismometer in subsurface Autonomous 3-axis alignment Bore-hole Type seismometer Carry-on drilling system on lander Carry-on system Autonomous drilling system Alignment Telecommunication Operation

13 Frequency characteristics of seismometer Earth s tide Free Oscillatio n Surface wave Body wave (digit/cm) Requirement STS-1 LUNAR-A Frequency Hz

14 Autonomous Drilling System Tunnel Boring Machine Mole 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 Using motor torque Air-bag support

15 3-axis Alignment Gimbals Heritage of Lunar-A alignment system Autonomous Gimbals using lunar gravity Light weight and compact mechanism Reduction of shock resistance from Lunar-A system Gimbals mechanism onboard Lunar-A penetrator

16 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/VIS Survival technology over two-weeks nights Geophysical probe development; seismometer, heat flow probe,.. The engineering study working group studies; Pin-point soft landing technology: Navigation, guidance, and hazard avoidance of lander Rover technology: Autonomous operation, telecommunication,.. Setting mechanism of geophysical probes