Transcript 月面環境評価 - cosmos.ru

DEVELOPMENT OF SELENODETIC
INSTRUMENTS FOR JAPANESE
LUNAR EXPLORER SELENE-2
H. Hanada1, H. Noda1, F. Kikuchi1, S.
Sasaki1, T. Iwata2, H. Kunimori3, K.
Funazaki4, H. Araki1, K. Matsumoto1, S.
Tazawa1, S. Tsuruta1
1 National Astronomical Observatory
2 Japan Aerospace Exploration Agency
3 National Institute of Information and
Communications Technology
4 Iwate University
KAGUYA (SELENE) → SELENE-2
• Successful KAGUYA
• Study of lunar landing mission(s) in JAPAN.
• SELENE-2 lunar lander
– SELENE Series 2, 3, …X
• Launch by H-IIA in 2016 ?
• Lander of 1000kg including
scientific instruments of 300kg
Mission instruments for SELENE-2
• Scientific instruments
– Science of the moon
• Geophysical/geodetic instruments
• Geological instruments
– Science from the moon
• Astronomical instruments
• Engineering instruments
• Environmental instruments
Proposal for SELENE-2
SELENE-2 instruments for Lunar intererior study
◆Gravity observations by VLBI
(Same-beam and Inverse VLBI)
◆Rotation observations by Lunar Laser Ranging
(new reflectors and a new ground network)
They are under review for onboard instruments
Another rotation observations by ILOM (In-situ
Lunar Orientation Measurement) is proposed for
SELENE-3
Selenodetic Candidate instruments
Observation method
SELENE-#
Purpose
VLBI
d-VLBI : Differential VLBI 2 (Kikuchi)
Gravity Fields
i-VLBI : Inverse VLBI
2/3 (Kikuchi)
LLR
Lunar Laser Ranging
ILOM
In situ Lunar Orientation
Measurement
2 (Noda)
Librations
3 (Hanada)
Librations
Questions to be addressed:
Is there a core in the Moon ?
Is the core metallic ?
Is the metallic core liquid ?
Is there an inner core center of the liquid core ?
Molten core ? Solid inner core ??
MOON
Lunar Laser Ranging (LLR)
Lunar Laser Ranging
Laser Ranging from the Earth to the Moon
started by Apollo in 1969 and continue to the
present
4 reflectors are ranged:
Apollo 11, 14 & 15 sites Lunakhod 2 Rover
LLR attained the
accuracy of less
than 3cm with
observations for
longer than 25 years.
Objectives of future LLR
•
•
•
•
Ephemerides and/or Reference systems
Gravitational physics (General Relativity)
Geodynamics
Lunar science and Selenophysics
Issues on LLR
• Deployment：Where on the Moon ?
• Type： “Array” or “Single”, “Prism or Hollow”
• Size：Reflection Efficiency more than A11 or A15
• Structure： Hard to be affected by gravitational and
thermal effects
• Optical Performance：Ray tracing simulation
• Dihedral Angle Offset：What is the optimal value ?
• Adaptive Optics：Option
Deployment ：Where on the Moon ?
● Area : Data Contribution (~77%)
新規?
2,000km
For Physical Librations:
Schickard
(44.3S, 55.3W)
Southern Hemisphere far
from A15 site about 2000km
or more
Tycho
（43.4S,11.1W）
Type : Array or Single, Prism or Hollow ?
• Prism array of small aperture (Apollo, Luna)
– Large range error due to optical libration
• Single prism with large aperture
– High accuracy of ranging
– Extremely high quality prism is necessary :
⇒ less than 10cm size CCP
• Single hollow with large aperture
– Lighter weight
– High accuracy
– Change of dihedral angle due to
thermal distortion will be a problem
Structure : Deformation by Earth’s Gravity
L
D
D=20 cm (L = 14.14 cm),
t = 1cm, “Cu”
Deformation: less than 1 μm
by Earth’s Gravity Field
Taniguchi, 2010
Structure : Thermal Deformation of CCR
LD
(mm)
(mm)
0.0000800
0.0000700
0.0000700
0.0000600
0.0000600
0.0000500
0.0000500
0.0000400
0.0000400
0.0000300
0.0000300
0.0000200
0.0000100
0.0000000
-0.0000100
0.0000200
Series21
Series16
Series11
Series6
Series1
L= 7.07 cm (D=10cm), < 3 nm
0.0000100
0.0000000
-0.0000100
1
3
5
7
9
11
13
15
17
19
21
1
3
5
7
9
11
13
15
17
19
21
0.0000800
Series21
Series16
Series11
Series6
Series1
L=14.14 cm (D=20cm), < 60 nm
NEC, 2010
Optical Performance (Ray Tracing Analysis)
ccrtxm141_hex_1a 200mm ccr wit
15:46:13
Beam Intensity at Image Surface
ccrtxm141_hex_1a 200
mm ccr with 1a defor
100.00
(0.000,0.000) DEGREES
23-Jul-10
DEFOCUSING 0.00000
1.0
0.9
DIFFRACTION ENCIRCLED ENERGY
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
0.0E+00 6.9E-03 1.4E-02 2.1E-02 2.8E-02 3.4E-02 4.1E-02 4.8E-02 5.5E-02 6.2E-02 6.9E-02
DIAMETER OF CIRCLE (MM)
.02888 mm
50.000
Efficiency
(Streal Ratio)
: 95.8 %
0.0000
Relative Field ( 0.000,
Wavelength
532.00 nm.
Defocus: 0.000000 mm
.02888 mm
0.000 )
POSITION
1
L=14.14 cm (D=20cm), < 60nm
Kashima, 2010
VLBI (Same-beam VLBI and Inverse VLBI)
VLBI (Very Long Baseline Interferometer)？
Quasar
Noise
Noise
VLBI : Improvement of Lunar Gravity field
Orbiter
Same-beam (Differential) VLBI Method
◇Doubly Differenced One-way Range
Sensitivity : <20 cm
Survival module
Inverse VLBI Method
◇Differenced One-way Range
◇2-way range between orbiter and S-module
Sensitivity : <10-20 cm
These new observations are expected to
improve the lunar gravity field.
Inverse VLBI
Radio signals transmitted from orbiter and lander
are received at a ground antenna. These signals are
synchronized via a reference signal from orbiter.
Received signals are cross correlated and a difference
of the propagation time is measured.
Expected accuracy is several tens to several ps. These
time difference corresponds to the distance of a few
cm to a few mm.
Same-beam VLBI method :
Improvement of lunar gravity model
Simulation result
2nd degree coefficients are improved by factor 3 or more.
Moment of inertia Topography, Moho, GRAIL/LRO/Kaguya data
 Constrain core density and radius
Conditions of the Simulations
Orbit parameters :
Perilune height = 100km,
Apolune height = 800km,
Orbit inclination = 70°
Landing position :
(0°、0°)
Tracking station :
Usuda(64m) and VERA(20m)
Data weight：
2-way Doppler = 1 mm/s, VLBI= 1 mm
Arc length of orbiter : 14 days.
Observation Period : 3 months
In-situ Lunar Orientation Measurement
（ＩＬＯＭ）
Principle of ILOM Observations
Telescope
Motion of a star in the view
Other objectives than lunar rotation
Pilot of lunar telescope （Engineering）
Establishment of a lunar coordinate system
Star trajectory and Effects of Librations
Trajectory of a star observed at the
Lunar pole (June 2006– Sep.2007)
Decomposition
of the trajectory
Polar motion and Librations extracted from the trajectory
After Heki
0.1m
Development of BBM
Objective
(Cooperation with Iwate univ.)
Motor
0.5m
Frame
Tube
Mercury Pool
Tiltmeter
Tripod
After Iwate Univ.
Specifications
Aperture
Focal Length
0.1m
1m
Type
Detector
Pixel Size
PZT
CCD
Accuracy
1/1,000 of pixel size (1mas)
5μm×5μm (1″×1″)
Number of pixels 4,096×4,096
View
1°× 1°
Exposure Time
40s
Star Magnitude
M < 12
Wave length
550nm – 750 nm
Issues on ILOM:
Technical issues
Improvement of the accuracy of centroid experiments
Correction of effects of temperature change upon star position
Keeping power during the night
Keeping warm during the night
Keeping inside thermally stable
Important condition of the lunar surface ?
How is the lunar dust ?
How dark is the lunar surface at night ?
How stable is the lunar surface ?
How quiet is the lunar surface ?
Summary
• Technical developments and scientific evaluations
for LLR, VLBI and ILOM are going on.
• LLR and VLBI instruments are under review for
SELENE-2 onboard instruments.
• ILOM is prepared for SELENE-3.
• We will investigate the lunar deep interior by
further improving accuracy of observations of the
lunar rotation and the gravity fields with new
technologies.
Fabrication of CCR
 ELID and Electroforming : with Omori Lab., RIKEN Inst.
ELID (Electrolytic Inprocess Dressing)
For making the “Master” of CCR
Surface Roughness: ±10 nm
Electroforming [Electrolysis]
Fabrication of One-unit CCR from “Cu”
 Now trying to make a surface with Cuhttp://www.jst.go.jp/pr/info/info96/zu1.html