1) The document discusses Korea's lunar exploration program, which includes the Korea Pathfinder Lunar Orbiter (KPLO) mission scheduled to launch in late 2020. 2) KPLO will carry several science payloads including PolCam, a polarimetric camera built by KASI that will create the first polarization map of the lunar surface. 3) Analyzing the polarization data from PolCam can provide information about lunar regolith properties like particle size and maturity, as well as titanium distribution, to advance understanding of space weathering processes.

1. Moon Through New Eyes
of
Korean Mission: KPLO/PolCam
Chae Kyung SIM(沈採耕)1, Young-Jun CHOI2
1Kyung Hee University 慶熙大學校
2Korea Astronomy and Space science Institute 韓國天文硏究員
2018/12/07
Galaxy Forum @ Beijing, China

2. Astronomy in Korean culture

3. Astronomy in Korea
•Scientific research
– KASI (Korea Astronomy and Space science Institute)
– Universities (Kyung Hee Univ., Seoul National Univ., Yonsei Univ., …
• Technological research
– KARI (Korea Aerospace Research Institute)
– Developing and operating satellites
– Planetary exploration program

4. Main Research Areas
 Optical Astronomy
- Galaxy Evolution, Variable Objects, KMTNet, BOAO, LOAO, SOAO, GMT
 Radio Astronomy
- Star Formation, Active Galactic Nuclei(AGNs), TRAO, KVN, ALMA, JCMT
 Space Science
- Space Astronomy, Space Geodesy, SLR,
Solar and Space Weather, Lunar and Planetary Science
 Theoretical Astronomy
- Cosmology, Astrophysics, Historical Astronomy
 Space Situational Awareness
- Technologies for Space Surveillance, Optical Surveillance, Radar Surveillance,
OWL-Net Development, Orbit Analysis and Estimation, Risk Analysis and Space
Catalog, Asteroid Characteristics and Risk Analysis

5. KASI facilities
 Overseas
PolSpeck, (KASI+KHU)
Lunar polarimetry
Speckle observation

6. The Moon
• It has been an old, good friend of ours.

7. The Moon
• Sometimes, we wanted to fly to the Moon.
• … and we did!
Jules Verne, «De la terre à la lune», 1865 Apollo 11, 1969

8. The Moon
• The journeys to the Moon had been decreased
and rejuvenated!

9. Korean lunar program - Plans
• Lead by KARI (Korea Aerospace Research Institute)
Phase 1 – Pathfinder orbiter
• Domestic Lead
+ International Collaboration
• To demonstrate the technology for
planetary exploration
• To build international cooperation
• To establish deep-space network
Phase 2 – Orbiter + Lander
• Domestic Development
• To demonstrate science / technology
• Landing site selection
• Support from international
collaboration

10. Phase 1: Korea Pathfinder Lunar Orbiter (KPLO)
• Overview
– Program started : 2016
– Launch date : end of 2020, Falcon-9 (SpaceX) @ Cape Canaveral, FL
– Budget : 197.8B KRW (~170M USD)
– Orbit : Polar orbit at altitudes of 100 ± 30 km
– Lifetime: 1 month (Trans-Lunar) + 1 year (on orbit)
– Mass : 550 kg (6 payloads)

11. Collaboration with NASA
Ju, 2017

12. Science payloads onboard KPLO
• LUTI (high-resolution camera) by KARI+
– Target-observations including future landing sites (R ~ 5 m)
• PolCam (wide-angle polarimectric camera) by KASI+
– First polarization map of the Moon, studying regolith and components of
its surface
• KMAG (magnetometer) by KHU+
– Measuring magnetic field of anomalies at lower altitudes (< 70 km)
• KGRS (gamma-ray spectrometer) by KIGAM+
– Mapping radiation and distribution of major elements near the surface
• ShadowCam (narrow angle camera) by NASA (ASU+)
– Measuring albedo patterns inside PSRs(permanently shadowed regions)

13. KPLO/PolCam – First polarimetry ever!
• Objectives
– Obtain the first polarimetry map of the lunar surface (|lat.| < 70 deeg.)
– Understanding space weathering process on the surface of airless bodies
– Supporting lunar landing site search
Science PI :
Sung-Soo Kim (KHU)
PI :
Young-Jun Choi (KASI)
KPLO
PolCam
Co-PI :
Kyungin Kang (SaTReC, KAIST)
Optics (Satbyul) Structure & Thermal (Mirae)

14. Polarimetry
– Polarimetric information is a function of phase angle
(source-target-observer angle)
– Multiband observation: 320 nm, 430 nm, 750 nm
P(%)
Phase angle, α (°)
Pmax map
Pmax
fitting phase curve
(positivebranch only)

15. Scientific Goals of PolCam
• Polarization map
– The first polarimetric map
• Regolith particle size
– Maturity (Age) estimation
• Titanium map
– Highest resolution Polarization Map
Particle size Map
Titanium map

16. Previous works
• Latitude dependency of particle size
– The agent of space weathering (SW)
– Parallel motion to ecliptic plane
(Jeong et al. 2015, ApJS)
• Latitude & longitude dependency of maturity index
– Major SW agent is solar wind flux (rather than micrometeoroids)
– Selective shield of magnetosphere of the Earth (Sim et al. 2017, GRL)

17. Latitudinal differences
Space-weathering agents

18. Longitudinal: Selective shield of geo-magnetotail

19. Mission operation analysis
• Phase angle coverage for one-year operation

20. Specifications
Classification Item Specification*
Imaging
Field of View 10° (across-track direction)
GSD Up to 100 m (in nominal orbit)
Swath Width Up to 35 km (in nominal orbit)
Type of Sensor CCD
Imaging Pixels 512 Pixel * 6 Channels
Spectral Bands 320, 430 & 750 nm
Polarization Filters
No polarization for 320 nm
0˚, 60˚, 120˚ for 430 nm
0˚, 90˚ for 750 nm
# of Head 2 Head
Optical Housing Material AL7075 (Black Anodized)
Mounting Direction
45˚ with respect to nadir
in the across-track direction.

21. Baseline design
• Structure
– Dimensions
• O-Box : 150 x 100 x 85 mm
• E-Box : 170 x 120 x 62 mm
– Mass : 3.0 kg
– Optical tilted angle : 45˚ from nadir for across track

22. Field-of-view
• Optical box and field-of-view

23. Focal plane
Lens
Bandpass filters layer
Filter base
Polarizer layer
CCD sensor
Sensor PCB

24. Plan-B: a sparse observation case
• Unfortunate cases of an orbiter mission
– mal-maneuver : offset from the intended phase angle
– observational gap due to mal-operation
– data gap due to wrong saving/downlink
– early termination
P(%)
Phase angle, α (°)
In a sparse observation case,
an approximate phase curve helps
to fit the curve
and estimate Pmax properly.
Pmax map

25. Phase 1
ImagesfromKARI

26. Phase 2
ImagesfromKARI

27. Phase 2
ImagesfromKARI

28. Phase 2
ImagesfromKARI

29. Stay tuned!
ImagesfromKARI