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Research

DEEP-South (Deep Ecliptic Patrol of the Southern Sky)

As of March 2016, more than 14,000 Near Earth Objects (NEOs) have been catalogued; however, the physical properties are only known for a tiny fraction of them. This is why physical characterization of the population has been an important problem for decades. Korea Microlensing Telescope Network (KMTNet), which consists of three identical 1.6 m wide-field telescopes with 18k×18k CCDs, is the first optical survey system of its kind. The combination of fast optics and the mosaic CCD delivers seeing limited images over a 4 square degrees field of view. The main science goal of KMTNet is the discovery and characterization of exoplanets, yet it also offers various other science applications, including DEep Ecliptic Patrol of SOUTHern sky (DEEP-South). The aim of DEEP-South is to discover and characterize asteroids and comets, including Near Earth Objects (NEOs).

KEEP-North (Kirkwood Excitation and Exile Patrol of the Northern Sky)

Most asteroids have been barely altered from the epoch of the Solar System formation, thus becoming an important factor in the studies of the formation and evolution of the Solar System. This is why an asteroid family is considered to be a key for studying the orbital evolution of the Solar System because they break from a single parent body. We are currently conducting KEEP-North to investigate the mechanism where the main belt asteroids are transported to the near Earth space, based on visual photometry of the population.

Lunar Infrared Spectrometer (LIRS) for Korean lunar exploration

The existence of water on the Moon is of utmost importance not only for lunar science but also for ISRU (In-situ resource utilization) in space exploration. The Lunar Infrared Spectrometer is currently being developed for Korean lunar orbiter to investigate traces of water that may exist in low temperature regions, especially in highlands to reconstruct a water distribution map of the Moon. We expect to discover how water circulates in different lunar environments and how lunar surface material evolves accordingly.

Study on the polarimetry of the Moon

We obtain surface compositions, particle sizes, surface roughness and maturity of airless bodies such as the Moon and asteroids, using the polarized data. We also study the surfaces and the space environment based on polarimetry. Currently, we are building a ground-based telescope equipped with a photopolarimetric system in order to reconstruct a lunar polarization map to prepare for a Korean Lunar mission.

Representative results of study

Photometric study on an asteroid family: Rotational Properties of the Maria Asteroid Family (AJ)

In this study, we found that the rotational properties of Maria family asteroids have been changed considerably by the non-gravitational forces such as the YORP effect based on the photometric observations. From the changes of semi-major axes due to the Yarkovsky effect, we estimate that approximately 37 to 75 Maria family asteroids larger than 1 km have entered the near-Earth space from the resonance region every 100 Myr.
Total of 3230 known members of the Maria asteroid family (gray crosses) projected onto the proper semi-major axis (AU) vs. absolute magnitude (H) plane. A total of 1152 members matched with the WISE IR observation are marked with the black [×] symbols, and the empty green square represents all 92 objects we used in this study from the light-curve observation. The filled blue and red circles stand for prograde and retrograde rotators, respectively, while the five rotators with the pole along the ecliptic are marked with open circles. The upper part of this figure is the density histogram with respect to the semi-major axis.

Figure: Total of 3230 known members of the Maria asteroid family (gray crosses) projected onto the proper semi-major axis (AU) vs. the absolute magnitude (H) plane. A total of 1152 members that matched with the WISE IR observation are marked with the black “×” symbols, and the empty green square represents all 92 objects we used in this study from the light-curve observation. The filled blue and red circles represent prograde and retrograde rotators, respectively, while the five rotators with the pole along the ecliptic are denoted by open circles. The upper part of this figure is the density histogram with respect to the semi-major axis

Multi-wavelength polarization study of the lunar surface: Multi-Band Polarimetry of the Lunar Surface. I. Global Properties (ApJS)

In this paper, the maximum polarization degree map on U, B, V, R and I regions for the entire near-side of the Moon’s surface with a spatial resolution of 1.3 km was constructed. According to our data, the particle size on the lunar surface is varied depending on the latitude of the Moon.
Map of maximum degree of polarization(Pmax) at the V band.

Map of maximum degree of polarization(Pmax) at the V band.

Histograms of median grain size [d] in maria (blue) and highlands (red) of the near side of the Moon. The distribution of [d] is presented as a function of selenographic latitude, which clearly shows the latitude-dependence of [d]

Histograms of median grain size [d] in maria (blue) and highlands (red) of the near side of the Moon. The distribution of [d] is presented as a function of selenographic latitude, which clearly shows the latitude-dependence of [d]

Map of median grain size [d]

Map of median grain size [d]

Facilities

  • Ground-based telescope and polarimetric camera
  • Observation scheduler and data pipeline
  • Lunar infrared spectrometer