Presentation Information
[PPS03-P07]Photometric Observations of One of JAXA's Next Generation Mission Candidates, NEA 162998 (2001 SK162)
*Tomohiko Sekiguchi1, Soya Takenaka1, Seiko Takagi2, Kazuya Doi2, Jin Beniyama3, Eri Tatsumi4, Julia de Leon4 (1.Hokkaido University of Education, 2.Hokkaido University, 3.Côte d'Azur Observatory, 4. Institute of Astrophysics of the Canary Islands)
Keywords:
Near Earth Asteroids,photometric observations in visible,sample return mission,D-type asteroids
Visible photometric observations of asteroid 162998 (2001 SK162), suggested to be a D-type asteroid based on near-infrared spectroscopic observations, were conducted using the Pirika Telescope at Hokkaido University.
BVRI photometric observations also confirmed its classification as a D-type asteroid. Specifically, it is considered a "red" Z-type, exhibiting relatively high reflectivity at longer wavelengths compared to other D-types.
The results verified its potential of 162998 as a candidate asteroid for Japan's next sample return mission.
Cometary nuclei with low activity levels and D-type asteroids are expected as candidates for JAXA's next small-body sample return mission. Cometary nuclei are considered to contain not only solid H2O but also various hydrocarbons, organic compounds, and even amino acids. D-type asteroids are expected to have compositions most similar to cometary nuclei. However, D-type asteroids are predominantly found among distant asteroids like the Jupiter Trojans, making sample return challenging. Narrowing the search to those with perihelion distances of 1 (+/-0.1) au and orbital inclinations less than 10 deg. significantly limits the number of known candidates.
We carried out visible photometric observations of near-Earth asteroid 162998 (2001 SK162), expected to reach magnitude V19 in early October 2025, using the Pirika Telescope (1.6 m) at the Hokkaido University Observatory. We converted the Bessel (Johnson "BV" Kron-Cousins "RI") filter magnitudes to magnitudes using the Pan-STARRS field catalog and ultimately obtained SDSS filter system (griz) magnitudes. After normalizing to the g-band and calculating the reflectance, the results showed that the relative reflectance of 162998 (2001 SK162) exhibits characteristics D-type asteroids. At longer wavelengths, it is closer to the Z-type, showing a reflectance greater than the average for the typical D-types. The results are consistent with visible spectroscopic observations conducted simultaneously at the 10.4 m Gran Telescopio Canarias (GTC).
This suggests the asteroid's surface may possess D-type properties while also showing effects of the space weathering due to the cosmic ray and the solar wind radiation. It is expected to contain organic matter and hydrated minerals, yielding results that make it a viable candidate for future exploration.
BVRI photometric observations also confirmed its classification as a D-type asteroid. Specifically, it is considered a "red" Z-type, exhibiting relatively high reflectivity at longer wavelengths compared to other D-types.
The results verified its potential of 162998 as a candidate asteroid for Japan's next sample return mission.
Cometary nuclei with low activity levels and D-type asteroids are expected as candidates for JAXA's next small-body sample return mission. Cometary nuclei are considered to contain not only solid H2O but also various hydrocarbons, organic compounds, and even amino acids. D-type asteroids are expected to have compositions most similar to cometary nuclei. However, D-type asteroids are predominantly found among distant asteroids like the Jupiter Trojans, making sample return challenging. Narrowing the search to those with perihelion distances of 1 (+/-0.1) au and orbital inclinations less than 10 deg. significantly limits the number of known candidates.
We carried out visible photometric observations of near-Earth asteroid 162998 (2001 SK162), expected to reach magnitude V19 in early October 2025, using the Pirika Telescope (1.6 m) at the Hokkaido University Observatory. We converted the Bessel (Johnson "BV" Kron-Cousins "RI") filter magnitudes to magnitudes using the Pan-STARRS field catalog and ultimately obtained SDSS filter system (griz) magnitudes. After normalizing to the g-band and calculating the reflectance, the results showed that the relative reflectance of 162998 (2001 SK162) exhibits characteristics D-type asteroids. At longer wavelengths, it is closer to the Z-type, showing a reflectance greater than the average for the typical D-types. The results are consistent with visible spectroscopic observations conducted simultaneously at the 10.4 m Gran Telescopio Canarias (GTC).
This suggests the asteroid's surface may possess D-type properties while also showing effects of the space weathering due to the cosmic ray and the solar wind radiation. It is expected to contain organic matter and hydrated minerals, yielding results that make it a viable candidate for future exploration.