亀田 真吾

Life-environmentology, Astronomy, and PlanetarY Ultraviolet Telescope Assembly (LAPYUTA) is a future ultraviolet (UV) space telescope that is selected as a candidate for JAXA's 6th M-class mission. Launch is planned for the early 2030s. LAPYUTA will perform spectroscopic and imaging observations in the far-ultraviolet spectral range (110-190 nm) with a large effective area (>300 cm2) and a high spatial resolution (0.1 arcsec). LAPYUTA has the following four objectives: (1) atmospheres of solar system planets, (2) atmospheres of exoplanets around the habitable zone, (3) structures of present-day galaxies, and (4) synthesis process of heavy elements from observations of neutron star mergers. The key to addressing these scientific goals is the measurement of the physical state of hydrogen, oxygen, and carbon. These elements are common in the universe and are involved in understanding the structure and evolution of the universe at various spatial scales, from planets to stars to galaxies, and UV spectral measurement is adequate for measuring the physical state of the elements. LAPYUTA aims to achieve resolution and sensitivity in the far-UV wavelength range comparable to the Hubble Space Telescope (HST) while using JAXA’s small scientific satellite. The mission part consists of a Cassegrain telescope with a 60 cm aperture primary mirror, four focal plane instruments, a medium dispersion spectrograph (MRS), a high dispersion spectrograph (HRS), a UV slit imager (UVSI), and a wide-field fine guide sensor (FGS). To achieve a highly effective area and high angular resolution, we are developing three key technologies: UV mirror deposition, a large high-precision detector, and a pointing disturbance correction function, as well as studying the concept of the telescope structure. The key technologies for ultraviolet observations developed here will serve as a stepping stone for Japan's participation in the Habitable Worlds Observatory (HWO).

Abstract Observations of exoplanet transits by small satellites have gained increasing attention for reducing biases in the detection of long-period planets. However, no unambiguous detection of an exoplanet has yet been demonstrated using optics with apertures smaller than 60 mm. Here, we investigated the detectability of exoplanet transits using the telescopic Optical Navigation Camera (ONC-T) on board the Hayabusa2 spacecraft, which has an effective aperture of only 15 mm. We conducted transit observations of the hot Jupiters WASP-189 b and MASCARA-1 b, collecting data for 10 and four events, respectively. The transit signal was detected with a signal-to-noise ratio (SNR) of 13 for WASP-189 b and 8 for MASCARA-1 b for each event. Stacking all events improved the SNR to 40 and 16, respectively. The transit midtimes of each event were measured with a precision of 6 minutes and were consistent with Transiting Exoplanet Survey Satellite (TESS) data to within 2 minutes. The planet-to-star radius ratio was determined with an absolute precision of 0.004 (6% relative) and agreed with TESS results to within 0.002 (3% relative). The recent ONC-T and TESS data enabled an update to the planetary ephemerides. We report a 4 σ discrepancy between the updated orbital period of MASCARA-1 b and previously reported values. ONC-T sets a new record for the smallest-aperture instrument to detect an exoplanet transit from space, advancing the frontier of exoplanet science with miniature instrumentation. Our results suggest that optics as small as ONC-T may be capable of detecting transiting long-period Jupiters: a population that remains underrepresented in current surveys.

Abstract NASA's OSIRIS‐REx mission successfully collected and returned ~121.6 g of bulk samples from the B‐type, near‐Earth asteroid (101955) Bennu to Earth in September 2023. Upon returning to Earth, the samples were transported to the NASA Johnson Space Center where most of the samples have been stored and processed. On August 22, 2024, 0.5 wt% of Bennu samples (0.663 g) and a contact pad that collected particles from the surface of Bennu were permanently transferred to JAXA from NASA based on a Memorandum of Understanding and a letter of agreement between the two agencies. Following this, all the Bennu samples have been curated under nitrogen‐purged gloveboxes, called clean chambers in a clean room at the Extraterrestrial Sample Curation Center in Sagamihara. While maintaining the pristinity of samples at the curation, we conduct a series of nondestructive analyses, including near‐infrared spectroscopy within the clean chambers. Bennu curation was conceptualized primarily based on the Hayabusa2 curation, whereas lessons learned from the Hayabusa2 curation were integrated into designing Bennu curation. Here, we describe preparations for the Bennu curation, with an emphasis on the differences from the Hayabusa2 curation.

Abstract MIRS (MMX InfraRed Spectrometer) is a push-broom imaging spectrometer onboard of the JAXA sample return MMX mission. It has been built by the French laboratory LESIA, today LIRA (Laboratory for Instrumentation and Research in Astrophysics) of Paris Observatory-PSL in collaboration with five other French laboratories, collaboration and financial support of CNES and close collaboration with JAXA and MELCO. MIRS, designed to accomplish the MMX scientific objectives, has been built to be adapted on MMX Exploration Module. MIRS will remotely observe the Martian system for three years. MIRS will observe Phobos, Deimos and Mars in the spectral range 0.9–3.6 µm to characterize surface composition of the satellites and investigate Martian atmospheric variations. An overview of the MIRS Flight Model is presented as well as the data processing and the expected results.