Next Generation Small-body Sample Return (NGSR) from primitive bodies as the next ISAS large-class science mission candidate

The Next Generation small-body Sample Return (NGSR) is a Japanese strategic large-class science mission candidate in the 2030s. Following Hayabusa, Hayabusa2, and upcoming Martian Moons eXploration (MMX), NGSR is planning to return samples from a Solar System primitive body. The samples returned by Hayabsua2 from the C-type asteroid Ryugu indicated the evolution process from its parent body and the transport of materials in the early Solar System [1]. However, the ultimate origin of the Solar System material and the formation of the first-generation planetesimals still remain unsolved. Thus, the science goals of NGSR include (1) unveiling the origin of the Solar System materials in galactic evolution and (2) unveiling the origin of the Solar System bodies to form planetesimals. To achieve these goals, we propose the NGSR Origins program targeting comets (NGSR-C), D-type asteroids (NGSR-D), and E-type asteroids (NGSR-E). The comet (e.g., 289P/Blanpain) is the target to investigate the origin of materials from pre-solar era and the formation process of planetesimals in the outermost Solar System. The D-type asteroid (e.g., 2001 SK162) is to constrain the evolution of organic matter and the formation process of planetesimals in the outer Solar System. The E-type asteroid (e.g., 4660 Nereus) is to investigate the evolution of materials in the innermost region of the Solar System and the formation process of inner Solar System. NGSR is strongly constrained by use of an H3 rocket and a Deep-Space Orbital Transfer Vehicle (DS-OTV) [2], a newly developing transportation system to be commonly used for many missions.

 The NGSR spacecraft system consists of a DS-OTV as the main spacecraft and a lander for sample collection [2]. A concept study assumes its launch in early half of 2030s, arrival at the target for exploration, and return of samples to Earth within 6~8 years (NGSR-E or -D) to 13 years (NGSR-C). The mission instruments are categorized into four types: (1) remote sensing instruments for characterization of the target body and the landing site selection, including an optical navigation camera, a laser altimeter, and a thermal infrared imager. (2) sample return devices: A bullet and/or pneumatic type sampler on the lander, a kinetic impactor, and a mass spectrometer on the lander to measure volatiles on-site. Most of the collected samples will be transferred to the reentry capsule on the DS-OTV after sampling and rendezvous docking of the lander to the DS-OTV. (3) interior structure measurements: bistatic radar system, and small landing seismometer units deployed onto the surface. (4) other optional instruments to improve the scientific significance of this mission, including a near infrared spectrometer, a 10kg-sized small scientific deployable probe like the Hayabusa2 MASCOT, and a small dust and volatile detector as international collaboration. There remains an opportunity for the other instruments before the final decision of instruments. We will present the mission design, science operation, and instruments at that time.

 

[1] e.g., Nakamura T. et al. (2022) Science, 90, eabn8671.

[2] Saiki T. et al., (2025) Acta Astronaut., 235, 120-128.