A Feasible Study of In-Situ Measurements of Light Isotopes and Organic Molecules with High Resolution Mass Spectrometer MULTUM on the OKEANOS Mission

International audience; The OKEANOS mission utilizing the Solar Power Sail is one of the candidates of the strategic middle-class space exploration to the outer Solar System lead by the JAXA. The mission is planning to be launched in 2030's, and rendezvous for spectral observations and landing for in-situ measurements of light isotopes and organic molecules to a D or P type Jupitar Trojan asteroid in 2040's. The flagship instrument on board is a high-resolution mass spectrometry (HRMS) system together with suits of remote-sensing instruments. Through in-depth scientific observations, the OKEANOS mission will provide critical input to the key questions of (1) constraining planet formation/migration theories, and (2) inventory and distribution of volatiles in the Solar System. We have conducted experimental tests of a sample canister sealing by a metal seal knife-edge, sample canister-MULTUM test, gas chromatograph-MULTUM coupling test for organics, and H and N isotopic measurements in the atmospheric air. Current performances are (1) high mass resolution was 30,000 at m/z = 20, (2) sample canister system with a knife-edge metal seal kept 90 % of a released gas in 1 hour for Cu or Au gaskets with/without regolith, (3) error meets the required precision and accuracy for nitrogen isotopic measurement but for hydrogen. These experiment tests need to continue for our scientific proposes on the asteroids.