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

Abstract

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.