Abstract: Asteroids carry information on the original composition of the solar system at the beginning of its formation.They are the living fossils for the study of the origin of the solar system.Some asteroids contain elements such as rare earths and metals，and the exploration of the material composition of asteroids is a prerequisite for space resource utilization.The current means of studying the composition of celestial bodies，such as spectral analysis and laboratory sample analysis，have problems such as noninsitu measurement，poor accuracy and susceptibility to contamination.The gamma ray induced by galactic cosmic ray may serve as a promising method to identify the composition of asteroids insitu.The gamma spectra induced by 0.1s cosmic ray irradiation were studied，and the characteristic gamma spectra of iron and oxygen were demonstrated，which are consistent with the authoritative nuclear database.The deconvolution of the simulated gamma spectra of S-type asteroids was performed using maximum likelihood estimation，and the deconvolution results are in good agreement with the true values.The absolute errors of element mass percentages are less than 5%.The method also shows an ultra-high sensitivity and can detect elements with low mass percentages as low as 3%.The method is also applicable to non-atmospheric objects，such as the Moon or Mars，to understand the material composition of the celestial bodies，therefore serving the engineering goals for space resources exploitation.In addition，based on the scientific data from a gamma spectrometer payload，it is possible to understand the geological history of the celestial bodies and to help answer the question of the solar system evolution.

Key words: cosmic rays, gamma detection, in-situ resource utilization, Monte Carlo simulations, asteroid exploration