The work constructs the Gas kinetic solver (GKUA) to solve the Boltzmann model equation. Then the solver is respectively confirmed by NS, DSMC and experiments in typical conditions during reentry. Furthermore, the Maxwellian gas-surface interaction model is utilized to study the effects of reflected gas molecules state ( \(\alpha_{e}\) ) on flow field and aerodynamic properties at various extent of gas rarefaction. Results reveal the temperature is more susceptible to the state of reflected gas molecules compared with pressure. And the larger gas rarefaction tends to weaken the effects. As for surface heat flux, it just increases with \(\alpha_{e}\) in lower gas rarefaction, while it behaves as the opposite trend with larger gas rarefaction. Freestream condition \(H = 50km,Ma = 8.0,AOA = 60^{o}\) is set for booster model in practical application. We experience the shrinks of aerodynamic pitch moment coefficient with more \(\alpha_{e}\) . These results are valuable for the construction of expired spacecraft forecasting platform which integrates exterior ballistics with aerothermodynamic computations to obtain tracks of spacecraft fragments in advance.
