Abstract: The impingement forces of atmospheric molecules to a freeflying plane wake shield facility(PWSF)in 300km lowearth orbit is investigated.Atmospheric gases are assumed Maxwellian gases.In our computation,the elastic and the complete inelastic collisions between atmospheric molecules and PWSF surfaccs are adopted to determine the impingement interactions.So,the real impingements are situated between the two interactions.Our results show that,for a 5m diameter PWSF in 300km orbit,the impingement force of the atomic oxygen(O) out of 6 main gas species is the greatest one,and the impingement force of argon(Ar)is the smallest one which is 4 orders of magnitude less than O's.The total force produced by the atmospheric molecules is less than 0082N