% O17

constants

z0 = 150e3;
z1 = 140e3;
H = 8e3;
rho0 = 1.3;
Cd = 1.5;
m = 1000;
A = 1;

td = -H/sqrt(R_E)*(exp(z1/H) - exp(z0/H))*m/(rho0*sqrt(G*M_E)*Cd*A)% decay time from altitudes z0 to z1, z1 < z0.

duration(0,0,td)