Calculate the amount of mass that will be out-gassed each day during the first week on orbit by a 10 kg source with Ea = 10 kcal/mole that meets the ASTM E 595 requirements and is held at a temperature T. The ASTM E595 requirement is that a surface at T = 125 C and a pressure less than 7e-3 Pa during 24 hours should have a Total Mass Loss (TML) less than 1%. Given:
clc; clear all; Ea = 10; % Ea is the activation energy [kcal/mole] R = 1.9859e-3; % R is the gas constant [kcal mole-1 K-1] M = 12; % Source Mase [kg] Days = 7; % Out-gassing interval [day]
dm = 0.01*M; % Allowed Total Mass Loss[kg] Ts = 125 + 273.15 ; % [K] % q0 - describes the specific out-gassing characteristics of the material q0 = dm/(2*exp(-Ea/(R*Ts))); % [kg/day^0.5]
Find the amount of mass out-gassed between time t1 and t2
T = [0,25,50,75,100,125]; dm = zeros(7,6); fprintf('Amount of mass out-gassed each day during a week, M_i = 12kg\n\n'); fprintf('Day %4d %4d %4d %4d %4d %4d [C] \n',T); T = T + 273.15; % [K] for i = 1:Days dm(i,:) = q0*(2*exp(-Ea./(R*T)))*(i^0.5-(i -1)^0.5)*1e3; %[g] fprintf([num2str(i),' %4.3f %4.3f %4.3f %4.3f %4.3f %4.3f \n'],(dm(i,:))); end
Amount of mass out-gassed each day during a week, M_i = 12kg Day 0 25 50 75 100 125 [C] 1 0.368 1.726 6.374 19.514 51.427 120.000 2 0.152 0.715 2.640 8.083 21.302 49.706 3 0.117 0.548 2.026 6.202 16.345 38.140 4 0.099 0.462 1.708 5.229 13.780 32.154 5 0.087 0.407 1.505 4.607 12.140 28.328 6 0.078 0.368 1.360 4.165 10.976 25.611 7 0.072 0.339 1.251 3.830 10.093 23.551
figure(1); semilogy(dm); hold on; semilogy(dm,'*'); title('Amount of mass out-gassed each day during a week, M_i = 12kg'); legend('0 C^o','25 C^o','50 C^o','75 C^o','100 C^o','125 C^o'); xlabel('Days'); ylabel('Out-gassed mass[g]');
Small Satellites 