The present disclosure relates to a gas sensor, including: a gas collecting chamber including: (a) a nanoporous wall including alumina, on a portion of the gas collecting chamber in the near vicinity of the solid propellant fuel; a micro pump attached to the gas collecting chamber; and a gas analysis device connected to the gas collecting chamber. The gas analysis device measures both type and concentration of gases collected in the gas collecting chamber via the nanoporous wall, the gases measured being selected from the group consisting of CO, CO2, NO, N2O, NO2 and combinations thereof. The present disclosure also relates to a method of sensing propellant degradation in solid fuel and a method of using a gas collecting chamber to sense such degradation.