Air density sensitive gauges for space craft

Claim 1

MEANS FOR MEASURING FREE-STREAM AIR DENSITY FROM A MOVING VEHICLE COMPRISING, IN COMBINATION WITH A VEHICLE, A SOURCE OF RADIANT ENERGY, MEANS ON THE VEHICLE MOUNTING SAID ENERGY SOURCE SUBSTANTIALLY IN THE FREE STREAM AND DIRECTED INTO THE FREE STREAM AT A RELATIVE LOCATION SUBSTANTIALLY FREE OF AIR DISTURBANCE BY THE VEHICLE, A RADIATION DETECTOR, MEANS ON THE VEHICLE MOUNTING SAID RADIATION DETECTOR SUBSTANTIALLY IN THE FREE STREAM AND DIRECTED INTO THE FREE STREAM AT A RELATIVE LOCATION SUBSTANTIALLY FREE OF AIR DISTURBANCE BY THE VEHICLE, THE LOCATION OF SAID DETECTOR BEING PROXIMATE TO SAID SOURCE WITH SAID SOURCE AND THE DETECTOR BOTH FACING INTO THE FREE STREAM IN AT LEAST APPROXIMATELY THE SAME DIRECTION SO THAT RADIATION FROM THE SOURCE BACK-SCATTERED BY THE FREE-STREAM AIR IS INCIDENT ON THE DETECTOR, AND MEANS RESPONSIVELY CONNECTED TO SAID DETECTOR FOR MEASURING THE PROPORTION OF RADIATION INCIDENT ON SAID DETECTOR, AND THEREFROM THE AIR DENSITY.