Method for gauging the liquid propellant tank of a spacecraft, said propellant tank comprising a thermally-conductive wall , having a known geometry and containing a volume of liquid propellant , and said spacecraft being equipped with means of propulsion capable of exerting, according to a given thrust axis , a high thrust allowing said spacecraft to achieve an acceleration of greater than or equal to 0.05 m/s 2 , said method being characterised in that it comprises steps of: - during a phase of high-thrust along said thrust axis exerted by said means of propulsion supplied with liquid propellant from said propellant tank , remotely controlling said spacecraft in which are attached, on the outer surface of said wall of the tank , a heating member and at least one temperature sensor in a known position in proximity to said heating member , said temperature sensor being arranged in a plane perpendicular to said thrust axis , referred to as plane of interest, in which the liquid-gas interface in said tank is likely to be located at some time during a phase of high-thrust exerted by said means of propulsion along said thrust axis , in order to implement steps of: ∘ heating the wall of the tank using the heating member ; ∘ and acquiring measurements of the temperature of the wall of the tank using said temperature sensor , at a rate of one measurement every 30 seconds or less; - determining the moment I at which the temperature measured by said temperature sensor changes, which corresponds to the moment at which a break of slope occurs on a digital curve representing the temperature recorded by said temperature sensor as a function of time, such a change indicating the presence in the plane of interest of the liquid-gas interface in the tank ; - and determining, from the geometrical data of the tank and the known position of the temperature sensor on the wall of the tank , the volume of liquid propellant present in said tank at the moment I. - during a phase of high-thrust along said thrust axis exerted by said means of propulsion supplied with liquid propellant from said propellant tank , remotely controlling said spacecraft in which are attached, on the outer surface of said wall of the tank , a heating member and at least one temperature sensor in a known position in proximity to said heating member , said temperature sensor being arranged in a plane perpendicular to said thrust axis , referred to as plane of interest, in which the liquid-gas interface in said tank is likely to be located at some time during a phase of high-thrust exerted by said means of propulsion along said thrust axis , in order to implement steps of: ∘ heating the wall of the tank using the heating member ; ∘ and acquiring measurements of the temperature of the wall of the tank using said temperature sensor , at a rate of one measurement every 30 seconds or less; ∘ heating the wall of the tank using the heating member ; ∘ and acquiring measurements of the temperature of the wall of the tank using said temperature sensor , at a rate of one measurement every 30 seconds or less; - determining the moment I at which the temperature measured by said temperature sensor changes, which corresponds to the moment at which a break of slope occurs on a digital curve representing the temperature recorded by said temperature sensor as a function of time, such a change indicating the presence in the plane of interest of the liquid-gas interface in the tank ; - and determining, from the geometrical data of the tank and the known position of the temperature sensor on the wall of the tank , the volume of liquid propellant present in said tank at the moment I. <EOS>