<P> This white, flexible fabric offered protection at up to 371 ° C (700 ° F). FRSI covered the orbiter's upper wing surfaces, upper payload bay doors, portions of the OMS / RCS pods, and aft fuselage . </P> <P> Gap fillers were placed at doors and moving surfaces to minimize heating by preventing the formation of vortices . Doors and moving surfaces created open gaps in the heat protection system that had to be protected from heat . Some of these gaps were safe, but there were some areas on the heat shield where surface pressure gradients caused a crossflow of boundary layer air in those gaps . </P> <P> The filler materials were made of either white AB312 fibers or black AB312 cloth covers (which contain alumina fibers). These materials were used around the leading edge of the nose cap, windshields, side hatch, wing, trailing edge of elevons, vertical stabilizer, the rudder / speed brake, body flap, and heat shield of the shuttle's main engines . </P> <P> On STS - 114, some of this material was dislodged and determined to pose a potential safety risk . It was possible that the gap filler could cause turbulent airflow further down the fuselage, which would result in much higher heating, potentially damaging the orbiter . The cloth was removed during a spacewalk during the mission . </P>

Which of the following metal is used in spacecraft to with stand high temperature