Protecting spacecraft from severe heating during hypersonic flight is a challenging task that leaves no room for error. Likewise it is difficult to simulate on the ground the effects of flying at Mach numbers greater than 20. But that is what the NASA Ames arc jet facility does for designers of human spacecraft and robotic probes. It requires directing multi-megawatts of electrical power inside a tube less than 3 inches diameter containing hundreds of water cooled parts. All of that to perform a test on piece of heat shield material that you can hold in your hand. Come and hear how this capability developed, and how it is used every day. John Balboni has worked as a research engineer at NASA Ames Research Center at Moffett Field for 25 years in the thermal protection test facility. His work lately has influenced the heat shield designs of the Mars Science Laboratory mission and the crewed Orion capsules.