Abstract: Tether-based reaction control systems for spacecraft undergoing atmospheric entry or reducing orbital energy, including systems that use atmospheric drag on one or more tethers to alter the angle of attack of the spacecraft during its atmospheric transit to reduce the thermal and mechanical loads on the spacecraft during the reentry process. Systems may include tethers that together generate a force that functionally acts on the spacecraft at a point that is offset from the spacecraft's center of mass. Such systems may be either actively or passively controlled.