For over 30 years, large, high-altitude balloons have been used in scientific and technological investigations to help us better understand the Earth and our atmosphere. More recent programs like the development of NASA’s Super Pressure Balloon (SPB) are meant to fulfill a similar role but over longer missions that cover greater distances and collect more data so that we may develop a greater understanding of the world around us. One issue with these large balloons is that there is little to no trajectory control as they float along with prevailing winds, putting the missions at nature’s mercy. Few forms of trajectory control exist today. In this summer research, I have been working on a theoretical model for a photophoretic thruster that would partially compensate for the drag experienced by these balloons. This thrust force would take advantage of surface temperature differences caused by the sun’s irradiance and a theoretical porous material developed in this research. This system would allow for long-term trajectory control that creates minimal payload and can lengthen the mission by maintaining the correct balloon flight path.