Making long-distance space travel efficient

Maximizing radiative cooling in a vacuum environment

Abstract

Nuclear propulsion has become a promising technology for long distance space flight. NASA has identified nuclear thermal propulsion (NTP), using uranium fission, essential for future Mars mission. A key challenge in NTP lies in the management of the excessive heat generated by the nuclear fission. Thus, an effective radiator design to maximize the cooling through radiation is crucial, as heat convection and conduction is not possible in the vacuum.  for space should maximize its heat dissipation. This study examines how the heat dissipation capacity of a ribbed radiator surface varies with different vertex angles. To test this, three aluminum model radiators each with a respective vertex angle of 0°, 20°, 40° and 60° were heated to 477.6 K in a near vacuum environment then cooled over a 55-minute period. Temperatures were recording every 10 seconds using a MLX90614 infrared sensor. These data were converted into radiant power (Watts) over time, then normalized by volume to produce W/m³ versus time graph. The 0° radiator consistently exhibited the highest W/m³, suggesting the optimal surface geometry for cooling. Initial hypothesis predicted the highest cooling efficiency of flat radiator surface by minimizing the reabsorption of emitted radiation. In addition, the efficiency of each radiator matched with higher surface area to volume ratios, suggesting that this metric is more important in creating efficient radiators than simply surface area.