Phase II Final Report - NASA's Institute for Advanced Concepts

Planetary Exploration Using Biomimetics
An Entomopter for Flight on Mars
3.5.3.5 Power Source
The processes and devices described above require power to produce hydrogen peroxide from
the Mars atmosphere, power in addition to what is required by the base lander or rover for normal
operation. To determine the impact this increase in power has on the overall system, the
increase in mass of the power system must be determined. Because the base-vehicle design has
not been established, the two most likely power sources for the vehicle are evaluated here. These
are a dynamic isotope power system and a photovoltaic battery power system.
For dynamic isotope systems, there are two main options, a Stirling or Brayton system. These
systems have specific power values on the order of 15 W/kg [194]. This system would include
either a Brayton of Stirling engine, radiator, and isotope heat source. A diagram of this system is
shown in Figure 3-163.
Figure 3-163: Dynamic Heat Engine Power System Diagram
The PV power system has a specific power for the array of 94 W/kg and a specific energy for the
battery storage of 300 W-hr/kg. These values are for a GaAs/Ge PV array and lithium ion
rechargeable battery [19]. The specific power for the array is an average over the daytime
period. Therefore, if the same amount of power is needed throughout the night, the array size
will need to double, assuming operation at the equator, where there are equal day and night periods.
Because this is a preliminary sizing, no efficiency losses of the battery-charging system
were taken into account. A diagram of the PV battery system is shown in Figure 3-164.
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Phase II Final Report