SPACECRAFT ENGINEERING

✓ Designed spacecraft structures and ground support equipment (GSE) in SolidWorks for the Vigoride spacecraft.

✓ Assembled and integrated the spacecraft qualification structure in a clean room environment.

✓ Developed water-based passive propellant management systems (PMD). Assembled, leak checked, tested and documented PMD experiments, with the most successful system chosen for flight qualification.

✓ Performed a thermal analysis for a Resistojet using Ansys and Thermal Desktop, which resulted in a 15% power saving.


1. Ground Support Equipment Design

The GSE assembly is made of hoist rings, a welded rectangular lifting structure (yellow), wires (green), a manufactured lift fixture (gray).

GSE calculations (see figure 1):

Taking the expected mass of the spacecraft, I set a Factor of Safety of 3. I calculated the total load with a factor of safety = maximum load. The expected failure modes were a) bolt shear stress b) thread tear-out in the interface between the lift fixture (gray) and the hoist ring.

The calculation showed that the margin of safety was greater than zero for all of the cases. In addition, an extra thread was added to the lift fixture (gray) to allow use of the fixture for horizontal lifting as well as for vertical lifting. This reduced costs by 50%.When the GSE was ready, we loaded a dummy load to test the lifting capacity of the ground support equipment and everything went well. The spacecraft was transported to the qualification test successfully.

Figure 1 – The Vigoride spacecraft lifting diagram. The design in symmetric, therefore only half of the lifting design is shown.

Figure 2 – A 3D printed mock-up of the Vigoride structure.

The bottom center blue part represents one of the Resistojets.

2. ResistojetThermal Analysis

This analysis was conducted to answer a) how much heat is required to maintain the Resistojet main heater at a constant temperature, b) how much heat is conducted to the spacecraft, and c) how much heat radiates to space.

The CAD geometry included parts with complex geometries, and it was unclear which part had the greatest thermal resistance and by what order of magnitude. To determine this, I used Ansys to calculate the 1D conductivity of 3D objects. Hand calculations verified the simulation results. Then the conduction values were summed up in an electrical analogous manner along with contact resistances. This provided the total conduction coefficient and the amount of heat required to keep the Resistojet hot. Switching over to Thermal Desktop, a simplified outer Resistojet shell was modeled. A conductor simulated the complex conduction path between the spacecraft and the outer surface (shield) of the Resistojet. Radiation from the shield to space was added and this provided us with the amount of radiated heat as well as the ratio of conducted to radiated heat, 70% and 30%, respectively. One part in the assembly was modified to decrease its’ cross section, which led to a 15% reduction in power per Resistojet.