The fuel delivery system involved an analysis of fuel and oxidizer choices, storage tanks and delivery tubes. Stainless-steel Grade 304N was chosen as the material for the fuel storage tank because it is easily welded, relatively inexpensive to produce and resistant to corrosion. Ultra-high molecular-weight-polyethylene was selected as an outer shielding for the fuel tanks because it is less vulnerable to cracking and resistant to micro-meteor strikes.
Cramped quarters for the six-to-nine-months-long trip to Mars was also a challenge. The students recommended the spacecraft’s frame have a cylindrical shape with a large rotating ring that can provide a gravitational feel for the astronauts. The spacecraft would be assembled in space with Inconel for the high stress areas, and steel and aluminum for lower stress large structural parts. Students also suggested an outer layer of Kevlar to absorb micro-meteor impacts.
For the windows, students suggested a three-panel design with an inert gas between the panes to minimize the chances of the windows rupturing. To overcome atmospheric temperatures, changes in pressure and ultraviolet radiation, the students recommended that the outer pane be fused silica and the inner pane be made of aluminosilicate glass. They also warned that since glasses and ceramics are brittle, precise engineering is essential.
The students suggested that the spacecraft have a blunt-bodied shape to reduce the heat created when plummeting through the Martian atmosphere and a ceramic heat shield because the material has a high melting point and is unlikely to deform. Reinforced carbon-carbon and carbon-ceramic composites are ideal heat-shield materials for re-entering Earth’s atmosphere, the students said. But at $2,600 for a four-by-four-inch sheet one-quarter-inch thick, “You’re not going to find it at Walmart,” one student said. “It’s not going to be a cheap project.”
Housing on Mars must provide sufficient oxygen, the ability to grow food and protection from ultraviolet radiation and temperature extremes. The students suggested using Martian concrete, comprised of 50 percent sulfur and 50 percent Martian soil.
They recommended distributing “organic bombs” around the planet to populate it with oxygen-creating plants. For the short-term, mega greenhouses could be built to grow food using human waste as fertilizer, they said.
Materials for a Mars ground vehicle must be lightweight, stable, vibration-dampening and be made of materials that could withstand extremely cold temperatures without becoming brittle. After comparing alloys of aluminum, iron and titanium, the students suggested a titanium alloy.
“I think they did quite well,” Srinivasan said of his students following their presentations. “A lot of this is beyond material that we cover in class, so they had to do research to figure out exactly what to do. The sulfur concrete – I hadn’t heard of that before.”
The project counted as 20 percent of the students’ grades. Srinivasan will teach the course again this fall semester, but the theme of the final project is yet to be determined. Last fall, the final project topic was fictional vehicles.
Wright State University became an independent institution in 1967 and spent the next 50 years growing into an innovative leader in undergraduate research. In 2017, it celebrates its 50th anniversary as an independent public university, culminating with a special homecoming celebration Sept. 29 through Oct. 1.