words and photos by Skylar Cole
In 2020, the National Aeronautics and Space Administration is set to send another rover to the ‘red planet’ to collect soil samples. Currently, NASA is developing new tires that will be able to better maneuver around the Martian terrain. But how are you supposed to create and test better tires if you have no previous sample of the terrain you need to compare and test against?
This is the question that Heather Oravec, Ph.D., a mechanical engineering research associate professor at the University of Akron, has been tasked with answering.
NASA’s Glenn Research Center (GRC) is developing revolutionary spring-based tires for the 2020 Mars rover mission. Oravec’s role is to develop the terrain to test said rover tires.
This task is easier said than done, as no Martian samples have been brought back to Earth. While simulants have been created before, they were created by different people for different purposes, to test magnetic, spectral, or chemical compositions but not the physical properties.
“We’re going to be looking at things like grain size distribution, particle shapes, bulk density — so those types of things tell us how the soil is going to behave in bulk,” Oravec says. “If it’s got a bunch of rounded particles that are all the same size, then it’s going to have a higher sinkage rate, so that means your vehicles will sink more easily because the particles will just slide over each other. If it has a bunch of angular particles with sharp angles and [the particles] have a different range, those will kind of pack together and form bridges together and that will be a little stronger.”
To develop the simulant, Oravec looks at data from previous missions and rovers, including Viking, Spirit, Curiosity, and Opportunity.
Currently, they are testing tires that are made out of a nickel-titanium alloy that Oravec calls a “memory metal.” If you were to bend a traditional metal, it would warp, but with “memory metals,” the atoms rearrange themselves and remember their original positions so that the metal can bounce back to its original form.
The metal has been formed into springs and wound together to create a sort of mesh. The mesh allows the tires to filter out sand and envelop the rocky terrain of the Martian surface.
“When you look at pictures of Curiosity, you can see a substantial amount of holes,” Oravec says. These holes are due to the fact that Curiosity’s tires are solid sheets made out of an aluminum alloy, which was not strong enough to withstand the rocky terrain.
“I’m more concerned with what’s actually on Mars and deciding what’s best for testing our wheels so the mission is actually successful,” Oravec says. “There’s a lot of Martian simulants that are made out of quartz materials, different silicas, and I’m not entirely sure what’s the best match yet. We’re still going through the literature review process.”
The end goal of her work is to not only have an accurate simulant, but “a simulant that can be shared globally with international partners, where everyone agrees… that this is going to be the soil that we use to test the vehicles.”
In parting, I asked Oravec a question that I think many people ask when they see news about Mars. I asked her if she thought we would ever get a human on Mars, and why it’s important.
“I do, I think they will. I think it will be a long time from now, obviously — the focus is the robotic mission right now and getting to the moon, and then Mars. Do I think it will be within the next decade? Probably not, but soon thereafter. In my personal opinion it is [important]. I think it’s exciting, it’s great to learn new things. It’s all based on what you’re interested in, whether that’s finding life somewhere else; are you interested in extending our earth capabilities; or are you interested in putting humans on Mars? It’s really all just what you’re interested in. I find it fascinating.”
Skylar Cole is a senior at Bio-Med Science Academy.