Model of a tumbleweed rover. Image: North Carolina State University |
New research from North
Carolina State University shows that a wind-driven “tumbleweed” Mars rover would be capable of moving across rocky Martian terrain—findings
that could also help the National Aeronautics and Space Administration (NASA)
design the best possible vehicle.
“There is quite a bit of interest within NASA to pursue the tumbleweed rover
design, but one of the questions regarding the concept is how it might perform
on the rocky surface of Mars,” says Andre Mazzoleni, PhD, an associate
professor of mechanical and aerospace engineering (MAE) at NC State and coauthor
of a paper describing the research. “We set out to address that question.”
Mazzoleni and Alexander Hartl, PhD, an adjunct professor of MAE at NC State,
developed a computer model to determine how varying the diameter and mass of a
tumbleweed rover would affect its speed and ability to avoid getting stuck in
Martian rock fields. Rock fields are common on the surface of Mars, which
averages one rock per square meter.
“We found that, in general, the larger the diameter, and the lower the
overall weight, the better the rover performs,” Mazzoleni says. In addition,
the study found that a tumbleweed rover would need to have a diameter of at
least six meters in order to achieve an acceptable level of performance—meaning
the rover could move through rock fields without getting stuck.
Using the model, the researchers also found that tumbleweed rovers are more
likely to bounce than roll across the surface, due to the spacing of the rocks
and the size of the rovers.
“Computer simulations are crucial for designing Mars rovers because the only
place where you find Martian conditions is on Mars,” says Mazzoleni. “Earth-based
testing alone cannot establish whether a particular design will work on Mars.”
Mars has approximately three-eighths of Earth’s gravity. And the atmospheric
density on the surface of Mars is only duplicated around 100,000 ft above the
Earth’s surface.
Tumbleweed rovers are attractive because they can cover much larger
distances, and handle rougher terrain, than the rovers that have already been
sent to Mars—such as Spirit and Opportunity. “This model is a tool NASA can use to assess the viability of different designs
before devoting the time and expense necessary to build prototypes,” Mazzoleni
says.
While tumbleweed rovers would lack the precise controls of the wheeled
rovers, they would also not rely on a power supply for mobility—they would be
literally blown across the Martian landscape by the wind.
The paper, “Terrain Modeling and Simulation of a Tumbleweed Rover Traversing
Martian Rock Fields,” is published in the Journal of Spacecraft and Rockets.
