In creating a virtual environment of the planet’s unique atmospheric conditions, scientists discovered that heat and radiation from the lander itself could affect daily readings, such as atmospheric pressure, wind velocity and temperature.

The Phoenix spacecraft landed on Mars in May 2008 and, for the next five months, fed back a steady stream of data to Earth. Well before the launch, a team of Canadian scientists at the University of Alberta helped in the development of the lander’s meteorological station (MET). MET was designed to collect measurements that would complement other data critical to the mission. Design and calibration experiments were difficult and expensive to perform, so the university turned to virtual testing with fluid dynamics software from ANSYS. While exploring the anticipated Martian environment, scientists discovered that, under certain wind conditions, heat emitted from the lander could cause a temperature sensor to show higher-than-atmospheric values.

The deck of the lander contains instruments used to collect external data, including atmospheric pressure, wind velocity and temperature sensors. This image depicts temperature contours showing the effect of the lander heating on the lowest of three temperature sensors. Image courtesy of ANSYS, Inc.

“With space missions, there is only one shot at getting it right. Any minor flaw could result in the instantaneous loss of years of preparation and hundreds of millions of dollars,” said Carlos Lange, associate professor of mechanical engineering at the University of Alberta. “Using simulation software from ANSYS, we learned that the internal heat generation and emission of radiation from the lander’s surface could increase temperature measurements. Similarly, obstacles upstream from velocity and pressure sensors could alter readings of wind magnitude and/or direction.” Therefore, Lange and his colleagues calibrated the instruments through a large parametric study. After the lander touched down on Mars, the university team used the results of such simulations to evaluate the raw mission data and find instances when these wind directions occurred. This process was key to preventing misinterpretation of the data by the Phoenix scientific team.

Effect of the support on the lander’s velocity sensor; red and yellow streamlines indicate flow direction. Image courtesy of ANSYS, Inc.

Simulation turnaround time was a concern to the team as well. During the mission, limited time and power resources were allocated daily to the operation of specific instruments. “To make decisions about the prioritization of data collection, strategic planners sometimes required input based on the results of the simulations. So we needed to quickly simulate new cases,” Lange said. This short time-response requirement was met by employing the high-performance computing capabilities of ANSYS software, running the simulations in parallel on a cluster to achieve, at times, super-linear speedup (speedup greater than an amount proportional to the number of processors used). The efficiency of high-performance computing capabilities and multi-core hardware together enabled new simulations to be completed within the timeframe required for decision making. The overall success of the University of Alberta’s work has allowed for additional simulations to be performed to aid in the explanation of certain phenomena found in the raw data.

“Software from ANSYS is used every day to design better products on Earth. And now, it’s helping to interpret data from Mars!” said Josh Fredberg, vice president, marketing, ANSYS, Inc. “Because of the depth of our product offering, its breadth across a wide range of disciplines, and the ability to tackle large problems quickly, the application of ANSYS software is virtually unlimited. Organizations are finding new, innovative ways of using engineering simulation to create products faster, to understand the world around us and to learn more about the universe.”