Future space missions will reach greater distances and span longer durations. Design of spacecraft and habitats to better accommodate space travelers will be more important than ever. To achieve this, mission planners and spacecraft designers need tools to help them better define habitable volume and identify mission and programmatic risks. Volume directly drives mass and cost, so well-informed estimates early in the design process are key.
“Once you put human beings into a space mission, it becomes much more complex,” said Simon Hsiang, chair of the Systems Engineering and Engineering Management Department in the Lee College of Engineering. “You now have life support elements such as food, water and oxygen. But you also have human-factor needs, and there must be a balance between the psychophysical needs of diverse people in the spacecraft and the fundamental mechanical needs of the ship.”
Hsiang is the principal investigator for the project “Computational Model for Spacecraft/Habitat Volume,” sponsored by NASA’s Human Systems Integration Division. Research started in the spring of 2016 and is scheduled to run until 2018. The UNC Charlotte researchers are working with NASA colleagues at Johnson Space Center in Houston, Texas, and Glenn Research Center in Cleveland, Ohio.
As part of their work, researchers are investigating scenarios such as that a family of four will soon be on its way to Mars, and NASA is the real estate agency that will provide living quarters for the four-year mission.
The mother, father and children all have different demands for how the space within the spacecraft will be used. Mom wants a nice living area with windows, Dad wants a functional work space, and the kids want a large play area. Meeting these human-factor needs is as critical to the success of the mission as the safety and mechanical functions of the spacecraft. How to achieve this within the limited volume of the craft is the challenge.
The UNC Charlotte team is using mathematical models to optimize the space considerations. With numerous scenarios for length of voyages, numbers of people and types of missions, there is a huge amount of data going into the models.
“One of the main considerations is the duration of the trip,” Hsiang said. “It’s similar to a car trip on Earth. If you’re just driving across town, you can be comfortable in a small Fiat. But if you’re crossing the country, you need something much bigger. Another major factor is the number of people. Is the space needed for a family of four going to Mars or for 10 scientists living and working on a space station?”
Some sections of a spacecraft can have multiple uses at different times. An advantage of space travel is that in zero gravity there is no up or down, so space can be arranged in numerous ways.
“There are all kinds of considerations, and you have to realize you can’t make everybody happy,” said Hsiang. “There have to be trade-offs. Our task is to determine the best compromises.”
Claudia Ramirez, a Ph.D. student in the UNC Charlotte Infrastructure and Environmental Systems program is involved in collecting the data about human preferences and then weighing them against spacecraft performance considerations.
“We have to find out what is most important to the astronauts,” Ramirez said. “These are the psychophysical factors. We have to determine what the four to six most important factors are to various user groups.”
The NASA user groups that are ranking the importance of the multiple factors are Task Performance, Safety, Health and Well-being, and Subsystems Integration.
“We have them rank factors for primary and secondary importance,” Ramirez said. “We enter this data into our model, which determines the best use for different space modules. We then use MATLAB to build a 3D representation of the optimal spacecraft. It’s like trying to arrange LEGO blocks into the smallest volume possible, with each block in an optimal position.”
Research team member Churlzu Lim, an associate professor in systems engineering, is involved in building the mathematical optimization models for the project.
“There are a lot of tasks that have to be accomplished in space travel such as eating, exercise, working and sleeping, and they all require space,” he said. “The data for these critical tasks are the building blocks we work with. Some can overlap and some can’t. Since the space in the craft is pricey, my goal is to find the best arrangement of blocks to minimize the total volume, which is a challenging mathematical optimization problem.”
Visualization charts from Lim’s model show the layout of building blocks, areas of overlap and orientations of human tasks performed in each block. Using the models, NASA can then estimate spacecraft volume needs for various missions, assess and create space layout based on volume and mitigate risk characteristics associated with volume.
“Compared to the research I’ve done in the past,” Lim said, “this project is very different. I really like working with NASA. For me it’s totally new, which makes it fun.”
Photo (left to right): Simon Hsiang, Churlzu Lim and Claudia Ramirez are working to optimize space travel.