Desert RATS: Human Factors

By Robert Howard and Chip Litaker
Dr. Robert Howard is the manager of NASA’s Habitability Design Center within the Space and Life Sciences Directorate at Johnson Space Center. At Desert RATS, Dr. Howard oversees human factors evaluations aboard both rovers and the Habitat Demonstration Unit.

Mission day 7 finds us at the mid-point of our 14 day D-RATS mission and my team, the human factors (HF) team, has been asked to explain a little bit about what we investigate in regards to habitability of the rovers and the Habitat Demonstration Unit (HDU). The field of human factors is a systematic application of discovering information about human capabilities, characteristics, limitations, and motivation in order to design technology and procedures for people to become more productive, safe, comfortable, and effective in the environments in which they use such items.

Habitation is the space which determines the overall living and working environment for an individual within a vehicle or habitat, which affects the quality of daily life and productivity while onboard a space vehicle. With the rovers, we study over 212 operational elements of each rover, 50 of which are for habitability alone. These elements include the crew interfacing with the displays and controls, preparing a meal, exercising, driving, visibility and daily habitat operations to name a few.

Preparing lunch

A crew member prepares lunch. (Note the small sink and water hose he is using to rehydrate his meal.)

HF engineers also look at a crew’s workload, fatigue, and thermal comfort while performing such tasks as driving, Extra-Vehicular Activities (EVA) and docking. We record the amount of water the crew uses, the weight of logistics (like clothing, food, equipment), and the amount of trash generated by the crew to understand the amount of consumables needed for a crew of two on a 7-day planetary mission. This in turn, assists mission planners who develop the missions the crew will possible go on in the future. By using standard human performance measures, HF engineers can obtain an understanding of the interaction between the human and the machine. This tells us if the crew can live effectively inside the vehicles we are designing.

Pre-flight clothing inventory

An HF engineer takes a pre-flight clothing inventory. The white container is called a soft locker. The crew can store clothing, personal items, and food in the locker for a mission.

Crew member relaxing

A crew member relaxes after a hard day at work. (Note the soft lockers hanging in the rover’s side hatch way next to the sleep bench on the right.)

The rovers are just one set of vehicles HF engineers are examining. On Mission Day 6, both rovers docked to the HDU, which simulates a working habitat called the Pressurized Excursion Module (PEM). The habitat has a geology station, a space suit maintenance station, a general maintenance station, and a medical station. While the crews are docked to the PEM, they live in the rovers and work in the PEM. The PEM is a very exciting development. The workstations allow the human crew to do many things on the moon that were previously impossible in human spaceflight.

Rovers docked

Both rovers docked to the Pressurized Excursion Module (PEM) around 5:00 p.m. on mission day 6.

While in the PEM, the crews have specific tasks to perform on each station. For example, they examine and analyze rock samples they collected while on a traverse and they fix items needing repair. Together, the two rovers and the PEM can support a crew for up to a month. The crew could use the rovers as living quarters and as vehicles to conduct scientific exploration of the Moon, then return to the PEM for resupply, maintenance, and evaluations of collected samples. As with the rovers, HF engineers want to understand how the volume and architectural layout of the habitat works for the crew while they are performing normal working tasks and interacting with all types of technology.

Analyzing rock sample

Crew members working in the geology glove box getting ready to analyze a rock sample.

Building a sensor

A crew member builds a solar powered temperature and water sensor.

By understanding how humans and machines interact with each other, human factors engineering in collaboration with vehicle design engineering can capture information on the design and present recommendations on how to improve the design to enhance the crew member’s performance and comfort. Information provided by HF engineers lends confidence to future planetary vehicle design. Field trials such as Desert RATS give HF engineers a more realistic testing environment to investigate the various elements of habitation.