As an undergraduate in electrical engineering and a graduate student in systems engineering, I cannot recall any of my professors discussing the human element in system design. We were taught to focus on designing hardware and software, rather than considering the human as part of the design. Systems engineering involves requirements, trade-offs, architecture development, and the verification and validation of requirements. I became the project manager for a project involving astronauts using the system. The project I was responsible for was called the “Voice Command System.” The goal of the experiment was to assess the utility of speech recognition technology for voice control of a spacecraft system. At the time, speech recognition technology was gaining momentum, with numerous products being developed that utilized it, including speech-to-text dictation and voice-controlled robots. This experiment taught me that while technology is essential, the integration of technology and humans is equally vital. If not properly implemented with human factors in mind, it can lead to a system failure. It was my first experience seeing how technology and humans using the technology need proper integration to work together efficiently and effectively.
Over the years, I gained knowledge and experience in Human Factors and Human Systems Integration (HSI) through flight experiments on the Space Shuttle, research, and collaboration with experts at NASA, specifically within the Johnson Space Center (NASA/JSC) Human Health and Performance Directorate (HHPD). In 2010, the Avionics Systems Division underwent a reorganization. Considering the division’s significant involvement in human interfaces with the Space Shuttle, Space Station, and the Commercial Crew Program, it was decided to establish a new branch focused on human interfaces and systems. As part of that reorganization, it became clear that this branch should work closely with NASA/JSC human factors experts in human-centered design. During a single afternoon session, I gained meaningful insights about HSI from an HHPD human factors engineer (HFE). As I learned more about HSI, I shared my insights with my engineering colleagues. I found that many engineers don’t truly understand human capabilities and limitations when designing a system, especially where the human interacts with the system. This is one reason why many products receive poor reviews. Do you remember (or ask your parents) the Video Control Remote (VCR) that required multiple button presses to program for recording a TV show? This was a clear example of a lack of HFE in the design. For the aviation and military industries, a human interface design without review from an HFE
expert or from an HSI perspective could lead to serious consequences, like a plane or ship crashing into another vessel. (See USS Fitzgerald, USS John S. McCain Collision Report – USNI News).
HSI is more than just HFE; it is a system engineering process that entails considering all aspects of a project involving humans throughout the development process. NASA has always considered the human in “human spaceflight’ critical in the design. However, times are changing, and at the time of writing, NASA is leading the efforts to return to the moon and beyond with the Artemis program. Unlike the Apollo program, Artemis’ objective is to provide for a sustained presence on the moon.
The Artemis Program aims to return to the moon, but this time to stay for extended periods, unlike the Apollo Program. This goal or requirement suggests that human factors must be considered at the onset in the cockpit, the vehicle, the Human Lander System, the habitat, the rover, and the spacesuit during excursions on the moon. Partners from the U.S. commercial sector, as well as those from other countries, will participate in this event. This means that considerations such as vehicle crew controls are essential, as what is not desired are different, unique crew controls that astronauts have to train for, or maintenance that varies and is cumbersome to do.
The Mercury, Gemini, and Apollo programs required astronauts to meet mission goals safely within a short time frame. In each of these programs, a significant effort was made to reduce human error in spacecraft control. At that time, there was no formal HSI process in place. However, it was essential to consider all aspects of including the astronaut in the system’s design, along with autonomously landing on the moon. Still, the program ensured Neil Armstrong and Buzz Aldrin trained to land on the moon manually.
During the Apollo 11 moon landing, data from the landing sensors and visual observations of where the Eagle was to land indicated it was unsafe to land. However, the training Neil received from an off-nominal landing proved beneficial, as Neil turned off the autonomous landing software and took control of the vehicle to land it safely on the moon’s surface. It became clear that training was essential in a mission or project. Training is one of the disciplines of HSI.
The Department of Defense found that most of the life-cycle costs occurred after the system had been developed and deployed. Not surprising. For the Space Shuttle Program, operational costs were much higher than expected. Why? Because the human element involved in maintenance and sustainment was not considered early enough. They treated the Space Shuttle program’s maintenance as if it were the same as that of an airplane, rather than understanding the complexity of maintaining the vehicle. The Shuttle required thousands of technicians to prepare for the subsequent missions.
Different industries define and address HSI in various ways, depending on the specific needs of each sector. The Department of Defense (DoD) focuses on ensuring the operational effectiveness of the military system and the soldier, as well as minimizing operational costs. Similarly, the Aerospace, Health Care, Railroad, and consumer electronics industries have slightly different focuses on HSI. For NASA, HSI defines the following disciplines: Human Factors Engineering, Maintenance/Sustainment, Safety, Training, Operations, and Habitability. The Key discipline is training. The reason for not factoring Manpower and personnel is that, like other industries, it depends on the project manager; however, this is noted. Whether it’s the railroad or aerospace industry, the critical part of HSI working in unison with systems engineering is the interaction required between the different HSI disciplines to optimize the system.
For HSIs to be effective, the HSI discipline leads must collaborate as requirements are being developed to identify and resolve conflicting or missed requirements early. HSI emphasizes interaction with HFE and the systems engineering process. This approach ensures that all aspects of the human’s interaction with the system are considered throughout the development cycle. The diagram shown is a NASA HSI interaction diagram that highlights the areas where the human system should exchange data, from initial development to operations.
Recalling the Voice Command System (VCS) flight experiment I led, I remember my team being involved in each of the six disciplines. At the time, I was not familiar with Human Factors or HSI. However, the NASA systems engineering process and interaction with the HFE assigned to the VCS project ensured that all these disciplines were addressed.
The HFE ensured that a task analysis was conducted on VCS using the Space Shuttle Closed-Circuit Camera System, along with the Shuttle robotic arm. Safety was evaluated from both hardware and software perspectives to assess their impact on Shuttle safety and VCS operation when using the robotic arm with the VCS. There was a strong focus on training because voice control was new, and the technology was still evolving. The team considered what supportability could be implemented on-orbit and developed a software reconfiguration plan in case the VCS software became corrupted. We collaborated with the mission control payload team to develop operational procedures for the astronauts, which were practiced during training.
I was pleased to be part of officially integrating HSI into NASA’s systems engineering process, which began with establishing an HSI Employee Resource Group. This effort led to the incorporation of HSI requirements and procedures into NASA’s systems engineering and project management practices. I had the opportunity to see HSI implemented in the Commercial Crew and Human Lander System programs. Hopefully, the NASA Artemis program will benefit from applying HSI in a space initiative that has never been attempted before: a human space exploration effort requiring long-term sustainment on the moon to prepare us for a future human mission to Mars.