This shift required a radical rethink of how flight controllers planned daily astronaut schedules. Central to Skylab’s scientific mission was the Apollo Telescope Mount (ATM), a specialized solar observatory that allowed astronauts to study the Sun in wavelengths obscured by Earth’s atmosphere. Solar activity, however, is inherently unpredictable. If a solar flare or major event occurred on the Sun, controllers needed to react immediately so the astronauts could point the ATM’s instruments at the phenomenon.
“We had to come up with a system that would allow us to plan in real time and accommodate the science people,” Windler recalled in a 2006 interview. “If something interesting happened on the sun, which it did several times, then we needed to be able to schedule the ATM work.”
To solve this problem, Windler and his team overhauled mission planning techniques, moving away from months-long pre-flight scheduling to short, dynamic operational cycles that adapted to real-time scientific opportunities.
“We invented a way of flight planning in real time, or cycles,” Windler explained. Under this framework, controllers and scientists engaged in a continuous daily dialogue. “One day the science people talked about what they wanted to do, and the ‘Science Czar’ got with them and said, ‘All right, then, we need these particular objectives for tomorrow.’”
This agile planning approach proved revolutionary. It allowed NASA to bridge the gap between traditional engineering-focused mission control operations and the dynamic needs of the scientific community. The real-time cycle system developed under Windler’s leadership laid the groundwork for how operational science would be conducted on future space platforms for decades to come.
The Shuttle Era, the Canadarm, and Private Industry
After the completion of the Skylab program in 1974, Windler brought his operational expertise to NASA’s next major endeavor: the Space Shuttle program. As NASA transitioned toward reusable winged orbiters, payload deployment and orbital construction became central mission goals.
Windler contributed significantly to the development and integration of the shuttle’s Remote Manipulator System (RMS), universally known as the "Canadarm." Contributed to the shuttle program by Canada through the Canadian Space Agency and built by Spar Aerospace, the mechanical arm allowed shuttle crews to deploy, capture, and maneuver heavy satellites in orbit. Windler worked to establish operational procedures for operating the robotic arm safely from the shuttle’s aft flight deck, establishing practices that would later become essential for satellite repair missions—such as those servicing the Hubble Space Telescope—and the assembly of large orbital structures.
Following a distinguished career at NASA, Windler retired from the space agency, but his involvement in human spaceflight was far from over. He joined the private aerospace industry, bringing decades of flight operations knowledge to the initial development phases of what would become the International Space Station (ISS).
