Paul Sengstock – Rest In Peace

Paul Sengstock passed away on January 28, 2021 at age of 88, spending his final months in hospice care. He is survived by his wife Judy – his college sweetheart, three children, and five grandchildren. Paul attended Northwestern University where he earned his degree in Electrical Engineering and was in the Navy ROTC program. Following his Navy career, he was hired by Hughes Ground Systems and moved to California, settling in Torrance.

At Hughes Space and Communications, Paul was part of Dr. Harold Rosen’s team that built and launched the first commercial communications satellites (Syncom I and II) in 1963. His contributions included design development and support of Launch and Mission Operations. Paul subsequently worked on several commercial HS376 spin stabilized spacecraft that were launched on several different expendable launch vehicles and then the first space shuttle optimized spacecraft, Syncom IV.

Syncom IV was the brainchild of Alois Wittman and Dr. Harold Rosen who handpicked a small dedicated team to run the program led by Ron Swanson as program manager and Jerry Dutcher as system engineering manager. The system engineering team consisted of Chuck Rubin mechanical and Paul Sengstock for spacecraft electrical interfaces that worked closely with NASA and the different Hughes functional areas during the development phase. Syncom IV required development of its own propulsion to transfer from the Shuttle orbit (LEO) to Geosynchronous orbit. It was to be secured to the Shuttle’s payload bay using a reusable “cradle” adapter encircling the lower half of the spacecraft’s cylindrical drum. Deployment in orbit was to be implemented through a “Frisbee” ejection, clearing the payload bay with a small residual velocity and low spacecraft spin. Spacecraft on-board timers would autonomously command deployment of the S/C omni antenna to enable command and telemetry capability, spin up the spacecraft to about 30 rpm and fire the solid rocket motor to achieve the first transfer orbit. Electrical interfaces with the shuttle, the on-board S/C timer, launch, mission control and operations control centers were Paul’s primary responsibilities.

Syncom IV S/C was offered to the Navy as a lynch-pin for 5 years of world-wide communication service from 4 geosynchronous locations. Options were identified for 2 years of service extension and Navy could purchase the satellites after option exercised. The project was renamed LEASAT for Leased Service.

The Leasat contract provided Hughes an opportunity to expand its business from a spacecraft manufacturer to developing the system architecture and providing hardware for an entire worldwide communications system, including being a service provider. Hughes responsibilities included financing, launching, insuring, building the ground control network and operating the satellites for their lifetime in addition to spacecraft manufacture. Hughes Communications Inc (HCI) was formed as a subsidiary to Hughes Aircraft to provide ground stations and become the service provider to the Navy.