Engineering topics
Publications and source records attributed to Nesmith, B. J..
The three advanced converter technologies for future potential radioisotope power sources for space were evaluated based on mission requirements for proposed NASA planetary missions.
The continuing development of new spacecraft technologies promises to enable the Solar Probe to be the first mission to travel in the atmosphere or corona of the Sun. The most significant technology challenge is the thermal shield that would protect the spacecraft from the flux of 3000 Suns (400 W/cm**2) at the perihelion radius of 4 solar radii while allowing the spacecraft subsystems to operate at near room temperature.
'Walk-off' in a dish-type solar thermal power system is a failure situation in which the concentrator remains fixed while the spot of concentrated sunlight slowly moves across the face of the receiver. The intense local heating may damage the receiver and nearby equipment. Passive protection has advantages in minimizing damage, but in a fully passive design the receiver must be able to withstand full solar input with no forced fluid circulation during the walk-off. An active walk-off emergency subsystem may include an emergency detrack or defocus mechanism or sun-blocking device, emergency power, sensors and logic to detect the emergency and initiate protective action, and cooling or passive protection of emergency and non-emergency components. Each of these elements is discussed and evaluated in the paper.