Compartment Temperature Research Articles

Nuclear Auxiliary Power Unit for Lunar Exploration

Unmanned soft lunar landing experiments by the United States are currently being planned by the National Aeronautics and Space Administration. All of these experiments will require some form of electrical power; and their success or failure will depend upon the development of a suitable, reliable electrical power generation system. The system utilized must be compact, lightweight and rugged. Certain requirements for such an experiment could be met by solar cell arrays. The reliability of solar cells has been well established; however, their usefulness for this mission is inherently limited. Experiments conducted during the lunar night require a large storage capacity, if solar energy is to be the spacecraft's only source of power. A radioisotope-fueled thermoelectric generator can fulfill all spacecraft power requirements continuously throughout the lunar day or night without special orientation. A radioisotope, such as Curium-242, may be used as the thermal energy source for a lunar experiment of short duration (90 to 120 days). Curium-242 does not occur in nature, but may be created by the neutron irradiation of Americium-241. This radioisotope requires very little radiation shielding to protect sensitive equipment, because of the low gamma flux associated with its decay. The rigors of the lunar climate produce an environment which present-day electronic equipment will not tolerate. By utilizing waste heat from the radioisotope generator, the electronics compartment temperature may be controlled within acceptable limits. All subsystems within the generator may be duplicated to improve its reliability.

Navigation in the Days of Sail

At the turn of the century I served in two four-masted barques under three captains hailing respectively from Nova Scotia, Liverpool and Glasgow. All three were rather elderly and their practice of navigation did not exhaust the theory even then included in the syllabus for second mate. However, it may be interesting to recall their methods.The captains personally had to supply, in addition to sextants and nautical tables, chronometers, charts, ‘Pilots’, patent logs and nautical almanacs. I doubt if they bothered about tide tables. These were all kept in the captains' bedrooms. Each of these captains rented and insured two chronometers. In port, if convenient, these went ashore to a chronometer dealer and just before sailing were brought on board, each with a card showing its maker's name and number with error of instrument and its daily rate. If at sea it was possible to get a longitude by bearings of the land and also longitude by sights, they would be checked and error and rate corrected. Of course in sail it was impossible to maintain an even temperature in the chronometer compartment. It was generally assumed that, owing to effect of change of temperature on the lubricating oil, a chronometer ran slower in cold weather and faster in hot. I don't know when they were cleaned. Perhaps if a ship did return to where the chronometers' owner had his place of business they might be cleaned before being issued to some other ship.