grown in sealed chambers, though experiments have shown that plants can thrive at pressures much lower than those on Earth. The use of electric lighting to compensate for the 354-hour night might be difficult: a single acre (0.405 hectare) of plants on Earth enjoys a peak 4 megawatts of sunlight power at noon. Experiments conducted by the Soviet space program in the 1970s suggest it is possible to grow conventional crops with the 354-hour light, 354-hour dark cycle. A variety of concepts for lunar agriculture have been proposed, including the use of minimal artificial light to maintain plants during the night and the use of fast-growing crops that might be started as seedlings with artificial light and be harvestable at the end of one lunar day. An experiment in the Chinese Chang'e 4 lunar lander mission demonstrated that seeds could sprout and grow in protected conditions on the Moon (January 2019). The cotton seeds were able to handle the harsh conditions, at least initially, becoming the first plants ever to sprout on the surface of another world. But without a source of heat, the plants died in the cold lunar night. Lampenflora which grows in caves that have fixed artificial light sources installed shows that plants exist that need very little light to survive. Energy Nuclear power A nuclear fission reactor might fulfill most of a Moon base's power requirements. With the help of fission reactors, one could overcome the difficulty of the 354 hour lunar night. According to NASA, a nuclear fission power station could generate a steady 40 kilowatts, equivalent to the demand of about eight houses on Earth. An artist's concept of such a station published by NASA envisages the reactor being buried below the Moon's surface to shield it from its surroundings; out from a tower-like generator part reaching above the surface over the reactor, radiators would extend into space to send away any heat energy that may be left over. Radioisotope thermoelectric generators could be used as backup and emergency power sources for solar powered facilities. The needed radioisotopes could either be imported from earth as they are relatively energy-dense, or produced in situ by neutron irradiation of suitable materials (e.g. - an unavoidably produced minor actinide in fission reactors operating with thermal neutrons - to produce the commonly used ) or separated chemically from the high level waste of the nuclear reactor (e.g. Americium-241).