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Radioisotope Heater Unit
A radioisotope heater unit (RHU) is a small device that provides heat through radioactive decay. They are similar to tiny radioisotope thermoelectric generators (RTG) and normally provide about one watt of heat each, derived from the decay of a few grams of plutonium-238—although other radioactive isotopes could be used. The heat produced by these RHUs is given off continuously for several decades and, theoretically, for up to a century or more. In spacecraft, RHUs are used to keep other components at their operational temperatures, which may be very different to the temperature of other parts of the spacecraft. In the vacuum of space any part of the spacecraft which doesn't receive direct sunlight will cool down so much that electronics or delicate scientific instruments break down. They are simpler and more reliable than other ways of keeping components warm, such as electric heaters. Spacecraft use Most lunar and Martian surface probes use RHUs for heat, including ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saturn
Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about 9 times that of Earth. It has an eighth the average density of Earth, but is over 95 times more massive. Even though Saturn is almost as big as Jupiter, Saturn has less than a third its mass. Saturn orbits the Sun at a distance of , with an orbital period of 29.45 years. Saturn's interior is thought to be composed of a rocky core, surrounded by a deep layer of metallic hydrogen, an intermediate layer of liquid hydrogen and liquid helium, and an outer layer of gas. Saturn has a pale yellow hue, due to ammonia crystals in its upper atmosphere. An electrical current in the metallic hydrogen layer is thought to give rise to Saturn's planetary magnetic field, which is weaker than Earth's, but has a magnetic moment 580 times that of Earth because of Saturn's greater size. Saturn's magnetic field strength is about a twen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermionic Converter
A thermionic converter consists of a hot electrode which thermionically emits electrons over a potential energy barrier to a cooler electrode, producing a useful electric power output. Caesium vapor is used to optimize the electrode work functions and provide an ion supply (by surface ionization or electron impact ionization in a plasma) to neutralize the electron space charge. Definition From a physical electronic viewpoint, thermionic energy conversion is the direct production of electric power from heat by thermionic electron emission. From a thermodynamic viewpoint, it is the use of electron vapor as the working fluid in a power-producing cycle. A thermionic converter consists of a hot emitter electrode from which electrons are vaporized by thermionic emission and a colder collector electrode into which they are condensed after conduction through the inter-electrode plasma. The resulting current, typically several amperes per square centimeter of emitter surface, d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermocouple
A thermocouple, also known as a "thermoelectrical thermometer", is an electrical device consisting of two dissimilar electrical conductors forming an electrical junction. A thermocouple produces a temperature-dependent voltage as a result of the Seebeck effect, and this voltage can be interpreted to measure temperature. Thermocouples are widely used as list of temperature sensors, temperature sensors. Commercial thermocouples are inexpensive, interchangeable, are supplied with standard Electrical connector, connectors, and can measure a wide range of temperatures. In contrast to most other methods of temperature measurement, thermocouples are self-powered and require no external form of excitation. The main limitation with thermocouples is accuracy; system errors of less than one degree Celsius (°C) can be difficult to achieve. Thermocouples are widely used in science and industry. Applications include temperature measurement for kilns, gas turbine exhaust, diesel engines, and o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radioisotope Thermoelectric Generator
A radioisotope thermoelectric generator (RTG, RITEG), or radioisotope power system (RPS), is a type of nuclear battery that uses an array of thermocouples to convert the Decay heat, heat released by the decay of a suitable radioactive material into electricity by the Seebeck effect. This type of Electricity generation, generator has no moving parts and is ideal for deployment in remote and harsh environments for extended periods with no risk of parts wearing out or malfunctioning. RTGs are usually the most desirable power source for unmaintained situations that need a few hundred watts (or less) of power for durations too long for fuel cells, batteries, or generators to provide economically, and in places where solar cells are not practical. RTGs have been used as power sources in satellites, space probes, and uncrewed remote facilities such as a series of lighthouses built by the Soviet Union inside the Arctic Circle. However, the Western Bloc did not use RTGs in this way due to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strontium-90
Strontium-90 () is a radioactive isotope of strontium produced by nuclear fission, with a half-life of 28.79 years. It undergoes β− decay into yttrium-90, with a decay energy of 0.546 MeV. Strontium-90 has applications in medicine and industry and is an isotope of concern in fallout from nuclear weapons, nuclear weapons testing, and nuclear accidents. Radioactivity Naturally occurring strontium is nonradioactive and nontoxic at levels normally found in the environment, but 90Sr is a radiation hazard. 90Sr undergoes β− decay with a half-life of 28.79 years and a decay energy of 0.546 MeV distributed to an electron, an antineutrino, and the yttrium isotope 90Y, which in turn undergoes β− decay with a half-life of 64 hours and a decay energy of 2.28 MeV distributed to an electron, an antineutrino, and 90Zr (zirconium), which is stable. Note that 90Sr/Y is almost a pure beta particle source; the gamma photon emission from the decay of 90Y is so infrequen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lunokhod
Lunokhod ( rus, Луноход, p=lʊnɐˈxot, "Moonwalker") was a series of Soviet robotic lunar rovers designed to land on the Moon between 1969 and 1977. Lunokhod 1 was the first roving remote-controlled robot to land on an extraterrestrial body. The 1969 Lunokhod 1A (Lunokhod 0, Lunokhod No. 201) was destroyed during launch, the 1970 ''Lunokhod 1'' and the 1973 ''Lunokhod 2'' landed on the Moon, and ''Lunokhod 3'' (Lunokhod No. 205, planned for 1977) was never launched. The successful missions were in operation concurrently with the Zond and Luna series of Moon flyby, orbiter and landing missions. The Lunokhods were primarily designed to support the Soviet human Moon missions during the Moon race. Instead, they were used as remote-controlled robots for exploration of the lunar surface and returning pictures, after the Apollo human lunar landings and cancellation of the Soviet human Moon programme. The Lunokhods were transported to the lunar surface by Luna spa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polonium-210
Polonium-210 (210Po, Po-210, historically radium F) is an isotope of polonium. It undergoes alpha decay to stable 206Pb with a half-life of 138.376 days (about months), the longest half-life of all naturally occurring polonium isotopes (210–218Po). First identified in 1898, and also marking the discovery of the element polonium, 210Po is generated in the decay chain of uranium-238 and radium-226. 210Po is a prominent contaminant in the environment, mostly affecting seafood and tobacco. Its extreme toxicity is attributed to intense radioactivity, mostly due to alpha particles, which easily cause radiation damage, including cancer in surrounding tissue. The specific activity of is 166 TBq/g, i.e., . At the same time, 210Po is not readily detected by common radiation detectors, because its gamma rays have a very low energy. Therefore, can be considered as a quasi-pure alpha emitter. History In 1898, Marie and Pierre Curie discovered a strongly radioactive substance ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Americium-241
Americium-241 (Am, Am-241) is an isotope of americium. Like all isotopes of americium, it is radioactive, with a half-life of . Am is the most common isotope of americium as well as the most prevalent isotope of americium in nuclear waste. It is commonly found in ionization type smoke detectors and is a potential fuel for long-lifetime radioisotope thermoelectric generators (RTGs). Its common parent nuclides are β from Pu, EC from Cm, and α from Bk. Am is not fissile, but is fissionable, and the critical mass of a bare sphere is and a sphere diameter of . Americium-241 has a specific activity of . It is commonly found in the form of americium-241 dioxide (AmO). This isotope also has one meta state, Am, with an excitation energy of and a half-life of . The presence of Am in plutonium is determined by the original concentration of plutonium-241 and the sample age. Because of the low penetration of alpha radiation, americium-241 only poses a health risk when ingested ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rosalind Franklin Rover
''Rosalind Franklin'', previously known as the ExoMars rover, is a planned robotic Mars rover, part of the international ExoMars programme led by the European Space Agency (ESA). The rover is named after Rosalind Franklin, a British chemist and DNA research pioneer. The mission was scheduled to launch in July 2020 in cooperation with the Russian Roscosmos, and was later postponed to 2022. The Russian invasion of Ukraine has caused a delay of the programme, as the member states of the ESA voted to suspend the joint mission with Russia. in July 2022, ESA terminated its cooperation on the project with Russia. , the launch of the rover was not expected to occur before 2028 due to the need for a new non-Russian landing platform. In 2024, the mission received additional funding to restart and complete the mission. The award went to Thales Alenia Space and launch was scheduled for 2028. ESA also signed an agreement with NASA to procure a US launch vehicle for the mission. Naming I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ExoMars
ExoMars (Exobiology on Mars) is an astrobiology programme of the European Space Agency (ESA). The goals of ExoMars are to search for signs of past life on Mars, investigate how the Martian water and geochemical environment varies, investigate atmospheric trace gases and their sources and, by doing so, demonstrate the technologies for a future Mars sample-return mission. The first part of the programme is a mission launched in 2016 that placed the Trace Gas Orbiter into Mars orbit and released the Schiaparelli EDM, ''Schiaparelli'' EDM lander. The orbiter is operational but the lander crashed on the planet's surface. The second part of the programme was planned to launch in July 2020, when the ''Kazachok'' lander would have delivered the Rosalind Franklin (rover), ''Rosalind Franklin'' rover on the surface, supporting a Exploration of Mars, science mission that was expected to last into 2022 or beyond. On 12 March 2020, it was announced that the second mission was being delayed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chandrayaan-3
Chandrayaan-3 ( ) is the third mission in the Chandrayaan programme, a series of Exploration of the Moon, lunar-exploration missions developed by the ISRO, Indian Space Research Organisation (ISRO). The mission consists of a Chandrayaan-2#Vikram lander, ''Vikram'' lunar lander and a Pragyan (Chandrayaan-3), ''Pragyan'' lunar rover, as replacements for the equivalents on Chandrayaan-2, which had crashed on landing in 2019. The spacecraft was launched on July 14, 2023, at 14:35 India standard time, IST from the Satish Dhawan Space Centre (SDSC) in Sriharikota, India. It entered lunar orbit on 5 August, and touched down near the lunar south pole, at 69°S, on 23 August 2023 at 18:04 IST (12:33 Coordinated Universal Time, UTC). With this landing, ISRO became the fourth national space agency to successfully Moon landing, land on the Moon, after the Soviet space program, NASA and China National Space Administration, CNSA. The lander was not built to withstand the cold temperatures of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
