Scale heightIn atmospheric, earth, and planetary sciences, a scale height, usually denoted by the capital letter H, is a distance (vertical or radial) over which a physical quantity decreases by a factor of e (the base of natural logarithms, approximately 2.718). For planetary atmospheres, scale height is the increase in altitude for which the atmospheric pressure decreases by a factor of e. The scale height remains constant for a particular temperature.
Extraterrestrial skyIn astronomy, an extraterrestrial sky is a view of outer space from the surface of an astronomical body other than Earth. The only extraterrestrial sky that has been directly observed and photographed by astronauts is that of the Moon. The skies of Venus, Mars and Titan have been observed by space probes designed to land on the surface and transmit images back to Earth. Characteristics of extraterrestrial sky appear to vary substantially due to a number of factors.
Ingenuity (helicopter)Ingenuity, informally called Ginny, is a small autonomous helicopter presently operating on the planet Mars. It is part of NASA's Mars 2020 mission. The helicopter arrived on the Martian surface attached to the underside of the Perseverance rover, which landed on February 18, 2021. The helicopter was deployed to the surface on April 3, 2021. Both the rover and the helicopter began their missions on Mars at the Octavia E. Butler Landing site near the western rim of the wide Jezero crater.
Multi-mission radioisotope thermoelectric generatorThe multi-mission radioisotope thermoelectric generator (MMRTG) is a type of radioisotope thermoelectric generator (RTG) developed for NASA space missions such as the Mars Science Laboratory (MSL), under the jurisdiction of the United States Department of Energy's Office of Space and Defense Power Systems within the Office of Nuclear Energy. The MMRTG was developed by an industry team of Aerojet Rocketdyne and Teledyne Energy Systems.
