A report discusses a class of balloon-borne robotic instrumentation systems that have been proposed for use in exploring Venus, Jupiter, Saturn, Uranus, and Neptune. The balloons would be of the Montgolfier type; that is, buoyancy would be achieved through heating of atmospheric gases contained in the balloons at ambient pressures. However, unlike the familiar fire-heated hot-air balloons invented by the Montgolfier brothers, the proposed balloons would be heated primarily by the Sun during the day and by infrared radiation from relatively warm planetary surfaces at night. The proposed balloons would be modified versions of solar/infrared-heated Montgolfier balloons that were flown in the upper stratosphere of the Earth by the French space agency CNES during the 1980s. The lower parts of those balloons were made of infrared-transparent polymeric materials to admit infrared radiation from below, the upper inside surfaces were blackened to maximize absorption of the admitted infrared radiation, and the upper outside surfaces were aluminized to minimize radiation of heat to outer space. During the day, the balloons would rise high due to solar heating. At night, the balloons would sink lower, with the descent slowed by heating due to compression of the contained gasses, as well as by heating from lower planetary radiation.
This work was done by Jack Jones, Matthew Heun, and Kerry Nock of Caltech for NASA's Jet Propulsion Laboratory. NPO-20264
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Solar/infrared aerobots for exploring several planets
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Overview
The document discusses the development of Solar Infrared Montgolfiere Aerobots (SIRMAS), a new class of robotic balloons designed for planetary exploration, particularly focusing on Venus. The research, initiated by G.M. Moskalanko in the late 1970s and early 1980s, explores various controllable balloon systems that can navigate the harsh atmospheric conditions of Venus.
SIRMAS utilize a combination of solar heating during the day and lower planetary infrared heating at night, making them viable for operation below the cloud tops and even at the surface of Venus. The document highlights that the solar intensity at Venus remains strong, with about 4.6% of the total incident solar intensity reaching the surface, which is significantly higher than that on the outer gas planets. This allows for effective energy capture and utilization by the balloons.
The design concept includes an ammonia/water balloon system that would evaporate both substances at Venus' high temperatures, allowing the balloon to ascend. At higher altitudes, water would condense, causing the balloon to deflate and descend. This cycle enables the balloon to stabilize at around 42 km altitude, where water remains buoyant in the carbon dioxide atmosphere. The document also discusses the potential for short-duration landings on Venus, facilitated by existing hot air balloon venting technology, although adaptations for the extreme Venusian environment would be necessary.
The research indicates that SIRMAS could provide lightweight, controllable solar/infrared aerobots capable of landing on the daylight side of Venus, where they could conduct scientific observations and gather data. The document emphasizes the importance of these technologies for advancing our understanding of Venus and other planetary bodies, as they offer a unique method for atmospheric exploration.
In summary, the document outlines the innovative approach of using solar and infrared heating in Montgolfiere balloons for planetary exploration, particularly on Venus, where traditional exploration methods face significant challenges. The potential for these robotic systems to operate effectively in extreme environments marks a significant advancement in planetary science and exploration technology.
