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By
Wikipedia,
High altitude balloons are unmanned balloons, usually filled with helium or hydrogen that are released into the stratosphere, generally reaching between 60,000 and 120,000 feet (18,000 - 36,500m). The most common type of high altitude balloons are weather balloons, other purposes may involve scientific groups and universities for conducting experiments in the upper atmosphere, and modern balloons generally contain electronic equipment such as radio transmitters, cameras, and sometimes satellite navigation systems, such as GPS receivers. These balloons are launched into what is termed "near space" - the area of Earth's atmosphere where there is very little air, but which is not high enough to be in the realm of satellites. A seasonal vortex in Antarctica allows balloons to be recovered very close to their launch site, making it a popular location for balloon-based research. Due to the low cost of GPS and communications equipment, high altitude ballooning is an emerging hobby. HistoryThe First Hydrogen Filled BalloonIn France during 1783, the first public experiment with hydrogen filled balloons involved J. A. C. Charles, a French professor of Physics and the Robert Brothers, renowned constructors of physics instruments. Charles provided large quantities of hydrogen, which had only been produced in small quantities previously, by mixing 540 kg of iron and 270 kg of sulphurus acid. The balloon called Charlière took 5 days to fill and was launched from Champ de Mars in Paris where 300,000 people gathered to watch the spectacle. The balloon was launched and rose through the clouds. The expansion of the gas caused the balloon to tear and descended 45 minutes later 20km away from Paris. Potential use of laser propulsion to increase maximal altitudeLaser propulsion (Lightcraft) ( A ground based laser or maser) could be used to heat the gas inside the a HAB from the ground to help achieve higher altitudes. Heating the gas will naturally cause it to expand - the pressure can then be released through nossels in the bottom of the craft providing additional lift. Heated internal gas would allow for lower internal pressures to be achieved while maintaining the overall volume of the gas and it's craft (a semi-rigid structure might help). (PV=nRT) This allows for the first stage of the craft to achieve higher altitudes - maintaining "lighter-than-air" equilibria at lower surrounding thin atmosphere densities.[ref-A] Furthermore, a similar system could be used to power High Altitude Platforms from the ground. The platform could be used to store fuel for a second stage which could resemble more conventional(rocket)(or hybrid) design. More importantly, the platform could be used to HARVEST oxygen.[ref-A] It is important to recognize that oxygen represents a large proportion of the mass of a conventional rocket. A large part of the cost of lifting a conventional rocket involves lifting this oxygen. A high altitude platform powered from the ground by laser or maser could be used to HARVEST oxygen from the surrounding low density air over time, condense and store it for a second stage to low orbit. (Oxygen is present at high altitudes - even if it is a very low density.) See also
External links
[ref-A] Holt, G. 2009. "Approaches to improving high altitude platforms to assist first stage to orbit". Journal of premature ideas and hypothetical approaches in science and engineering. :) Vol 1. Issue 1. ghol7955@gmp.usyd.edu.au
Text from Wikipedia is available under the Creative Commons Attribution/Share-Alike License; additional terms may apply.
Published in July 2009. Click here to read more articles related to aviation and space!
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