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| Quite a few people have had some nice success sending balloons into near space. |
| Quite a few people have had some nice success sending balloons into near space (i.e. in the stratosphere which doesn't quite so cool). Balloons do get to half of the official limit of outer space though: [Karman line|http://en.wikipedia.org/wiki/K%C3%A1rm%C3%A1n_line] |
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| !!! Cool and successful projects |
| !! PARIS |
| The Paper aircraft released into space (near space actually): [PARIS|http://en.wikipedia.org/wiki/Paper_Aircraft_Released_Into_Space] |
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| !! KickSat |
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| Zach designed micro satellites that can be put inside a cubesat standard module and is trying to get these launched. See [Kicksat|http://kicksat.wordpress.com/]. The satellites themselves are really just PCBs with some solar cells and wires as antenna at the moment but they could surely be extended if they actually work well. |
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| !!! Theory and documentation |
| !! Solar sails |
| [Solar sails|http://en.wikipedia.org/wiki/Solar_sail] are a cool idea but they don't work until you are at least 800km from Earth. |
| !! Atmospheric calculators |
| * [http://www.digitaldutch.com/atmoscalc/] |
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| !!! Brainstorming |
| !! Solar sail for use in stratosphere |
| The idea is to use the that that there is still some atmosphere left. |
| The sail would need to: |
| # absorb light on one side so that it becomes hot |
| # act as an insulator so that the other side is cold |
| # this would create a difference of temperature between the two sides and change the temperature of the surrounding atmosphere. |
| # the temperature difference could result in a pressure difference which would push the sail |
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| Apparently at 50km (limits of ballon flight), the pressure is still 75 Pascal or N/m2 and temperature 270k. This means a 50k temperature difference for the air could create 15 pascal of pressure difference. |
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| A naive interpretation would be that every square meter could lift about 1 kg of load. |
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| The sail could also be the balloon itself that lifted the payload. Tthere are actually [solar balloons|http://www.solar-balloons.com/] that can lift themselves to 50000 feet. |
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| In our case the idea would be to use helium inside to lift first and then heat the air below the balloon and cool the air above to create a push upwards. |
|
| !! Communication with device |
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| Wifi is cheap, ubiquitous and unregulated. Wikipedia [documents|http://en.wikipedia.org/wiki/Long-range_Wi-Fi] some pretty long range links (over 200km) that require directional antennae. |
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| Pointing one antenna is reasonably easy but pointing the antenna on the balloon seems much trickier... |
|
| !! Near Space Telescope |
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| If we bring some decent telescope up with a balloon and point it up we get a small space telescope. |
| This reduces: |
| * atmospheric losses. The main benefit is for blue and ultra-violet (20% and more). So for the other colors, the benefit is not really awesome for amateurs... |
| * lens effects caused by atmospheric turbulences |
| * no blue sky even during the day: you could observe during the DAY. |
| The downsides are: |
| * more cosmic rays? |
| * stability is an issue and may reduce the ability to benefit from the absence of atmospheric turbulences (awesome seeing). |
| Given the risk of not recovering the telescope, we need a cheap telescope maybe [DIY|Do it Yourself telescopes] |
|
| !! Balloons and blimps |
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| A balloon can fly very high (50km) and is pretty safe (no explosives involved if it's helium). |
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| The air weighs about 1.3kg per cubic meter at sea level, so a balloon of a couple cubic meters should be enough to lift a good payload. |
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| Since helium is expensive, it might be tempting to use hydrogen instead. |
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| If a cubic meter at ground level there would be about 50 moles of dihydrogen, which would release about 50*286kJ = 15MJ if inflamed by air and require about the same energy to produce from water. |
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|
| ! Reading |
|
| * Nicolas Regnault's PHD Thesis (in French): http://tel.archives-ouvertes.fr/tel-00006558/en/. This contains interesting background info that's quite readable |
| ** discussions about detection of supernovae, how they are visible with regular light |
| ** discussions on merging information from different telescopes |
| ** discussions about the effect of atmosphere (seeing, absorption). |
| * [FAA rules for balloons and rockets|http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&rgn=div5&view=text&node=14:2.0.1.3.15&idno=14] |
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