| At line 13 added 67 lines |
| !! 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/] |
|
| !!! 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. |
|
| 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 |
|
| 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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