|
|
Thread Tools | Display Modes |
#41
|
|||
|
|||
Technologies for Moon mission useable for missions further out
Steve Willner wrote:
Michael Turner writes: Since you're going to need electricity for many other purposes anyway, I like the idea of using LEDs in both lunar and martian agriculture. Notice that the electricity you have to supply to the LEDs, depending on assumptions, is more than you would have to supply to heaters. Take a look at Fig 9 in the Hublitz et al. paper. You need something other than solar panels to supply electricity for heaters at night. Turning off lights at night on the other hand is OK. -- Mvh./Regards, Niels Jørgen Kruse, Vanløse, Denmark |
#42
|
|||
|
|||
Technologies for Moon mission useable for missions further out
On Jul 1, 10:36 am, (Steve Willner) wrote:
.... They seem to be assuming a perfect emitter and a factor of 2.25 for the ratio of radiating surface to greenhouse area. These strike me as very conservative assumptions. Perhaps they are trying to compensate somehow for their apparent assumption of agriculture only in mid-summer? Since you're going to need electricity for many other purposes anyway, I like the idea of using LEDs in both lunar and martian agriculture. Notice that the electricity you have to supply to the LEDs, depending on assumptions, is more than you would have to supply to heaters. Take a look at Fig 9 in the Hublitz et al. paper. Which shows not electricity specifically, but heat gain. And not from LED illumination, but from incandescent lamps. Apples and oranges comparison. What I thought we were now talking about is a system where most heat is supplied separately from illumination. Fig. 9 suggests to me that you might as well separate the two functions. It also suggests to me that, as long the simplest and most manageable design is an opaque insulating shell over your plants, you might as well simplify further and locate agriculture in a lava tube, not on the surface. Solar storm particles would drill right through that insulating layer and (probably) kill your plants, unless the shell is covered with very thick pile of Martian regolith. Well, nature might have prefabricated such shielding: cave ceilings. Why waste it? -michael turner |
#43
|
|||
|
|||
Technologies for Moon mission useable for missions further out
On Jun 27, 7:12 am, Michael Turner
wrote: Both are problematic for water supply, but Mars has ice caps, at least. The Moon? Over the long run, the cheapest place from which to fetch water for a lunar base might actually end up being Phobos, ... That was my opinion until a few months ago. Recently Chandrayaan 1's mini-SAR radar seems to indicate thick ice sheets at the lunar poles. http://blogs.airspacemag.com/moon/20...e-of-the-moon/ http://www.nasa.gov/mission_pages/Mi..._deposits.html And LRO has recently given additional confirmation. This article was posted July 1, 2010: http://www.onorbit.com/node/2335 600 million tons at each pole. Sheets 2 or more meters thick. |
#44
|
|||
|
|||
Technologies for Moon mission useable for missions further out
On Jun 28, 7:31 pm, Alain Fournier wrote:
Phobos is still quite deep in the Martian gravity well. Why not go get it in the main asteroid belt? Surprisingly, being in Mars' gravity well makes Phobos and Deimos more accessible, not less. From LEO, trans Mars insertion is about 3.6 km/sec. On arrival at a 300 km altitude Martian periapsis, a 1.4 km/sec burn suffices to change the hyperbola into an ellipse with a 5981 km altitude apoapsis. When this ellipse reaches apoapsis, a .6 km/sec burn will circularize the orbit. So from LEO to Phobos takes about 5.6 km/sec delta V. LEO to a main belt asteroid takes in the neighborhood of 8 to 10 km/ sec delta V. Could take a lot more if the orbit has a good inclination (as a lot of asteroid orbits do). |
#45
|
|||
|
|||
Technologies for Moon mission useable for missions further out
On Jul 2, 12:51 pm, Alain Fournier wrote:
Michael Turner wrote: At least with light-guides (and perhaps PV cells on the surface powering LEDs underground) LEDs aren't particularly useful in this case. The reason why LEDs use much less electricity than old fashioned light bulbs for the same amount of light is that LEDs emit very little heat. So, the inefficiency of less efficient lights is very efficient in this case, they heat the greenhouse. LEDs probably are still the best choice because you can choose your wave lengths more precicely and because they last for such a long time, which is useful because an artifically lighted greenhouse needs so much lights that changing the light bulbs can be a waste of time. But there advantage is minimal. Alain Fournier I'm assuming it's better to manage heat and light as individually controllable resources. Using incandescents combines the two even in cases where you don't want or need both. -michael turner |
#46
|
|||
|
|||
Technologies for Moon mission useable for missions further out
Alain Fournier wrote:
[[about MLI]] Right, I wouldn't think that kind of insulation would be helpful on Mars. On the Moon maybe because of longer nights and because MLI is more efficient in vacuum than in the Martian atmosphere. MLI doesn't work on or near the Martian surface -- the atmospheric pressure is too high. -- -- "Jonathan Thornburg [remove -animal to reply]" Dept of Astronomy, Indiana University, Bloomington, Indiana, USA "Washing one's hands of the conflict between the powerful and the powerless means to side with the powerful, not to be neutral." -- quote by Freire / poster by Oxfam |
#47
|
|||
|
|||
Technologies for Moon mission useable for missions further out
greenaum wrote:
On Wed, 9 Jun 2010 20:35:21 EDT, Robert Heller sprachen: Air recycling: probably some sort of CO2 scrubber and/or some sort of CO2 = C, O2 conversion: photosynthesis? Water recycling: solar still? Food: farming / gardening (Air/Water/Waste recycling on the side...). It's worth pointing out that the only serious experiment into biospheres, Biosphere 2 (you know, the giant airtight greenhouse they built in the desert), failed horribly. Tho it did provide lots of interesting information into why it failed. But their aim was to support around 8 people in a closed system *on Earth*! And they didn't manage that. The site's still there, but before any sort of long-term colony off-world, we need to revisit that project, and get it right first. It's infinitely cheaper and safer to do it here before we start sending colonists to the Moon. Biosphere 2 was putting too much emphasis on being closed. You don't want a martian habitat to be completely closed. You want to bring in more stuff from time to time. There is nothing wrong with pumping in some gas from outside and going to get the ores you need. In fact you have to do that if you want to expand. And if you are going to pump in some gas anyway, being completely air-tight is not important. You want to lose as little air as practical but don't go nuts about being air-tight. I do agree that more experience in a somewhat closed system living quarters would be nice, but you don't have to build such a big thing as Biosphere 2 just to avoid all exchanges with the outside. Exchanges with the outside aren't all that bad. Alain Fournier |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
NASA seeks ideas for mission, capailities and technologies | Jacques van Oene | News | 0 | November 11th 04 03:59 PM |
multiple launch moon mission vs. Single Launch moon missions | Fred K. | Policy | 2 | March 20th 04 02:29 PM |
New moon and mars missions... | Robert Kent | Space Shuttle | 6 | January 18th 04 08:06 PM |
All Moon Missions Were Unmanned | OM | History | 5 | August 12th 03 09:07 PM |
All Moon Missions Were Unmanned | Bill Sheppard | Misc | 1 | July 23rd 03 04:51 PM |