They may not need real insulation with the thin martian atmosphere.
Since we have so many people interested in the subject has anyone actually tried to live on potatoes for a year?
if we use just artificial light then considering the efficiency of the solar cell and transmission we need 4 times the area of the greenhouse to have the same light as what is outside the greenhouse
The same MIT study using NASA growth model that used more standard crops, calculated that MarsOne would need to use closer to 240 m2 of growth space per person. Much as I don't like repeating myself ad nauseum, ESA MELiSSA's 9 crops are in my opinion the best choice for a crop model.
Quote from: guckyfan on 04/16/2018 07:46 amThey may not need real insulation with the thin martian atmosphere.As I mentioned above (and has been mentioned many times before), Mars' atmosphere is thick enough for convection cooling to dominate over radiation emission.
Additionally, bespoke systems for greenhouses on Mars are worthless for anything else. Uniquely complex systems that serve no other role, can be diverted to no other purpose. OTOH, artificially lit hydroponic grow modules merely means more of the power system you already have (power which can be diverted in emergencies), and merely more pressure vessels of a type you already use for every other form of habitation.If you want to scale anything on Mars, you want to avoid unique systems and focus on commonality and modularity. For any task, it will be better to have ten copies of one system than five unique systems of the same scale that do the same job slightly more efficiently.
Quote from: Paul451 on 04/17/2018 02:14 amQuote from: guckyfan on 04/16/2018 07:46 amThey may not need real insulation with the thin martian atmosphere.As I mentioned above (and has been mentioned many times before), Mars' atmosphere is thick enough for convection cooling to dominate over radiation emission.What are you trying to say? That greenhouses are not efficient in retaining heat? Even here on Earth with the dense atmosphere and wind even single pane glass houses are very efficient in retaining heat. It can only be better on Mars.Quote from: Paul451 on 04/17/2018 02:14 amAdditionally, bespoke systems for greenhouses on Mars are worthless for anything else. Uniquely complex systems that serve no other role, can be diverted to no other purpose. OTOH, artificially lit hydroponic grow modules merely means more of the power system you already have (power which can be diverted in emergencies), and merely more pressure vessels of a type you already use for every other form of habitation.If you want to scale anything on Mars, you want to avoid unique systems and focus on commonality and modularity. For any task, it will be better to have ten copies of one system than five unique systems of the same scale that do the same job slightly more efficiently.Again, what are you trying to say? It is not efficient to make a dedicated design for greenhouses for growing plants? Should they use the same design as for habitats for commonality?
Greenhouses in cold climates have to be heated in the winter. This is a legitimate challenge for Martian night.
Quote from: guckyfan on 04/17/2018 05:15 amQuote from: Paul451 on 04/17/2018 02:14 amQuote from: guckyfan on 04/16/2018 07:46 amThey may not need real insulation with the thin martian atmosphere.As I mentioned above (and has been mentioned many times before), Mars' atmosphere is thick enough for convection cooling to dominate over radiation emission.What are you trying to say? That greenhouses are not efficient in retaining heat? Even here on Earth with the dense atmosphere and wind even single pane glass houses are very efficient in retaining heat. It can only be better on Mars.Greenhouses in cold climates have to be heated in the winter. This is a legitimate challenge for Martian night.
Quote from: Paul451 on 04/17/2018 02:14 amQuote from: guckyfan on 04/16/2018 07:46 amThey may not need real insulation with the thin martian atmosphere.As I mentioned above (and has been mentioned many times before), Mars' atmosphere is thick enough for convection cooling to dominate over radiation emission.What are you trying to say? That greenhouses are not efficient in retaining heat? Even here on Earth with the dense atmosphere and wind even single pane glass houses are very efficient in retaining heat. It can only be better on Mars.
Quote from: Paul451 on 04/17/2018 02:14 amAdditionally, bespoke systems for greenhouses on Mars are worthless for anything else. Uniquely complex systems that serve no other role, can be diverted to no other purpose. OTOH, artificially lit hydroponic grow modules merely means more of the power system you already have (power which can be diverted in emergencies), and merely more pressure vessels of a type you already use for every other form of habitation.Again, what are you trying to say? It is not efficient to make a dedicated design for greenhouses for growing plants? Should they use the same design as for habitats for commonality?
Additionally, bespoke systems for greenhouses on Mars are worthless for anything else. Uniquely complex systems that serve no other role, can be diverted to no other purpose. OTOH, artificially lit hydroponic grow modules merely means more of the power system you already have (power which can be diverted in emergencies), and merely more pressure vessels of a type you already use for every other form of habitation.
Plants cant be titled towards the sun.
Plants dont absorb the entire natural light spectrum. Right off the bat that is a factor of two efficiency for LED.
so most of the time you are shining light on dirt.
But I assume you are referring to having sun-tracking systems on the solar panels.
Quote from: johnfwhitesell on 05/31/2018 12:22 pmso most of the time you are shining light on dirt.Whether you are using natural-light greenhouses or artificially lit grow-chambers doesn't alter you choice of farming methods. Greenhouses happily grow sprouts in smaller specialised areas and then space them out as they grow. Likewise, most commercial hydroponics is done in natural-light greenhouses.
Plants do not have a flat surface pointed towards the sun.
Quote from: Paul451 on 06/01/2018 01:04 amQuote from: johnfwhitesell on 05/31/2018 12:22 pmso most of the time you are shining light on dirt.Whether you are using natural-light greenhouses or artificially lit grow-chambers doesn't alter you choice of farming methods. Greenhouses happily grow sprouts in smaller specialised areas and then space them out as they grow. Likewise, most commercial hydroponics is done in natural-light greenhouses.Yes most greenhouses aren't LED. However we were talking about LED greenhouses. And that does change the farming methods. Did you see the link I provided?
As I said, hydroponics can be done in a natural light greenhouse as well, the advantages of hydroponics has nothing to do with the difference between using natural vs artificial lighting. (And in practice, almost all commercial hydroponics is done in naturally-lit greenhouses. Likewise, commercial greenhouses routinely move plants to optimise area-coverage.)The method of farming doesn't have any influence over whether you use natural sunlight, or pure LED, or LED-boosting of natural sunlight. Arguing for hydroponics doesn't argue for artificial lighting.
Guys, if this is absurd to you:"I typically go for walks outside without a spacesuit so I guess all the people on Mars will do the same."Then this should be absurd to you:"All the greenhouses on Earth use natural light so natural light is the thing they should use on Mars."
As an alternative to LEDs for use in underground or badly lit areas , we can also consider the use of steerable mirrors.These would be easier to produce on Mars than LEDs + solar panels.