So it turns out the backpack concept proposed in "The Ultimate Traveler's Backpack" is a real product, so that is really cool. Gizmodo had a run down on a backpack with many of the features I outlined which you can read here.
Friday, August 26, 2016
Wednesday, August 24, 2016
Make the Dark Side of the Moon Cool (Why We Should Build a Space Elevator on the Moon version 0)
This post will be part of a series, intended to serve as a reference point for how you might potentially write a white paper, in this case on promoting space elevators on the moon, each post in the series will build on the previous document, until the language meets the necessary level of professionalism. The author asks that readers provide feedback and suggestions for this document. Who knows maybe someone might actually use the idea.
Every year NASA gets a hyperbole inducing volume of suggestions* for how they should invest their research dollars, ranging from congressional line items, mandating what should be researched over the coming years, letters from school age children making their own suggestions on potential science experiments (like my little brother did when he was in the fifth grade), more seriously are research proposals coming from well reputed scientists working at various research institutes, and once in a while chicken scratch on the back of envelopes and napkins outlining how we really can build the starship Enterprise. This article hopes to be a bit better than a back of the envelope mission proposal.
A major pain point of any mission sent into space from the planet Earth is minimizing how much mass is required for the mission. Even relatively massive pieces like the lunar landers used in the Apollo missions where optimized down to the last gram. As humanity's aspirations to the stars begin to become actual mission plans, those responsible for planning the mission will benefit from having as diverse a portfolio of design and system solutions as possible. When planning a mission, sometimes engineers can plan on further improvements in technology to save mass, a key example would be the computers that control a space craft, during the Apollo missions, astronauts would brag about a machine that could fit in a single room, that same level of processing power now fits in your cellphone, not only that, the smaller computer requires far less electrical power, continuing a virtuous cycle of design. Solar panels have also become far more efficient, with panels on satellites converting roughly 40% of the sunlight they are exposed to into useable electricity, compared to 14% in 1961. Future missions might also benefit from the use of micro-gravity manufacturing techniques, instead of relying on components that must be strong enough to survive the harsh acceleration of gravity, engineers at firms like Made In Space, are producing 3-D printers capable of creating a range of potential space craft components. These developments are exciting (at least for space and engineering nerds), but they are still relatively limited, because all of these technologies and solutions, need to be launched from the surface of the Earth, what if we had an alternative? Enter the world of space mining.
The boom of space mining firms like Planetary Resources and Deep Space Industries have sparked imaginations around the world, is humanity finally getting ready to live in the science fiction world's we used to dream about? Fingers are most definitely crossed. While mining asteroids for useful materials is exciting and over the coming generations our descendants will most likely be incredibly dependent on industries based around converting asteroids into useful materials there are resources much closer to Earth that should be considered. The dark side of the moon is a near perfect near to mid-term location for humanity to expand its reach. The lunar surface has incredibly large volumes of readily accessible oxygen, iron, and aluminum, while there are other resources to gather from the lunar surface, this article is intended to make a case using the most readily available and understood resources. With access to relatively cheap sources of oxygen for rocket engines, iron for radiation shielding, and aluminum for structural elements, engineers would be empowered to change how they design deep space missions. Instead of having to launch a probe with all of its fuel, future missions could fill up on oxygen before continuing on to other celestial bodies. Future space stations would no longer need to launch with complex walls intended to minimize micro-meteorite damage while minimizing mass, instead, tiles of iron could be added to the exterior of the station on an as needed basis.
Outlining cool uses for the basic chemical elements of lunar regolith is all well and good, but how will future missions gain access to the surface of the Moon to use these resources, two words "space elevator". A space elevator is roughly speaking, a long ribbon of material that has been placed in orbit around a planet or moon, where one end of the ribbon is in contact with the surface, on the other end of the ribbon, there is a counter weight. The overall length of ribbon is dependent on two characteristics of the celestial body they are built around, the more massive the planet or the slower the day, the longer the tether needs to be. The pull of gravity also impacts how strong the tether needs to be, on planet Earth you need tether's made out of materials that can, currently, only be made in laboratories in small quantities. For a tether on the moon the elevator can be made from materials currently available, for example kevlar. With an operational space elevator on the surface of the moon, future missions to and from the moon would only require sufficient fuel to dock with the space elevator, as opposed to requiring sufficient fuel to safely land on the surface and then fight against the lunar gravity well on the return trip. Getting to the point where materials are routinely going to and from the surface of the moon will take many years, but might have a timeline as follows.
Phase 0: NASA and partner organizations request contract bids for companies that will build the first Lunar Elevator
Phase 1: The first space elevator satellite is deployed on the dark-side of the moon (Pink Floyd album sales experience a light resurgence). The system is only capable of moving payloads of a few dozen kilograms per container (potentially more, but we are being conservative in estimations) The small mass flow rate is not considered useful for industrial applications, but allows scientists of partner nations to do far more analysis of the chemistry of lunar regolith
Phase 2: Improved versions of the initial space elevator probe are now deployed in a constellation around the initial space elevator satellite. The larger number of probes allow the space elevator consortium to start shipping semi useful quantities of liquid oxygen and other resources. One client for the liquid oxygen are space mining firms, looking to minimize their launch costs while pursuing asteroids further afield.
Phase 3: Using the Phase 2 constellation, the Lunar Mining Consortium beings to manufacture their next generation space elevator, this elevator is intended to allow the transportation of thousands of kilograms at a time. At this point there are multiple small semi-autonomous research stations and mining sites on the dark side of the moon.
Phase 4: The Lunar Mining Consortium continues to add to the initial space elevator system. There is a habitat at stationary orbit, serving as a depot and manufacturing facility, where space craft can refuel, receive modifications and exchange crews and/or cargo. The number of facilities on the lunar surface continue to grow. A small number of mirrors have been added to reflect sunlight towards various research stations to ensure they receive enough power during the Lunar night
Phase 5: The elevator has multiple termination points across the lunar surface, including the north and south poles. The mirrors now ensure that lunar facilities now only require battery power for <10% of the Lunar night. Lunar manufacturing capacity has reached the point that more than 20% of the material put into space in a given year came from the Moon. Only organics and more complicated electronics are likely to still launch from Earth in the coming decades. As a result of the shear volume of materials arriving and departing the Lunar Elevator Station, engineers have added even larger engines and rail guns to preserve the elevator's orbit.
Phate 6: Using lessons from the Lunar Mining Consortium, humanity forms the Mars Elevator Group, and begins to outline a Martian space elevator, opening up Mars for more ready colonization.
The motivations for developing space mining are quite reasonable, the more materials that can be harvested outside of the Earth's gravity well, the greater flexibility our civilization will have. That being said there needs to be a dollars and cents argument made to those who hold the strings. The easiest is for rocket fuel. for traditional rockets that use hydrogen and oxygen, the oxygen makes up 8/9ths of the mass of the fuel needed (this doesn't include the tanks holding the hydrogen and oxygen). Now imagine you have a reasonably affordable source of liquid oxygen on the moon. Now you need way less mass devoted at launch to your liquid oxygen supply. For crewed missions to Mars that will, potentially, be a massive saving. Now to developing the space elevator itself, in theory engineers could make a massive rail gun on the surface of the moon, and use that to launch materials into space, true, but the applications are reduced, building a space elevator on the Moon allows scientists to have a real test bed for space elevator technologies, these technologies could inform how we build a space elevator on Mars and maybe one day the Earth.
The rational behind suggesting the formation of the Lunar Mining Consortium is to promote international collaboration, projects like the ISS have done wonders for promoting cooperation here on Earth, a massive engineering project where dozens of governments can share in innovations and natural resources will hopefully promote a more unified Earth.
Well thanks for reading version 0, feedback and notes are appreciated.
*honestly the author isn't sure how many ideas NASA gets, but assumes it is a lot.
Every year NASA gets a hyperbole inducing volume of suggestions* for how they should invest their research dollars, ranging from congressional line items, mandating what should be researched over the coming years, letters from school age children making their own suggestions on potential science experiments (like my little brother did when he was in the fifth grade), more seriously are research proposals coming from well reputed scientists working at various research institutes, and once in a while chicken scratch on the back of envelopes and napkins outlining how we really can build the starship Enterprise. This article hopes to be a bit better than a back of the envelope mission proposal.
A major pain point of any mission sent into space from the planet Earth is minimizing how much mass is required for the mission. Even relatively massive pieces like the lunar landers used in the Apollo missions where optimized down to the last gram. As humanity's aspirations to the stars begin to become actual mission plans, those responsible for planning the mission will benefit from having as diverse a portfolio of design and system solutions as possible. When planning a mission, sometimes engineers can plan on further improvements in technology to save mass, a key example would be the computers that control a space craft, during the Apollo missions, astronauts would brag about a machine that could fit in a single room, that same level of processing power now fits in your cellphone, not only that, the smaller computer requires far less electrical power, continuing a virtuous cycle of design. Solar panels have also become far more efficient, with panels on satellites converting roughly 40% of the sunlight they are exposed to into useable electricity, compared to 14% in 1961. Future missions might also benefit from the use of micro-gravity manufacturing techniques, instead of relying on components that must be strong enough to survive the harsh acceleration of gravity, engineers at firms like Made In Space, are producing 3-D printers capable of creating a range of potential space craft components. These developments are exciting (at least for space and engineering nerds), but they are still relatively limited, because all of these technologies and solutions, need to be launched from the surface of the Earth, what if we had an alternative? Enter the world of space mining.
The boom of space mining firms like Planetary Resources and Deep Space Industries have sparked imaginations around the world, is humanity finally getting ready to live in the science fiction world's we used to dream about? Fingers are most definitely crossed. While mining asteroids for useful materials is exciting and over the coming generations our descendants will most likely be incredibly dependent on industries based around converting asteroids into useful materials there are resources much closer to Earth that should be considered. The dark side of the moon is a near perfect near to mid-term location for humanity to expand its reach. The lunar surface has incredibly large volumes of readily accessible oxygen, iron, and aluminum, while there are other resources to gather from the lunar surface, this article is intended to make a case using the most readily available and understood resources. With access to relatively cheap sources of oxygen for rocket engines, iron for radiation shielding, and aluminum for structural elements, engineers would be empowered to change how they design deep space missions. Instead of having to launch a probe with all of its fuel, future missions could fill up on oxygen before continuing on to other celestial bodies. Future space stations would no longer need to launch with complex walls intended to minimize micro-meteorite damage while minimizing mass, instead, tiles of iron could be added to the exterior of the station on an as needed basis.
Outlining cool uses for the basic chemical elements of lunar regolith is all well and good, but how will future missions gain access to the surface of the Moon to use these resources, two words "space elevator". A space elevator is roughly speaking, a long ribbon of material that has been placed in orbit around a planet or moon, where one end of the ribbon is in contact with the surface, on the other end of the ribbon, there is a counter weight. The overall length of ribbon is dependent on two characteristics of the celestial body they are built around, the more massive the planet or the slower the day, the longer the tether needs to be. The pull of gravity also impacts how strong the tether needs to be, on planet Earth you need tether's made out of materials that can, currently, only be made in laboratories in small quantities. For a tether on the moon the elevator can be made from materials currently available, for example kevlar. With an operational space elevator on the surface of the moon, future missions to and from the moon would only require sufficient fuel to dock with the space elevator, as opposed to requiring sufficient fuel to safely land on the surface and then fight against the lunar gravity well on the return trip. Getting to the point where materials are routinely going to and from the surface of the moon will take many years, but might have a timeline as follows.
Phase 0: NASA and partner organizations request contract bids for companies that will build the first Lunar Elevator
Phase 1: The first space elevator satellite is deployed on the dark-side of the moon (Pink Floyd album sales experience a light resurgence). The system is only capable of moving payloads of a few dozen kilograms per container (potentially more, but we are being conservative in estimations) The small mass flow rate is not considered useful for industrial applications, but allows scientists of partner nations to do far more analysis of the chemistry of lunar regolith
Phase 2: Improved versions of the initial space elevator probe are now deployed in a constellation around the initial space elevator satellite. The larger number of probes allow the space elevator consortium to start shipping semi useful quantities of liquid oxygen and other resources. One client for the liquid oxygen are space mining firms, looking to minimize their launch costs while pursuing asteroids further afield.
Phase 3: Using the Phase 2 constellation, the Lunar Mining Consortium beings to manufacture their next generation space elevator, this elevator is intended to allow the transportation of thousands of kilograms at a time. At this point there are multiple small semi-autonomous research stations and mining sites on the dark side of the moon.
Phase 4: The Lunar Mining Consortium continues to add to the initial space elevator system. There is a habitat at stationary orbit, serving as a depot and manufacturing facility, where space craft can refuel, receive modifications and exchange crews and/or cargo. The number of facilities on the lunar surface continue to grow. A small number of mirrors have been added to reflect sunlight towards various research stations to ensure they receive enough power during the Lunar night
Phase 5: The elevator has multiple termination points across the lunar surface, including the north and south poles. The mirrors now ensure that lunar facilities now only require battery power for <10% of the Lunar night. Lunar manufacturing capacity has reached the point that more than 20% of the material put into space in a given year came from the Moon. Only organics and more complicated electronics are likely to still launch from Earth in the coming decades. As a result of the shear volume of materials arriving and departing the Lunar Elevator Station, engineers have added even larger engines and rail guns to preserve the elevator's orbit.
Phate 6: Using lessons from the Lunar Mining Consortium, humanity forms the Mars Elevator Group, and begins to outline a Martian space elevator, opening up Mars for more ready colonization.
The motivations for developing space mining are quite reasonable, the more materials that can be harvested outside of the Earth's gravity well, the greater flexibility our civilization will have. That being said there needs to be a dollars and cents argument made to those who hold the strings. The easiest is for rocket fuel. for traditional rockets that use hydrogen and oxygen, the oxygen makes up 8/9ths of the mass of the fuel needed (this doesn't include the tanks holding the hydrogen and oxygen). Now imagine you have a reasonably affordable source of liquid oxygen on the moon. Now you need way less mass devoted at launch to your liquid oxygen supply. For crewed missions to Mars that will, potentially, be a massive saving. Now to developing the space elevator itself, in theory engineers could make a massive rail gun on the surface of the moon, and use that to launch materials into space, true, but the applications are reduced, building a space elevator on the Moon allows scientists to have a real test bed for space elevator technologies, these technologies could inform how we build a space elevator on Mars and maybe one day the Earth.
The rational behind suggesting the formation of the Lunar Mining Consortium is to promote international collaboration, projects like the ISS have done wonders for promoting cooperation here on Earth, a massive engineering project where dozens of governments can share in innovations and natural resources will hopefully promote a more unified Earth.
Well thanks for reading version 0, feedback and notes are appreciated.
*honestly the author isn't sure how many ideas NASA gets, but assumes it is a lot.
Tuesday, August 9, 2016
My First Lazy Programmer Moment
One of the ways I have been trying to improve my programming abilities has been to go to a website called Project Euler and do some of their coding challenges. In one of the problems you are asked to write a program that goes over 400 numbers in a 20x20 array and manipulate the numbers
12 07 44
38 90 13
25 64 53 (something like this, but you know, bigger)
After cutting and pasting these numbers into Sublime (a coding text editor), I attempted to turn this grid of numbers into an array that I could manipulate for the rest of the challenge. (for those less familiar an array is a way for a computer program to store a large number of pieces of information)
The easiest to make an array in ruby is to put square brackets [] around the pieces of information you are trying to work on. in code it would look something like
new_array = [12, 07, 44, 38, 90, 13,25, 64, 53]
For whatever reason my computer did not to recognize the array I made as actual numbers, (well it did but it was trying to treat the numbers like they were base 8, the 9s really confused it)
One tedious solution came to mind turn all of these numbers into strings. (a string is a collection of symbols that you would see on your keyboard they are enclosed by "quotation" marks, a number in string form is treated differently than a pure number)
Within a few minutes of trying to make the array an array of strings. Tediously adding quotes around each pair of digits another option came to mind. Instead of turning each number into a unique string, turn the entire array into a string that can be used. In the awesome weirdness of programming, computer languages like ruby will act as if strings are an array, with each individual letter/number/symbol acting as a different spot in the array. With this in mind I wrote a new program, that would turn one massive string into all of the different elements of the array that I needed.
In code this solution looks something like this
number_source = "12 07 44
38 90 13
25 64 53"
@storage=[]
def make_into_numbers(target_string)
biggest_size = target_string.length
counter = 0
while counter < biggest_size
@storage.push(target_string[counter..(counter+1)].to_i)
counter += 3
end
end
The way the program works is as follows. The method make_into_numbers takes in a source string, in this case, our giant grid of number, and moves those numbers into a new array. Because the numbers are always 2 digits long and followed by a space, it seemed easier to have the program jump three places grab the first and second number from that start point and continue on. For a sanity check, I had am output that would displace particular positions in the array that I could visually confirm that I was generating an appropriate array. Once I confirmed that it worked, that part of the code was removed.
I know for more experienced programmers something cleaner might have been used, where the numbers were extracted by looking for the next space in the grid, or even cleaner, but this approach took me less than 5 minutes to write and it made me a bit happy. Suggestions for better approaches are always welcome.
We have something called a method (methods are the pieces of code people write in ruby to get the various tasks they want done). The method is called "make_into_numbers" in the parentheses we have "target_string" this is a stand in phrase allowing the computer to know what data to manipulate while allowing the programmer to more readily re-use the code with only changing a few words.
Tuesday, August 2, 2016
Making Gravity In Science Fiction
This blog has highlighted on several occasions that I am a massive sci-fi nerd (if this is news to you, this is probably your first time reading here). When science fiction writers or TV producers have a space ship generate (or simulate) gravity they achieve it in three major ways. Spin the ship, in movies like Interstellar or 2001 a Space Odessey, the crew is provided with something akin to gravity by spinning part or all of the ship. This rotation effectively pushes crew members outward and the ground pushing back feels something like gravity. In the TV show The Expanse (which I highly recommend, the more people who watch it the more likely I'm going to get the 30+ seasons of the show that I desire (and now I jinxed it))(back to the expanse) in the show humans have created advanced engines that are so efficient that ships can be in almost constant acceleration, this means that so long as the ship is under thrust, crews will experience some degree of faux gravity. Another alternative is the use of "mag boots" specially designed footwear or general attire that has the ability to be attracted to the surface of the ship when crew members need it to be, and when they move their foot up, the magnetic attraction is removed. This solution is incredibly reasonable, unfortunately, no one seems to have made a show where people in "mag boots" mode actually looks like only their feet want to go down. (this is not to say doing so is easy, just an observation that it would be cool to see a space battle where mag boots are in use and while a crew member is reloading they just let the empty magazines float there, or less dramatically, while fixing an engine crew members are surrounded by their tools floating nearby.)
The most popular option for ship,s gravitym hand wavium generators. Hand Wavium Grav generators are popular in , Star Trek, Star Wars, Earth Above and Beyond, Farscape, Stargate...... read all of the shows. What irks me is that writers generally ignore how weird the behavior of ships gravity is. (the one exception that does come to mind is the first episode of the TV show Enterprise (the prequal Star Trek show with Scott Baccula), and all they say is that there are weird points in ships where the gravity doesn't quite work.
What would be nice is a middle ground from truly hard science fiction solutions to simulating gravity and just getting rid of the problem with a quick phrase that only power nerds care about. A "gravity laser" for space craft. A reasonably advanced civilization might be able to create a narrow beam of gravity that could provide a pulling force on the entire ship. What is cool about this technology, is if this attractive force is only effective in a single direction you also have a means of reaction-less thrust, helping to minimize how much space the ship "needs" for fuel. While this approach is still very much fictional, to me it feels a bit more grounded.
I hope you enjoyed the post and if you have any questions, feed back, thoughts, please feel free to comment. I will try to add a drawing later tonight.
The most popular option for ship,s gravitym hand wavium generators. Hand Wavium Grav generators are popular in , Star Trek, Star Wars, Earth Above and Beyond, Farscape, Stargate...... read all of the shows. What irks me is that writers generally ignore how weird the behavior of ships gravity is. (the one exception that does come to mind is the first episode of the TV show Enterprise (the prequal Star Trek show with Scott Baccula), and all they say is that there are weird points in ships where the gravity doesn't quite work.
What would be nice is a middle ground from truly hard science fiction solutions to simulating gravity and just getting rid of the problem with a quick phrase that only power nerds care about. A "gravity laser" for space craft. A reasonably advanced civilization might be able to create a narrow beam of gravity that could provide a pulling force on the entire ship. What is cool about this technology, is if this attractive force is only effective in a single direction you also have a means of reaction-less thrust, helping to minimize how much space the ship "needs" for fuel. While this approach is still very much fictional, to me it feels a bit more grounded.
I hope you enjoyed the post and if you have any questions, feed back, thoughts, please feel free to comment. I will try to add a drawing later tonight.
Monday, August 1, 2016
How Hot Gets Cold
This post is an attempt at create a reference page that is as reader friendly as possible. If you think any of the examples are too dense, please feel free to comment, it means I need to work on getting better at communicating.
This blog, and a lot of mechanical engineering work has a really big question to answer, when you do any kind of work, moving a car, use electricity to power a chip, or launch a rocket into space, you have heat, more often than not that heat is not something you want in your project. To get rid of heat engineers generally have 3 major ways to cool things off, conduction, convection, and radiation (not the nuclear kind).
First general rule of heat transfer, heat moves from where it is warmest to where it is coldest. For that heat to get from the warm spot to the cool spot, any combination of conduction, convection, or radiation can be used.
Cooling through conduction. Pick up a glass of ice water and your hand starts to feel cold. This is the conduction of heat from your warm body to the cold glass. Now instead of picking up a glass of ice water, you pick up a styrofoam cup filled with ice water, your hand doesn't feel nearly as cold. The water in the cup is no cooler than the glass, but your hand feels colder, this is because of something called thermal resistance. The greater the thermal resistance the harder it is for something that is hot to lose heat to something that is cold.
Convection is a bit more complicated in practice (but who cares, this is an intro). Imagine using a fan on a hot day, even though the air the fan is blowing on you isn't any colder you feel more comfortable. The reason you feel cooler in front of a blowing fan is because of something called "forced convection". The faster you move air molecules away from your body the cooler you will feel, this is because your body is naturally conducting heat to the air around you, but the air does not necessarily want to move that heat away from your body, by blowing air, the warm atoms are more likely to move away from your body.*
Radiative cooling. Instead of transferring heat by means of physical contact, radiative cooling lets heat escape through electro-magnetic radiation. This is what allows the Predator to hunt Arnald Schwarzenegger in the first Predator movie. The warmer an object is the more thermal radiation it will emit. Where the concept of radiative cooling gets complicated, is that everything is emitting some amount of thermal radiation. What does this mean for you or me, most of the time nothing that you need to worry about? For blog posts like how the Death Star deals with its Heat, or more recently Window Cooling (better title suggestions are always appreciated) this concern for radiative cooling is really important, if the cooling system isn't pointed at something really cold, they won't work that well. The best direction to point a radiative cooler is at the cold emptiness of space.
Radiative cooling is often called black body cooling. The reason for this term is that the closer an object is to being as black as humanly possible the better it is at cooling. If you want your spaceship to avoid losing heat, you make it as shiny and reflective as possible, to help with cooling, you want it to be as black as possible, this is one of the reasons scientists are obsessed with making really black materials.
*there are cases where you can use convection to warm something, but the hope here is to keep the intro as straightforward as possible.
This blog, and a lot of mechanical engineering work has a really big question to answer, when you do any kind of work, moving a car, use electricity to power a chip, or launch a rocket into space, you have heat, more often than not that heat is not something you want in your project. To get rid of heat engineers generally have 3 major ways to cool things off, conduction, convection, and radiation (not the nuclear kind).
First general rule of heat transfer, heat moves from where it is warmest to where it is coldest. For that heat to get from the warm spot to the cool spot, any combination of conduction, convection, or radiation can be used.
Cooling through conduction. Pick up a glass of ice water and your hand starts to feel cold. This is the conduction of heat from your warm body to the cold glass. Now instead of picking up a glass of ice water, you pick up a styrofoam cup filled with ice water, your hand doesn't feel nearly as cold. The water in the cup is no cooler than the glass, but your hand feels colder, this is because of something called thermal resistance. The greater the thermal resistance the harder it is for something that is hot to lose heat to something that is cold.
Convection is a bit more complicated in practice (but who cares, this is an intro). Imagine using a fan on a hot day, even though the air the fan is blowing on you isn't any colder you feel more comfortable. The reason you feel cooler in front of a blowing fan is because of something called "forced convection". The faster you move air molecules away from your body the cooler you will feel, this is because your body is naturally conducting heat to the air around you, but the air does not necessarily want to move that heat away from your body, by blowing air, the warm atoms are more likely to move away from your body.*
Radiative cooling. Instead of transferring heat by means of physical contact, radiative cooling lets heat escape through electro-magnetic radiation. This is what allows the Predator to hunt Arnald Schwarzenegger in the first Predator movie. The warmer an object is the more thermal radiation it will emit. Where the concept of radiative cooling gets complicated, is that everything is emitting some amount of thermal radiation. What does this mean for you or me, most of the time nothing that you need to worry about? For blog posts like how the Death Star deals with its Heat, or more recently Window Cooling (better title suggestions are always appreciated) this concern for radiative cooling is really important, if the cooling system isn't pointed at something really cold, they won't work that well. The best direction to point a radiative cooler is at the cold emptiness of space.
 |
| The blackest material made potentially helping NASA keep spaceships cold source extremetech.com |
Radiative cooling is often called black body cooling. The reason for this term is that the closer an object is to being as black as humanly possible the better it is at cooling. If you want your spaceship to avoid losing heat, you make it as shiny and reflective as possible, to help with cooling, you want it to be as black as possible, this is one of the reasons scientists are obsessed with making really black materials.
 |
| How NASA keeps satellites from getting too hot (or cold) source NASA |
*there are cases where you can use convection to warm something, but the hope here is to keep the intro as straightforward as possible.
 |
| How hot things can get (added 10/19/2016) |
Wednesday, July 27, 2016
Passive Window Cooling Idea
I may be a little obsessed with the Fan Group's research into radiative cooling. (what can I say, I really hate excessive summer heat).
As the Greater Boston area is in the midst of a rather unpleasant summer heat wave, the mind turns to ways to help cool our human made environments. (A big thanks to Willis Carrier for inventing modern AC) While active heat pumping has the advantage of being incredibly fast, it does increase our civilization's energy demands, and until those energy sources are no longer adding greenhouse gasses, we are leaving ourselves in a nasty little feedback loop. One potential means of increasing how efficiently we cool our homes, would be to create a window unit that passively provides radiative cooling while still allowing light through. The design would have 3 major parts, the transparent cooling surface, heat pipes, and a small solar panel to power a fan. After a user puts their cooling panels into place, the houses heat would be transported from the inside through the heat pipes. To ensure that as much heat is being taken away from the house as possible, a small fan attached to a heat sink, similar to what you would see inside your computer, would blow air as necessary. Sounds great in theory, but let's try to figure out how useful this idea would be.
Each square meter of radiating material would provide roughly 850 watts of cooling or the equivalent to 2900 BTUs (about half the cooling of what a window unit made for a small room would provide. This means that for a small room (about 125 square feet), you would need about 2 square meters of cooling surface (I am making a distinction for reasons I will go into later). Without knowing how heavy all of the elements would be it would be pre-mature to comment on how unwieldy the mass of the system would be, that being said just that amount of area would be hard. If this magical room had 4 decent sized windows, you would still need each panel to be at least 0.5 m by 1 m (or about 19.75 inches by 39.5 inches, unless this thing is folded up before you open it, not easy to safely place out of your window). The reason the size of the panel needs to be at least half a meter by a meter, not exactly that size is a matter of how radiative cooling works. Black body radiators need to be pointed at something colder than they are, in the case of this technology, the cold of space, if the surface of the panel is perfectly smooth, your cooling window is now most likely pointed at your neighbor's house, probably picking up the heat being reflected and or emitted by the neighbor.
If the panel was to have a bunch of ridges creating a cool 3-D panel, probably a bunch of 45 degree slopes, you are only getting about 70% of the equivalent height of the array. so now instead of being half a meter by a meter, the panel needs to be 0.5 m x 1.5 meters to get the same effect. Now home owners have to spend the energy installing these far more massive panels, or putting in way more small panels to get a similar effect.
We are quickly running into a design that seems less and less appealing, which is what I came to realize, as excited as I am about passive window cooling units, they start seeming pretty silly as a primary means of cooling a home. Small seasonal units might still find a niche market, for home owners who want to minimize the amount of work their actual AC system needs to work, but the real market for passive cooling technologies would most likely come from larger businesses that want seasonal cooling capacity. Instead of designing a window unit that needs to be small and light enough for a home owner to put in, engineers should focus their efforts on creating two types of passive cooling installations, seasonal and permanent. Designing a building to permanently have passive cooling systems on the outside, would make the most sense as to be customized for the building's use case (read too difficult to properly be analyzed in this blog), the seasonal solution is a bit easier (as I am looking at the problem from my perspective). Imagine giant shutter looking structures. some intended to allow light in, others to maximize cooling. Businesses and organizations who require massive amounts of air-conditioning could lease these panels and have them place around their building at the beginning of the summer, drastically offsetting how much energy the would need to devote to air-conditioning. The challenge for this use case is the business atmosphere, realistically without either utility or government mandates to minimize peak energy consumption during the summer months, it could be difficult to inspire wide spread adoption of this kind of cooling technology. If society had the will power to invest in more passive cooling technologies, there would be less demand for peaking power plants (the most expensive types of electrical generators), reducing the overall cost of energy, which is generally a good thing.
A quick note on the passive window unit. While I don't think it makes sense for most American consumers, I do think the idea has merit in regions where power is less reliable or more expensive.
The idea behind this post is I generally only quickly outline an idea or act like I've seen the future and it must include my "brilliant" solution, I wanted to convey, at least in a small way, how I iterate through ideas and what problems I try to consider. I hope this provides a small sense on how I try to create solutions to problems.
As always, questions, comments, feed back what-have-you always welcome.
As the Greater Boston area is in the midst of a rather unpleasant summer heat wave, the mind turns to ways to help cool our human made environments. (A big thanks to Willis Carrier for inventing modern AC) While active heat pumping has the advantage of being incredibly fast, it does increase our civilization's energy demands, and until those energy sources are no longer adding greenhouse gasses, we are leaving ourselves in a nasty little feedback loop. One potential means of increasing how efficiently we cool our homes, would be to create a window unit that passively provides radiative cooling while still allowing light through. The design would have 3 major parts, the transparent cooling surface, heat pipes, and a small solar panel to power a fan. After a user puts their cooling panels into place, the houses heat would be transported from the inside through the heat pipes. To ensure that as much heat is being taken away from the house as possible, a small fan attached to a heat sink, similar to what you would see inside your computer, would blow air as necessary. Sounds great in theory, but let's try to figure out how useful this idea would be.
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| Fig 1 On the left a flat panel trying to radiate heat away on the right, the bumpy pattern points the heat towards space |
If the panel was to have a bunch of ridges creating a cool 3-D panel, probably a bunch of 45 degree slopes, you are only getting about 70% of the equivalent height of the array. so now instead of being half a meter by a meter, the panel needs to be 0.5 m x 1.5 meters to get the same effect. Now home owners have to spend the energy installing these far more massive panels, or putting in way more small panels to get a similar effect.
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| Fig 2: Cooling panels to go outside big buildings |
A quick note on the passive window unit. While I don't think it makes sense for most American consumers, I do think the idea has merit in regions where power is less reliable or more expensive.
The idea behind this post is I generally only quickly outline an idea or act like I've seen the future and it must include my "brilliant" solution, I wanted to convey, at least in a small way, how I iterate through ideas and what problems I try to consider. I hope this provides a small sense on how I try to create solutions to problems.
As always, questions, comments, feed back what-have-you always welcome.
Friday, July 22, 2016
Br(e)aking In Space
A common theme in the planning of deep-space missions(and this blog), is slowing a spaceship down enough to enter into orbit around a particular planet or moon. As a general rule mission planners at NASA, ESA, and Roscomos need make sure the mission has enough fuel to get their ship going the right speed. Generally speaking you can slow your ship down using two tools, rocket fuel and the gravity of other planets (I won't try to communicate gravity boosts/br(e)aking because I'm not familiar enough with the concept to do a reasonable highschool physics explanation(use the link if you want to know more)). What I would like to suggest is a way to augment the rocket fuel option.
One of the many proposals that scientists and engineers have put forth for reducing the cost of launching ships into Earth orbit, is the use of micro-wave lasers (called masers) to help to heat up rocket fuel, the warmer the rocket fuel is, the more energy coming out of the engine's exhaust port.(this is like way over simplifying it). This is awesome and hopefully sooner than later it will be another alternative way for research satellites to enter orbit (humans may not want lasers pointed at their rocket ship during the near term (personally it would depend on proven safety records of various technologies available), but how does it help us change velocity around other planets. Short term, not at all. Looking towards the future, it isn't unreasonable that there will be a relatively steady stream of space probes , and hopefully human explorers, trying to get around the inner solar system. At that time governments and private bodies might begin to collaborate on creating a network of maser base stations on the larger rocks in the inner system of planets. Initially the stations would only be placed on our Moon and one of Mars' moons. Assisting astronauts on their missions to the Red planet and back, as time went on other large asteroids could add these laser arrays to increase mission flexibility.
While I am excited about this idea, that being said it wouldn't be perfect, getting the arrays at the target destinations would not be easy, so probably not a good idea for the first missions.
If engineers and budgets allowed for it, I would try to emphasize the energy beaming system to put out different kinds of power, from visible light to micro-waves. The larger range of frequencies would allow for different missions to benefit, for space probes returning from the outer planets, the beams could focus additional power for the ion engines, either reducing the needed mass of the solar panels or just overall boosting thrust. For missions not using ion engines, the focus would be on the use of the maser.
Additional ideas and comments are welcome, thanks for taking the time to read.
*7/26/2016 An edit I wrote break not brake, an observant reader had the decency to inform me of my mistake privately, Sorry 'bout that.
One of the many proposals that scientists and engineers have put forth for reducing the cost of launching ships into Earth orbit, is the use of micro-wave lasers (called masers) to help to heat up rocket fuel, the warmer the rocket fuel is, the more energy coming out of the engine's exhaust port.(this is like way over simplifying it). This is awesome and hopefully sooner than later it will be another alternative way for research satellites to enter orbit (humans may not want lasers pointed at their rocket ship during the near term (personally it would depend on proven safety records of various technologies available), but how does it help us change velocity around other planets. Short term, not at all. Looking towards the future, it isn't unreasonable that there will be a relatively steady stream of space probes , and hopefully human explorers, trying to get around the inner solar system. At that time governments and private bodies might begin to collaborate on creating a network of maser base stations on the larger rocks in the inner system of planets. Initially the stations would only be placed on our Moon and one of Mars' moons. Assisting astronauts on their missions to the Red planet and back, as time went on other large asteroids could add these laser arrays to increase mission flexibility.
While I am excited about this idea, that being said it wouldn't be perfect, getting the arrays at the target destinations would not be easy, so probably not a good idea for the first missions.
If engineers and budgets allowed for it, I would try to emphasize the energy beaming system to put out different kinds of power, from visible light to micro-waves. The larger range of frequencies would allow for different missions to benefit, for space probes returning from the outer planets, the beams could focus additional power for the ion engines, either reducing the needed mass of the solar panels or just overall boosting thrust. For missions not using ion engines, the focus would be on the use of the maser.
Additional ideas and comments are welcome, thanks for taking the time to read.
*7/26/2016 An edit I wrote break not brake, an observant reader had the decency to inform me of my mistake privately, Sorry 'bout that.
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