Slashdot Mirror
It isn't Easy Being Green and Getting to LEO
MWTJ writes "The BBC has a story about the environmental impact of the space shuttle. One of the things that started the modern environmentalist movement were pictures of the Earth from space, so we could see the beauty of the planet as never before. We could also see environmental destruction from space. But what is the impact of the space program on our planet? The story talks about the switch to Freon-free insulation, the use of clean-burning hydrogen/LOX fuel, and other factors. What else could be done to get to space with minimal harm to the planet?"
Develop nanotech and use it to build a space elevator. Cheap, clean, safe, easy access to space!
Real_men_don't_need_spacebars.
We do a shuttle launch once every, what, four months even under the optimal conditions that never happen? And the city of Houston, Texas alone is pumping out how much greenhouse gas every day just from the cars alone?
Why is it we never actually care about the environment except at times that it's stupid to do so? Oh noes, think what nuclear power could do to the environment under extreme and unlikely circumstances that can be totally avoided with a modicum of competent regulation! We'd better avoid that and stick with the huge belching coal plants built in the 1970s and grandfathered in from the time before emission controls, that's sooo much more ecologically friendly.
1) Get to space.
As long as you're stuck on this step, you're going to have to have an entire planet's worth of heavy industries, energy generation, and resource extraction being performed on the surface of said planet.
Arguing about the "greenness" of space exploration is like someone having a heart attack deciding not to call an ambulance because being a passenger in a vehicle that's going faster than the posted speed limits in city streets is a health hazard.
A space elevator (always popular on /.) would be about the cheapest way up in theory provided you write of the energy cost of building the damn thing over a long lifetime.
Still, I think the posts and articles about the environmental impact of the Shuttle are mostly crap. Cars that do 40mpg instead of 20mpg on an urban-cycle would have much more positive impact on the environment. Using the heat from power station cooling systems to heat offices/factories in local areas would do more. Recycling your plastic, glass bottles, cans, and paper would do more.
Nasty as the perchlorate SRBs are, they're worth the inconvenience if NASA can use them to build (say) a 100 ton heavy launcher to replace the Shuttle.
This is not a sig
I'm sorry, but this is the same argument used with why we need to be driving hydrogen cars, and it irritates the shit out of me.
Skipping over the solid rocket boosters as cheerfully as the article summary did- perhaps Professor Fraser would care to explain to us where all the hydrogen and oxygen came from?
If you do the math in terms of the energy produced, and realize that both distillation-by-refridgeration and electrolysis are hugely inefficient, you start to realize the amount of energy required to make all that hydrogen and oxygen is incredible. Chemical methods involve pretty toxic chemicals, so you're not getting out of it that way. Guess how most of our (United States) electricity is supplied? That's right- coal. Which generates huge amounts of carbon soot, carbon dioxide, and radioactive particulate.
I noticed that they also skipped quite nicely over hydrazine, used in the thrusters...
Please help metamoderate.
Electromagnetic launchers are practical NOW. "Just accelerate the space cargo in a vacuum tube until escape velocity is achieved, while climbing a high mountain." Only one key technology has been needed, and it got invented just a couple years ago. At the END of that vacuum tube, a means is needed to keep the atmosphere from rushing in while still letting the cargo exit. The plasma valve is the answer to that problem.
http://www.nuclearspace.com/a_liberty_ship.htm It is simple, no nuclear materials comes out of the exausts. All you do is super heat some material to rediculous levels and your done. Any activity has a negative impact, but then the biggest human contibutor to radioactivity in the atmosphear is burning coal. As for accidents, you need about 1000 accidents to release as much nuclear materails as those above ground attomic tests. Oh, and make them BIG ...
Parent is actually correct. Damage to the shuttle due to foam coming off increased by a factor of 11 (!) after changing to the new enviro-wacko friendly formulation. See for example this.
There is a sound suppression system built into the launch pad which is designed to prevent the infrastructure from being damaged from the sound waves generated beginning six seconds before liftoff when the orbiter's main engines ignite and run up to full thrust.
Watch launch footage carefully and you will be able to see that the clouds mentioned begin to appear at that point. While some of them are deflected exhaust from the aluminum perchlorate fuel used for the solid rocket boosters, most of the big clouds are actually water steam.
This can be confirmed by looking at footage of liquid-fuelled rocket launches. Liquid fuel doesn't produce those big visible trails the way solid fuel does -- the clouds are visible only at first and the rocket itself has no trail as long as it has no solid boosters. (The shuttle does indeed lose its trail after SRB separation, as do Deltas and Titans and others).
i am a soviet space shuttle
LOX and liquid hydrogen gives the best ISP for any rocket fuel, and that burns quite cleanly indeed. The Shuttle SRBs are a mess, though, IIRC. And apparantly the fuel for the attitude jets is so toxic that it can make you sick just by looking at a wreked shuttle part from 30 feet away (ooooh kaaaay, like I believe *anything* the news tells me these days ...).
Liquid Hydrogen is a bit difficult to prepare and store for use in commercial spaceflight, however. Anyone know how completely propane burns in a rocket engine? I'd guess that it burns very cleanly, given the performance requirements. It seems to me that a fuel tank divided into LOX and liquified propane is probably the way that comercial spaceflight will go once they go higher than the 100km mark, and there won't really be any environmental impact from that.
Socialism: a lie told by totalitarians and believed by fools.
As I see it, the part that has the most impact on the environment and as well is the most critical part today are the solid fuel boosters.
One feature that could be used for the light shuttle is to have a launch vehicle that carries and accelerates the shuttle to a speed and altitude where the rockets can work best. By using ordinary jet engines for the first step you wouldn't need to carry the oxygen for the first stage, which is a major weight contribution.
This will of course require several different design issues to be solved, but since Burt Rutan has done this (on a sub-orbital scale) it isn't impossible.
If the carrier would be able to go supersonic before the release of the shuttle it would be even better, but then there are a lot of issues to take into account like interfering shock waves occuring at separation. A lot of fun for those guys that like extreme calculations! :->
If builders built buildings the way programmers wrote programs, then the first woodpecker would destroy civilization.
I highly agree that electromagnetic launchers would be damn useful. I also think that most people are thinking of using them in the wrong way. Let me explain:
Due to high acceleration, electromagnetic launchers are probably not the best choice for launching humans or delicate equipment. Rockets are likely to be cheaper for this for the time being. In order to have a launcher which would be useful for human launches, the launcher would have to be very long, and thus very expensive. However, a launcher which was designed for bulk transport would not need to be very expensive at all. This is because, unlike in a rocket, the majority of capital expense stays on the planet. In order to have a cheap (and thus, likely to be actually built) system, you want to minimize the expense involved in building the launcher. One of the best ways to do this is to reduce the size of the projectile. People tend to think of launchers as firing something about the size of a Gemini capsule or Space Shuttle. However, if the launcher is going to fire a projectile the size of a coke can, a much smaller launcher could be built. Electromagnetic launchers can have very high fire rates - why launch one large projectile when many small ones will contain the same mass and use the same energy?
The atmosphere of course puts limits on the size reduction of the projectile. A large or dense projectile loses a smaller proportion of its energy to drag. However, if we make the launcher small enough to put on an airplane, then we can launch from the stratosphere for a fairly low cost. This would enable the use of small projectiles without too much energy loss to atmospheric drag. I would expect the cost of a launcher to be less than the price of an airplane which could mount one. Lets assume it is a plane similar to a 727. A 727 has a payload of about 50,000 kg including fuel. Let's say that 10,000 kg of that is projectiles, with the rest of the payload being used to carry the crew, the launcher, and the fuel for the plane and the launcher. To get to LEO, the fuel for the launcher would be about 2 times the mass of the projectiles, so that works out about right for a short flight. Assuming a fire rate of about 1/sec for 1 kg projectiles, the payload of the plane would be shot in about 3 hours.
So, presuming we had a bulk launcher which cost $20 million and could launch small projectiles into LEO at not much more than the cost of fuel, the price per kg would likely be on the order of $10/kg. Of course the launcher could only be used for launching bulk materials, but as an example:
A Delta 4 heavy rocket delivers a payload of 23000 kg to LEO at a cost of about $170 million. If we were to take that same $170 million and put $20 million into a plane-based launcher, $50 million into various upkeep costs (personnel, ground site, the inevitable bureaucracy), and $100 million into launch fuel, you could put 10 million kg into LEO. It would take a year of flying 3 flights a day with the launcher plane to put this much mass in orbit.
Of course, the mass would not be a nicely formed satellite or spaceship, but the point is that for the same cost, you get to put 4300 times the mass into orbit. 100 million kg is about twice the mass of a WWII battleship like the Bismarck, and is plenty of mass to build an orbital factory to turn some of that mass into something useful. In addition, metal encapsulated fuel pellets could be sent into orbit - fuel in orbit is worth much more than fuel on the ground.
This sort of project would only take a few million to get off the ground, and if things don't work, then you have the opportunity to retool your system, which is not as easy with exploding rockets. The real challenge lies in making the projectiles go where they are supposed to so they can be gathered in orbit to be used.