Don’t forget to start your novel on Sunday!
The radio crackles.
“Dying, I call you. Please, give my children a better life than their barren homeworld.”
Above, three trillion parachutes unfurl.
So.. cheating, I was thinking of this song when I wrote Maybellene. I am strongly thinking about expanding this into a reasonable short story. Micro fiction is hard.
My palms sweating, gravitator rumbling, she slips into Acube space. Green light flashes and twin positron beams pin me into red leather. Dragging light.
I’m starting a book for National November Writing Month. (nanowrimo) I’m going to write a new novel in the Waylaid series…which consists of one novel. No great shakes yet, but I’m working on it.
If you want to join in on my pain, look me up on nanowrimo. @Sablehawk of course.
This isn’t science fiction, but I’m willing to help anyone who wants it. I know science fiction as well as anyone. This novel is more fantasy/history based.
There has been a lot of discussion the last few days about some fellow who printed a “plasma gun” and was shooting a bb at 450 ft/s. I’ve got some experience working with Dr. Mohamed Bourham back in 1992 – 1995. Plasma Engineering at NCSU. So I feel like responding to the usual threads.
The usual crap is:
- This must be fake.
- Regulate this before someone gets hurt.
- Really this isn’t very impressive.
- I don’t know much about 3D printing, ask Chad Ramey if you need to know. He runs (ran last year) Georgia Tech’s 3D lab. I’ve done some laser cutting and some milling, mostly plastic but a little steel. But, you can basically 3D print any shape. Usual limitations involve re-curvature and support of extended structures, same as any model building.
- Seriously, regulating 3D printing is as purposeless as regulating sex acts between consenting adults. Completely F*d up. Unless you decide to regulate the transfer of CAD files on the internet. You are outa luck.
- First off, 3D printing is cool, but milling is better. You can do a much better product with a 3D milling machine and a block of steel. Lexan makes a great ablative barrel material and a good bullet, but that’s it. This is a cute toy which could be sold next to the CO2 powered (paint ball) markers. No more dangerous (unless you shock yourself playing with wiring.)
So, what is a Plasma Gun?
Technical term – Electro-Thermal Chemical Plasma Device. Why? You use an electrical current to heat plastic so that it chemically changes into gas. The gas, mostly Hydrogen, is further heated to become a plasma. You get some Carbon deposition along the walls, which is good for encouraging all the current to flow through the gas. The Hydrogen gets hot, like 30 – 50,000 degrees Celsius. I normally divide by 11 k and call it electron-Volts, so around 3 eV.
The plasma expands at a much greater speed than speed of sound, so it won’t be limited to 1 km/s. Depending on how much energy you can get stuffed into that plasma. Well, a Dragon Con friend of mine asked for a plasma story, so I figure I can write that up today.
So, Here is the story. I was working in the lab and we had an idea to do an experiment, accelerating a 10 gram mass of Lexan with a plasma pulse. We were trying to determine how much momentum was coming down the barrel as a function of V applied. This mattered to some materials experiments we were working on. (Trying to separate out the thermal shock from the physical shock) So Eric and I decided to give it a try.
So, the ETCP device is set up in a wire Faraday cage about 10 feet on a side, lined with lead bricks. Hey, we worked in a reactor, there were lead bricks spare. We built three cubicles out of them, and lined them all with Faraday cages…we made a lot of EMP.
The device is solid stainless steel, bolted to the table, which is bolted to the floor. Very Immobile. The end was pointed directly at the wall, so if we pulled the rear seal off the experiment, the “bullet” er Lexan Mass would fly out of the back and hit a target in the center of the wall. We hooked up a pair of laser beams to measure the crossing speed of our 5 foot racetrack, and got to business.
I carved a bunch of 10 gram Lexan masses. They were about the size of your pinkie fingertip. (Little things) Eric put some bolts into the wall and suspended a chunk of Aircraft Aluminum, 3/4 inch thick, 4 inches wide, a foot long. We ran up a charge on our mass of capacitors. When we got to a good charge, I’d insert a bullet and we’d duck into our control room, turn on the warning light for 5 minutes, and he’d fire the gun. The Lexan converted to plasma on arrival on target, completely destroyed the bullet.
A few hours, a new charge, a new bullet, a new shot, a new velocity. Science! Each shot made a huge, single, noise. Like smacking a garbage can with a hammer. Scared the neighbors something awful.
So, at around 45,000 V, the shot made a sound like ringing a dinner bell, *ding a ling a ding a ling a ding a ling a ling a* It went on for a few seconds, louder, dimmer, louder, dimmer, louder… done.
We looked at each other, what the heck? Checked out the room, no damage, but the target was behind the control station folded in half. Marks on the walls, all the walls. Oh crap. The 10 gram mass of Lexan had folded the aluminum in half and bounced it off of every wall, probably twice. Dr. Doster decided that we didn’t need to be doing that experiment any more. But hey, we got to 3.54 km/s. Beat that.
The final question is “Why are we doing this at all?”
- The Exploration Gene?
- Use of Resources on Earth is Limited?
- Protection of the Human Race?
- There will always be arguments of “Because it is there,” forever and ever. Humans are like that. But honestly, seeing Earth from orbit would be awesome, but the space between Earth and Mars is full up of NOTHING. Almost as bad as space between Earth and Jupiter, Saturn, Pluto, the next star. 99.99999 % of space is nothing. The other 0.000001% is amazing views…which, since we can’t see them with the naked eye, might as well be seen with a camera.
- We can extract resources in space without digging up the Earth. Yeah, not so much. There are good reasons to dig up resources in space, but we can cleanly extract resources from Earth for thousands of years before we NEED anything from an asteroid. Especially considering the cost of delivering it to the Earth.
- Sure, I would feel “safer” with mankind an interstellar species…but if we can’t make it on Earth, we won’t survive long in space. Filtering Earth water is EASY compared to water rationing on a colony.
Colony: “What is our acceptable Cyanide level again, honey? I think we have a pressure leak in one of the grey water tubes. Well, don’t drink anything till I check for bubbles in the piss tank.” When THAT sentence is comparable to
Earth: “Gosh, I think we’ll need to start a billion dollar desalination plant again or our almond harvest may fail.”
So, 4. Growth.
Science is easy, but its really easy when no one is checking your answers. I can define a specific spectrum as a “Magnetostar, magnetic-spinning neutron star” and have people nod wisely, but … its just a model. Heck, almost everything in Astronomy is just a model. (Really, really good models, don’t get me wrong, this is science, but we can’t really check the answer, can we?)
Engineering isn’t like that. When we build something, you can kick the tires, or whatever it has, and determine if it is better than the previous model. But if you want something good in the future, start building in the present.
In time, humanity will move into space as a natural progress. We will find ways to survive in the big dark, we will extract resources – sunlight is the easy one – and build habitats. In time, we will have an Interplanetary Civilization. Each build is hard, each round of improvements will take decades. People will die. Habitats may fail. But, this is growth.
The development of one project for the International Space Station improved water reclamation from waste by over an order of magnitude. ECLSS.
Before, we only reclaimed less than 50% of water, now we reclaim 95%. A person used over a cubic foot of water a day, now that is down to cubic inches. Improvements will continue to be made, but they don’t happen automatically.
And those way-out science models drive some of these concepts. When we see a light curve that indicates something passing in front of a star, we get an idea of size. It blocks 20% of the sun’s light… wow, that’s big. It has weird gaps in it… it is cloud-like? It might be a meteor swarm, or it might be a habitat cloud.
Unfortunately, at over 1000 light years, it is unlikely that we’ll ever get answers of engineering questions from these aliens, if they exist. But, if the engineering is possible, we will do it and I’d prefer sooner to later.
As I mentioned last time, in The Future of Space Flight – Nuclear Propulsion, the nuclear thermal engine is a necessary step for moving cargo and fuel in near-Earth Space. This isn’t to say that nuclear engines aren’t capable of taking us to the outer planets, but the ISP gains still leave us shipping a huge amount of fuel. In the distant future, we may have a fuel depot in the outer planets. I can envision a robotic ice station in Jovian orbit, however, it isn’t near or necessary.
I’d rather not get into the depths of ISP, there is a Wikipedia if you need it, but lets just say that the push part of a rocket has 2 parts (theoretically) the mass of the engine and the mass of the fuel. The ISP really just talks about the fuel needed. ISP of 500 means that 1 tank of fuel gets you to … lets just say 10 km/s. If your ISP changes to 1000, you’d only need 1/2 a tank of fuel to get you to 10 km/s. If your ISP goes to 10,000 – you only need 5% of the fuel your first space ship needed. This leaves out that the engine might weigh ten times more. Meh, Rocket Science is hard.
What is best for near? Ion drives. The Nuclear Thermal engine has an ISP around 1000 s. Maybe, when they cross an MWatt, they may look at one of the enhanced propulsions, which may lead to 2000 s ISP. BUT, that starts trading on excess electric power, which is excess weight. (Not as excess as all that, since you could assume that the delivery of cargo included delivery of a working nuclear reactor, but, this works with Ion drives as well.)
Ion drive? From Hall Effect to VASIMIR, they involve the same things:
- Heat something up a lot. (Argon, Helium, Lead) till it becomes an ionized gas. (Shoot the lead with a laser, works fine.)
- Confine and heat the plasma
- Let the Plasma Escape, slowly, at great temperature.
The VASIMIR has a low-ish ISP, around a few thousand, but the thrust can be significantly higher than Hall Effect thrusters.
VASIMIRs are good for near planets, where the balance of thrust and low fuel use gives you short mission times. You may drop the Mars trip, a distance 1 – 3 AU depending on date, to six months or less. Very reasonable. Jupiter, at a distance of 4 -6 AU, would take about a year. However, at that time, we start getting in fuel to mass ratio issues again.
The Hall Effect Thruster may have an ISP on the order of 40,000.
What does that “MEAN?” It means that a ship with a Hall Effect thruster will have a very high final velocity. It may take years to reach that velocity. Hall Thrusters usually run about a ten micro G. A push felt that would leave an adult male weighing in at 220 lbs on the Earth, at about 1 gram on the spacecraft. Literally, you couldn’t feel the thrust.
Now, Alta’s Hall thruster has much lower ISP (factor of 10) and much higher thrust (factor of 10) than theoretical, but that’s one of the trade offs. If you design a mission, the farther away you are going, the lower, constant, thrust you can deal with if your ISP is high enough.
Your final velocity could easily be in the 10’s of km/s. Velocities like that let you get to Pluto with enough fuel left to park, not just fly by into infinity. Had the mission designers agreed to a better power supply for the New Horizon mission, then they could have selected an Ion drive, and be parked around Charon as we speak.
Not that I think Pluto is anything but a big comet, but think about a decade of data, instead of one picture. That’s the future of spaceflight.
I’ll get back to my future of space flight next time, but I got distracted by a funny story, so I’ll tell you all one. This is a story about a Soyuz, a Soviet era manned crew vehicle that astronauts and cosmonauts have used to get to the ISS, Mir, etc.
Figure 1. From the top, the escape rockets, the Soyuz capsule, the Soyuz spacecraft, the other 90% is rocket.
Figure 2. A perfectly good landing of a Soyuz Capsule
Initial Note: The temperature is measured at present at 0.5 degrees above baseline. The temperature increase from baseline may be caused by many factors, including CO2. Experimental data is needed to verify the models.
We can thank Dr. Hansen for his work disproving the effects of CO2 on global temperature. His work appears to disprove the catastrophic anthropogenic global warming theory. I understand, that as he has made millions of dollars promoting global warming, he probably doesn’t see this result as publishable.
Figure 1. Hansen’s models of global warming following a steady increase in our production of CO2 (1.5%), a continued production of CO2 at the current (year 1989) rate, and an abrupt halt of producing CO2.
On Figure 1, you can see that Dr. Hansen predicts a large increase in temperature driven directly by the increase of CO2 in the atmosphere. Temperatures by 2015 are 1.5 degrees above baseline. While the US and Europe have reduced production of CO2 significantly, world production of CO2 remains significantly above year 2000 levels, leading to the top line prediction being the predicted outcome.
Figure 2. A combination of Figure 1 and current temperature data.
On Figure 2, you can see the current temperature data plotted along with the predictions made in Hansen’s model. It is clear from observation that, with the exception of 1998, the data falls along the lowest line of prediction. 1998 has been explained as a specific Pacific Ocean event, resulting in the hottest year on record.
Conclusions: The model which contained no CO2 forcing more correctly predicted the future than either model which contained CO2 forcing. CO2 forcing does not appear to correctly predict future temperatures.
Further Study: CO2 is known to absorb specific bands of IR light at 2349 cm−1 and at 667 cm−1. Addition of CO2 does increase absorption of heat in the atmosphere at those two wavelengths, however, those wavelengths may be sufficiently filled such that no further addition of CO2 causes added absorption. However, that is just a theory and needs further modeling and experimental data to prove. Alternatively, the current heating may have nothing to do with CO2. The CO2 heating may become significant at some future partial pressure. Again, modeling and testing is needed to quantify this assertion.