Project Orion Revisited. - Why not an Earth Launch?

soph · 2002-12-14 10:39:04

if the fallout can be contained, then it would be very attractive. maybe a specially designed shield around the launch site. if it could be designed so that pulses were only needed at the launch site, and not in the atmosphere, then all the radiation from launch could be contained within the launch site. once outside of the atmosphere, the danger is gone.

RobertDyck · 2002-12-14 20:41:12

I will add a little fuel to your fire. I heard about a year ago that scientists found that an electron beam combined with a laser to strike each electron with a photon of a specific energy caused the electron to flip into a positron. This permits creating positrons with much less energy; and, most importantly, creating positrons without a cyclotron. Since the neck of every computer monitor and TV picture tube has an electron gun, this has the potential of creating positrons with a very compact device.

But your post uses the word "antipositron". A positron is the same as an electron but with a positive charge instead of negative. A positron added to an antiproton creates antimatter hydrogen. Are you talking about positrons or negative matter? Negative matter is theoretically composted of negative energy and exhibits negative gravity. However, it has never been observed or otherwise proven to exist. Are you talking about positrons, also known as anti-electrons? The prefix "anti" usually referrs to reversal of charge. That would make an antipositron just a normal electron. Is that what you're talking about?

Shaun Barrett · 2002-12-15 06:22:33

Hi Robert!

I noticed that "antipositron" thing too and just assumed it was a slip of the pen. Since an antipositron, as you say, would be a plain old-fashioned electron(! ), I assumed they meant positrons.
Nevertheless, confirmation of that would be interesting ... and confirmation of the whole story would be very exciting indeed!

Something else I noted was your comment: "Negative matter is theoretically composed of negative energy and exhibits negative gravity. However, it has never been observed or otherwise proven to exist."
I'm not sure from this whether you mean that negative matter or negative gravity has never been proven to exist?
Negative matter, anti-hydrogen, has in fact been produced in considerable quantity, but whether or not it exhibits negative gravity has yet to be determined.

This is an interesting article which appeared only a matter of weeks ago. I remembered reading somewhere that anti-hydrogen had been created, but I was surprised at just how much of it!!
:0

This whole CERN report has got me intrigued! If anybody hears anything more about it, I'd be very grateful if they would take a minute and post it here.
Thanks ahead!

RobertDyck · 2002-12-15 08:18:31

Some physicists speculated based on symmetry that matter composed of energy may be balanced by negative matter composed of negative energy. If it exists then a reaction of normal matter with negative matter would not explode, they would just quietly cancel each other. Then matter would have 4 states: normal matter, antimatter, negative matter, and negative antimatter. Antimatter is matter with the opposite static charge. The universe has various asymmetries so there is no reason negative energy has to exist.

This isn't the first time CERN created antimatter. I remember reading several years ago of their first success, that time they weren't able to contain it; they could contain antiprotons but antihydrogen lasted a fraction of a second before it hit a wall and destroyed itself. They can contain it now, but 1 mole of hydrogen atoms masses 1.0079 grams and 1 mole is 6.02*10^23 so 50,000 atoms is really not much.

Phobos · 2002-12-15 13:51:46

I bet politics will kill the commercial production of antimatter even before it becomes a reality. If people go nuts about fission and fusion they're definately going to demand the end to antimatter production since it helps create the ultimate nuclear reaction. My crystal ball shows treaties rolling down the pike that prevent the use of antimatter in space and just about anywhere else.

soph · 2002-12-15 14:03:11

i doubt it. if its kept under the rug until it becomes mainstream, it can work. just call it "highly advanced propulsion technology"

Echus_Chasma · 2002-12-15 15:46:47

Let me get this right, I'm only 14 and this stuff is like whoosh over my head. :-P

Anti-matter is pretty much the same as conventional matter except that the charges of the electrons and stuff is opposite.

Is that right? Could some-one elaborate it a bit more for me so that I can understand.

Thanx.

soph · 2002-12-15 15:52:09

well basically. im just about your age, and from what i gather, negative charge is at the center, and positive is at the outside. this causes the normal matter to go nuts, and they kill each other. this creates a lot of power.

Echus_Chasma · 2002-12-15 15:58:07

Aha, that sounds quite cool.

Cheers.

RobertDyck · 2002-12-15 16:38:18

Ok, so I was an instructor at Red River College for a year. I taught introduction to computer programming using C language. Now "Professor Rob" gets to explain physics.

Every atom has protons and neutrons in the nucleus, and electrons orbit around it. Protons have positive charge, electrons have negative charge, and neutrons have no charge but do have magnetism. The number of electrons will always be the same as protons, unless it has static electric charge. The number of neutrons can very, but neutrons keep the protons from pushing each other apart, they keep the nucleus together. Protons and neutrons are relatively heavy, electrons are light-weight but fly around very fast (a fraction of the speed of light). Interactions of the electrons cause chemical reactions, but the number of electrons are determined by the number of protons.

Now antimatter has all the charges backwards. Antiprotons have a negative charge, anti-electrons have a positive charge, and anti-neutrons have a magnetic field that's oriented backwards. To make it more complicated somebody decided to give a name to anti-electrons: they are called positrons. If a positron and an electron collide they will convert all of their mass to energy using Albert Einstein's famous formula E=MC^2. However, electrons and positrons don't have much mass so that doesn't give much energy. Protons have roughly 1835 as much mass as an electron so if a proton and an antiproton collide they release a great deal of energy. A neutron masses about as much as a proton plus an electron (actually a little more), so a neutron and an antineutron will also produce a lot of energy if they collide. If a positron hits a normal proton nothing will happen, they will just bounce off. You have to get opposite charges for the reaction. Actually, if an electron hits a normal proton it will create a neutron. The proton/antiproton reaction releases all of its mass as energy so that is a very rich fuel. Neutron/antineutron reactions would also produce energy, but since they don't have a static charge they are harder to contain.

A fission bomb, also known as an atom bomb, converts less than 1% of its mass to energy. A fusion bomb, also known as a thermonuclear bomb, converts more of its mass to energy, but it is still less than 1%. An antimatter bomb would convert 100% of its antimatter plus an equal mass of matter to energy. Since antimatter is so expensive and difficult to contain, a thermonuclear bomb will always be a more effective (dangerous?) weapon. However, antimatter could be a very powerful rocket fuel.

Of course there are complicating details. If you accelerate a proton or neutron to close to the speed of light it will gain mass. Relativity determines how much. The energy released by a proton/antiproton reaction does not remain as pure energy for long; in a faction of a second some of it is converted into new subatomic particles. There is no control over what new particles are created. A great deal of the energy is released as radiation and heat.

soph · 2002-12-15 16:42:06

so i kinda had the right idea?

Echus_Chasma · 2002-12-15 17:05:10

Ahh, I get you now.

Cheers heaps.

Shaun Barrett · 2002-12-16 00:31:18

Hi Robert!

Going back a few posts to my question to you about negative matter - I was barking up the wrong tree!
I understand now what you were referring to ... thanks for the clarification.

I appreciate the enormous difference between 50,000 atoms and 6*10^23 (Avogadro and all that! ), but I am still amazed at the 50,000 anti-hydrogen atoms!! I was imagining a few dozen or something along those lines!

I'm still hanging out for more information on what's happening at CERN, though. If there's any truth to that story, it sounds like somebody could have stumbled upon a new way to produce a lot of energy in a short space of time ... more than the fire extinguishers could cope with anyway!!

Actually, it only just occurred to me to qualify my jocularity by expressing the reservation that I hope nobody was injured in the alleged incident.
???

RobertDyck · 2002-12-16 06:02:21

The CanDu reactor (Canadian Deuterium) is a heavy water reactor. It is much safer than 3 mile island. The Pickering reactor had the worst accident possible with a CanDu reactor: it leaked radioactive coolant into the lake. They had to close the beaches for 2 weeks; that is all. No casualties, no irradiated cows. Furthermore a 3 Mile Island style reactor has to be shut down for about 3 months to refuel. The CanDu can replace its fuel without shutting down. They use robots to remove spent fuel rods while the reactor is operating (radiation is too high for humans to do it). Any heavy water reactor cannot melt down like 3 Mile Island, and cannot explode like Chernobyl. If you don't want to buy a Canadian design then any heavy water reactor would have the same advantages. The only down side to CanDu is that it is the second most efficient producer of plutonium (military breeder reactors are first), and it is THE most efficient producer of tritium. Despite the fact that India and Pakistan signed contracts that they wouldn't use CanDu reactors or Canadian nuclear technology to produce bombs, they did anyway. That is why Canada is embarrassed and so strongly against nuclear weapons in the subcontinent. However, I believe that modern heavy water reactors are safe. I strongly believe in nuclear power and every nuclear technology in space except Orion. Pardon me if I don't want to ride on nuclear explosions. Nuclear reactors on Earth require safe recycling of nuclear waste, and that should be factored into operating cost of a nuclear power plant. Europe has already demonstrated this can be done, and further work in nuclear recycling is just technology development. However, I do not want to tie a manned Mars program to another issue that has political opponents. Nuclear power would greatly enhance manned exploration of space, and the current U.S. administration is willing to pursue it, but I don't want to make it a prerequisite.

TJohn · 2002-12-16 11:02:18

As I've said before, Orion IS the best chance of getting a permanent manned presence back into space and nuclear power IS a must for the manned Mars mission. Maybe combine the two technologies to achieve both goals. If we keep hedging, stalling, and constantly being afraid to put nuclear power to an even better use, then be prepared for mankind never to leave the planet.

soph · 2002-12-16 14:03:04

Nothing since, the environmentalists prophecies of endless catastrophes have been proven to be nothing but babble. I think it's nuclear or nothing.

if something works, we should use it, whether or not it comes with the nuclear tag in it.

what im saying is, if its safe and effective, we dont have to throw it out because its not nuclear. and vice versa.

and i support nuclear power, but chernobyl didnt seem like babble to me. neither did hiroshima or nagasaki. now, dont take this and say im anti-nuclear, im not. but you cant be too extreme either way. saying there are no drawbacks to anything is ridiculous.

Preston · 2002-12-16 22:00:45

That is the number of deaths (~26) that came immediately to fireman and other workers at the time of the accident. But from thyroid cancer and other such events, we find that "Figures from the Ukraine Radiological Institute suggest that over 2,500 deaths were caused by the Chernobyl accident." (http://www.chernobyl.co.uk/) 135,000 were evacuated.

Nuclear power is, of course, much safer now.

AltToWar · 2002-12-18 05:14:41

1: there is a difference between reciving a small dose of radiation, and actually ingesting/inhailing radioactive particle that emit small doses of radiation.

the first is reletively harmless, the second will continue to increase your risk of cncer for the duration it is within the body.

there is a direct link between the total amount of radiation over time one recieves and the odds of getting cancer. A brief exposure to small amounts of radiation is trivial (yet do indeed increase the risk of cancer, trivially). Ingesting a particle creates a constant amount of low level radiation that will increase the risk of cancer considerably as long as the particle is within the body.

2: Is it not just as ignorat to blanketly reject any concern over radiation and health issues as it is to blanketly condemn nukes?

Just admit it, your the Tim Taylor of Rockets You would love a Fission Pulse Lawnmower! Admit it!

Austin Stanley · 2002-12-18 13:50:00

Don't completely dismiss the Ukraine Radiological Institute results. There is some truth there. The rates of thyroid cancer in areas effected by the fallout have risen dramaticly. For example my girlfriend's mother who lives in Minsk, Belaruss as well as her best friend and about half the people in their Church have thyroid cancer. Thankfully, my GF's mother and her best friends cancer is not malignet. However, not all there friends at the church have been so lucky. To my knowlege one has died from the cancer, and several have had to have there thyroid's removed in response. I worry constantly about my Girlfriend, a native Belarussian, who lived in Minsk up untill 1999. She was only 4 at the time and should be at a much greater risk than her parents. I'll be the first to point out here that the plural of these ancedotes is not data. But to say the disaster didn't have a signifigant harmful effect on people's health and lives is not true. It's surely effected my life and I don't live anywhere near the Ukraine!

I still belive in nuclear power, as does my girlfriend, but it a tool we must treat with respect. And we shouldn't idly dissmiss dumping nearly 200 tons of radioactive material (like what happened at Chernoable) as no big deal! Thousands had to be rellocated and over a hundred lost there life directly due to the incident. It IS a big deal, and we should be carefull with these tools.

Phobos · 2002-12-18 14:14:33

It's a shame the Chernobyl style nuclear plants ever came into existence. People are quick to use them as fodder against nuclear power even though most Western plants don't use that dangerous design. The Chernobyl type plants used graphite instead of water as a moderator which means that once the water is gone the reaction steps us and causes a meltdown. And I know water is a moderator but meltdowns are a lot less likely in modern designs because water acts as both the moderator and the coolant. Once the water is gone the reaction stops. The Chernobyl plants also lacked a lot of the containment features that Western plants have. As far as the statistics on death and environmental damage go fossil fuels are definately th worse. If we switched to hydrogen fuel produced by nuclear power plants the chances of giant oil slicks like those that happened in Spain and Alaska would be greatly reduced and no longer would our lungs be tortured by the toxic, acid rain and global warming causing chemicals that are constantly pumped into the air from coal and gas burning plants.

soph · 2002-12-18 14:31:16

ive heard that theyre shutting down nuclear plants across the US and Europe. if theyre truly safe, its a shame. i guess we'll have to wait until fusion comes out for widescale nuclear power.

btw, how do the radiation and waste stats of fusion compare to those of fission?

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Re: Project Orion Revisited. - Why not an Earth Launch?

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