Interstellar peoples community starship.

[silverslith]

With what I've been finding out regarding the nasty properties of energetic protons in space and particularly the radiation belts around magnetic planets, I'm real glad we have powerful magnetic fields at our disposal in the IPCS.

 

BBC NEWS | Science/Nature | Space shield to block radiation

British scientists are planning to see whether a Star Trek-style deflector shield could be built to protect astronauts from radiation.

They argue that magnetic shields could be deployed around spacecraft and on the surfaces of planets to deflect harmful energetic particles.

 

Several countries' space agencies have announced their intentions to resume human exploration of the Solar System.

 

Scientists hope to mimic the magnetic field which protects the Earth.

 

Details have been presented at the Royal Astronomical Society's National Astronomy Meeting in Preston, UK.

 

There are a variety of risks facing future space explorers, not least of which is the cancer-causing radiation from cosmic rays and solar flares that astronauts will encounter when they venture beyond the Earth's protective magnetic envelope, or magnetosphere.

 

The nice thing is that magnet technology is really quite evolved here on Earth. The question is can you take it into space?

 

Mike Hapgood,

Rutherford-Appleton Laboratory

 

The Earth's magnetosphere deflects many of the energetic particles from space; others are largely absorbed by the atmosphere.

 

Between 1968 and 1973, the Apollo astronauts were only in space for about 10 days at a time.

 

They were simply lucky not to have been in space during a major eruption on the Sun that would have flooded their spacecraft with deadly radiation.

 

Crew members on the International Space Station can retreat to a thick-walled room during times of increased solar radiation.

 

Stable field

 

But these protective shelters would not be practical on long-duration space journeys, since the "drip-drip" of energised particles is thought to be as harmful to the health of astronauts as large solar storms.

 

 

Potentially damaging solar activity is hard to predict

 

The harmful particles come from the Sun, in the form of the solar wind, and from sources outside our Solar System.

 

To create the deflector shield around a spacecraft or on the surface of a planet or moon, scientists need to generate a magnetic field and then fill it with ionised gas called plasma.

 

The plasma would held in place by a stable magnetic field (without the magnetic field, the plasma would simply drift away). This shield could be deployed around a spacecraft or around astronauts on the surface of a planetary body such as the Moon.

 

As energetic particles interact with the plasma, energy is sapped away from them and they slow down.

 

"You don't need much of a magnetic field to hold off the solar wind. You could produce the shield 20-30 kilometres away from the spacecraft," explained Dr Ruth Bamford, from the Rutherford-Appleton Laboratory in Didcot, UK, one of the scientists on the team.

 

Dr Mike Hapgood, from the Didcot-based research centre, told BBC News: "The nice thing is that magnet technology is really quite evolved here on Earth. The question is can you take it into space?'"

 

The team from Rutherford-Appleton plans to build an artificial magnetosphere in the laboratory. They would eventually like to fly a test satellite which would test the technology in space.

 

'Shields on'

 

The idea has been likened to the deflector shields which protect the USS Enterprise and other spacecraft in Star Trek. Like their fictional counterparts, these shields could also be switched on and off.

 

 

The planned moon base will be exposed to solar radiation

 

An artificial magnetosphere could come in handy anywhere in the Solar System where humans would need to be for long durations.

 

A permanent Moon base, of the type Nasa plans to build, could be buried under lunar soil to protect the occupants and equipment from space radiation. But inhabitants will still be vulnerable when venturing outside in their spacesuits.

 

"Our warning systems aren't very good [for solar flares]. You might be able to say: 'this is a dangerous period in terms of solar activity', but you might be on red alert for weeks," said Dr Hapgood.

 

"If you've got a problem, you might not want to wait a week to fix it. You might want a device to deploy on the surface as a shield that would blunt the effect of a flare at ten minutes' notice, it adds an extra level of safety."

 

The idea for the shields draws on technology pioneered in experimental nuclear fusion reactors. Nuclear fusion is not yet a mature technology.

 

It works on the principle that energy can be released by forcing together atomic nuclei rather than by splitting them, as in the case of the fission reactions that drive existing nuclear power stations.

 

At the Jet experimental fusion facility at Culham in the UK, magnetic fields were used to keep plasma away from the interior wall of the reactor.

 

This represents a reversal of that technology: "We want to use the same technique to keep an object in the middle away from plasma that's on the outside," said Dr Bamford.

 

But the plasma needed to protect against particles from the solar wind and elsewhere would actually be weaker than that generated in experimental fusion reactors like Jet.

[CraigD]

With what I've been finding out regarding the nasty properties of energetic protons in space and particularly the radiation belts around magnetic planets, I'm real glad we have powerful magnetic fields at our disposal in the IPCS.

]British scientists are planning to see whether a Star Trek-style deflector shield could be built to protect astronauts from radiation. …

A strong artificial magnetic field is great for protecting against charged particles – though designing one that doesn’t allow or even encourage them to strike the ship at the magnetic poles of its magnets is challenging.

 

Bamford, Hapgood, et. al. are even more ambitious, proposing to also use the magnetic field to hold a plasma (atoms with their electrons disassociated from their nuclei) in order to protect against uncharged particles (high-energy photons, presumably). I’ve long been somewhat puzzled by such proposals, as plasmas tend to be emitters, not absorbers of photons. Absorption depends largely on the electrons being associated with discrete orbitals around their nuclei, a rare state in most plasmas. I’d need to see some experimental results before dismissing my suspicion that these scientist/technologists are simply misguided in this proposal – a quick home experiments, using a laser pointer, plasma globe, stick incense and jar, reveals that the apparent opacity of the visible sheets and blobs of plasma in these devices is an illusion, having no noticeable effect on the brightness of a laser beam passing through them – or, in other words, plasma doesn’t cast a shadow. A quantum physical explanation of why this is so eludes me, but it appears to be.

 

Once your spacecraft is out of the domain of low velocity flight around stars and planets with dangerous charged particle radiation, and into the domain of interstellar flight at speeds greater than .01 c, the threat of collisions with uncharged particles begins to dominate. At a speed of .01 c relative to the interstellar medium, neutral hydrogen, with a density of about [math]1 \, \mbox{atom/cm^3}[/math], now has an energy of about 50,000 eV/atom, for an energy flux of about [math]1.5 \times 10^{11} \, \mbox{eV/cm^3}[/math], about 1000 times the peak of the Earth’s Van Allen belts. Worse, data from sources like NASA’s Ulysses solar polar orbiter suggest that for every trillion or so H atoms, a dust particle massing about [math]10^{-14} \, \mbox{kg}[/math] or larger will be encountered. Depending on how much larger, such a collision could be catastrophic.

 

A solution of Robert W. Bussard’s (famous for the Bussard ramjet spacecraft concept) is to assure no uncharged matter exists in the path of your ship by sweeping the space with powerful lasers, reducing everything to ionized plasma.

[silverslith]

I think the logic of the trapped Plasma in the field bubble is to provide a friction force and for ionisation for the uncharged particles and a friction to slow down the charged particles that are trapped by the field.

Neutrons are pretty rare and do little damage as they go right thru you with little chance of a collision.

Fortunately photon radiation won't be affected by the crafts velocity and its much easier to shield with a hull than high energy protons which are by far the largest hazard. Gamma and xrays are much lower in flux density out there anyway.

The cylindrical field of the EM drive in the IPCS may be better than a normal polar magnetic field, and a combination of both may be possible with no dead spots.

[CraigD]

I think the logic of the trapped Plasma in the field bubble is to provide a friction force and for ionisation for the uncharged particles and a friction to slow down the charged particles that are trapped by the field.

Possibly. The dynamics seem complicated, and not clearly described in the BBC article. The original literature my be more clear.

Neutrons are pretty rare and do little damage as they go right thru you with little chance of a collision.

I think you’re confusing neutrons and neutrinos.

 

Neutrinos are very common (the Sun produces about [math]2 \times 10^{38} \, \mbox{/s}[/math], nearly 100000 times the number of solar wind particles), but so weakly interacting that they’re almost impossible to detect.

 

Neutron radiation is a major kind of potentially dangerous radiation. It’s associated with both nuclear fission and fusion, and is responsible for the nuclear fission chain reaction. It’s very dangerous to biological life, a characteristic exploited by the neutron bomb, a type of “enhanced” fusion (“H”) bomb that kills while doing comparatively little physical damage. Neutrons induce radiation in target atoms, and can transform target atoms into radioactive isotopes, as well as damage crystal structures, causing materials to become brittle or “swollen”. They’re more difficult to shield against than electrons and neutrons, requiring many light atoms (eg: H2O) rather than few heavy ones (eg: lead shielding). Unfortunately, most plant and animal tissues are good neutron shields, so neutrons can penetrate ordinary radiation shielding (eg: lead aprons), preferring the human being behind it.

Fortunately photon radiation won't be affected by the crafts velocity and its much easier to shield with a hull than high energy protons which are by far the largest hazard. Gamma and xrays are much lower in flux density out there anyway.

True, but the hazards of uncharged particles – non-ionized atoms, dust grains, or even the occasional large body shouldn’t be ignored.

 

I can’t see how magnetic shielding can work without some sort of ionizing system, such as powerful lasers – unless the magnet is so strong it can ionize neutral atoms (strip them to plasma).

[silverslith]

cheers Craig.

Your right, neutrons are best absorbed by protons in hydrocarbons or water. Still at decent energies they mostly pass through stuff as dense as u238 metal 7cm thick without hitting anything at all. Interesting physics with this in nuke bombs. While the tamper-a shell of 10cm thick 238 would normally let most escape, the pressure vs inertia compresses them to several times the normal density making them far better neutron reflectors, and providing often more energy than the core through fast neutron fission. The deuterium in an H bomb also provides less energy, mainly being a neutron multiplier for an outer u238 shell.

Neutrinos are far more common in space and thank the creator of our universe they don't affect much at all, passing through the earth with only small percentage losses.

[JoeRoccoCassara]

This is a what if question.

 

Say for some reason the IPCS had to use all of its fuel when it had been out of orbit for 5 days (Everything that the nuclear reactor could produce in 5 days) and go as fast as it could. How fast would it go?

 

 

I know that its a stupid question, but its on topic and I have to get my post count up.

[silverslith]

This is a what if question.

 

Say for some reason the IPCS had to use all of its fuel when it had been out of orbit for 5 days (Everything that the nuclear reactor could produce in 5 days) and go as fast as it could. How fast would it go?

 

 

I know that its a stupid question, but its on topic and I have to get my post count up.

 

OK. by out of orbit, what is meant?

1.) on the surface of an earth like planet, lets say earth for arguements state.

2.) in interplanetary space.

3.) in interstellar space.

Now assuming that burning all your energy and having no way to make more is not the situation as its a very bad situation to put yourself in:

1.) The reactor is reved up with protons from an internal storage loop and injected with a near critical mass of actinides kept available for energetic proton scarce situations. Or hafnium batteries are used if the technology has matured. The force from EM thrust against earths field is assumed to be at worth at least 1g acceleration within the earths magnetosphere as this is well within current superconducting technologies. So 36000m/s or130000 kmph, less gPE is achieved after one hour, ~0.5-1million kmph by leaving the magnetosphere in 5 hrs. If its a bigger planet with a stronger magfield more to a lot more. We don't land on silly little planets with no magfield, they are not worth the effort.

2.) we don't hang around in interplanetary space. If we are there we are going somewhere else. If we are going fast enough we can use solar wind protons scooped by the magfields as well as internal stores and actinide backups to rev our reactor and stock our fast particle stacks. Within an hour we can launch at crew bearable g's in whatever direction. (hopefully). Driving through dust belts and radiation belts will help pick up fuel and reaction mass if we are short.

3.) We are going at over 30 000 km/s probably close to 300 000 000 km/s. We are impatient folks and don't like to waste time between star systems. We would not be there without sufficient high energy particle stacks to stop and these are also the loud pedal for our reactor. Also at that velocity, interstellar protons are fast and ready to be scooped into our reactor. Any junk lying round the ship could be processed by the reactor and turned into highly energised thrust particles.

[JoeRoccoCassara]

Ok, thanks for answering.

[silverslith]

No problem. I enjoyed it. Talking to myself is boring.:phones: