Interplanetary Radiation, Shielding, and Fatality

[Muchoman798]

Interplanetary Radiation

Hello All! This is a thread for a general discussion on potential mods pertaining to interplanetary radiation. Talk about parts, details of radiation, and anything else here.

Why have radiation?

KSP is not a realistic game. There are many inaccuracies; sacrifices to make it practical to run and fun to play. Most of these have to do with the physics of the game. There are a lot of good compromises, but sometimes, they make the game far too easy.

An interplanetary mission should be a huge challenge. Building a tiny rocket that just does a little flyby makes things seem far simpler than they really are. There's no need to worry about carrying the massive amounts of food needed, nor blocking the huge amounts of radiation that would be faced.

Many mods have been made that add a bit of this challenge (like TAC life support.) However, I have not yet seen one that implements fatal radiation (KSP Interstellar has the ground work, but it isn't in yet.) By having the need to deal with radiation, a huge challenge arises in the game.

How would it impact gameplay?

Players would need to wait longer before sending a Kerbal to Duna or Eve, as they'd need to unlock the radiation shields. This would emphasize unmanned probes quite a lot more than at present. There would need to be much more mass or much more power output on most ships, making the design more difficult. Interplanetary travel would not be an easy task.

The technology tree would be slower to progress through, as players would only be able to advance to the manned interplanetary stage by, as mentioned above, flying probes. Using temperature senors, barometers, and other unmanned devices would roughly halve the science gotten from manned missions with crew reports, EVA reports, surface samples, and module cleaning. I think this would make the challenge of progress more fun.

Kerbals would face high chances of death from radiation poisoning if they weren't properly shielded. This could bring a higher need for larger crews, medical supplies, or probe systems in case of total crew death. Even Kerbals in orbit around the big blue potato would face risks. Rather than just leaving Kerbals in space stations for years and years, players would need to cycle them to keep risks low.

Landings would would become a huge challenge, if players wanted to establish lasting bases. Each pod would need more mass for the shielding, meaning more fuel, meaning more mass. It would also encourage Apollo-style landings, where a heavier craft stays in orbit and a landing vessel goes down independently. Otherwise, the shielded, interplanetary stage would face a huge challenge with taking off and entering orbit again.

Basically, any mod like this would just make the game harder, which can be more fun.

What would the mod entail?

A moderate amount of things. There'd need to be at least five parts, parts which provide shielding. There would also need to be a plugin in order to add radiation as a thing.

The size of this mod would depend on the depth wanted. It could only affect Kerbals, in which case it would be relatively simple. Or, things could be made more realistic, adding solar flares, damage to satellites, Van Allen belts, and detailed magnetic fields.

A wide range exists in between, with a number of potential compromises and abbreviations. Planets and low planetary orbits (<150km) could be made entirely safe. Maybe simply being within the sphere of influence of certain planets grants increased protection. While these things would greatly reduce the accuracy and challenge of the mod, they'd make it easier to create.

In addition, there would need to be some way to track the total absorption of radiation by each Kerbal over the duration of a mission, and a potential cool down when returning home.

Note: I do not think it'd be a good idea to distinguish alpha particles and EM radiation. This would make the amount of shielding needed far too high, as a ship would need multiple shield types. Any mod like this should add a challenge, but not make the game unplayably hard.

Parts? Parts.

The way I see it, this mod would not need a ton of parts. Some of them could simply be modified stock parts. Here is a list of what I think would be suitable:

Hitchhiker Storage Container w/ Lead Shielding

In essence, this would just be a much heavier version of the current part. The model could be changed to reflect this, with a bit of bulging in the middle, but other than that, it'd be a simple .cfg change.

This would be one of the earliest available shields, with fairly high effectiveness, and would be entirely passive. However, it is to be very heavy. The way to play with this as an interplanetary crew-pod

would be to switch all Kerbals to it once en-route to the destination.

Hydrogen-Rich Plastic Capsule

A plastic capsule. In a game where everything explodes, even pieces of solid metal. This is a passive, lightweight form of shielding, that works to block out about 60% of the interplanetary radiation. There

is one drawback however: the impact tolerance. I'd probably place it around 2.0 m/s (lower than anything else,) just to make sure there is enough of a drawback to keep this from being favorable. It would

also be high up on the tech tree. The only way this pod's abilities could be balanced is if high g-forces shattered it.

ElectroMagnet Shield

Two huge magnets placed at opposite ends of the craft. These would block out most radiation, and require a moderate amount of electricity. They would be less massive than the lead shielding, but more

massive than the Dynamo shield. This could probably be powered by a single XL solar panel, and would cease to function immediately after any power cut out.

Magnetic Dynamo Shield

This device would utilize the same concept as the Earth's geodynamo: a metal sphere would be rotating in a conductive, convective liquid to produce a magnetic field around the entire ship, protecting it

against most radiation. This shield would be active, requiring constant electrical input. It would continue to function after loss of current for several hours, maybe days, but not indefinitely. This shield type

would require a huge amount of electricity (6 XL solar panels,) but be less massive than the electromagnet shield.

Plasma Shield

A shield generating a layer of super hot plasma between the craft and outside space. This device would completely block out all radiation, including light from Kerbol. However, it would only create a cylinder

the crew capsules. Just make sure to turn it off before going on EVA. The power requirement would be around 8 XL solar panels, which would need to be attached away from the crew quarters. This sort of

shield would give two advantages: missions could go indefinitely, with no regard to radiation, and the mass of the device would be incredibly low. However, minor amounts of fuel (Xenon, probably) would be

consumed whenever re/starting the shield.

HotBox

A small device used in cases of extreme emergency. Should a solar flare occur, increasing radiation amounts, and the craft has magnetic shields, this is required to keep doses acceptably low. In addition, it can

serve as a back up for three days in case of a failure of other devices. After three days, Kerbals would need to switch back to the pod for at least two days. While this allows players to use only this on inter-

planetary missions, it would be incredibly tedious. Would house a single Kerbal if 0.5m, and three if 1.0m (meant to be attached on top of command pods.)

Directional Shield

Certainly the cheapest in terms of mass, this shield would only block out 40% of the radiation of an interplanetary voyage, if pointed directly at Kerbol. This is a rough approximation of solar radiation vs. galaxy

background radiation. This shield would be passive and of fairly low mass, though still higher than a Plasma Shield.

Decontamination Module

Used to treat radiation sickness in flight. Prohibitive for use due to its excessive mass, and high position on the tech tree.

Radiometer

Measures the ambient radiation level in several situations. A scientific instrument, functioning much like the thermometer.

Actual Interplanetary Radiation

Before coming up with a lot of these parts and ideas, I did a bit of research into what the actual radiation from an interstellar flight would be. If unshielded, a journey between Earth and Mars and back of 360 days could give an astronaut up to 1.5 Sieverts of radiation. This comes half a Sievert below "severe radiation poisoning." It can be fatal.

When shielded in a manner tested by the Curiosity rover, a one way trip produces about 0.5 Sieverts. NASA sets 1.0 Sieverts (Sv) as the lifetime limit on all of their astronauts, making the journey just barely acceptable. It should be noted, however, that the limit of 1 Sv is for a career of spaceflight, not a single year. A six month stay aboard the ISS gives the same dose as 20 years on Earth (roughly 20mSv.) So, the total from a trip to Mars and back gives roughly 1000x that of a year on Earth, and 25x that of a year aboard the ISS.

There are two primary sources of ionizing radiation during an interplanetary flight: solar radiation and galaxy background radiation (GBR.) In general, the two are comprised of different particles. GBR is made up largely of alpha particles, and solar radiation is mostly high-energy electromagnetic radiation. These two radiation types interact differently with shields. Lead protects well against EM radiation, but amplifies alpha particle effects (over short distances.) Water (particularly salt water) works well against alpha particles, hence its use in nuclear cooling pools (which you can swim in, actually,) but very, very poorly against EM radiation.

When in a magnetic field, the radiation levels quickly drop off, unless something is in a Van Allen belt. Here, they spike to levels higher than in interplanetary space. Atmospheres further diminish the effects of radiation.

Well, that seems to be all. Please leave your thoughts and comments on all of this below. I mainly want to know if people would like to play with this mod, were it to be made.

[Dwight_js]

I would be very interested in this mod. I would suggest that there should be a calculator built in to help you estimate how long a Kerbal can survive in different situations given the amount and type of shielding on a craft in the VAB (like the TAC Life support caltulator). The values it spits out could be dependent on research that you have done in the different environments, which would further encourage players to send probes with radiation sensing devices out into space and to the surface of other planets before going with a manned mission.

For solar flares, I'd like there to be some way to set up an observation/early-warning system so that you can plan the orbital maneuvers of ongoing missions accordingly - ie, delay a burn or launch if you know your Kerbals are going to have to be in the lead box in a few hour's time.

Great job on the concept though.

[Mr Shifty]

There are two primary sources of ionizing radiation during an interplanetary flight: solar radiation and galaxy background radiation (GBR.) In general, the two are comprised of different particles. GBR is made up largely of alpha particles, and solar radiation is mostly high-energy electromagnetic radiation. These two radiation types interact differently with shields. Lead protects well against EM radiation, but amplifies alpha particle effects (over short distances.) Water (particularly salt water) works well against alpha particles, hence its use in nuclear cooling pools (which you can swim in, actually,) but very, very poorly against EM radiation.

Great idea for a mod. Just a couple clarifications here:

- Both solar and galactic harmful radiation are mostly particulate, that is they generally consist of charged particles (protons, electrons, atomic nuclei), not EM radiation.

- Most galactic radiation (85%) is actually protons, not alpha particles (helium nuclei), though there is significant population of alpha particles.

- I gather that that main difference between GCRs (galactic cosmic rays) and SEPs (solar energetic particles) is that GCRs are a relatively constant background that give a radiation dose over time, while SEPs can erupt into high intensity flares (e.g. solar proton events) that can be lethal very quickly. (In radcon circles, we term these "chronic dose" (accumulates over a longer time span) and "acute dose" (short, high intensity dose.)) GCRs are also higher energy than SEPs and thus are very difficult to shield by any method. (Well, a giant magnetic flux belt and 100 km of atmosphere seem to work pretty well.)

- Shielding: It's not that lead, particularly, amplifies GCRs, it's that most structural materials, when bombarded by cosmic rays, emit secondary radiation in the form of high energy neutrons (like a cue ball hitting another pool ball.) The high energy neutrons themselves pose a radiation hazard and have to be slowed down using materials like polyethylene or water, and then captured using materials like lithium or boron. A tertiary effect of the neutron capture reaction is that EM radiation (gamma rays) are emitted, which have to be shielded against using a dense material like lead.

- Dangerous EM radiation (x-rays and gamma rays) from the sun is relatively rare; it typically only occurs during intense solar flares. There is (apparently) a diffuse gamma ray background throughout the inner solar system because of interactions between the sun's light and cosmic particulate radiation, but I don't gather that's a worry for human space exploration.

- Salt (sea) water is not good for shielding because it would corrode metal parts, and because the ionic impurities in the water become radioactive when exposed to radiation. Salt water is normally used for tertiary cooling (i.e. condensing steam after it's passed through a turbine). It's only used for direct cooling (and/or shielding) in an emergency. Boron is often added to shield water though, for its neutron capture capability.

- The effectiveness of any shielding depends on how much shielding is between you and the radiation source. Additionally, shield water produces capture gammas, which must be shielded against with additional lead or iron shielding. In other words, swimming in a cooling pool or shield tank is probably not a good idea.

- Lead is a great material for terrestrial shielding projects. But it is extremely heavy and is a terrible structural material because of its softness and low melting point. It's also poisonous to touch.

[Nicholander]

This idea NEEDS to be made into a mod! And i think it should be more complex, but not to complex, with the some of the stuff that was put in the "What would the mod entail?" section.

[astroboy820]

Although I've never created a mod, it doesn't seem like a very hard concept to create. It would take the actual solar system data of radiation reading and scale it to KSP specs. I think that if someone were to work at it for a bit, it would take a few hundred lines of code and it would be done. I don't know C#, but I could probably code the plugin in Java but that wouldn't help anybody...

[Redjoker]

To simplify the process, the interstellar mod already models radiation levels in different areas of space although there are currently no effects. You could use it to model how much radiation the kerbal would receive. I believe it also calculates some shielding on command pods that could be altered on a pod by pod basis for the types of parts you are planning.