# Kerbal Health
This mod introduces many aspects of astronauts' health management to KSP. It makes the game more challenging but also more realistic, encourages smarter mission planning, and adds to the fun. It works well alongside most popular mods.
The following factors may affect kerbal's health:
You can adjust all factors' effects in the Difficulty Settings. Quirks of a kerbal may also affect their health factors. You can check current values for a specific crew member in the Health Monitor.
Certain parts (such as Hitchhiker and crew cabins) can additionally reduce the effect of a health factor (Confinement in this case) allowing for much longer and healthier flights, at a cost of Electric Charge. Hab rings in some mods can help overcome Microgravity issues for long-term stations and interplanetary missions while cupolas alleviate Loneliness.
One of the drains on kerbals' health is Stress. Stress may be reduced in two ways (combinable): training and having colleagues on board.
Training level for a part can range between 0% and 100%, and the vessel training level is its parts' weighted average with weights being their Complexity.
Kerbals can be trained to specific part types, e.g. Mk 1 Pod or the Science Lab. Only parts that are marked to have Complexity (which is measured in %) need to be trained for; these are mostly crewable parts. The more different part types are on the vessel, the longer training will take. Stupider kerbals will also train slower than smarter ones (depending on your difficulty settings).
Training can take two forms:
In-flight training takes place automatically whenever the kerbal is on a mission and not landed on the home planet (i.e. Kerbin). They will gradually get used to the parts on their vessel and therefore slowly reduce the Stress they take from spaceflight. More challenging situations provide significantly more training speed, based on their science multiplier. However, this process gives diminishing returns. For instance, an astronaut with 0% training may increase their training level by 1% per day, but when they reach 50% training, they will only get 0.5% per day, and so on. So you can never really reach 100% training, but the more experience with a part a kerbal has, the less Stress they will take.
Training at KSC has the obvious benefit of preparing the kerbal for their mission without exposing them to its dangers. It is recommended that you train your kerbals at KSC before sending them to where no kerbal has gone before. The drawback is that KSC training has a cap, which depends on your Astronaut Complex level. You can't increase their training level beyond that without actually going to space. The kerbals also have to be healthy (i.e. have no health conditions) to train, and they won't recover their health while they are training at the KSC.
KSC training level caps based on your Astronaut Complex facility level:
To start KSC training, load the vessel in the Editor, open the Health Report and click "Training Info" button. From there, you can select which kerbals to train.
If you disable KSC training in the Settings, kerbals are always assumed to be fully KSC-trained for all parts. In-flight training still takes place as usual.
The other way to reduce Stress is to have more than one kerbal of a certain profession on a vessel. Then they are assumed to be working in shifts or helping each other, and their Stress level is reduced accordingly. For instance, a Pilot who loses 0.8 HP/day to Stress when alone will lose 0.4 HP/day if there is another Pilot on the ship.
Tourists don't benefit from having more "colleagues" on a vessel. Instead, they get peace of mind from knowing that there is professional crew to look after them. Their Stress is reduced by the number of non-Tourist crew members on the vessel plus 1. For example, a Tourist that normally loses 0.8 HP/day to Stress will lose 0.4 HP/day if there is one crew member, 0.27 if there are two crew members etc.
Certain parts (such as the Cupola) provide Recuperation bonuses. If a kerbal receives, say, a 1% recuperation bonus, he/she will recover 1% of their lacking health (i.e. of the difference between their current HP and the maximum HP) every day. This change works in parallel with the normal health factors above.
Example: A 5-star kerbal (maximum HP = 150) currently has 55 Health Points and is in a vessel that gives him 2% recuperation. The vessel has 10 units of living space, he has connection and he has a crewmate. Therefore he recovers (150 - 55) x 2% = 1.9 HP per day and loses also (0.5 + 2 x 2 / 10 + 1) = 1.9 HP per day. It means that the marginal change balances out the "normal" change and his health will stay around 55 HP (37%) until the situation changes.
As you see, this mechanics may allow some kerbals to stay relatively healthy indefinitely. It may look cheaty, but the point is that: (1) there should be a way to design long-term missions without spamming crew space, (2) it requires a lot of heavy parts and therefore still difficult, (3) the balanced health level is usually far from 100% and may fall lower if circumstances change (e.g., new crew arrives and fills the station), (4) these bonuses require a lot of EC, (5) radiation still keeps mounting (see below).
Recuperation is not stacked and has crew cap. It means that one Cupola provides 2% Recup for 1 kerbal, 2 Cupolas give 2% for 2 kerbals (not 4%!), etc. If you have more kerbals than the crew cap, Recuperation will be split among them evenly (e.g. 2 kerbals with 1 Cupola will get 1% Recup).
Decay is the opposite to Recuperation: for every percentage point of Decay, your kerbal will lose 1% of their remaining health per day. Fortunately, it is very rare.
All kerbals on missions are affected by radiation, which slowly but semi-permanently reduces their maximum HP. Radiation is measured in banana equivalent doses (when you eat a banana, you get approximately 1e-7 Sv of radiation). 1e7 (10,000,000) bananas reduce max HP by 10%; 1e8 (100,000,000) bananas kill a kerbal.
The amount of Radiation a kerbal receives depends on many factors. Most importantly, it is determined by their location. Many planets and some moons have magnetic fields that stop some radiation; atmospheres are also very effective in shielding it (see wiki for more). Being close to a celestial body helps screen some rays too. E.g., radiation level at Kerbin's sea level is 1,000 times lower than in interplanetary space just outside Kerbin's SOI. Cosmic radiation is also a bit higher closer to the Sun. To check environment before sending astronauts, you can use magnetometers and Geiger counters provided by supported mods or embedded in advanced stock probe cores.
Being on EVA takes away all the protection your ship provides and dramatically increases radiation level. Artificial radiation is created by certain parts like atomic engines and nuclear reactors.
You can protect kerbals from radiation (both cosmic and artificial) by adding shielding to the vessel. It is provided by some parts, like structural panels, heat shields and mk3 cargo bays. These parts and most crew pods can be improved by adding Radiation Shielding to them in the Editor. You can never eliminate all radiation, but you can reduce it to non-dangerous levels.
Beware of solar radiation storms! They can blast your kerbals in a planet's SOI or in interplanetary space with amounts of radiation ranging from high to enormous. You will be warned, usually, a few hours in advance and the kerbals will automatically take cover in the shelter, if there is one. The shelter is determined as the most protected part (or set of parts) that can fit the entire crew. You will see shelter exposure in the Health Report and Health Monitor details. The frequence of solar storms depends on the phase of the solar cycle going (on average) from one storm every 6,667 days to one storm every 437 days.
If you have Kerbalism installed and enabled "Use Kerbalism Radiation" option in the settings, Kerbal Health's radiation calculations will be replaced with those of Kerbalism (but Kerbal Health shielding will still apply). Kerbalism has a more realistic and complex radiation model, but its balance is very different from Kerbal Health's.
It is possible to cure radiation by decontaminating a kerbal, but it is hard. To start decontamination, the kerbal has to be at KSC at full health and with no health conditions. You also need fully upgraded R&D Facility and Astronaut Complex. Every decontamination costs 100,000 funds (in Career mode) and 1,000 science points (in Career and Science mods). It cures 100,000 banana doses per Kerbin day and stops if you send the kerbal on a mission. The kerbal undergoing decontamination temporarily loses 70% of their health and will need to rest afterwards. As always, each value can be adjusted in-game. If your astronaut discovers an anomaly, they may also be miraculously decontaminated by unknown forces (but only one kerbal per anomaly).
Whenever a kerbal levels up, there is a chance that he or she will acquire a health quirk. Discovering an anomaly can also grant a free quirk. These can be positive or negative and usually affect kerbals' vulnerability to various health factors and dangers. Chances of getting some quirks depend on courage and stupidity of a particular kerbal. The full list can be found in the Kerbal Health Wiki.
Kerbals' organisms, like our own, are not always predictable. Sometimes, not very often, you may see unexpected events that can impact your whole mission. Kerbals acquire (or lose) certain conditions as a result of these events. Having parts with a Sick Bay (such as the stock Science Lab) helps alleviate the symptoms.
Conditions can be disabled or their chances and effects changed in game settings. You can also easily add, modify or remove conditions (see wiki for details).
Kerbal Health should work well alongside most other mods and will try to adapt to them with smart MM patches. Some have better, manually balanced support though:
Making History is supported but not required.
If you would like to include special support for your (or your favorite) mod, let me know.
This mod has been created by Garwel and is distributed under MIT license.