That's not really the case. You will find engines that are full of electronics and pretty much comparable to modern car engines.

However! Keep in mind that certifying a new aircraft engine is an order or two of magnitude more complex and expensive process than anything that gets into a car. You want to change the type of spark plugs? Change to an ignition system? Well, tough luck! Needs to be recertified.

There is also the fact that unlike a car engine, where if you get an electronic failure your check engine light comes on and you call a tow truck, in an airplane if something dies, it is a full blown possibly life-or-death emergency.

So you do not want to stuff your plane with a ton of electronic gadgets that could fail. The simpler the better in this case. Or you must provide redundancy, which is very expensive compared to e.g. a pair of magnetos for ignition. The other issue is weight, especially for ultralights but even for bigger aircraft.

The more complex electronics you add to the engine, the more it will cost to have it certified and even more to maintain. Keep in mind that a modern Cessna 182 costs upwards of $600 000 new today, the engine and related avionics being a large part of it.

You can't compare this at all with car engines. It is a completely different regulatory and reliability ball game.

There are plenty of modern electronically controlled (FADEC - that's what you know as ECU from car engines) and fuel injected aviation engines around.

However, typically not in your flight school's 40 years old Cessna 152/172 but in bizjets, larger helicopters and high end GA planes, like Cirrus SR22, DA-62, for example - which has two diesel (!) engines. Lycoming produces multiple engine types that are fully electronically controlled, Continental does as well, Rotax has several fuel injected engines, etc.

It is both regulation (anything aviation takes ages to get certified - both fuel and engines using it must be certified to be legal to use) and also the old engines which simply can't run on unleaded gas.

It is not a question of octane number so much but engine lubrication, fouling and knocking. Older planes with engines not designed for unleaded gas would require additives for this reason - the same as old cars do when fueled with unleaded gas.

Aviation is a slow moving field - not many people still drive cars made in the 60-70s but there are many many planes that are even older than that still in service (esp. with private owners, flight schools, etc.) - and none of them can handle unleaded fuel without additional steps. Either using fuel premixed with an additive (the most common solution) or an expensive engine modification which may not even be available for the old engine types still in use.

Oh and the unleaded avgas is more expensive than regular one too. Given that the price of fuel is one of the largest costs when flying, it is likely not going to help its popularity either.

The answer would be likely - "it depends".

Water isn't likely to be affected even by high doses of powerful x-ray radiation from an industrial CT machine (orders of magnitude more powerful than a medical x-ray/CT). It could get a bit warm from the absorbed energy, though.

However with the bottle it would depend a lot on what that bottle has been made from. Glass and metal are very unlikely to be affected to any significant degree even by a strong x-ray source. Plastic - would depend on the dose (time & energy) and what kind of plastic are we talking about. Some could start decomposing/breaking down under the intense x-ray radiation and possibly leach some nasty stuff into the water.

That is very unlikely to happen with a low energy medical x-ray and one-shot exposure, though. However, if you leave a plastic bottle inside of an industrial CT-machine during a multiple hour scan using a high energy beam (e.g. because you are scanning an engine piece made out of metal), there I would be quite careful because who knows how the plastic could react.

And finally, as mentioned by others - it is not enough to be "in the vicinity" for the bottle to be affected by the rays. It would need to be directly in the path of the beam from the x-ray source (or some reflection). X-rays are very directional, the same (or even more so, given it is a shorter wavelength) as light.

Given how well the x-ray machines are shielded and enclosed to avoid accidentally exposing the operators, if your bottle outside of the machine got damaged by x-rays then you would have much much worse problems to care about than some stuff possibly leaching into water ...

You have completely missed my point. The orbital mechanic is a completely different issue and certainly can be calculated so that the two objects meet - we are doing rendezvous and dockings routinely.

The point is that even if you do all of this, carry all that extra fuel (and equipment!) required to decelerate and enter the orbit permitting to dock with the space station - would you want to take the risk?

It is not about "failing to decelerate" and hitting the station as some sort of space projectile. The problem is it would be a spacecraft that has likely not been tested to do this before - and will likely never do this after (deep space missions are usually one-offs). What if something goes wrong during the final approach and puts the station at risk?

We have seen what could happen when the Russian Mir got punctured by some ill-thought maneuvering. Only quick thinking and some crazy heroics by the crew has saved the station. And that was a spacecraft actually designed to dock with the station, equipped for that and one that has just undocked, so it was known to be in working order. Unlike something coming from deep space after who knows how many years - and in who knows what state.

In addition to what /u/electric_ionland said, there is the whole safety thing. If anything goes haywire with the complicated rendezvous and/or docking, you have just put an irreplaceable space asset and 7 people in danger - that in addition to losing whatever samples the spacecraft was returning.

Anything flying to ISS has to be specifically certified for it and the whole approach and docking process needs to be extensively tested before even the first test flight is allowed. Obviously not an option for a one-off deep space mission.

That doesn't mean that this couldn't be done sometime in the future but it is just too impractical and risky today.