Space travel issues and solutions?

Excluding technological issues such as oxygen systems the greatest difficulties involve human nature and biology. In a lengthy zero gravity environment the body loses bone density, loss of muscle tone and strength. The food which must contain the essential nutrients must be in a form that can be easily eaten as well as being able to remain reasonably fresh for a long time. Then there is the problem of having sufficient amounts of drinkable water since the body requires a daily minimum. Then there is the problem of personal hygiene in such things as elimination of waste from the human body.

Human nature has to be taken into account as well. Cooperation and an ability to get along with others is essential if the astronauts are to survive long space journeys. So tests such as personality, problem solving, etc. would have to be administered before the astronauts were selected for the trip.

Okay....

1. Life support.

Overheating will likely *not* be the problem - the problem will the cold. Space - and, especially deep space - is cold. On the planet Mars, it cools off to about -120F during the night. On Titan, Saturn's largest moon, it's about -300 - and, it gets colder as you go deeper. So, you'll need heat, which is easily done through electric power. Both fuel cells and nuclear reactors (like on Submarines) can supply electricity for.a very long time.

Air - also an issue.- will need to be recycled. On Apollo and the Shuttle, they used scrubbers that used a catalyst to free carbon from CO2, to provide oxygen. It's kind of a hassle, but doable. Ideally, you could develop a means to synthesize oxygen the way plants do - or, use plants directly... But, it takes a LOT of plants to support just a few astronauts.

Next is protecting the crew... Water and other soft materials provide excellent shielding against hard radiation; The Orion capsule (and some space station plans) stow water in the walls of the spacecraft, and store both food and water, along with clothing along the outer walls, which will stop about 92% of harmful radiation. (But, high speed electrons and some high frequency waves - gamma and X Ray radiation are difficult to stop...)

2. Travel

We know we can use chemical means of acceleration; trouble is, the bang for the buck... You need a lot of fuel to attain high speed, and when you get to your destination, you need a lot of fuel to slow down. There's Ion power, which is a very low - but constant - force of acceleration/deceleration; but again - you need some dense fuel to carry with you.

But, like with all travel - your biggest enemy is time. Something will, inevitably, go wrong on your spaceship; by limiting travel time, you limit the amount of time something bad can happen. So, with our present technology, you'd want to boost the craft through a chemical means - and lots of boosters - as fast as you can get it; then, use an Ion drive to *slow* your approach the rest of the way, with chemical retro-burns every so often until you reach your destination...

Issues with this plan: Cost, and weight - in that order. Especially for a manned craft... It would need to be enormous.

Dying of old age on a trip that takes hundreds/thousands of years. Such as going to another star system.

Inability to go to a place because it is too far away. Such as Pluto or beyond.

Keeping things warm. Inside the orbit of Mars there is enough solar radiation to keep warm. But beyond Mars the ambient temperature is way below zero. For example the moons of Jupiter at at about minus 160 Celsius.

A crew needs supplies of food water and air.