Question: What difficulties must be overcome to send a human being into space safely?
Space is not a very hospital place.
None of the conditions required for Human life to exist are present in interplanetary space or on any of the other planets.
Human beings and other living creatures need certain conditions to exist for them just to remain alive.
We need an atmosphere to breath: In space there is no atmosphere and on the planets that do have an atmosphere it is not suitable for Man.
We can only survive between a small range of temperatures: In space the temperature varies from very cold - away from the sunshine - to very hot - in sunshine.
None of the planets or their satellites have a suitable range of temperatures for use to survive in without protective clothing.
We also need food and water, which must be carried with us, and we produce waste which must be dealt with safely.
Human beings are used to the Earth's gravity. In interplanetary space the gravitational field strength is much lower (close to zero but never equal to zero), so objects are effectively weightless.
Astronauts' bones and muscles become weaker while they are in space and this can cause them problems when they return to the Earth's gravity.
The Earth's atmosphere and magnetic field protect us for most of the cosmic radiation (radiation from the Sun and distant objects in space) and we cannot survive for long without protection from this radiation, in space or on planets with thinner/different atmospheres and no magnetic field. Space is also full of micro-asteroids.
Although these asteroids are very small, they can be travelling fast enough to go straight though a space suit or even the hull of a spacecraft, causing an air leak or a penetrating wound to an astronaut.