Preparing for every eventuality
Though each space flight is unique in its content, the profile for its preparation and execution is essentially the same: A mission is identified and assigned its objectives; a flight plan is created and the hardware prepared; the flight crew is selected and trained; then eventually the vehicle is launched, flies its mission, and then returns to Earth. All this is then followed by evaluations of the crew, research, and mission performance and examination of returned hardware in preparation for the next mission. This is a basic overview but it stands true for all successful missions flown to date, regardless of the country of origin, or mission objectives.
While this may be the plan, it does not always turn out that way. Human space flight is a high-performance, high-risk endeavor, which will always carry an element of danger for the mission, hardware, and crew. It has been demonstrated several times that accidents can occur during any of the stages of a mission, from training to recovery. For each of these potential risk areas, safety features, systems, and procedures were built in to help protect or possibly rescue a crew.
Some of these were introduced or modified for use on future flights only after an emergency had occurred during a previous mission.
Each crew is trained in emergency or contingency procedures and is provided with medical kits, escape equipment, and alternative flight plans to help deal with olf-nominal stations. Mission planners develop alternate mission profiles to gain at least something from the mission should the primary objective have to be abandoned or curtailed, but this has to be done with crew safety in mind at all times. Though mission success is at the forefront of each crew in their execution of their flight, crew safety is the overriding factor and the primary responsibility of the mission commander. As much as each crew member would want to perform to the maximum and contribute as much as they could as a team member, they all have homes and families to return to. The expectation, excitement, and personal rewards of flying in space run strong in each crew member, but never as strongly as the desire to come home safely. Accepting the risk is part of being a space explorer, but these are not foolhardy individuals willing to risk their own fives or threaten the safety of others.