Question:How does manned space flight more difficult and expensive than unmanned spaceflight?
In order to send astronauts in to space, the spacecraft must provide the astronaut with all the requirements for life and protect them from all the harmful conditions found in space.
Spacecraft provide the conditions needed for astronauts to survive. They provide:
1: An Earth like atmosphere and air pressure; and equipment to remove waste gases such as carbon dioxide which are poisonous to people if not removed from the atmosphere.
2: Food and water and waste disposal must be carried.
3: Thermal insulation and heating to provide a suitable temperature for human life.
4: For long term space travel (not just a few days); Exercise equipment to reduce the effects of weightlessness, such as weakened bones and muscles. On the International Space Station, astronauts use bung cords to pull themselves down onto a treadmill to simulate gravities pull whilst running.
5: Walls and windows that are designed to withstand the impact of 'micrometeorites' (tiny pieces of fast-moving rock). The also reduce but do not completely protect astronauts from all the cosmic radiation in space, which can cause cancer. This limits how long a mission can last without damaging the health of the astronauts.