Why hasn't anyone been on mars?

Answer 1

There are several reasons why there has been no manned spaceflights to Mars:

1. Space missions are costly and sufficient funding simply hasn't been available to plan such a trip.
2. It takes a long time to get to Mars - anywhere from 150 to 300 or so days.
3. The technology required to support such as mission has yet to be developed.

As well, there are the challenges facing those astronauts who are travelling to Mars, including:

1. The psychological effects of isolation
2. Lack of access to immediate medical care
3. The negative effects of zero-gravity on human bodies, which can result in muscle loss, loss in cardiovascular fitness, and bone loss.
4. Exposure to cosmic rays and other ionizing radiation
5. The issue of having an adequate food supply that provides all the nutrients required for human health.