I read a while back that one of the biggest issues with a human mission to Mars is the landing, I can't remember the article but a brief search turns up this on

I read a while back that one of the biggest issues with a human mission to Mars is the landing, I can't remember the article but a brief search turns up this one that covers the relevant points: http://www.universetoday.com/7024/the-mars-landing-approach-getting-large-payloads-to-the-surface-of-the-red-planet/ http://www.universetoday.com/7024/the-mars-landing-approach-...