I agree many are more accessible. However the value of a destination is not simply in how accessible it is. You can mine one or two resources on an asteroid easier than any from Mars. You can not obtain all the resources needed to sustain a base or a colony on an asteroid as you can on Mars. Now if you have a comercial use for an asteroid that is a profitable business it would be the place to start our expansion into space. I don't believe that is the case at current launch costs.

I believe Mars is of more scientific interest and has the greater long term potential so it should be our priority for exploration. That doesn't mean ignoring asteroids though. I think we should try to use the two year minimum cost launch window for Mars and follow each asteroid mission with another based on the results of the previous one. I am thrilled the Dawn mission escaped cancellation. I also think we need to support cost effective detection of NEOs > 140m. When we have a system proven capable of handling the volume of data that will generate and are approaching the 90% goal, I think we should then push on down to the 30m level.

Regards,
Mark