For now our next challenge is a successful space shuttle mission. Its not a challenge, its a waste of money! Think about the time from when we first learned to fly to landing on the moon spanned over 60 years. For the last 30 we've been wasting our time and money on a glider that hasn't produced jack crap!
I have to say that the Shuttle is not the most cost efficient way to deliever payloads into low earth orbit.
But it is a proving ground with the ISS that will allow us to live and work in space for long periods of time.
You cant run until you know how to walk.
As for being a waste of money, just the Hubble Mission alone was worth the data that has been obtained.
