Considering how little progress we've made, I hardly think that our lifespans are the primary limiters in that venture. I mean you can travel to Mars in 8 month

Considering how little progress we've made, I hardly think that our lifespans are the primary limiters in that venture. I mean you can travel to Mars in 8 months-3 years, yet we haven't. Energy is our primary limitation right now. We have nuclear but are too afraid of launching large quantities of the raw materials into atmosphere in case of a catastrophic failure (and showering land OR sea with some heavy radioactive metal). We also have fossil fuels which are very energy dense, but still heavy/expensive. And finally we have solar which has been a long-term popular form of spacecraft energy, but it doesn't provide enough to travel between planets YET. Ultimately if we invented "infinite safe energy" tomorrow I don't see Mars or greater space exploration as being too big of a challenge. In particular as getting stuff into atmosphere is now energy-free, and your only limit is the cost of the raw materials.