We haven't been to the Moon since December 11, 1972. Since then, no human has left low Earth orbit. It's about time we head back!
Once we're there it would be a good idea to stay. NASA has set forth plans to return to the Moon and to finally set up a permanent base. NASA has plans that could land us on the Moon in as little as five years. With the SLS on its way to becoming reality and with assistance from private companies like SpaceX and Orbital ATK we have the technology to accomplish this project.
An Apollo-era Saturn V rocket cost about $46,000 per kilogram to launch and send to the Moon. The space shuttle costs ran about $60,000 per kilogram. SpaceX currently only charges $4,750 per kilogram! The cost of launching has dropped significantly since the 60s and 80s.
Current plans estimate the cost to be around $10 billion for the project. Instead of just traveling to the Moon for a visit, this trip would be the start of a Lunar Base. The Evolvable Lunar Architecture plan would not only be a scientific lab it would be the start of a new economy. Mining the moon could quickly begin once the initial base is set up.
A lunar base would also be important for any future plans for traveling deeper in space. Any trip to Mars or deeper could use the Moon base as a pit stop to refuel and prepare to travel across our solar system!
Plans for a Moon Base - https://sservi.nasa.gov/articles/scientists-reveal-design-plan-for-future-lunar-base/
Lunar Outpost Plans - https://en.wikipedia.org/wiki/Lunar_outpost_(NASA)
The Roadmap to the Moon - https://www.extremetech.com/extreme/277788-nasa-sets-new-roadmap-for-moon-base-crewed-missions-to-mars