We have sent them there before and they have explored it a great deal. Today we are building robots that can explore 24/7 for years without the need of humans or the fear of safety for human lives. Radiation will be a MAJOR problem if humans remain on the moon for longer periods of time, which is being suggested, because there's simply no way to keep the exposure to cosmic radiation at low enough levels to insure human safety. Even with recent advancements in protective gear it is only about 40 to 50 percent effective and that means humans are going to be overexposed to all of the radiation that is out there. Once the humans leave the protection of the magnetosphere that surrounds the Earth and protects them somewhat from radiation they are going to be in a very serious area of safety. Why is it humans must get back to the moon before they have ample safety procedures in place to protect themselves from all of this radiation that will damage them and will lead to many other biological problems like broken DNA and cancers as well. With the safety that humans need to make them totally safe from overexposure it is going to take longer to create that technology, so why don't humans wait for that to happen before risking other humans lives? Robots can do the almost same things a human can do for allot less money and no safety problems.