To Mars Obama just proposed having astronauts orbiting Mars in the mid-2030s. I already know that in 2035 we'll have a fairly close approach to Mars. However, this time frame is interesting for another reason. Sending a vehicle in orbit around Mars is all we really need to do to set the stage for a space elevator mission sometime afterwards. Even though proponents of the project say it can be operational in 20 years, unforeseen problems might arise. The idea here is not to build a space elevator for earth, but to build one that might land on Mars five to ten years after we get a crew orbiting it more permanently. Mars's day is only 39 minutes longer than our own, and it has 1/3rd of the gravity. That means that it will be far easier to engineer a space elevator for Mars. The next advantage of building one on Mars as opposed to the earth is that a giant tether wrapping around the earth is a major risk for people on the ground, but it hardly matters if one wraps around Mars. Phobos Phobos has very low surface gravity and has a lot of useable materials for sustained existence near Mars. Because its escape velocity is only 40 m/s, it might be easiest just to get close to the tiny moon and send astronauts or robots with jet packs to explore and utilize the resources of that tiny moon. The University of Arizona recently approved funding for a mission to an asteroid to learn to extract its resources. It's not certain if we'll be learning to do this stuff on Phobos in that initial mission, but we will eventually if we begin sending things farther into outer space.