In an open invitation to the entire scientific and human spaceflight communities, NASA has announced it will accept suggestions on where to land humans on Mars.
The agency will hear these proposals at a conference in Houston this coming October called the "Landing Site/Exploration Zone Workshop for Human Missions to the Surface of Mars." NASA hosts events like these from time to time when collecting proposals — a second one for the proposed 2020 Mars rover will be held later this summer.
An ideal site would be ripe for exploration while being able to sustain life
The invitation also spells out the criteria for NASA's ideal landing site, or "exploration zone." An ideal exploration zone would contain multiple "regions of interest" — areas ripe for scientific investigation or rich with resources to sustain the humans' presence — within 100 kilometers (about 60 miles) from where the humans land.
NASA will use the proposals from this workshop to develop engineering and support systems for Mars, and could use robotic missions (like the 2020 rover or the spacecraft that already orbits Mars) to scout the potential sites in greater detail.
A crewed mission to Mars might not happen until at least the 2030s, if it happens at all. There are very valid concerns about how Mars' harsh conditions — extreme temperatures, radiation, dust storms — would affect the human body over time. And while the agency is currently testing the spacecraft that would get us there and building a giant rocket to launch it, budget concerns and divided government support always loom as threats. With those things in mind, picking a landing site might be the easiest step in the process.