Assuming that NASA receives the funding necessary and makes the technological advances that are needed in space travel, the first humans could land on Phobos, one of the moon's of Mars, by 2033 and on the surface of the Red Planet by 2039, according NASA.

Scientists from NASA say they can't not rely on another "John F. Kennedy moment," which was the 1961 call by the president to land people on the moon.   This moment led to an increase in its budget, boosting it to 4.5 percent share of the budget.  Today, NASA's budget is less than 0.5 percent of the budget and NASA wants to take things slow by creating multiple missions to ensure a safe landing first on Phobos, and then the Red Planet itself.

"Landing on Mars isn't just a pipe dream. It's achievable. Mars matters to humanity and the pursuit of human progress. (...) NASA will launch ExoMars orbiter designed to circle the Red Planet next year, and there are plans to launch another Mars rover in 2018. Robots are great for preliminary data and preparation, but we need humans on the Martian surface," said Charles Bolden, NASA Administrator.

The march to Mars has already begun, with the rovers Curiosity and Opportunity continuing to roam the surface sending back valuable data, photos and other information about the Red Planet.  Recent data acquired by the rovers even indicates that Mars could have once supported microbial life.

In another study conducted by a team of scientists led by NASA's Geronimo Villanueava of the Goddard Space Flight Center, Mars had an ocean covering 19 percent of its surface 4 billion years ago

"Keeping the cost of manned Mars exploration low could be done by treating Mars exploration as a network of missions with linked objectives," said Oliver de Weck, an aeronautics and astronautics professor at the Massachusetts Institute of Technology. "Using Mars water, hydrogen and methane could cut the initial mass sent to low-Earth orbit for a Mars mission by 48 percent," he added.

Landing on Phobos will rely on technology that is currently under development by NASA such as the Space Launch System and the Orion capsule but will leave out other newer, more experimental technologies such as nuclear thermal propulsion.  While there is no doubt that a human mission to Mars is a popular goal for scientists, it lacks the same urgency as the initial moon landing and will be accomplished over decades instead of just a few years.