Humankind made history when it landed on the Moon during the Apollo missions, but the next major hurdle is putting astronauts on Mars to explore the red planet's surface in person.
Exploring Mars isn't a new idea; it's been on NASA's radar for decades. Unfortunately, official plans never materialized because of budget constraints and objective deviations that took place every time a new president would take office in the United States.
With each new president came new visions that shifted the space agency's focus, and these changes regularly impacted NASA's ability to meet and complete essential objectives that would make projects like Martian exploration possible.
Similar problems exist today, hence why NASA hasn't sent humankind to Mars just yet. Technological capabilities aren't the limiting factor of NASA's space exploration potential, but rather the political priorities at any given time.
Given the circumstances, there's a strong possibility that NASA won't be the first to set foot on Mars. Commercial space companies or competing government space agencies could very well earn that title before NASA ever gets the chance to.