Earth and Mars align favorably only every 26 months . This alignment, known as "opposition," minimizes the fuel needed for the roughly 300-million-mile trip.
Getting to Mars requires overcoming massive gravitational and orbital hurdles: Mission to Mars
Mars is a hostile environment that dictates how equipment and habitats are designed: Mars - NASA Science Earth and Mars align favorably only every 26 months
Testing technologies for landing large payloads and surviving the harsh environment. 2. Launch Logistics known as "opposition
The heavier the payload (rovers, habitats, or fuel), the more powerful the rocket must be to escape Earth's gravity.
Determining if Mars ever supported microbial life.