Nasa officials said Tuesday that the scientists will have to overcome some of the challenges ahead of any future astronauts, including the deadly radiation from the cosmos, potential vision loss, and atrophying bones.
The US space agency believes it can put humans on the Red Planet within 25 years, but the technological and medical hurdles are immense.
"The cost of solving these problems is that it's going to take about 25 years to solve those," said former Nasa astronaut Tom Jones, who flew on four space shuttle missions before retiring in 2001.
"We need to get started right now," he told reporters in Washington.
At an average distance of about 140 million miles (225 million kilometers), Mars poses scientific problems an order of magnitude greater than anything encountered by the Apollo lunar missions.
With today's rocket technology, it would take an astronaut up to nine months to reach Mars – the physical toll of floating that long in zero gravity would be huge.
For instance, scientists think prolonged weightlessness can cause irreversible changes to blood vessels in the retina, leading to vision degradation.
And after a while in zero G, the skeleton starts to leach calcium and bone mass.
With gravity only one-third of Earth's scientists do not know the effects of a presumed one-year mission to the surface of Mars.
One way to reduce the wear and tear on the human body is to cut down on travel time to Mars.
Jones called for nuclear propulsion systems that would have the added benefit of generating electricity on flights.
"If we start now, in 25 years we might have these technologies available to us and protect us from these long transit times," he said.
Under current conditions, just an outbound trip to Mars would take so long that any astronaut would receive the same amount of radiation than ordinarily would be deemed safe over the course of an entire career.
"We do not have the solution in terms of shielding, cosmic rays and solar flares that you get during transit time," Jones said.
In addition, the Harsh Air Force has been working to improve the safety of the Earth's atmosphere and the environment.
NASA currently has a new robotic lander called InSight zooming towards Mars, due to land on November 26 after taking off from California on May 5.
The US $ 993 million project aims to expand human knowledge of interior conditions on Mars, informed to send explorers there, and reveal how the Earth formed billions of years ago.
Jim Garvin, chief scientist at the NASA Goddard Space Flight Center, said he would fill in "critical unknowns" and help build a key understanding of Mars.
In 2020, another mission will see NASA to send a rover to Mars that aims to determine the habitability of the Martian environment, search for signs of ancient life, and assess the natural resources and hazards for future human explorers.
Additionally, private firms like SpaceX and other nations are building missions.
Some experts see new exploration of the Moon as a future mission to Mars, as astronauts could learn about extracting water or using technology and apply those lessons to future Mars missions.