NASA (and Congress) want humans on Mars by 2030.

And those first colonists could spark the evolution of an entirely new species.

There is harmful radiation that is much more intense on Mars, in addition to less sunlight and weaker gravity, all factors that could cause significant changes to the colonists’ bodies. As the colonists reproduce with one another, the evolution process could take as little as 6,000 years, according to Dr. Scott Solomon, author of “Future Humans: Inside the Science of Our Continuing Evolution.”

Solomon believes humans’ bones will thicken due to the decrease in gravity, and skin will darken to better protect against radiation. Mars has almost no protective magnetic field, exposing humans to harmful levels of radiation, but skin pigmentation helps block radiation effects.

But Dr. Nathalie Cabrol, a planetary scientist at the SETI Institute, told NBC News she believes skin will actually become paler due to the lack of sunlight.

Such opposing predictions prove how little we know about what to expect in trying to colonize the red planet.

A recent paper published in Space Policy states that there are numerous aspects to the Martian environment that will be impossible to replicate on Earth. And Konrad Szocik, the paper’s lead author, doesn’t believe NASA’s current preparations come anywhere close to readying astronauts for the journey.

“We cannot simulate the same physical and environmental conditions to reconstruct the Martian environment, I mean such traits like Martian microgravitation or radiation exposure,” Szocik told seeker.com. “Consequently, we cannot predict physical and biological effects of humans living on Mars.”

Szocik believes astronauts will need electronic devices to enhance their senses, and drugs to dull their panic. He also says there needs to be a population of at least 500 in a potential colony to avoid inbreeding.

NASA’s preparations for Mars have included sending astronauts to the International Space Station for prolonged periods and placing people in inhospitable environments, like Antarctica. In March 2016, Scott Kelly and Mkhail Kornienko returned to Earth after spending a year on the ISS to understand the physical and physiological long-term effects of living in space. NASA also studied Kelly’s body and compared it to his twin brother, Mark, who stayed on Earth.