December 11, 2017, US President Donald Trump signed a directive that ordered NASA to prepare to return astronauts to the moon "followed by human missions to Mars and other destinations."
The dates set by the Space Agency are 2024 for the Moon and March 2033, but according to experts and industry inspectors, it is highly unlikely to impede a herculean bet on the Apollo program's scope in the 1960s.
"The Moon is the proven foundation for our possible mission to Mars," NASA administrator Jim Bridenstine said at a conference this week.
"The moon is our way to get to Mars in the fastest and safest way. That's why we go to the moon."
According to Robert Howard, head of the lab developing future space habitats at the legendary Johnson Space Center in Houston, the barriers are not as much technical or scientific as much as a budget and political will.
"Many people want us to have an Apollo moment and get a president stand up like Kennedy and say we have to do it and the whole country gets together," he said.
"If that happened, I would actually say 2027. But I don't think it will happen. I think we will be lucky in our current strategy to do so by the 2037 date."
But Howard said he would be pessimistic and suppose political dithering was ahead, "it could be the 2060s."
From the design, manufacture and testing of the rockets and spaceships required to learn the best way to grow lettuce: all the basic work remains to be done.
Just getting there takes at least six months, as opposed to three days to the moon.
The whole mission can take two years, because Mars and Earth are wardrobe for each other every 26 months, a window that must be taken.
Important information is finding a way to protect astronauts from prolonged exposure to sun and cosmic radiation, says Julie Robinson, NASA's Chief Scientist for the International Space Station.
"A second is our food system," she added. The current plant system ideas "are not packable, portable or small enough to bring to Mars."
And then it is about dealing with medical emergencies: the astronauts must be able to treat themselves in the event of accidents.
"In fact, I think a big thing is the costumes," added Jennifer Heldman, a planetary scientist from NASA.
One of the great grabs of the Apollo astronauts was their gloves, which were too inflated and prevented them from doing good work.
NASA is developing a new suit, the first in forty years, called xEMU, but it will not be ready for its first outing on the International Space Station for a few years.
On Mars, dust will become even more problematic than on the moon. The Apollo astronauts returned with large amounts of moon dust in their modules. Keeping out of habitats will be crucial for a mission that involves spending months on the red planet.
Techniques to exploit Martian's resources to extract water, oxygen and fuel necessary for people to live there are not yet – and must be tested on the moon at the end of this decade.
Finally, there is the most fundamental question: how will a group of people cope with the psychological stress of being completely isolated for two years?
It will not be possible to communicate in real time with the Houston Mission Control: radio communication takes between four and 24 minutes between the planets, one-way. NASA plans to test delayed communication exercises on board the ISS over the next few years.
Artificial intelligence must also be developed to help and control the astronauts.
A researcher commissioned by NASA to study the probability of coming to Mars by 2033 was the "unthinkable" target.
"It's not just budget," says Bhavya Lal from the Science and Technology Policy Institute. "It's also the organization's bandwidth, how many things can NASA do at the same time?"
For Lal, the more realistic time frame was 2039.