Michael Meyer, the lead scientist for the Mars Exploration Program at NASA Headquarters in Washington, revealed how the space agency chooses where to land on the Red Planet on Sunday at the annual meeting of the American Geophysical Union (AGU) in San Francisco.

Landing on Mars simply can't be a matter of trial and error, given the years of rigorous engineering and scientific work and the months of long arduous journey in outer space. "You can't say, 'here are ten different sites, let's go to them. Each mission- it's one shot. You definitely want to pick the right one," Meyer said.

According to him, the "spectacular" participation of the bigger science community is an essential component in selecting sites for both robotic and human landings. Thanks to the more advanced technology, NASA now uses space orbiters deployed in Mars - the Mars Reconnaissance Orbiter, for example - to give the experts a picture of what makes an ideal landing site, and to ultimately refine the list of candidate sites.

"The first human landing sites workshop in 2015 yielded 47 landing site proposals. NASA is looking to set up a semi-permanent base, dubbed an 'exploration zone,' where crews can live off the land and explore up to a 60-mile (100-kilometer) radius. There will be more workshops and more reconnaissance as the list narrows down in years to come," an article by NASA stated.

Meyer added that NASA also takes into consideration that astronauts, making sure they can make the best of the surroundings. "Is there a place to land? Are there resources that you can make use of there, such as water so that you can make your own fuel? Are there interesting things in the area for the astronauts to explore," he told the AUG audience.

"You feel like you know the place already, and then when you get there. It's different. It's always a great surprise," the astronaut continued.

Continuing the open process started with Spirit and Opportunity, NASA is holding landing site workshops for both the next rover, Mars 2020, and a future human landing site mission, ECN Mag reported. Last year, over 400 participants attended the first human landing sites workshop by NASA.