Wednesday marks the 40th anniversary of NASA’s Viking 1 probe becoming the first spacecraft to land on Mars. It was arguably the milestone that turned Mars from a distant, ephemeral interest into a tangible obsession we could study directly. We had put humans on the moon just eight years prior. The prospect that a human could set foot on the red planet finally felt real and achievable.

Of course, 40 years later, we still have not achieved that goal. It’s wrong to say, however, that we’re no less close. At the “Viking at 40” symposium hosted by NASA’s Langley Research Center, a panel discussion called “The Future of Mars Exploration” honed in on exactly how much progress we’ve made — and more importantly, exactly what else we need to accomplish before humans on Mars goes from obsession to achievement.

“The Apollo crowd and Viking crowd had one very important thing in common: they just closed the doors around everyone else who told them it can’t be done,” said Greg Williams, a deputy administrator under NASA’s Human Exploration and Operations Mission Directorate. The Mars team has taken the same tact in devising how its journey to Mars will occur.

The 'Journey to Mars' plan.

Each phase of the journey will mean moving the operational time scale into longer increments, and adjusting to those things. For example, under the Earth-Reliant phase (which is where we are currently), we can get humans back from the ISS in a matter of hours if we wanted to. When we move out to the Earth-Independent phase, we won’t have that luxury. A crew on the surface of Mars that needs to return home will still need months at the very least.

So Williams emphasizes that the key is to make things more autonomous, and push our infrastructure and technology beyond Earth’s orbit and out into deep space.

“We’re going to exploit the advantages of having this large natural satellite orbiting around Earth,” said Williams. He’s talking about the moon — which NASA has long known is key to getting us to Mars. The moon and cis-lunar space will be an essential proving grounds for setting up communications instruments, deep spaceflight infrastructure, and testing out the spacecraft we’ll be using to get us to the red planet.

The new Space Launch System is pivotal for helping us send heavy spacecraft fitted with enough resources to help the crew onboard survive. Orion will be that spacecraft, which Williams says will be able to sustain a crew for up to 1,000 days.

Navy divers attach a towing bridal to the Orion Crew Module during the first Exploration Flight Test in 2014.

Besides those things, there are two essential pieces necessary for helping send humans to Mars. Moving spacecraft from chemical propulsion to something faster and more sustainable is one. NASA is planning to test out one of these technologies, solar electric propulsion, on the Asteroid Redirect Mission coming up next decade. Steve Jurczyk, associate administrator of the agency’s Space Technology Mission Directorate, says they’re also looking at nuclear electric, nuclear thermal, and even very high power electric propulsion technologies like plasma propulsion. Unfortunately, it’s clear that for now, NASA has quite a bit of work to do to shore up development of new propulsion technologies and ween us off of chemical fuels.

Another essential piece, of course, is related to human habitation — and it’s why the International Space Station continues to be such an important lab in testing these things. Jurczyk isn’t shy about saying the agency and its engineers really need to improve the reliability of life support systems if they’re going to ensure a crew can make the seven to eight month journey over to Mars and back and all the life support systems will stay in one piece.

A few of the companies designing deep space habitat concepts.

NASA is actually outsourcing that problem to private companies. Williams discussed the fact that the agency is looking at deep space habitat designs from several different companies and hoping to select one of those designs soon for the development of a working, testable prototype by the mid-2020s. In all likelihood, we’ll see habitats like these floating around in cis-lunar space and allowing human populations to stretch off beyond low-Earth orbit.

Ellen Stofan, NASA’s chief scientist, explains that when it comes to making sure astronauts are in good shape, nutrition and exercise can’t be overestimated. “Those things that keep us healthy here on Earth actually keep our astronauts healthy in space, too,” she said. The trick is to make sure astronauts have access to exercise equipment and good food. That’s the reason the ISS crew is testing out new exercise devices and trying to grow fresh vegetables up in a microgravity environment.

Stofan discussed the future role of modern medical technology and emerging genetics for future astronaut health and safety — ideas that she hit on just last week, while acknowledging that we still had more to uncover when it came to solving eyesight degradation for humans in space, and better determining the role of epigenetic in protecting people against cosmic radiation. But she thinks by the time the 2030s roll around, “we’ll be ready on the human side to get humans to mars healthy and ready to work, and get them back to Earth healthy as well.”

Lastly, there’s the entire issue of making sure when humans do get on the surface, they already have the tools and infrastructure they need to actually live and work on the Martian surface. According to Jurczyk, “we’re going to need new technologies.” And he means lots of them. Just a few of them will include power infrastructure, new suits to handle extreme climates, robots that can help build and maintain existing infrastructure, and the ability to sustainably produce fuel, water, oxygen, and structures on the surface of the planet. Jurczyk and NASA envision astronauts on Mars, “living off the land as much as they possibly can.”

NASA seems to have its work cut out for it.

Photos via NASA, Getty Images / U.S. Navy, Greg Williams/NASA, NASA/JSC