The future of space travel might seem stalled at the moment, but Aldo Spadoni believes humankind won’t remain earthbound for long.

A longtime advanced projects manager for Northrop Grumman, Spadoni is now retired at 60 but still working as a technical consultant for his former employer and movies like “Iron Man.” For him, it’s not science fiction or even an untenable reality that the U.S. and other countries can again explore Earth’s moon and one day finally reach Mars. With continued growth in private initiatives, cooperation between governments and — most importantly — innovative engineering, he thinks that the next 100 years look bright for space travel.

“Planning for the next 100 years has nothing to do with prediction,” Spadoni said. “We have to make sound plans. We have to think for the long term, and we have to keep the ‘mission’ focused.”

Private Space Initiatives Give Hope

The general public might think that the pace of space exploration has slowed since NASA ended the Space Shuttle program in 2011, but several developments point to actual progress. First, the habitable International Space Station has hovered in low-Earth orbit for more than 7,000 days running, and astronauts from the U.S., Canada, Europe, Japan and Russia continue to conduct groundbreaking research onboard.

At the same time, private initiatives are all aiming to win the “Billionaire Space Race” by respectively trying to build spacecraft that will lead to sustainable and consistent trips to the moon, Mars and maybe beyond, said The New York Times.

Those initiatives give Spadoni hope that in about 25 years, moon colonization will begin, and that within a century, Mars will start to be inhabited by Earthlings. Even though NASA hasn’t had an extended period of triumph like the successive Mercury, Gemini and Apollo programs that initiated the first human spaceflights and subsequent landings on the moon, the future of space travel is far from limited, he said.

For one, billionaire ventures as well as other private efforts like Stratolaunch are reducing the potential cost of space launches and journeys, Spadoni said. The competition for profit in private industry can lead to innovative engineering at a lower cost than government projects, he said. Stratolaunch, for example, looks promising for its ability to launch satellite-carrying rockets at an altitude of 35,000 feet, he said. Because it is an airplane, Stratolaunch can take off from many locations and avoid costly weather-related delays.

And NASA’s plan to someday launch an outpost for astronauts near the moon, the Lunar Orbital Platform-Gateway, shows Spadoni that government space programs still have a vital role in space exploration. If public and private work together, there should be a forward thrust in space travel not seen since the days of Apollo, he added.

Overcoming Gravity and Radiation

Even if private sector and government cooperation kick-starts a steady round of space missions, that still doesn’t mean there won’t be hurdles to overcome if the moon and Mars are to be explored and colonized in the next 100 years.

First, Spadoni said, there are two unavoidable hurdles that will always make space travel expensive and physically challenging: radiation and gravity.

Radiation poses a risk once space flights pass low-Earth orbit. “Radiation protection wouldn’t be too hard [for those living] on the moon or Mars because we could bury habitats under several feet of rock or dirt,” Spadoni said. But humans would have to first build those habitats and travel to the moon and Mars, which could take six to eight months and lengthen exposure to radiation. A spacecraft with an effective radiation shield that is also lightweight would be essential, and might not be expensive if private companies intend to profit from its development, he explained.

Journeys to Mars and extended colonization both there and on the moon mean overcoming the problems of low gravity. It would be ideal to have space travelers experience gravity levels as close to Earth as possible, and that would mean the creation of artificial gravity through a spinning spacecraft or other mechanisms, Spadoni said. “That’s hard to do,” he added. “Also, how much artificial gravity is enough? Is one-sixth of Earth’s gravity enough?”

Cooperation for Exploration

With an expanded roster of people and organizations wanting to explore space, ethical issues could arise. A private company could have nefarious reasons for going to space, including warfare or the strip-mining of planets’ natural resources, Spadoni said. And he thinks it’s not far-fetched to wonder if children who are born in a moon or Mars colony might not be accepted on Earth should they try to journey back.

Basically, there’s no road map for this next chapter in space exploration, but to prevent space from becoming a lawless place, “we need global cooperation,” Spadoni said. Space travel could be a necessity if Earth succumbs to environmental degradation, disease or war, he added. That’s why cooperation, economic incentive and engineering ingenuity are musts if future generations are to make homes away from Earth.