Spaceflight Insider

Science journalist outlines challenges of settling the Moon and Mars

An illustration of base on lunar south pole. Credit: NASA

An illustration of base on lunar south pole. Credit: NASA

Human settlement of the Moon and Mars will require overcoming numerous challenges, including generating the energy to get off Earth, living in low gravity, facing extreme temperatures, protecting people from toxic radiation, growing food, and cost, according to science journalist Christopher Wanjek.

In an April 6, 2021, online lecture sponsored by the Space Telescope Science Institute (STScI) titled “Spacefarers: How Humans Will Settle the Moon, Mars, and Beyond,” Wanjek, who authored a book with the same title in 2020, focused on the engineering, emotional, and economic challenges that will confront human activity in space over the next 30 years.

“I think we’ll be on the Moon in 10-15 years with science bases and on Mars in 20-25 years,” he predicted, attributing future progress in human space exploration heavily to commercial companies like SpaceX, which are currently driving space exploration.

While some scientists, such as the late Stephen Hawking, profess “doom and gloom,” with claims that humanity has 100 years to get off the Earth or face extinction, Wanjek strongly disagrees.

“There is nothing that can happen to the Earth that will make it less habitable than any place in the solar system,” he said, noting that the usual threats cited, such as overpopulation, pandemics, nuclear war, an asteroid strike, and climate change may kill many but will not wipe humans off the planet.

“If we’re living on Mars in a self-sufficient way, we have the technology to deflect an asteroid,” he emphasized. If we have the technology to terraform Mars, that same technology could also be used to “terraform” Earth in a way that mitigates the effects of climate change.

Wanjek believes the main reason for human space exploration is not establishing large colonies on other worlds but largely economics, such as augmenting energy production, offloading supercomputing, mining other worlds, setting up space-based manufacturing, and even space tourism.

Moon versus Mars

As the most Earth-like solar system world other than Earth itself, Mars could potentially host a human colony, Wanjek stated. “It has every element we need for life,” including a day/night cycle, an axial tilt similar to that of Earth, an Earth-like landscape, and 38% of Earth’s gravity.

Artist’s depiction of humans living on Mars. Image Credit: NASA

The Moon is far less hospitable because it has lower gravity, temperatures that fluctuate between extreme heat and extreme cold as a result of its day/night cycle, and dust in the form of razor-sharp regolith particles that could tear people’s lungs.

Wanjek envisions the Moon becoming like Antarctica on Earth, a place visited by scientists for several months at a time, possibly with a small permanent crew to maintain infrastructure. The most logical location for such an endeavor is the lunar south pole, where there is a steady, shallow angle of sunlight along crater rims to generate power via solar panels.

If ice deposits known to be present on both lunar poles could be harvested, settlers could use them to generate oxygen for breathing, drinking water, and rocket fuel.

It may be possible to grow plants under glass, but scientists do not know whether the plants could survive the high levels of radiation on the lunar surface.

The greatest danger to potential settlers is the Moon’s low gravity. “We know one g is good, and zero g is bad. We don’t know how much gravity is necessary for good health. We could learn about that from living on the Moon.”

“We should make the Moon the next International Space Station (ISS),” a place to do research in astronomy, geology, and biology, he said.

For lunar mining to be feasible, there would have to be a market for the products. Lunar tourism is a more likely option, especially if the cost can lowered to $1 million a person, or even better, $100,000 a person.

Mars is more suitable for establishing cities, but settling it faces major hurdles, starting with how to get there. Once a spacecraft is beyond Earth’s atmosphere and magnetosphere, it will be subject to very high levels of radiation on the nine-month journey to the Red Planet.

The spacecraft carrying astronauts to Mars would have to have strong radiation protection as well as some form of artificial gravity.

“It’s tantamount to homicide sending astronauts nine months in zero gravity,” Wanjek said.

As already seen from the difficulty in landing rovers on Mars, the planet’s weak atmosphere and weak gravity make landing on it perilous.

Once on the planet, astronauts would face the threat of dust storms that can last for months, during which times settlers would need a power source other than solar panels.

Mars’s low atmospheric pressure — six millibars as opposed to 1,000 millibars on Earth — may require settlers to wear bulky spacesuits whenever stepping outside controlled habitats.

Those habitats would have to provide protection from radiation. Wanjek envisions building them on the sides of mountains, where residents could look out of big windows at the Martian surface.

The MOXIE instrument being lowered into the Perseverance rover in March 2019. Photo Credit: NASA/JPL-Caltech

Oxygen could be generated by pulling carbon dioxide out of the atmosphere. The Mars Oxygen In Situ Resource Utilization Experiment (MOXIE), an instrument on the Perseverance rover, is designed to collect atmospheric carbon dioxide and electrochemically separate it into carbon monoxide and oxygen in anticipation of this need.

Farming on Mars will be difficult because Martian soil contains perchlorates, which are toxic to humans. The best option will be to grow plants hydroponically, he said.

Current technology is nowhere near being able to terraform Mars. That would require raising the planet’s atmospheric pressure to 150 millibars. While carbon dioxide could be liberated from the subsurface, there is not enough of it to generate the atmosphere humans need.

“It is feasible from an engineering and emotional viewpoint to have thousands of people on Mars. The question is whether it’s feasible from an economic point of view. Mars has little value to trade,” Wanjek stated.

The cost of getting off the Earth needs to be brought down significantly, which requires moving beyond chemical rockets, he stressed.

Alternative locations for human settlement

Options for space colonization other than the Moon and Mars could include rotating habitats carved within asteroids; Mercury, whose gravity is similar to that of Mars, where people could live in regions between dawn and dusk; Venus, where people could live in upper parts of the atmosphere; Saturn’s moon Titan, which is very cold; Saturn’s moon Enceladus, which has hydrothermal vents and is therefore the most likely solar system location other than Earth to host life; and even Pluto and Charon.

The further outward one travels in the solar system, the harder it becomes to place human settlements due to radiation and extreme cold, Wanjek said.

He cited the late writer Isaac Asimov, who advocated placing artificial habitats complete with artificial gravity and climate control in orbit around planets or moons.

Residents of orbiting habitats could visit the planets they seek to explore without having to permanently live there, giving them the best of both worlds.

Ultimately, human space exploration has the potential to improve life back on Earth, Wanjek said.

“Do we want a future of no space activity, fighting over finite resources, or daily access to space with infinite resources?” The latter “would make life on Earth better for all of us,” Wanjek said.


Laurel Kornfeld is an amateur astronomer and freelance writer from Highland Park, NJ, who enjoys writing about astronomy and planetary science. She studied journalism at Douglass College, Rutgers University, and earned a Graduate Certificate of Science from Swinburne University’s Astronomy Online program. Her writings have been published online in The Atlantic, Astronomy magazine’s guest blog section, the UK Space Conference, the 2009 IAU General Assembly newspaper, The Space Reporter, and newsletters of various astronomy clubs. She is a member of the Cranford, NJ-based Amateur Astronomers, Inc. Especially interested in the outer solar system, Laurel gave a brief presentation at the 2008 Great Planet Debate held at the Johns Hopkins University Applied Physics Lab in Laurel, MD.

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