Why to colonize Mars rather than the moon?

The space race between Russia and the United States is over, but that doesn't mean interest in the moon has dried up – now, along with national governments, multi-billion dollar companies are making moon (and Mars, by association) landing a priority.

This generation's race, in proper form, is taking place between former PayPal CEO, amateur rapper and Tesla tycoon Elon Musk and Amazon's owner Jeff Bezos, who also owns the Washington Post.

The logic appears to be: Once the European regulators get too tough, you've gotta set up shop somewhere else.

Musk and Bezos both plan to visit the moon before NASA's Artemis mission plans to land in 2024, picking up where the 12 moonwalkers of the Apollo missions left off. However, the main goal isn't the moon, but Mars.

Musk says he's going to space because "there's nothing more exciting than being out there among the stars”, while Bezos' ambitions are fueled by a belief that "we will run out of energy” on Earth.

Musk published an ambitious self-authored study last year outlining his vision of Mars colonization. The report acknowledges the importance of visiting the moon first as a sort of stopping-off point, a choice Bezos and NASA have also deemed prudent.

Both Bezos and Musk have pledged to assist in NASA's recently announced 2024 mission to the moon, Artemis. The mission, previously scheduled to send humans to the moon by 2028, was hastened to 2024 in March by an order issued by the Trump administration. 

Read more:Orbiting lunar base: German astronaut Reiter on Deep Space Gateway

If everyone cares about Mars more, why are we going back to the moon? 

Neil Armstrong and Buzz Aldrin's initial Apollo 11 moon landing was more of a political triumph over the Soviet Union than a scientific one – the mission lasted just 3 days, and little actual scientific work was performed.

However, in the following Apollo missions, astronauts collected rocks allowing scientists to better understand the composition of the moon's surface, many of which they preserved for later generations with better technology to study.

With new remote sensing technology, scientists recently discovered the existence of water on the north and south poles of the moon. This discovery, paired with the knowledge acquired from the preserved moon rock, will better guide Artemis venturers on a quest to discover lunar water.

The existence of this water could be fairly groundbreaking if, with further exploration, more is discovered and scientists are able to find ways to extract it. An ample supply of lunar water could help support a space station on the moon - which was previously considered unlikely due to a general understanding that the moon was drier than the Sahara.

At this point, if anyone wants to colonize Mars, they will need to take laborious, energy-heavy trips from Earth lasting up to 8 months one-way. A moon station could help mitigate the lengthy journey, according to planetary geologist Georgiana Kramer. This could save Mars-faring rockets time, energy and money. 

Read more: Moon station 'Deep Space Gateway' to be built by Russia and US

Can we use lunar water?

Because the moon isn't tilted on an axis, like Earth, the poles receive no sunlight at all. Water ice exists in deep craters on these poles, where Artemis plans to land.

NASA planetary geologist Sarah Noble said the source of the water is still unknown, but that it could be the result of comet and meteorite deposition (because the moon has no atmosphere to ward them off); solar winds from the sun, which could bring hydrogen that mixes with oxygen-hosting minerals on the moon's surface; or early lunar volcanism, which could have released water that is still trapped.

Early lunar volcanism also created lava tubes, which are also found on Earth in volcanic areas in Hawaii and Colorado. They are long, cave-like tunnels on the surface of the moon, where lava once flowed and has now cooled.

When the feasibility of life on the moon is discussed in online forums such as Reddit, the idea of placing a space station inside one of the lava tubes is often raised. Both Kramer and Noble confirm this could potentially work, depending on what's discovered during the Artemis mission. The rock, Kramer said, could shield the sun's radiation and feature relatively normalized temperatures.

Noble said in the short term, life in the tubes isn't part of NASA's plan, but in the long term, they could be investigated by robots.

It will be impossible to know whether these theories are accurate until scientists are able to sample the water, however, which is why Artemis plans to land on the south pole of the moon, where much of it is concentrated. Up to this point, scientists haven't had any physical interactions with lunar water, Kramer said.

If a good amount of water is discovered, it could be used for rocket fuel and drinking, which could make Mars exploration easier. 

Read more: SpaceX tourist revealed: Japanese billionaire Yusaku Maezawa to fly around moon

Which place is better for life: Mars or the moon?

All of that said, Mars simply has more resources than the moon, Robert Zubrin, an aerospace engineer, wrote in a treatise published by the National Space Society's magazine "Ad Astra".

"In contrast to the Moon, Mars is rich in carbon, nitrogen, hydrogen and oxygen, all in biologically readily accessible forms such as carbon dioxide gas, nitrogen gas, and water ice and permafrost. Carbon, nitrogen, and hydrogen are only present on the Moon in parts per million quantities, much like gold in seawater," he wrote.

Zubrin is the author of Mars Direct, a research paper-turned-book advocating for Mars exploration, and heads the Mars Society, which also advocates for Mars exploration.

The moon does not receive enough natural sunlight to grow plants of any variety, Zubrin writes, but Mars does, which will allow future colonists to sustain themselves in a way they never could on the moon.

This is all in addition to the moon's lack of an atmosphere, extreme weather changes and barren, radioactive surface.

Zubrin's analysis of Mars illustrates why life on the moon is only considered in the context of the lunar body serving as a stopping-off point on the way to something bigger and better - or, at least, more sustainable for human populations.