It’s night-time. Work is over, Dinner has been eaten, and you’re just about to go to bed. You lay down for a short while, but your mind decides it’s not done with the day yet. You think. You let ideas run their course. But you are still not tired. Eyes wide open. You decide to pull the curtains to welcome the night sky into your room. It’s bright outside. The sky is radiant, you notice, but only barely, as your eyelids slowly start collapsing under their own weight. You start drifting away, and just as you are about to close your eyes for the night, you glance upward. It’s the moon. Our moon. A celestial constant in an otherwise ever changing sky. Under its glow, you fall asleep, reassured that, no matter what, the moon will be there all night, just as it has been for millennia.
Our moon has pledged its allegiance to earth for a long time now: almost for as long as the earth has existed by some estimates. But this loyalty has not always been rewarded with the attention that it merits. The moon and its understated presence, both in the night sky and in our ambitions of becoming a space-faring civilization, have been gathering the limelight as of late. Not one, but 2 major developments regarding the moon in the short span of a month.
On October 26th, 2020, NASA’s SOFIA – short for Stratospheric Observatory for Infrared Astronomy- discovered the presence of water on the sunlit surfaces of the moon. Now while the presence of water on the moon is not surprising news, any significant amount detected thus far had only been in the darker, shadowed parts of the moon.
By the way, the moon has no “dark-side.” All sides are lit, but it just so happens that the moon is tidally locked to earth, which means see the same side of the moon every night. It has, however, poles, parts of which are shadowed. It is in these poles that water was previously discovered. These poles were able to store some water because they were protected from the otherwise extreme temperatures on the rest of the moon’s surface. The lack of an atmosphere means that temperatures on any given lunar day can fluctuate by more than 200 degrees Celsius. That meant that whatever water could have been on the moon would quite easily just evaporate off its surface. This is why the presence of water on the sunlit surfaces comes as such a surprise. It is where you would least expect to find it. The amount of water is still miniscule, even when compared to the water content of some of the harshest deserts on earth. Yet, the mere fact that there seems to be a mechanism that is generating, or at least storing water, is of great significance in humanity’s next chapter in space exploration.
On the other hand, China’s Chang’e-5 spacecraft launched moonward on November 23rd, 2020. It’s mission is to try and understand the history of the moon by bringing back lunar rocks that are younger than any of the samples we already have. The samples that are supposed to be brought back are a billion years younger than the ones collected by Apollo. Scientists intend to study the late-stage volcanism that should answer questions about the moon’s younger surfaces. It’s a short 23-day mission, after the end of which we should have a clearer picture of how our rocky neighbour came to be. This mission is one of a series of missions that, in theory, should culminate into the “International Lunar Research Station” in 2030. But, given how close the moon is, it’s actually quite surprising how we still do not know so much about it. For one, we’re still not totally sure how it was formed. We have theories, of course, the likeliest of which is a spectacular one. According to it, the moon was the result of a collision between the earth and a Mars sized planet named Theia. The impact from the collision ejected material that eventually morphed into what we see today as the moon. This theory seems most likely because the composition of lunar rocks brought back from the Apollo missions is very similar to what can be found on Earth as well, suggesting they were from the same source. There are new theories still about whether that initial collision led to the birth of just one moon, or two. This is because the crust on the moon is not even. Parts of it are significantly thicker than others, and scientists believe that it could have been caused by a collision on one side that led to the uneven thickness. Regardless, the moon was far from the gentle orb of light that we see today. Soon after it had formed, it was a fiery ball of magma. But even at its hottest, most ravaging state, our cosmic companion was already preparing earth to harbour life.
You see, like how the earth tugs on the moon, the moon, too, tugs on the earth. The gravitational pull goes both ways, and as such, soon after the collision, the moon's pull is what helped to stabilize the earth’s axial tilt allowing the seasons to exist, and to do so in a stable manner. Had it not been this way, we would have had a dizzying barrage of ice ages and extreme warm climates all at the same time. That would’ve been terrible for complex life, as it depended on a stable climate to evolve. This axial tilt and its constancy are down to the size and number of a planet’s moons. In fact, the earth is the only planet among the 8 major ones in the solar system to have 1 moon. Mars, on the other hand, has 2 but both are rather small, and as such, mars wobbles about 10 degrees from its normal tilt of 25 degrees. We also have the moon to thank for stirring up the “primordial soup” with its power to influence tides. Without that, organisms may never have amassed enough nutrients to form into complex life forms. This tidal connection between the earth and the moon has another interesting property. Because the earth spins faster than the rotation of the moon around it, the tides are always ahead of the moon. So, not only is the moon causing tides, but it is also pulling them back. In fact, in the early days, the earth was spinning 4 times faster than it does now. But, over time, that has slowed down to the 24-hour days we have now.
But why is there an uptick in talks about the moon lately? Well, for starters, there is the Artemis program, which is an incredibly ambitious program that intends on having the next man and the first woman on the moon in the next 5 years. While we have already been to the moon, this time, scientists seek to learn how these astronauts could spend prolonged periods in space to be better suited for longer space travel, such as travel and the subsequent colonization of Mars. You see, in the scale of outer space, the moon is really, really close. And given we have already visited it numerous times already, it’s quite surprising that we haven’t visited it again in such a long time. Recent discoveries though stir up some much-needed excitement about the moon. While it has been overlooked in the past few decades, having a colony on the moon is the logical next step in our space endeavours. Water is obviously one of, if not the biggest concern in having a stable presence on the lunar surface. Now, this is important for both drinking... and jet fuel. Jet fuel contains the very same ingredients as water, hydrogen and oxygen. The recent discoveries certainly shed some optimistic light on the possibility of using this water, but scientists could also use the solar wind and the hydrogen that came with it and combine it with the oxygen found in lunar dust.
Speaking of solar wind, we also need to think about protecting ourselves from the harmful radiation in space. Solar wind is essentially charged particles from the sun that are constantly being ejected into space. They move extremely quickly, and are upwards of 1 million degrees celsius. Particles don’t sound dangerous, but the radiation most definitely is.
It’s no wonder that astronauts who have been to the moon have shorter lifespans than their earthly brethren. Besides, one of the reasons you see so many craters on the moon's surface and not so many on ours is that the moon is simply not big enough to hold on to an atmosphere that would burn asteroids up on entry. It's also why there is no insulation on its surface, which is why you see the crazy 200-degree temperature differences between day and night.
All these things pose a significant risk for a future colony on the moon. You and I take our atmosphere for granted every day. But had it not been there, even something as small as an intergalactic grain of sand would have the velocity many many times that of a bullet and could cause a lot of damage. It’s also one of the ways the moon is a time machine, as the crater-ridden surface preserves a chunk of our history in its lunar dust. Pretty much whatever has hit the moon has also hit the earth; we just don’t see its remnants. All of this has led scientists to consider lava caves as a possible place to live. When the moon was still an active fireball, lava seeped through some of the layers of its surface. It eventually cooled down, as we know and the lava dissipated, but the pathways it took remain. Those lava caves offer protection from both the speeding debris and the temperature extremes. The absence of an atmosphere and thermal insulation is obviously down to the moon's small size. But while this size is a disadvantage for these aspects, it is a tremendous advantage in others. You see, the small size of the moon means the gravitational pull on its surface is much less compared to that of the earth. 1/6th , in fact. That would mean that the same rocket would require significantly less energy to lift off from the moon than it would need to lift off from earth. That is why a colony on the moon is the logical next step.
Another reason why the efforts to colonize the moon could set the scene up for larger efforts later is its geopolitical implications. Conquering the moon famously became the focal point of the tensions between the United states and the USSR. But beyond showcasing humanity’s ability in what it can achieve when it is truly motivated, the cold war also showed that adversaries can and do come together out of a mutual concern for their own safety and rights. Both the US and USSR agreed to a treaty in 1967 that would allow free access and prevent national appropriation of celestial bodies, including the moon. This law holds to this day. Today, the adversaries have changed, yet the competition remains. While this competition should spur technological innovation, we have to wonder what its implications will be socially and politically. If there is, indeed, a colony, who gets to go? Who gets to live? On a planet so devoid of other resources, light is power. Very few sections of the moon get regular sunlight. Who gets authority over those sections? These are social problems, not technological ones. And as such, the moon here is not so much a blank slate, but a template for interplanetary policy. Not just for Mars and any other planet we colonize in the future, but also for the pale blue dot we are already on right now.
The moon actually moves away from the earth about 4 cm a year. We know this because the Apollo astronauts actually left a retroreflector on the surface that scientists can point lasers to, which can then be used to calculate the distance of the moon from earth. So, it seems, our companion in the night sky is leaving us, slowly but surely. Or is it? You see, once the spin of the earth and the rotation of the moon are equal, neither party will be tugging at each other any more than they need to remain in orbit. It is at that point that the moon will stop moving away from us. However, when all these forces cancel each other out, the solar wind remains unaccounted for. Far, far into the future, that force will cause enough drag to slow the moons rotation- so much so that it starts coming back closer to earth. And given enough time, it will come so close that earth's gravity, the endearing force that had held it close for all this time, will rip the moon apart. In its own, poetic way, the moon will return to where it came from. But that isn’t destined to happen for another 50 billion years or so. And it's way more likely that the earth will be swallowed by the expanding sun before then, and when the lights go out for one last time, the moon will actually accompany us, just as it always has done all this time. The moon really will be there with us forever. From the birth of life, to our inevitable demise, the moon will witness all of it.
- MA, MM