In Photos: Harvard’s 373rd Commencement Exercises


Rabbi Zarchi Confronted Maria Ressa, Walked Off Stage Over Her Harvard Commencement Speech


Former Harvard President Bacow, Maria Ressa to Receive Honorary Degrees at Commencement


‘A’ Game: How Harvard Recruits its Student-Athletes


Interim Harvard President Alan Garber Takes the Political Battle to Washington


Dear Elon: There Is No Planet B

Mars is not, and will never be, our “Planet B.”

By Daniel L. Leonard, Crimson Opinion Writer
Daniel L. Leonard ’21, a Crimson editorial editor, is a joint History of Science and Philosophy concentrator in Winthrop House. His column appears on alternate Mondays.

When I was younger, I looked to the stars for humanity’s future. But recently, a chant I heard at a climate rally reminded me to keep my attention close to the ground: “There Is No Planet B.”

There are some people who disagree with this slogan; they believe that “Planet B” really exists, orbiting the Sun just a bit further than Earth. One such believer is Elon Musk. If you visit Musk’s twitter account — which I don’t recommend, it’s pretty cringy — you’ll see that his cover photo is an illustration of the planet Mars in four stages of development. The first shows the red Mars that we know today; the second depicts a greening Mars with a small liquid ocean; the third expands the foliage and waterways and even introduces a Martian atmosphere; the fourth is almost indistinguishable from Earth.

This process, known as “terraforming,” is a massive technological undertaking whereby a celestial body, like a planet or a moon, is modified in order to become habitable for humans. It’s a common theme in science fiction, but some people — like Musk — think it could actually be achieved. Elon thinks of Mars as a backup planet in case something goes wrong on Earth. All we need to do is tweak Mars’ current features to be more like Earth’s, and voila: humanity has a cozy new home.

Unfortunately, Elon Musk is wrong. Mars is not, and will never be, our “Planet B.”

There are many non-trivial features of Mars that we simply cannot change. Mars’ gravity is only 38 percent that of Earth, and its year lasts 687 days — both factors would make adapting to life on Mars a significant challenge for Earth plants and animals. But, as proponents of terraforming would point out, not every feature of Mars is as immutable as these.

Currently, Mars’ soil is full of perchlorates — hazardous chemicals that could kill the crops we try to grow. Fortunately, perchlorates dissolve in water, so all we have to do is rinse out the soil. So... how do we get water on Mars?

Well, thankfully, Mars has a lot of water already in the form of frozen ice caps. Freeing up that water requires heating up Mars’ surface temperature well above its current -81°F average. But, hold on... how do we do that?

Well, the main reason Mars is so cold is due to its very thin atmosphere, which is incapable of trapping in the Sun’s heat. If Mars were to have an Earth-like atmosphere, the planet should begin to heat up, melting the ice, allowing us to grow crops. Makes sense. But how do we produce a thick Martian atmosphere?

That’s the trillion-dollar question.

And unfortunately, this is where we hit a dead end. Existing proposals for how to give Mars an atmosphere require three main ingredients: lots of money, lots of time, and technology that we don’t yet possess. Plus, even if we could give Mars the right atmosphere, the planet has no way to hold on to it. Unlike Earth, Mars has a relatively weak magnetosphere — a magnetic “shield” that protects a planet’s atmosphere from escaping into outer space. Without a strong enough magnetosphere, any atmosphere that we give Mars would be stripped away by the force of solar winds.

Clearly, Mars will never be a second Earth. But even if it were technically possible to terraform Mars, there are other compelling reasons to avoid doing so.

The first is an aesthetic argument. While some people might look at Elon’s cover photo and feel excitement, I feel the opposite. Why on Earth do we need another Earth in this solar system? Mars is such a unique planet, with its high mountains, deep canyons, and beautiful rust-red soil. We don’t need another blue-and-green marble orbiting the Sun. (Maybe I’m just biased because red is my favorite color.)

If that doesn’t convince you, consider the scientific loss. As it stands, scientists are unsure if Mars has any lifeforms. Some speculate that there may be microbial life living deep below Mars’ surface. This would be an astounding discovery. Tragically, terraforming would erase our ability to confirm the existence of life on Mars — it would be near-impossible to distinguish which microbes were native to the planet and which were brought with us from Earth.

Ultimately, I think people like Elon Musk are driven by a genuine sense of scientific curiosity when they discuss terraforming Mars. Even so, I think the idea is a ridiculous distraction. Those who tantalize us with fantasies of other habitable worlds are doing humanity a grave disservice. Any attempt to terraform Mars would be a massive failure, and would cost precious time and resources that would be far better spent on protecting the Earth. While fighting climate change is a challenge, it’s one million times easier to keep Earth habitable than to start a new habitable planet from scratch.

There is no Planet B. This fact shouldn’t scare us; instead, it should make us cherish our home on Planet A.

Daniel L. Leonard ’21, a Crimson editorial editor, is a joint History of Science and Philosophy concentrator in Winthrop House. His column appears on alternate Mondays.

Want to keep up with breaking news? Subscribe to our email newsletter.