You’re standing on the edge of Valles Marineris. It's the grandest canyon in the solar system. You take a step, expecting the heavy thud of your boots on the red dust, but instead, you feel... light. Almost floaty. If you’ve ever wondered what is the gravity on Mars, you’re essentially asking how it feels to lose two-thirds of your body weight overnight. It’s a trip.
Mars is a bit of a lightweight. It’s the second smallest planet in our neighborhood, only beating out tiny Mercury. Because it’s so much smaller and less dense than Earth, its gravitational pull is significantly weaker. We’re talking about $3.721 m/s^2$. On Earth, we deal with $9.807 m/s^2$. Basically, the gravity on Mars is about 38% of what you’re used to right now.
Imagine weighing 200 pounds here on Earth. You step onto a scale on the Martian surface, and it reads 76 pounds. You’re the same person, same mass, but the planet just isn't pulling on you that hard. It’s like living in a permanent state of "moon-lite."
How Gravity on Mars Actually Works (The Physics Part)
Gravity isn't magic. It's just mass. Newton figured this out a long time ago, and Einstein refined it, but for our purposes, it comes down to how much "stuff" is packed into the planet beneath your feet. Mars has about 10% of Earth’s mass. You might think that means it should have 10% of the gravity, right?
Not quite.
Size matters too. Mars is roughly half the diameter of Earth. Because you’re standing closer to the center of its mass than you would be on a giant like Jupiter, the pull is stronger than the mass alone suggests. That’s why we get that 38% figure.
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If you tried to jump on Mars, you’d soar. On Earth, a decent vertical leap might get you a foot or two off the ground. On Mars, you’d easily clear six feet. You’d feel like a superhero, but a very slow-motion one. The "hang time" would be incredible. You’d go up, stay up for what feels like forever, and drift back down.
The Newton-Meter Breakdown
To get technical for a second, the formula for surface gravity is $g = \frac{GM}{r^2}$.
- $G$ is the gravitational constant.
- $M$ is the planet's mass.
- $r$ is the radius.
When you crunch those numbers for the Red Planet, you realize that Mars is actually quite "fluffy" compared to Earth. It’s less dense. Our planet has a massive, scorching iron core that’s incredibly heavy. Mars has a core too, but it’s smaller and likely contains more lighter elements like sulfur. This internal structure is exactly why the gravity on Mars remains one of the biggest hurdles for future colonization. It’s not just about the weight; it’s about what that weight—or lack thereof—does to the human body over years.
Your Body on Low Gravity: It’s Not All Fun and Games
Living with 38% gravity sounds like a blast until you talk to a doctor. We evolved for Earth’s 1g. Our hearts are pumps designed to shove blood upward against the constant drag of Earth's pull. Our bones are scaffolding built to support a specific weight.
What happens when that weight disappears?
- Muscle Atrophy: Your muscles don't have to work as hard to move you around. Within weeks, they start to wither. Even the heart muscle can shrink because it doesn't need to pump as vigorously.
- Bone Density Loss: This is the big one. Without the "loading" of gravity, your body thinks your bones are unnecessary. Astronauts on the ISS lose about 1% to 1.5% of their bone mineral density per month.
- Fluid Shifts: On Earth, gravity pulls fluids toward your legs. On Mars, that fluid migrates toward your head. You get "puffy face" and "bird legs." It can even change the shape of your eyeballs, messing with your vision.
NASA has spent decades studying this. Researchers like Dr. Kevin Fong have documented how microgravity wreaks havoc on the vestibular system—that's your inner ear's balance center. On Mars, you’d probably feel nauseous for the first few days. Your brain would be screaming because the signals from your eyes wouldn't match the signals from your ears. You’d be clumsy. You’d drop things. You’d probably trip over a rock and fall in slow motion, which sounds funny until you realize a suit puncture in a vacuum is a death sentence.
The Atmosphere Problem
Gravity does more than just keep your feet on the ground. It holds onto the air you breathe. This is where Mars really struggled.
Billions of years ago, Mars might have been a lot like Earth. It likely had thick atmosphere and liquid water. But because the gravity on Mars is so weak, it couldn't hold onto its gases. Solar winds from the sun literally stripped the atmosphere away, molecule by molecule.
Today, the Martian atmosphere is 100 times thinner than Earth’s. It’s mostly carbon dioxide. If you stood on the surface without a pressure suit, the low pressure would cause the oxygen in your blood to fizz out like a shaken soda. It’s a direct consequence of that low gravitational pull. Without enough mass to tether an atmosphere, a planet becomes a cold, dead desert.
Walking on Mars: The "Lope"
If you ever watch footage of the Apollo astronauts on the Moon, they don't walk. They hop. They do this weird, side-to-side shuffle. That’s because the Moon’s gravity is even lower—about 16% of Earth’s.
On Mars, you wouldn't necessarily need to hop, but you wouldn't walk normally either. Scientists have used "gravity-offloading" rigs (basically giant treadmills on springs) to simulate the Martian gait. They found that humans naturally transition to a "lope" at much lower speeds than they do on Earth.
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It’s an efficient way to travel. You’d cover more ground with less energy. If you were a marathon runner, you’d probably set world records on Mars, assuming you had a lightweight life-support system. But there’s a catch. Because your traction depends on your weight, you’d find it harder to stop or change direction. You’d have the momentum of your full mass, but the "grip" of a much lighter person.
Why We Can't Just "Fix" It
You see it in sci-fi all the time. "Gravity generators." Spinny sections on spaceships.
In reality, we have no way to artificially create gravity on a planetary scale. We can't just add mass to Mars. To get Mars up to Earth-level gravity, you’d need to smash about nine other Mars-sized planets into it. Not exactly a weekend DIY project.
The only real solution for future colonists is centrifugal force—spinning habitats—or just plain old exercise. Astronauts on Mars would likely need to spend two to three hours every single day on high-resistance bungee machines just to keep their skeletons from turning into Swiss cheese.
The Martian Born
Here’s a wild thought that biologists actually lose sleep over: What happens to a baby born in Martian gravity?
We have zero data on how a human embryo develops at 0.38g. Would the spine grow too long? Would the heart be too weak to ever visit Earth? If you grew up with the gravity on Mars, Earth would feel like a high-pressure torture chamber. You’d weigh nearly three times more. Your bones might literally snap under the "new" weight of your own body.
This creates a "one-way" problem. Colonizing Mars might not just be a move; it might be a permanent biological divergence. We’d become a different version of human.
Engineering Challenges of Low G
From a technology standpoint, the gravity on Mars is a double-edged sword.
Landing is a nightmare. On Earth, we use parachutes because the atmosphere is thick. On the Moon, we use rockets because there's no atmosphere. Mars is in the "cursed middle." The atmosphere is too thin for parachutes to do all the work, but the gravity is just strong enough that you need a lot of fuel to slow down.
This is why NASA had to get creative with things like the "Sky Crane" for the Curiosity and Perseverance rovers.
However, getting off Mars is much easier. You don't need a skyscraper-sized Saturn V rocket to reach orbit. A much smaller vehicle can punch through the thin air and escape the 3.721 m/s^2 pull. This makes Mars a perfect "gas station" for the rest of the solar system. If we can manufacture fuel there, it’s a much cheaper jumping-off point than Earth.
What You Should Do Next
If you're fascinated by the physics of other worlds, don't just stop at reading. The implications of Martian gravity are being solved in real-time by people at SpaceX, NASA, and ESA.
- Check out the NASA Human Research Program. They publish open-access papers on how they’re trying to solve the bone-loss issue. It’s dense, but it’s the real science behind the sci-fi.
- Use a gravity calculator. There are plenty of web tools where you can input your weight and see what it would be on every planet from Mercury to Neptune. It puts the scale of the solar system into perspective.
- Watch raw footage of the Mars rovers. Look at the way the dust settles when the wheels turn. It doesn't billow like it does on Earth; it falls differently. You can literally see the gravity in the movement of the dirt.
- Support space medicine research. The tech developed to keep astronauts healthy in low gravity—like portable bone density scanners and advanced telemedicine—is already being used to help elderly patients and people in remote areas right here on Earth.
Mars isn't just a rock in the sky. It's a laboratory for what the human body can endure. Understanding its gravity is the first step toward eventually walking on it. Just remember to bring your resistance bands—you're going to need them.