The planet Mars has something in common with Earth. Both planets have roughly the same amount of surface area and a similar tilt in their axis of rotation. In addition, there is strong evidence that both planets have undergone climate change in the past. On Mars, this evidence points to a place that once had a living atmosphere and liquid water on its surface.
At the same time, the two planets are different in many ways. One of these is that gravity on Mars is a fraction of the amount on Earth. When the time comes to send astronauts to Mars for any kind of research, it is extremely important to understand the possible impact this will have on humans.
Differences between Mars and Earth
The differences between Mars and Earth are crucial for life as we know it. For example, the atmospheric pressure on Mars is only a fraction of what it is on Earth (7.5 millibars on Mars averages over 1000 on Earth.) The average surface temperature on Mars is -63°C, much lower than Earth’s average surface temperature of 14°C.
And while the length of a Martian day is similar to Earth’s 1 day (24 hours 37 minutes), the length of 1 Martian year (687 days) is significantly longer. Comparing the gravity of the two planets, the gravity on the surface of Mars is 62 percent lower than that of Earth. Mars‘ gravity is only 0.376 of Earth’s. A person weighing 100 kg on Earth weighs only 38 kg on Mars.
This difference in surface gravity is due to several factors. The most prominent of these are mass, density, and radius. Although Mars and Earth have almost the same surface area, Mars is only half the diameter of Earth and has a lower density. Compared to our planet in terms of size, Mars has about 15 percent of Earth’s volume and 11 percent of its mass.
Mars Gravity Calculation
Scientists have calculated Mars’ gravity based on Newton’s Universal Theory of Gravitation, which states that the gravitational force exerted by a body is proportional to its mass. When applied to a planet-like spherical body of a given mass, the surface center of gravity will be inversely proportional to the square of its radius. When applied to a spherical body of a given density, it will be approximately proportional to its radius.
These proportions can be expressed by the formula g = m / r2. Here g is the surface gravity of Mars (Earth’s gravity is expressed as 9.8 m/s²), m is the mass, expressed as a multiple of Earth’s mass of 5.976 – 1024 kg. r is the radius, expressed as a multiple of Earth’s (average) radius of 6.371 km.
For example, Mars has a mass of 6.4171 x 1023 kg, which is 0.107 times the mass of Earth. It also has an average radius of 3,389.5 km, equivalent to 0.532 Earth radii. The surface gravity of Mars can therefore be expressed mathematically as 0.107 / 0.532², where we get the value 0.376. Based on the Earth’s gravity, Mars’ gravity corresponds to a value of 3.711 m/s².
Effects of Mars’ Gravity on Humans
The effects of prolonged exposure to this gravity on the human body are unknown. However, ongoing research on the effects of low gravity on astronauts has shown that it can have detrimental effects on muscle mass, bone density, organ function, and even vision loss.
Understanding the impact of Mars’ gravity on terrestrial life is an important first step if plans are to send astronauts to other planets or asteroids. The effects of long-term exposure to a gravity one-third the size of Earth’s gravity will be key to any plans, such as upcoming manned space programs.
For example, projects such as “Mars One” could increase the likelihood of diseases such as muscle deformation and osteoporosis for its participants. A recent study of astronauts on the International Space Station (ISS) found a 30 percent loss of muscle performance and a 15 percent loss of muscle mass due to zero gravity for 4-6 months.
As we get closer to the 2030 NASA manned mission to Mars, it is expected that more research initiatives will be undertaken, and decisions will be made accordingly.