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Mercury, the first planet in our solar system's orbit, often gets overlooked compared to planets like Mars. Yet, recent discoveries from NASA's MESSENGER probe suggest that Mercury might be just as captivating, if not more so, than its more famous counterparts. While humans may not be able to live on Mercury, the idea is not as impossible as it once seemed, and exploring this planet could provide valuable insights.
With the rise of private space companies like SpaceX, new missions to Mercury may be on the horizon. Space exploration costs have been decreasing due to technological advances and growing competition, making such missions more feasible. The most recent mission to Mercury was NASA's MESSENGER probe, launched in 2008.
Why should we continue to explore Mercury and other parts of the solar system? There are strong scientific and astronomical reasons that make Mercury an intriguing target for further research.
10. Mercury is Denser Than Any Planet in the Solar System, Except for Earth
Mercury's density is a notable feature to keep in mind. Why? The planet has a core composed of molten iron, contributing to its heavy mass. When humans venture to other parts of the solar system, they must deal with the challenges of low or zero gravity. Extended exposure to low gravity can weaken the human body, which is adapted to Earth's gravity.
Despite its small size, Mercury experiences a gravitational acceleration of 9.85 feet per second squared (3.7 meters per second squared), which is comparable to Mars. This relatively strong gravitational pull, although weaker than Earth's, makes Mercury a potential target for human exploration in the future.
9. Mercury Is Cooler Than Venus
Although Mercury is the closest planet to the Sun, it is not the hottest. Venus, the second planet from the Sun, holds that record. Mercury has a very thin atmosphere, known as an exosphere, with only trace amounts of gas. Despite this, it is bombarded by intense solar radiation, being on average 36 million miles (58 million kilometers) away from the Sun.
On the Sun-facing side of Mercury, temperatures can soar up to 800°F (427°C). However, Venus, the hottest planet in our solar system, experiences even higher average temperatures of 872°F (467°C). Mercury’s sparse exosphere does not trap heat, causing temperatures to plummet to -275°F (-170°C) on the side facing away from the Sun.
8. No human probe has ever set foot on Mercury.
Mercury remains unexplored by humans, a feat only made possible in the past 60 years with the advent of space travel. Though our technology is still evolving, discussions on whether humans should venture to other planets persist.
While many focus on the Moon and Mars as potential destinations, other ideas are being explored, such as creating a floating cloud city on Venus or a crater-based city on Mercury to research the Sun. With companies like SpaceX leading the way, humanity may soon journey to places previously unvisited, including Mercury itself.
7. Mercury provided critical evidence for Einstein's theory of General Relativity.
Mercury’s orbit is notably elliptical, meaning its distance from the Sun varies by 14.3 million miles (23 million kilometers). Among all the planets in our solar system, Mercury’s orbit has the highest eccentricity, making it more elongated and less circular than the rest.
Early observations of Mercury’s orbit revealed a discrepancy between the predictions of Newton’s gravitational theory and the actual precession or wobbling of its orbit as it completed multiple orbits around the Sun.
Einstein’s general relativity theory accurately describes the behavior of Mercury’s orbit. According to the University of Central Florida, Einstein’s theory predicts that the precession or wobble of Mercury’s orbit should be greater than what Newton’s laws would suggest. This prediction aligns with the observations made by astronomers studying Mercury’s orbit.
6. Mercury has a thin atmosphere containing oxygen and sodium.
Though Mercury resembles our Moon in appearance, recent studies have shown that it possesses a more complex core and surface structure. Heavier than Earth's Moon due to its iron core, Mercury's thin atmosphere contains oxygen and sodium. However, it is not thick enough to support breathing.
The presence of oxygen in Mercury's atmosphere is a remarkable find, potentially beneficial for future technology if humans ever travel there. It’s possible that the oxygen could be captured and compressed for astronaut use. Based on data from NASA's MESSENGER probe, oxygen makes up 42% of Mercury's thin atmosphere.
5. Mercury is the smallest planet in the solar system.
Mercury is a compact, dense planet. If it were the size of a golf ball, Earth would be about the size of a grapefruit. With a diameter of 3,032 miles (4,880 kilometers), Mercury is the smallest of the eight major planets in our solar system.
Despite its smaller size compared to Earth, which has a diameter of 7,926 miles (12,760 kilometers), Mercury remains a large object. A human astronaut or robotic rover would require a significant amount of time to explore it fully. A rover on Mercury for extended periods would likely need a small nuclear isotope generator for power, especially when operating in the planet’s shadowed regions or craters.
4. To human eyes, Mercury would appear dark grey.
What you see depends on your perspective or equipment. As the saying goes, 'Beauty is in the eye of the beholder.' The various wavelengths of electromagnetic radiation from the Sun would make Mercury appear dark grey to an observer with human eyesight.
To an alien observer with infrared vision, one half of Mercury would shine brightly due to its absorption of heat from the nearby Sun, while the other half would remain dark. For humans, Mercury would seem rather dull and uninviting. However, there would be ample opportunities to harness sunlight to generate power for future space bases.
3. Mercury Has a Massive Impact Crater
Mercury is particularly vulnerable to collisions from objects like asteroids and comets because of its thin atmosphere, which doesn't offer much protection. The planet's surface is marked with numerous craters, some of which are enormous. It resembles Earth's moon, which also features many craters. One of the largest craters on Mercury is the Rembrandt crater, measuring 444 miles (715 kilometers) across.
This colossal crater was captured by the MESSENGER space probe in 2008. Although it remains uncertain whether an asteroid or comet created it, the object responsible was likely larger than a skyscraper. Impact craters are often ideal sites for building space bases on hot planets, as the shadows they cast offer protection from excessive radiation from a star like the Sun.
2. Mercury Contains the Element Chromium
Chromium plays a vital role in producing shiny stainless steel and plating for classic cars. Additionally, when spacecraft are coated in stainless steel, the chromium protects them from corrosion, particularly when they land in Earth's oceans. SpaceX's Falcon and Starship rockets are constructed using stainless steel, which incorporates chromium. In the future, Mercury could be an ideal location for chromium mining, as the planet has abundant amounts of the element.
The largest concentration of chromium on Mercury is found in its heavy core. Chromium's resistance to corrosion is valuable for structures and vehicles exposed to the elements, especially harsh outdoor conditions and toxic acids. The MESSENGER space probe's data shows that chromium on Mercury's surface averages 200 parts per million.
1. Mercury Hosts Water in the Form of Ice
In 2008, the MESSENGER space probe uncovered evidence of water ice in the planet's large, dark craters. This ice may be native to Mercury or a result of comet impacts. The idea of water ice on a planet so close to the Sun is intriguing and unusual.
The discovery of water ice on Mercury opens up potential for sustaining future human space explorers with coolant and hydration. Water is essential for life, and without it, permanent life on a planet’s surface is unsustainable. Future space bases, whether through terraforming or aquaponic agriculture, could only thrive if water is available or brought from Earth.
