Physical Science:

Mars [Figure 12.1.5] is the fourth planet from the Sun and the second-smallest planet in our solar system, after Mercury. It is often referred to as the Red Planet because of its reddish appearance, which is caused by iron oxide or rust on its surface. Mars has a diameter of approximately 6,779 kilometers, which is about half the size of Earth. It has a thin atmosphere composed mainly of carbon dioxide, with small amounts of nitrogen and argon. Mars also has the largest volcano and the deepest canyon in the solar system. There is evidence that liquid water once existed on Mars, and there are signs of dried-up riverbeds, lakes, and even an ancient ocean. The search for signs of life on Mars is a major focus of current and future missions. Several spacecraft, including rovers and orbiters, have been sent to Mars to study its surface, atmosphere, and geology. In 2020, NASA’s Perseverance rover successfully landed on Mars and began exploring the Jezero Crater, which is believed to have once been a lakebed and could contain evidence of past microbial life. Mars is also a target for future human exploration, with plans for manned missions and even eventual colonization. However, the harsh conditions on Mars, including its thin atmosphere and extreme temperatures, make any such missions challenging and expensive.

The thin atmosphere of Mars does not provide significant protection from the sun’s radiation and solar wind, which means that the planet’s surface is bombarded by high-energy particles. However, the atmosphere does help to regulate the planet’s temperature and weather patterns. The temperature on Mars can vary greatly, ranging from an average of about -63°C (-81°F) at the equator to as low as -143°C (-225°F) at the poles during the winter. During the summer, temperatures can reach a maximum of around 20°C (68°F) at the equator. The Martian atmosphere also contains clouds, dust storms, and seasonal weather patterns. Dust storms can sometimes cover the entire planet and can last for weeks or even months, affecting the solar-powered rovers and landers that are exploring the surface.

While the Mars missions have not yet found definitive evidence of life on Mars, they have provided valuable data and insights into the planet’s geology, climate, and potential habitability. Future missions, including the joint NASA-ESA Mars Sample Return mission, are planned to bring back samples from Mars for further analysis, which may help answer the question of whether life exists or has ever existed on the planet.

Mars has two small moons, named Phobos and Deimos, which are thought to be captured asteroids. Phobos is the larger and closer of the two moons, and is heavily cratered with deep grooves and ridges on its surface. Its surface is thought to be composed of a mixture of rock and dust, and it orbits Mars at a distance of only 9,377 km (5,827 miles), which is closer than any other moon in the Solar System relative to its host planet. Deimos is smaller and more irregularly shaped than Phobos, and has a smoother surface with fewer craters. Its surface is also thought to be composed of a mixture of rock and dust, and it orbits Mars at a distance of about 23,460 km (14,577 miles). Both Phobos and Deimos are relatively small and irregularly shaped, and are thought to be composed of materials similar to those found in asteroids. They have been studied in detail by several spacecraft, including the Mars Reconnaissance Orbiter, which has provided us with high-resolution images and valuable scientific data about these small moons of Mars.