In 2056, pollution and overpopulation have caused an ecological crisis on Earth. As part of the first stage of terraforming, automated interplanetary missions seeded Mars with atmosphere-producing algae. The crew of Mars-1, consisting of Quinn Burchenal, Bud Chantila, Robby Gallagher, Kate Bowman, pilot Ted Santen, and Chip Pettengill, is dispatched to investigate when the oxygen produced by the algae mysteriously decreases.
Finding fossils preserved from early Mars might tell us that life once flourished on this planet. We can search for evidence of cells preserved in rocks, or at a much smaller scale: compounds called biosignatures are molecular fossils, specific compounds that give some indication of the organisms that created them. However, over hundreds of millions of years these molecular fossils on Mars are subject to being destroyed or transformed to the point where they may no longer be recognized as biosignatures. Future missions must either find surface regions where erosion from wind-blown sand has recently exposed very ancient material, or alternately samples must be obtained from a shielded region beneath the surface. This latter approach is being taken by the ExoMars rover under development where drilled samples taken from a depth of up to 2 meters will be analyzed.
We've learned a lot about Mars from the past 30 years of lander, rover, and orbiter missions. We have confirmed the existence of past water on the Martian surface, that Mars was once a habitable planet, and that it once had a thicker atmosphere than it does today.
The planet's cold, thin atmosphere means liquid water likely cannot exist on the Martian surface for any appreciable length of time. Features called recurring slope lineae may have spurts of briny water flowing on the surface, but this evidence is disputed; some scientists argue the hydrogen spotted from orbit in this region may instead indicate briny salts. This means that although this desert planet is just half the diameter of Earth, it has the same amount of dry land.
Mars also has the largest volcanoes in the solar system, Olympus Mons being one of them. The massive volcano, which is about 370 miles (600 km) in diameter, is wide enough to cover the state of New Mexico. Olympus Mons is a shield volcano, with slopes that rise gradually like those of Hawaiian volcanoes, and was created by eruptions of lava that flowed for long distances before solidifying. Mars also has many other kinds of volcanic landforms, from small, steep-sided cones to enormous plains coated in hardened lava. Some minor eruptions might still occur on the planet today.
Channels, valleys and gullies are found all over Mars, and suggest that liquid water might have flowed across the planet's surface in recent times. Some channels can be 60 miles (100 km) wide and 1,200 miles (2,000 km) long. Water may still lie in cracks and pores in underground rock. A study by scientists in 2018 suggested that salty water below the Martian surface could hold a considerable amount of oxygen, which could support microbial life. However, the amount of oxygen depends on temperature and pressure; temperature changes on Mars from time to time as the tilt of its rotation axis shifts.
It remains uncertain how Phobos and Deimos were born. They may be former asteroids that were captured by Mars' gravitational pull, or they may have formed in orbit around Mars at roughly the same time the planet came into existence. Ultraviolet light reflected from Phobos provides strong evidence that the moon is a captured asteroid, according to astronomers at the University of Padova in Italy.
Phobos is gradually spiraling toward Mars, drawing about 6 feet (1.8 meters) closer to the Red Planet each century. Within 50 million years, Phobos will either smash into Mars or break up and form a ring of debris around the planet.
Mars lost its global magnetic field about 4 billion years ago, leading to the stripping of much of its atmosphere by the solar wind. But there are regions of the planet's crust today that can be at least 10 times more strongly magnetized than anything measured on Earth, which suggests those regions are remnants of an ancient global magnetic field.
NASA's InSight lander has been probing the Martian interior since touching down near the planet's equator in November 2018. InSight measures and characterizes marsquakes, and mission team members are tracking wobbles in Mars' tilt over time by precisely tracking the lander's position on the planet's surface.
These data have revealed key insights about Mars' internal structure. For example, InSight team members recently estimated that the planet's core is 1,110 to 1,300 miles (1,780 to 2,080 km) wide. InSight's observations also suggest that Mars' crust is 14 to 45 miles (24 and 72 km) thick, on average, with the mantle making up the rest of the planet's (non-atmospheric) volume.
The carbon-dioxide-rich atmosphere of Mars is also about 100 times less dense than Earth's on average, but it is nevertheless thick enough to support weather, clouds and winds. The density of the atmosphere varies seasonally, as winter forces carbon dioxide to freeze out of the Martian air. In the ancient past, the atmosphere was likely significantly thicker and able to support water flowing on the planet's surface. Over time, lighter molecules in the Martian atmosphere escaped under pressure from the solar wind, which affected the atmosphere because Mars does not have a global magnetic field. This process is being studied today by NASA's MAVEN (Mars Atmosphere and Volatile Evolution) mission.
However, the seasons that Mars experiences are more extreme than Earth's because the Red Planet's elliptical, oval-shaped orbit around the sun is more elongated than that of any of the other major planets. When Mars is closest to the sun, its southern hemisphere is tilted toward our star, giving the planet a short, warm summer, while the northern hemisphere experiences a short, cold winter. When Mars is farthest from the sun, the northern hemisphere is tilted toward the sun, giving it a long, mild summer, while the southern hemisphere experiences a long, cold winter.
Robotic spacecraft began observing Mars in the 1960s, with the United States launching Mariner 4 in 1964 and Mariners 6 and 7 in 1969. Those early missions revealed Mars to be a barren world, without any signs of the life or civilizations people such as Lowell had imagined there. In 1971, Mariner 9 orbited Mars, mapping about 80% of the planet and discovering its volcanoes and big canyons.
In 2003, Mars passed closer to Earth than it had anytime in the past 60,000 years. That same year, NASA launched two golf-cart-sized rovers, nicknamed Spirit and Opportunity, which explored different regions of the Martian surface after touching down in January 2004. Both rovers found many signs that water once flowed on the planet's surface.
As of September 2021, Ingenuity had made more than a dozen flights on Mars, showing that aerial exploration of the planet is feasible. Perseverance documented the 4-pound (1.8 kg) chopper's early flights, then began focusing in earnest on its own science mission. The big rover has already collected several samples, part of a big cache that will be brought back to Earth, perhaps as soon as 2031, by a joint NASA-ESA campaign.
July 2020 also saw the launch of the United Arab Emirates' first Mars mission, called Hope, and China's first fully homegrown Mars effort, Tianwen 1. The Hope orbiter arrived at Mars in February 2021 and is studying the planet's atmosphere, weather and climate.
Dr. Simon Morden trained as a planetary geologist and geophysicist, realized he was never going to get into space, so decided to write about it instead. His award-winning writing career blends narrative science, science fiction, fantasy, and horror. He is a past winner of the Philip K. Dick Memorial Award for his Metrozone series of novels set in post-apocalyptic London. He lives in England.
Mars is often called the 'Red Planet' because it appears in the sky as an orange-red star. The colour caused the ancient Greeks and Romans to name it after their god of war. Today, thanks to visiting spacecraft, we know that the planet's appearance is due to rust in the Martian rocks.
Mars is the fourth planet from the Sun. It orbits the Sun at an average distance of 228 million km, half as far again as the Earth, so human visitors would find it very cold. Although summers near the equator can be quite warm, the average temperature is 63 degrees Celsius below zero - similar to winters in Antarctica. The nights are also bitterly cold.
This steampunk yarn combines area majority and secret role selection with a healthy dose of player interaction. Each round, you compete to board rocket ships destined for particular regions of the titular planetoid. A rocket generally specifies in which region it will land and how many astronauts it carries. As soon as one reaches capacity it blasts off and is replaced by a new ship on the launch pad. After three specified rounds in the game you will score each region by awarding points in the currency of resource tokens (randomly seeded to begin the game) based on area majorities.
Large-scale volcanism on Mars started before the planet was even a billion years old and was active for roughly a billion years thereafter. Globally, volcano building pretty much stopped after that. There's evidence of some lava flows on Olympus Mons that date back to only a few million years ago, but these were small-scale events and were probably sporadic. By three or so billion years ago the era of active volcano construction on Mars was over. For comparison, most of the active volcanoes on Earth are less than a million years old. 041b061a72