December 9, 2014

Data from NASA’s Curiosity rover have revealed fascinating new details about the ancient geology of Mars, including the formation of Mount Sharp (also known as Aeolis Mons) and the abundance of surface water. The findings have also increased the likelihood that Earth may not have been the only planet in the solar system with primitive life billions of years ago.

Curiosity scientists reported that they think they have discovered why a 3-mile- (5-kilometer-) high mountain sits in the middle of Gale Crater, the impact crater where the rover landed in August 2012. Before Curiosity, scientists knew that Mount Sharp, like some mountains on Earth, consists of layer upon layer of sediment (layers of dirt, stone, and other materials laid down over many millions of years. But they did not know how Mount Sharp formed because, unlike Earth, Mars has not been shaped by plate tectonics. One theory was that the mountain formed from material that was thrown up as an asteroid or meteor crashed onto the surface there about 3.5 billion years ago. Another theory suggested that the mountain was “excavated” as sediments were eroded from around the peak. Studies made as Curiosity treks up the mountain now suggest that both wind and water were likely involved in the process.

Patterns of sedimentary deposits in Gale Crater suggests the crater held a lake more than 3 billion years ago, filling and drying in cycles that lasted tens of millions of years. (NASA/JPL-Caltech/ESA/DLR/FU Berlin/MSSS)

Curiosity scientists think that Gale Crater experienced repeated wet and dry episodes that lasted for millions, or tens of millions, of years. During the wet episodes, rivers carrying water filled with sand and rock flowed over the crater’s rim to the floor, forming one large lake or even several smaller lakes. Over time, the sediments settled out of the water and hardened into layers that may have completely or partially filled the crater. During the dry episodes–when the water in the lakes evaporated–Martian winds sculpted the mountain by blowing away some of the sediment around the rim. Gradually, the mound in the center of the crater grew higher and higher.

Mount Sharp in Gale Crater likely formed from layers of sediment (yellow) carried by wind and by rivers flowing over the crater’s rim (above). The sediments then settled out in the center of the crater, forming rock (brown). Wind then eroded the sedimentary rock around the rim, forming Mount Shap. (NASA/JPL-Caltech/ESA/DLR/FU Berlin/MSSS)

The existence of surface water–as well as underground water–on Mars for such a long period–perhaps 1 billion years–increases the chances that primitive life may have developed on the planet billions of years ago. In such a stable environment, which could have lasted for some 1 billion years, life could have arisen on the red planet some 3.8 billion years ago, as it did on Earth.

Additional World Book articles:

• Mars Pathfinder
• Phoenix [spacecraft]
• Space exploration (Probes to Mars)
• The Search for Water on Mars (a Special Report)

August 6, 2012

The largest and most advanced robotic laboratory ever sent to another planet made a perfect landing on Mars early Monday morning after a descent so complicated and perilous that mission controllers referred to it as “the seven minutes of terror.” The automobile-sized rover, named Curiosity, touched down at 1:32 a.m. Eastern Daylight Savings Time, capping an 8 ½-month, 354-million-mile (570-million-kilometer) journey from Earth. Its mission is to answer one of the most important questions in planetary science–whether Mars is, or ever has been, capable of supporting microbial life. Mission controllers at NASA’s Jet Propulsion Laboratory erupted into cheers and high-fives as Curiosity set down in Gale Crater, an impact crater that may once have held a lake. Moments after landing, Curiosity beamed back its first photographs of the Martian surface.

One of the first images of Mars taken by Curiosity after landing. (Image credit: NASA/JPL-Caltech)

The rover’s nail-biting landing involved a rocket-powered sky crane, the world’s largest supersonic parachute, and the incredibly precise detonation of 79 explosive devices. A failure at any stage of the descent would have doomed the mission. Curiosity, officially named the Mars Science Laboratory, began its plunge through the Martian atmosphere seven minutes before landing. At an altitude of 7 miles (11 kilometers), the parachute deployed to slow the lab, which was traveling at 13,200 miles (21,243 kilometers) per hour. At precise moments, the heat shield then the parachute and part of the rover’s protective shell broke away, leaving only the rover and its sky crane, which fired its rockets. At about 65 feet (20 meters) above the surface, the crane began lowering the rover using three cables. Once Curiosity touched down, the cables broke away and the crane flew off to crash land away from the drop site.

The rover carries a scientific payload about 15 times as massive as those carried by NASA’s Mars rovers Spirit and Opportunity. Curiosity, which has been described as a self-contained geology laboratory, holds 10 sophisticated instruments, two of which were provided by Spain and Russia. Unlike earlier rovers, Curiosity will be able to gather samples of rock and soil, process them, and then distribute them to on-board instruments.

NASA's Curiosity rover is lowered onto the Martian surface by the sky crane, new technology designed specifically for this mission. (Image credit: NASA/JPL-Caltech)

Curiosity’s prime target is Mount Sharp (also known as Aeolis Mons), a mysterious 3-mile- (5-kilometer-) high mountain in Gale Crater consisting of layers of rock that may have been laid down over billions of years. Although the mountain looks similar to layered mountains on Earth, scientists do not know how it formed because, unlike Earth, Mars has not been shaped by plate tectonics. As the rover scales the mountain, it will analyze the layers in an attempt to discover how Mars, which was once warmer and wetter, became so cold and dry. It will also search for organic (carbon-bearing) molecules necessary for life as we know it. Curiosity is scheduled to explore the surface of the red planet for two Earth years (one Martian year). However, because it is powered by a nuclear generator, its mission may be extend for much longer.

Additional World Book articles:

• Mars Pathfinder
• Phoenix [spacecraft]
• Space exploration (Probes to Mars)
• The Search for Water on Mars (a Special Report)