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)

October 4, 2013

Hopes that microbes may be living beneath the harsh surface of Mars have been seriously dampened by new findings from the Curiosity rover. Over the past 10 years, Mars-orbiting satellites and telescopes on Earth have produced data showing small but significant amounts of methane gas in the red planet’s atmosphere. Although methane can be produced by geological processes, most of the methane in Earth’s atmosphere is a by-product of animal digestion or comes from decaying plants. Perhaps, scientists thought, the same was true on Mars. However, a study by Curiosity failed to detect any methane at all, scientists at NASA’s Jet Propulsion Laboratory reported.

From October 2012 to June 2013, Curiosity searched for signs of methane in samples of the Martian atmosphere using its Sample Analysis at Mars (SAM) laboratory. The previous research had revealed methane levels of up to 45 parts per billion (ppb). But Curiosity’s data showed nothing above 1.3 ppb, the minimum detectable by the SAM laboratory. Curiosity’s findings suggest that the satellite and telescope readings were incorrect or that the gas has disappeared. But Sushil Atreya of the University of Michigan, Ann Arbor, one of the paper’s co-authors, said, “There’s no known way for methane to disappear quickly from the atmosphere. Methane is persistent. It would last for hundreds of years in the Martian atmosphere. Without a way to take it out of the atmosphere quicker, our measurements indicate there cannot be much methane being put into the atmosphere by any mechanism, whether biology, geology, or by ultraviolet degradation [breakdown] of organics delivered by the fall of meteorites or interplanetary dust particles.” Scientists who reported finding methane argued that more research was needed to rule out the existance of microbial life.

Gravel at this site photographed by Curiosity shows evidence of an ancient streambed. (NASA/JPL-Caltech/MSSS)

The search for existing life on Mars is not quite over, however. Curiosity scientists plan to retune the SAM laboratory to enable it to detect amounts of methane of less than 1 ppb. Moreover, Curiosity’s findings don’t totally rule out the presence of life on Mars. “This important result … reduces the probability of current methane-producing Martian microbes, but … addresses only one type of microbial metabolism. As we know, there are many types of terrestrial microbes that don’t generate methane,” said Michael Meyer, NASA’s chief scientist for Mars exploration.

The SAM laboratory findings also don’t affect efforts to determine whether life existed on Mars in the past. Only two months after landing, Curiosity found direct evidence that billions of years ago, a deep, fast-moving stream of water once flowed across Gale Crater, the rover’s landing site. This discovery showed that Mars had once been capable of supporting life. Whether it did is an open question.

Additional World Book articles:

• Mars Pathfinder
• Mars Science Laboratory
• Space exploration
• The Search for Water on Mars (a special report)

March 14, 2013

Mars once had an environment that could have been hospitable to microbial life, according to new findings by Curiosity, the most advanced rover to ever reach the red planet. The discovery by the rover, formally known as the Mars Science Laboratory (MSL), was announced by the National Aeronautics and Space Administration (NASA) this week. Since landing on Mars in 2012, Curiosity has added to the evidence from other rovers and space probes that Mars was a very different planet in the distant past than the wasteland we see today.

For its latest activity, Curiosity examined rock samples drilled from an area thought to have been part of a Martian river system at one time. The samples proved to be partially made of a type of clay that suggests conditions similar to those needed for life on Earth. Furthermore, many chemicals identified in the sample are also essential for life, including nitrates and nitrites, two chemicals used for energy by microbes on Earth.

The new findings are significant in that they show Martian water that was nearly neutral, not too acidic and not too alkaline. Earlier samples collected from other regions of the planet had found evidence of water that was less friendly to life. The discovery of nitrates and nitrites also revealed a possible source of energy for developing microbes.

A hole in a rock called "John Klein" is the site of Curiosity's first sample drilling on Mars. The drilling took place on Feb. 8, 2013. The hole is 0.63 inch (1.6 centimeters) in diameter and 2.5 inches (6.4 centimeters) deep. (NASA/JPL-Caltech/MSSS)

Many scientists think that even though the surface of Mars may not have been ideal for life, there is a possibility that life may have developed early in the planet’s history and adapted to living underground.

Additional World Book articles:

• Microbiology
• Probing the Planets (a special report)
• The Search for Water on Mars (a special report)
• Space exploration (2003) (a Back in Time article)

November 1, 2012

The first analysis of Martian soil by the rover Curiosity has revealed minerals remarkably similar to those found near volcanoes in Hawaii. NASA scientists reported that the soil contained significant amounts of feldspar, pyroxene, and olivine, minerals typically associated with volcanic eruptions on Earth.

The analysis was the first by the rover’s Chemistry and Mineralogy Instrument (CheMin), one of 10 sophisticated scientific instruments aboard Curiosity, the most advanced robotic laboratory ever sent to another planet. Mineral analysis is vital to the rover’s mission, determining whether Mars is, or ever has been, capable of supporting microbial life.

A graph based on an analysis of a soil sample from Mars reveals minerals commonly found in volcanoes in Hawaii. (NASA/JPL-Caltech/Ames)

Curiosity picked up the soil from a site named Rocknest. A sieve in CheMin filtered out all particles larger than 0.006 inch (150 micrometers), about the width of a human hair. The remaining particles were bombarded with X rays to determine their particular internal structure. According to NASA scientists, the minerals are much younger than the water-worn pebbles photographed by Curiosity in September. Those pebbles provided direct evidence that a deep, fast-moving stream of water once flowed across Gale Crater, the rover’s landing site. The soil minerals apparently had only a limited exposure to water and date from a “transition time” when the crater was changing from a wet to a dry environment.

Olympus Mons, a shield volcano, on Mars is the largest volcano in the solar system. (NASA)

Mars has some of the largest volcanoes in the solar system. The highest peak in the solar system is the Martian mountain Olympus Mons (Latin for Mount Olympus). It rises about 16 miles (25 kilometers) above the surrounding plain to a height about three times that of Mount Everest, the highest point on Earth. Olympus Mons, which is more than 370 miles (600 kilometers) in diameter, is a shield volcano, like the volcanoes on Hawaii. Shield volcanoes have slopes that rise gradually. They form from eruptions of lava that can flow for long distances before becoming solid.

Additional World Book articles:

• Hawaii Volcanoes National Park
• Mars Exploration Rover Mission
• Mars Pathfinder
• Phoenix (spacecraft)
• Space exploration (Probes to Mars)
• The Search for Water on Mars (a Special Report)

X-ray diffraction, commonly used on Earth

Determines minerals’ internal structure by recording how their crystals interact with X rays

September 28, 2012

Rounded pebbles photographed by Curiosity, NASA’s newest Mars rover, are direct evidence that a deep, fast-moving stream of water once flowed across Gale Crater, the rover’s landing site, scientists announced on September 27. Curiosity scientists said the pebbles had been eroded and smoothed out while being carried down a stream or river that ran for perhaps 25 miles (40 kilometers) across the Martian surface. “This is the first time we’re actually seeing water-transported gravel on Mars. This is a transition from speculation about the size of streambed material to direct observation of it,” said science co-investigator William Dietrich of the University of California, Berkeley. The pebbles are too big to have been blown to the site by the wind. By comparing the size and shape of the Martian pebbles to pebbles found in streambeds on Earth, Curiosity scientists determined that the water on Mars was moving about 3 feet (0.9 meter) per second with a depth somewhere between ankle and hip deep. The largest and most advanced robotic laboratory ever sent to another planet, Curiosity is designed to answer one of the most important questions in planetary science–whether Mars is, or ever has been, capable of supporting microbial life.

The rounded pebbles found on Mars (left) are similar to rocks transported and cemented together by water on Earth (right). Some of the rocks are several inches (centimeters) wide. (NASA/JPL-Caltech/MSSS and PSI)

The pebbles were found in two tilted conglomerates named Hottah and Link. Conglomerates are rounded pebbles embedded in a fine-grained material. Scientists described Hottah as looking like a “jack-hammered … slab of city sidewalk.” The conglomerates lie about halfway between the north rim of Gale Crater and Mount Sharp, the rover’s ultimate destination. From the many channels found at the base of the rim, the scientists determined that the water flows may have lasted for thousands, even millions of years. “A long-flowing stream can be a habitable environment,” said Mars Science Laboratory Project Scientist John Grotzinger of the California Institute of Technology in Pasadena.

Scientists have long believed that water apparently has existed near the surface of Mars over part of the planet’s history. Evidence collected by spacecraft has suggested that liquid water apparently carved Mars’s large channels, smaller valleys, and young gullies. Scientists also concluded that vast quantities of ice exist within about 3 feet (1 meter) of the surface near the south pole and perhaps near the north pole. They also theorized that water is probably present beneath the surface today, kept liquid by Mars’s internal heat.

The water in the ancient streambed found by Curiosity likely flowed into Gale Crater from a channel called Peace Vallis. As the water flowed over the rim of the crater, it created an alluvial fan, a fan-shaped deposit of layered gravels, sands, silts, and other materials. Curiosity's landing site is marked by a cross in the black oval. (NASA/JPL-Caltech/UofA)

Additional World Book articles:

• Mars Exploration Rover Mission
• Mars Pathfinder
• Phoenix (spacecraft)
• Space exploration (Probes to Mars)
• The Search for Water on Mars (a Special Report)

September 14, 2012

After “flawlessly” completing a series of instrument tests this week, Curiosity, NASA’s newest Mars rover, was scheduled to resume its journey across the surface of the red planet Friday evening. So far, Curiosity has traveled 269 feet (82 meters) across Gale Crater, its landing site. After this short drive, Curiosity’s controllers began testing its operating systems and 10 scientific instruments. Curiosity’s next target is Glenelg, a rocky spot in the crater. The rover will study the area with a high-resolution camera and a spectrometer, which determines the level of chemical elements in rock and soil. The largest and most advanced robotic laboratory ever sent to another planet, Curiosity is designed to answer one of the most important questions in planetary science–whether Mars is, or ever has been, capable of supporting microbial life.

A pebble about 3 inches (8 centimeters) in diameter dominates an image of the Martian surface taken by Curiosity's high-resolution Mars Hand Lens Imager (MAHLI). The patch of ground shown is about 34 inches (86 centimeters) across. (NASA/JPL-Caltech/Malin Space Science Systems)

Curiosity's Alpha Particle X-Ray Spectrometer (APXS) (center) can determine the abundance of chemical elements in rocks and soil. (NASA/JPL-Caltech/Malin Space Science Systems)

The rover’s prime target is Mount Sharp (also known as Aeolis Mons), a mysterious 3-mile- (5-kilometer-) high mountain in Gale Crater. Mount Sharp consists 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. 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.

Three of Curiosity's left wheels appear in a composite image made by the MAHLI. The lower slopes of Mount Sharp, the rover's ultimate destination, appear in the distance. (NASA/JPL-Caltech/Malin Space Science Systems)

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)

A new Mars rover named Curiosity lifted off for the red planet atop an Atlas 5 rocket from Cape Canaveral in Florida on November 26. The rover’s mission is to answer one of the most exciting questions in planetary science–whether Mars is, or ever has been, capable of supporting microbial life. The rover is scheduled to land on Mars in August 2012, after spending 8 ½ months traveling some 354 million miles (570 million kilometers) through space.

A channel on Mars that may have been carved by flowing water appears in this photograph from the European Space Agency's Mars Express orbiter. Images taken by the orbiter showed evidence of water on Mars both now and in the planet's past. Photo courtesy European Space Agency.

Officially named the Mars Science Laboratory, the car-sized rover carries a scientific payload about 10 times as massive as those carried by NASA’s three previous Mars rovers. Curiosity, which has been described as a self-contained geology laboratory, holds eight sophisticated instruments powered by a nuclear generator. Two of the instruments 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. The rover is set to land in Gale Crater, near the foot of a 3-mile- (5-kilometer-) high mountain whose lower layers contain minerals that formed in water.

Scientists are anticipating the complex process of getting Curiosity onto the Martian surface as “six minutes of terror.” When Curiosity is about 1 mile (1.7 kilometers) above the surface, a rocket-powered platform called the “sky crane” will drop from the protective shell holding the rover. After flying Curiosity to Gale Crater, the sky crane will lower the rover by tether.

Additional World Book articles:

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