March 9, 2016

Next month, in April, a deep-ocean drilling project will begin off the Yucatán coast in the Gulf of Mexico. Most such oceanic drill projects are concerned with oil exploration. This isn’t your usual drill team, however. The drillers in this case come from the International Ocean Discovery Program, the National University of Mexico, and the University of Texas. And they will be drilling into Chicxulub Crater, an impact crater formed by a giant asteroid that helped kill the dinosaurs some 65 million years ago. They won’t be looking for oil; they’ll be looking for answers.

The Chicxulub Crater along the northern coast of Mexico’s Yucatán Peninsula formed when an asteroid hit the earth about 65 million years ago. Debris from the impact may have led to the extinction of the dinosaurs.
Credit: WORLD BOOK map

At the end of the Cretaceous Period, dinosaurs were the dominant land animals on the planet. Other reptiles filled the seas, and birds—descendants of dinosaurs—roamed the skies. Mammals existed, but they were far smaller and less common than today. Then, an asteroid at least 6 miles (10 kilometers) wide slammed into the Yucatán Peninsula, in present-day Mexico. The impact threw up large amounts of gas and dust into the atmosphere. This material would have blotted out the sun for many years. Plants that use sunlight to make their food would have died out, followed by the animals that ate them. With no more prey animals, large carnivores starved as well.

When the dust settled, about half of all species on Earth had gone extinct. All the dinosaurs—except birds—were dead. Only a few kinds of other reptiles survived. Mammals survived too and over time evolved to become the dominant large-bodied animals on land and in the sea.

The Yucatán asteroid formed a large impact crater, which is now partly on the peninsula and partly in the Gulf of Mexico. Tens of millions of years of plate tectonics and erosion have taken their toll on the crater, and it is barely visible in satellite images today. But the mark that it left in the rocks should still be clear.

The team plans to use a drilling ship to sample rock deep beneath the ocean floor. In drilling into the crater, scientists hope the presence (or lack) of microfossils (tiny preserved remains of ancient organisms) will teach them more about the nature of the asteroid impact and how quickly life returned to the area afterwards.

The drilling evidence may also better explain how responsible the impact was for the mass extinction at the end of the Cretaceous Period. Most scientists agree that the asteroid did most of the damage, but others argue that other causes, such as massive volcanic activity in present-day India, were more to blame. Such extinction hypotheses are not mutually exclusive, however: it may have taken more than one disaster to knock out the dinosaurs. In fact, they may even be linked. Recent studies have suggested that the Yucatán impact caused the spike in volcanism on the other side of the globe in India. Whatever the case, the drilling team will help get to the bottom of this and other stories, as well as to the bottom of the impact crater itself!

December 19, 2013

The Mars Science Laboratory, nicknamed Curiosity, has made a number of remarkable discoveries since it landed on Mars in the summer of 2012. The most recent feather in the rover’s cap is the discovery of a primordial lake within Gale Crater, the landing site of the small vehicle. Unlike previous evidence of liquid water on the planet, this new finding, in an area called Yellowknife Bay, hints of water similar to the liquid fresh water found on Earth. The new discovery paints the surface of Mars as a much more inviting environment for life as we know it to form. The water in the lake appears to have been both long standing and neither too acidic or alkaline for life as we know it.

The lake seems to have been relatively large and may have remained on the planet for thousands of years, if not more. Furthermore, the water seems to have been present around 3.5 billion years ago, about the same time scientists think life began on Earth. The discovery of the lake also reinforces the findings that what look to be stream beds, channels, deltas, and other landforms on the planet were created by water and are exactly what they appear to be.

The possible extent of an ancient lake inside Gale Crater is shown in an illustration superimposed on a satellite photo. The possible extent of the lake was estimated by mapping ancient lake and stream deposits and recognizing that water flowed from the crater rim into the basin (arrows). The water would have pooled in the linear depression created between the crater rim and Mt. Sharp (center of crater). The area’s history likely included the coming and going of multiple lakes of different sizes as climate conditions evolved. (NASA/JPL-Caltech/MSSS)

The most thrilling discovery to come from the exploration of the planet would surely be the discovery of life, whether the life existed in the past or is currently still thriving. Although the planet has since dried out and the atmosphere nearly vanished, some scientists believe the planet could still harbor life under the planet’s surface. Further exploration is needed to confirm this hope. There has even been talk for many years of the possibility that life on Earth was carried here by meteorites that originated on the Martian surface. Many meteorites came from Mars. Did they they carry some of the building blocks for life to Earth? Did they actually carried life itself as tiny passengers?

Additional World Book articles:

• Probing the Planets (a special report)
• The Search for Water on Mars (a special report)
• Space exploration 2011 (a Back in Time article)
• Space exploration 2012 (a Back in Time article)

January 8 2013

The NASA rover Curiosity, currently exploring the surface of Mars, has successfully used its brush tool for the first time. The tool’s rotating wire bristles are designed to sweep dust off the surface of rock. Brushing away dust gives Curiosity’s survey instrument–the arm-held hand lens camera and X-ray spectrometer–a clearer view of the texture and chemistry of the underlying rock–critical in selecting rock suitable for drilling.

The “dusting” is the final step toward the first deployment of Curiosity’s hammer-drill. The drill will produce a powdered sample that will be analyzed by the rover’s on-board laboratories. “We wanted to be sure we [have] an optimal target for the first use [of the dust removal tool],” stated Diana Trujillo of NASA’s Jet Propulsion Laboratory.

Curiosity’s Dust Removal Tool has cleaned a patch of rock in preparation for the rover’s first attempt to drill into the Martian surface. (NASA/JPL-Caltech/MSSS)

Curiosity, which landed on Mars in August 2012, is currently exploring an area known as Yellowknife Bay, a small depression in Gale Crater. The ultimate goal of the experiment is to determine whether microbial life might have flourished in Gale Crater in some past environments. Curiosity has already identified rock deposits laid down billions of years ago by running water, proof that other environments once existed in the crater.

Additional World Book articles:

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

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)