1 . A study confirmed that the cracks found on Mars’s surface last year by the Curiosity Rover are evidence of ancient lakes that likely dried up about 3.5 billion years ago. The new study provides further evidence of what the climate on the Red Planet may have been like in its ancient past.
The study, published online in Geology, proved that cracks on Mars’s surface previously photographed by Curiosity are dry mud cracks which could have only been formed when wet ground was exposed to the air. This conclusion was based on an analysis of a single area of rock known as “Old Soaker.”
Researchers used the Curiosity rover and information from its many tools including the Mars Hand Lens Imager, ChemCam Laser-Induced Breakdown Spectrometer (LIBS) and the Alpha Particle X-Ray Spectrometer (APXS) to study both the physical appearance and the chemistry of the rock, which is described as no bigger than a coffee table.
The analysis showed that cracks on the rocks were formed by exposure to air, rather than heat or the flow of water. In addition, the shape of the cracks suggests it experienced a single drying event on the planet, rather than getting wet and drying over repeatedly. The position of the cracks, closer to the center of the ancient lake rather than alongside it, also suggests that the lake levels changed often, rising and falling over time.
“The mud cracks are exciting because they help us to understand this ancient lake system,” lead study author Nathaniel Stein, a geologist at the California Institute of Technology in Pasadena, said, referring to the ancient lake system on the planet.
Scientists have known of the existence of ancient water on Mars for years. A 2015 NASA study that measured water in Mars’s atmosphere suggested that ancient oceans may once have had more water than our own Arctic Ocean. However, because the planet has less gravity and a thinner atmosphere than Earth, this water evaporated(蒸发) into space over the course of several billion years.
1. What is the Curiosity Rover?| A．An organization. | B．A scientist. |
| C．A planet. | D．A machine. |
| A．The cracks are near the center of an ancient lake. |
| B．Mars was getting wet and drying more than once. |
| C．The lake level on Mars seldom changes over time. |
| D．The cracks on the rocks were formed by water flow. |
| A．Ancient water still exists on Mars now. |
| B．The gravity on Mars is stronger than that on Earth. |
| C．The atmosphere on Earth is thicker than that on Mars. |
| D．The ancient Arctic Ocean had more water than it has now. |
| A．Water on Mars. | B．A trip to Mars. |
| C．A study on Mars. | D．Cracks on Mars. |
