TURNING OVER A NEW LEAF

摘要

Inspired by aspen leaves, researchers at the University of Warwick believe they can increase the life expectancy of robots exploring Mars-or any other slightly windy planet. Even though the Mars Opportunity rover had an impressive run-15 years-it depended for energy on its solar panels, and when a planet-wide dust storm blocked sunlight, the rover's fate was seated. The Warwick scientists have devised an energy-harvesting mechanism that could be used as an emergency generator. Using mathematical modeling to better understand the physical properties that make the aspen leaf tremble in the slightest breeze-notably, the flat shape of its stem-they designed a mechanical equivalent. The resulting device uses a cantilever beam to mimic the stem and a curved blade tip with a circular arc cross section acting like the main leaf. Low-speed wind tunnel tests found it more responsive than the blunter bodies typically envisioned for energy harvesters-making it ideal for the anemic atmosphere and thin winds on Mars.