MARS Whirlybird

摘要

Superficially similar to the Curiosity rover that landed on Mars on 6 August 2012, Mars 2020 has a number of significant design and payload changes. An important addition is the Mars Helicopter Scout (MHS), a game-changer designed to enhance traverse route mapping and decrease time taken to drive the rover to desirable sampling sites. It will also maximise the value of the roving vehicle itself as it seeks out the very best places to search for samples to cache, waiting retrieval by a sample-return mission, hopefully later in the next decade. The desire to use the rarefied atmosphere of Mars to fly heavier-than-air machines around has been evolving over the last 20 years. There is much merit to this idea. Very few places on Mars are free of significant surface obstructions and there are many vertical surfaces that warrant a closer look than could ever be achieved by a wheeled vehicle roaming around. But there are significant problems. While gravity is low (3.76 m/sec~2), reducing the weight of a given mass, the atmosphere has a variable density (0.4-0.87 kPa), changing through cycles of condensation and sublimation; the amount of atmosphere available for lift changes according to the season as well as with altitude above mean surface level.