A NEW VEHICLE FOR PLANETARY SURFACE EXPLORATION: THE MARS TUMBLEWEED

摘要

THE SURFACE OF MARS IS CURRENTLY BEING EXPLORED WITH A COMBINATION OF ORBITING SPACECRAFT, STATIONARY LANDERS AND WHEELED ROVERS. HOWEVER, ONLY A SMALL PORTION OF THE MARTIAN SURFACE HAS UNDERGONE IN-SITU EXAMINATION. LANDING SITES MUST BE CHOSEN TO INSURE THE SAFETY OF THE VEHICLES (AND HUMAN EXPLORERS) AND PROVIDE THE GREATEST OPPORTUNITY FOR MISSION SUCCESS. WHILE WHEELED ROVERS PROVIDE THE ABILITY TO MOVE BEYOND THE LANDING SITES, THEY ARE ALSO LIMITED IN THEIR ABILITY TO TRAVERSE ROUGH TERRAIN; THEREFORE, MANY SCIENTIFICALLY INTERESTING SITES ARE INACCESSIBLE BY CURRENT VEHICLES. IN ORDER TO ACCESS THESE SITES, A CAPABILITY IS NEEDED THAT CAN TRANSPORT SCIENTIFIC INSTRUMENTS ACROSS VARIED MARTIAN TERRAIN. A NEW "ROVER" CONCEPT FOR EXPLORING THE MARTIAN SURFACE, KNOWN AS THE MARS TUMBLEWEED, WILL DERIVE MOBILITY THROUGH USE OF THE SURFACE WINDS ON MARS, MUCH LIKE THE TUMBLEWEED PLANT DOES HERE ON EARTH. USING THE WINDS ON MARS, A TUMBLEWEED ROVER COULD CONCEIVABLY TRAVEL GREAT DISTANCES AND COVER BROAD AREAS OF THE PLANETARY SURFACE. TUMBLEWEED VEHICLES WOULD BE DESIGNED TO WITHSTAND REPEATED BOUNCING AND ROLLING ON THE ROCK COVERED MARTIAN SURFACE AND MAY BE DURABLE ENOUGH TO EXPLORE AREAS ON MARS SUCH AS GULLIES AND CANYONS THAT ARE CURRENTLY INACCESSIBLE BY CONVENTIONAL ROVERS. ACHIEVING MARS WIND-DRIVEN MOBILITY; HOWEVER, IS NOT A MINOR TASK. THE DENSITY OF THE ATMOSPHERE ON MARS IS APPROXIMATELY 60-80 TIMES LESS THAN THAT ON EARTH AND WIND SPEEDS ARE TYPICALLY AROUND 2-5 M/S DURING THE DAY, WITH PERIODIC WINDS OF 10 M/S TO 20 M/S (IN EXCESS OF 25 M/S DURING SEASONAL DUST STORMS). HOWEVER, BECAUSE OF THE MARTIAN ATMOSPHERE#S LOW DENSITY, EVEN THE STRONGEST WINDS ON MARS EQUATE TO ONLY A GENTLE BREEZE ON EARTH. TUMBLEWEED ROVERS THEREFORE NEED TO BE RELATIVELY LARGE (4-6 M IN DIAMETER), VERY LIGHTWEIGHT (10-20 KG), AND EQUIPPED WITH LIGHTWEIGHT, LOW-POWER INSTRUMENTS. THIS PAPER PROVIDES AN OVERVIEW OF THE TUMBLEWEED CONCEPT, PRESENTS SEVERAL NOTIONAL DESIGN CONCEPTS, MISSION SCENARIOS, AND HIGHLIGHTS RECENT TESTS AND ANALYSES OF TUMBLEWEED PROTOTYPES.