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FOCUS ON DESIGN 7 8 | H I G H - P E R F O R M A N C E C O M P O S I T E S W hen engineers at NASA's Jet Propulsion Laboratory (JPL) were given the job of sending another rover to Mars, they knew they faced a sizeable challenge. The NASA rover mission launched in 2003, for example, involved the twin golf-cart sized (5 ft/1.6m long) Mars Exploration Rovers, Spirit and Opportunity. Each weighed a mere 185 lb/84 kg. The proposed mission, how- ever, would require a rover the size of a mini-compact car — about fve times as COMPOSITES CARRY THE CURIOSITY heavy and twice as long (1,984 lb/900 kg and 10 ft/3m long). The reason for the substantial size increase is that the rover, nicknamed Curiosity, is more than an explorer — it is a robotic investigator. Offcially des- ignated as the Mars Science Labora- tory (MSL), Curiosity is exactly that, and its overall mission is to determine the planet's habitability for humans, as part of NASA's long-term Mars robotic explo- ration program. It was equipped to gath- er samples of Martian rocks and soil, take them on board and distribute them to test chambers inside its 10 analytical instruments. But frst it had to get there. Protecting precious cargo For the 127-million mile trip from Earth to Mars, Curiosity was enclosed inside a spacecraft aeroshell. Comprising a back shell and a heat shield to protect the rov- er during entry into Martian atmosphere, the aeroshell was jointly designed by JPL and Lockheed Martin Space Systems Aluminum Cruise Stage (1,303 lb/591 kg) Parachute Composite backshell (carbon fber/cyanate ester w/aluminum honeycomb core and SLA thermal protection) Descent stage Carbon fber/cyanate ester proboscis on sky crane Curiosity rover (1,989 lb/900 kg) Composite heat shield (carbon fber/cyanate ester sandwich structure w/aluminum honeycomb core and PICA thermal protection) Aeroshell Entry Vehicle (7,026 lb/3,459 kg) Backshell interface plate (BIP) Parachute support structure (PSS) Bridle Umbilical Device PICA tiles From launch to touchdown, composites per formed in flight and • An aeroshell capable of delivering the much heavier (5x) Curiosity rover safely to Mars and through the intense heat of atmospheric entry. • A sandwich construc- tion that unites the heat shield's biconic (two-cone) design in a single struc- ture for one-off molding and cure. • Material selection (including the use of abla- tives) that permits oven- cure rather than autoclave cure of the aeroshell's composite back shell and heat shield. DESIGN RESULTS NASA/JPL's MSL FLIGHT SYSTEM 0514hpc FOD-OK.indd 78 4/22/2014 3:40:10 PM