photos by jeff cremer of orange julia and sulfur yellow butterflies drinking the salty tears of a tracajá turtle in the peruvian amazon. sodium is a scarce resource in the western amazon, where there is little mineral content to rain water, so the butterflies have learned to get it where they can. luckily for the butterflies, the turtles don’t much mind, despite deriving no reciprocal benefit themselves. (see also: previous turtle posts)
Does the “7 Minutes Of Terror” sound like a cheesy horror flick or a theme park ride to you? It’s not. That’s the phrase NASA used to describe the entry, descent and landing (also known as EDL) sequence of the Mars rover, Curiosity. Seven minutes is the time it took for Curiosity to go from the top of the Martian atmosphere to the surface of Mars. It was by far the most complicated and ambitious Mars landing ever attempted.
It required a carefully orchestrated set of maneuvers that had to be controlled entirely by computer. Even the slightest error could mean disaster. The spacecraft began to decelerate as it entered the Martian atmosphere and was guided using small rockets, then at approximately 1,000 mph a supersonic parachute was deployed to further slow the descent allowing the heat shield to separate at around 370 mph. Curiosity then separated from its parachute and began its powered descent at 70 mph using retrorockets that slowed the rover and brought it close enough to the surface that it could be lowered to the ground via a sky crane. It was a daring feat of engineering that captivated the world had everyone holding their breath until they heard the words of the mission controller, “Touchdown confirmed. We’re safe on Mars!”