Complex sentence: On 16 December 2014, NASA reported detecting an unusual increase, then decrease, in the amounts of methane in the atmosphere of the planet Mars; as well as, detecting Martian organic chemicals in powder drilled from a rock by the "Curiosity" rover.
Split into simpler sentences: On 16 December 2014, NASA reported detecting an unusual increase, then decrease, in the amounts of methane in the atmosphere of the planet Mars. Organic chemicals have been detected in powder drilled from a rock by the "Curiosity" rover.