Transit (astronomy) of Mercury from Saturn and a transit of Venus from Saturn. No missions were planned to coincide with the transit of Earth visible from Mars on 11 May 1984 and the Viking missions had been terminated a year previously. Consequently, the next opportunity to observe such an alignment will be in 2084. On December 21, 2012, the "Cassini–Huygens" probe, in orbit around Saturn, observed the planet Venus transiting the Sun. On 3 June 2014, the Mars rover "Curiosity" observed the planet Mercury transiting the Sun, marking the first time a planetary transit has been observed from a celestial body besides
Curiosity (rover) ("Mount Sharp"), at the center of the wide crater. Thus, it is believed that the rover may have the opportunity to study two billion years of Martian history in the sediments exposed in the mountain. Additionally, its landing site is near an alluvial fan, which is hypothesized to be the result of a flow of ground water, either before the deposition of the eroded sediments or else in relatively recent geologic history. According to NASA, an estimated 20,000 to 40,000 heat-resistant bacterial spores were on "Curiosity" at launch, and as much as 1,000 times that number may not have been