The Mars Exploration Rovers, Spirit and Opportunity landed on Mars to explore the Martian surface and geology, and searched for clues to past water activity on Mars. They were each launched in 2003 and landed in 2004. Communication with Spirit stopped on sol 2210 (March 22, 2010). JPL continued to attempt to regain contact until May 24, 2011, when NASA announced that efforts to communicate with the unresponsive rover had ended. Opportunity arrived at Endeavour crater on 9 August 2011, at a landmark called Spirit Point named after its rover twin, after traversing 13 miles (21 km) from Victoria crater, over a three-year period. After a planet wide dust storm in June 2018, the final communication was received on June 10, 2018, and Opportunity was declared dead on February 13, 2019. The rover lasted for almost fifteen years on Mars — although the rover was intended to last only three months.
Beneath The Icy Crust Of Enceladus. The research paper written by scientists with the Cassini mission, published in the journal Science, suggests the presence of hydrogen gas. Hydrogen gas, that could potentially provide a chemical energy source for life, is pouring into the subsurface ocean of Enceladus from hydrothermal activity on the seafloor of this bewitching, distant moon-world. Vast regions of dark dunes also extend across Titan's exotic landscape, especially around its equatorial regions. Unlike Earth's sand, the "sand" that creates Titan's dunes is composed of dark grains of hydrocarbon that resemble coffee grounds. The tall linear dunes of this misty moisty moon-world appear to be quite similar to those seen in the desert of Namibia in Africa. Because Titan's surface is pockmarked by relatively few impact craters, its surface is considered to be quite young. Older surfaces display heavier cratering than more youthful surfaces, whose craters have been "erased" by resurfacing. This resurfacing is caused by processes that cover the scars left by old impacts as time goes by. Our own planet is similar to Titan in this respect. The craters of Earth are erased by the ongoing processes of flowing liquid (water on Earth), powerful winds, and the recycling of Earth's crust as a result of plate-tectonics. These processes also occur on Titan, but in modified forms. In particular, the shifting of the ground resulting from pressures coming from beneath (plate tectonics), also appear to be at work on this veiled moon-world. However, planetary scientists have not seen signs of plates on Titan that are analogous to those of our own planet. Earlier infrared data did not have sufficient resolution to separate MK 2 from Makemake's veiling glare. The astronomers' reanalysis, however, based on the more recent HST observations, indicates that much of the warmer surface spotted earlier in infrared light may simply be the dark surface of the companion MK 2.