NASA’s Curiosity rover has discovered a large number of opals on Mars that could help solve the question of whether life ever existed on the Red Planet and provide water for any future human missions to the Martian surface.
Considered a gemstone, opals display shimmering colors that usually look like rainbows. These gems are formed when silicon oxides dissolve in a moist environment and then harden in the cracks between rocks. This process transforms opals into miniature oases that can contain up to 20% water.
Martian opals have previously been spotted from afar by NASA’s orbiter, and have been identified in Martian meteorites that have fallen to Earth. Now, a team led by Travis Gabriel, a research scientist at the US Geological Survey, shows that the Curiosity rover has also encountered light-colored opal deposits on the Martian surface.
Gabriel and his colleagues said these opals were formed during a “huge fluid event in recent Martian geological history” that may have made Mars habitable for longer than previously thought, and may even have preserved microbial life in the alien gem stones, according to a recent study published in the Journal of Geophysical Research: Planets.
The high water content of opals could make them a useful source of hydration for future humans on Mars, especially at the planet’s equator, where there is much less water ice than at the poles.
Curiosity landed in Gale Crater on Mars in August 2012 and has made many discoveries since then. The rover collected evidence that water likely flowed over Gale Crater billions of years ago, creating conditions that were suitable for life. Its successor, NASA’s Perseverance rover, is now also searching for ancient lakebeds for signs of past life on Mars.
Gabriel and his colleagues realized that Curiosity had been bumping into opals over the years. The team discovered light-colored rocks surrounding geological features known as “fault halos” along several sections of the rover’s journey. Observations suggest that these halos contain reserves of water-rich opals.
Scientists know that Mars was much wetter and warmer about 3.7 billion years ago, but the presence of opal deposits in Gale Crater suggests that the planet may have also experienced short-term flooding during the past few hundred million years. Although it is unlikely that life still survives on the dry Martian surface, these brief floods may have helped microbes survive deeper underground, or preserved microbial remains in opals.
“Given the widespread fracture networks discovered in Gale Crater, it’s reasonable to expect that these potentially habitable subsurface conditions extended to many other regions of Gale Crater as well, and perhaps in other regions of Mars,” said Travis Gabriel. “These environments would have formed long after the ancient lakes in Gale Crater dried up.”
Even if these opals do not ultimately point to life on Mars, they could be an important part of the human life support system on Mars. The team estimated that about 1.5 gallons of water could be harvested from the meter-long halo, allowing astronauts to quench their thirst with extraterrestrial opals.
Thus, the recent research may open a window into the Martian past, when microbes may have lived in former lakes and reservoirs, and pave the way for future human settlement of the Red Planet.