From the Other Side of Mars, Spirit Also Sees Evidence of a Watery Past
The Mars rover Spirit has found signs that water once existed near Gusev Crater, although probably in far smaller quantities than what the rover Opportunity detected on the other side of the planet, NASA scientists reported Friday.
The latest piece of the Martian geologic puzzle was revealed after a small section of a volcanic rock nicknamed “Humphrey” was ground away by Spirit’s rock abrasion tool, uncovering dark specks, hollows and cracks within a glassy matrix.
A small amount of water apparently had moved through the rock, helping to fill the voids with minerals as the volcanic magma cooled and crystallized, said Ray Arvidson, the mission’s deputy principal investigator.
Scientists are unsure whether the water was present in the magma when it was released by volcanic eruptions, or if the effects on the rock were caused by contact with small amounts of ground water.
Spirit’s discovery followed the dramatic announcement Tuesday that the area around Opportunity in Meridiani Planum had been “drenched” in water -- either from ancient oceans or lakes, or by percolation from massive underground deposits.
The finding in Gusev Crater by Spirit, while scientifically intriguing, did not suggest the kind of once-habitable environment found by Opportunity.
“It’s by no means the gobs of water on Meridiani,” Arvidson said at NASA’s Jet Propulsion Laboratory in Pasadena.
He said the differences between the Gusev Crater and Meridiani sites just mean “that Mars is a diverse planet.”
Spirit landed Jan. 3, and has been on Mars for 62 sols -- Martian days, which run about 40 minutes longer than Earth days.
Both rovers have operated without significant problems since Spirit recovered from a computer glitch that left it partially crippled for a week and a half in late January and early February.
Spirit is headed to the rim of a crater dubbed “Bonneville.” The journey should take another 12 sols. Bonneville is about 50 feet deep and 500 feet across. If scientifically intriguing and not too treacherous, Spirit will drive inside for a look.
Opportunity, which landed Jan. 24, will continue working near the bedrock outcropping near its landing site.
The next stop, said Matt Wallace, a mission manager, will be a small depression dubbed “Berry Bowl” by scientists because it contains pebble-like structures they call blueberries.
Scientists believe the pebbles, technically called concretions, formed from mineral deposits when the ancient rock formation was soaked with water.
