All posts for the month November, 2010

Tell Us It Used to be Wet and Warm

Light-colored mounds of a mineral deposited on a volcanic cone more than three billion years ago may preserve evidence of one of the most recent habitable microenvironments on Mars. Courtesy NASA

Mars exploration just continues to turn up more surprises all the time. Recent observations from the Mars Reconnaissance Orbiter uncovered evidence of mineral deposits of what’s called “hydrated silica” on the Martian volcano Nili Patera.  This is a form of silica that has some amount of water in its composition, which implies the existence of water.

The deposits are on the flanks of the volcanic cone and are startling evidence that there was a hydrothermal environment in that area at one time. Hydrothermal is a term that implies heated water or steam, which had minerals such as silica dissolved in it.  To get this deposit, Mars had to have heat and water — just the sort of cozy environment where life has always flourished on Earth.  While we don’t see evidence of life on Mars, the fact that hydrothermal environments once existed means that the places where life could evolve and thrive did exist on Mars, in the very distant past. This is yet another discovery that adds a data point to our continuing search for and confirmation of Mars’s watery and possibly warmer past.

Will She Wake Up?

The Mars Spirit Rover continues to snooze away at the location where she has been stuck since last year.  The little rover has been silent since March 22, 2010, but operators haven’t given up on hearing from the spacecraft. Project technicians are listening for Spirit, and are hoping that as the year wears on and solar insolation levels rise, the rover will get her batteries charged, wake up, and phone home.

She Found Evidence of Water

This mosaic of images shows the soil in front of NASA's Mars Exploration Rover Spirit. It is presented in false color to make some differences between materials easier to see. Bright-toned soil was freshly exposed by the rover's left-front wheel during the drives and can be seen with a "sand wave" shaping that resulted from the unseen wheel's action. Spirit's panoramic camera (Pancam) took the component images during the period from the 2,163rd to 2,177th Martian days, or sols, of Spirit's mission on Mars (Feb. 2 to Feb. 16, 2010). The turret at the end of the rover's arm appears in two places because of movement during that period. Image Credit: NASA/JPL-Caltech/Cornell University

In the meantime, though, analysis of data sent back from Spirit last year shows evidence that water — maybe in the form of melting snow — has been trickling into the subsurface layers and has been doing so for some time. The evidence lies in layers of soil beneath the rover.

Insets in the upper left and lower right corners of the frame show magnified views of the nearby inscribed rectangles within the mosaic. Each rectangle covers about 25 centimeters (10 inches) of surface. The top inset and upper portion of the mosaic include targets within soil layers exposed by the action of Spirit’s wheels in April 2009 and examined in detail with instruments on Spirit’s arm during the five subsequent months. “Olive pit” and “Olive leaf” are two of the analyzed targets.

It seems that under a thin covering of windblown sand and dust, relatively insoluble (meaning “unable to dissolve in water) minerals like hematite are concentrated near the surface and more-soluble ferric sulfates have higher concentrations below that layer. This suggests that has moved downward through the soil, dissolving ferric sulfates and carrying them down to the lower layers.  The brightness and color of the freshly disturbed soil seen in the center area of the mosaic indicates the this formerly hidden material is sulfate-rich. Before Spirit drove into this patch, the surface looked like the undisturbed ground highlighted in the lower-right inset. Flecks of red material in the surface layer resemble the appearance of the surface layer at other locations where Spirit’s wheels have exposed high-sulfate, bright soils.

I think it’s pretty cool that we can do such astonishing geological studies on a planet that is some 15 or so light-minutes away and out of human reach.  But, our little geology rangers have given us the chance to sift the soil of Mars, sniff its atmosphere, and study the long-range surface changes. This is learning and exploration at its best!

Time to Get Ready for the Leonids

Can you believe it’s November already?  It seems like just a few days ago we were still enjoying summer.  But, time passes and the sky changes, and new sights are looming on the horizon — among them the Leonid meteor shower.  It peaks this year on November 17, so if you’re planning to check it out, plan your observing time for around midnight on the 17th into the wee hours of the 18th.  According to MeteorBlog, the Leonids shower is the strongest one of five showers this month, and thus gives you a good chance of seeing some celestial fireworks. These streaks in the sky come from material shed by Comet Tempel-Tuttle as it orbits the Sun. Once a year, Earth’s orbit intersects that path of debris and some of the dust particles and mineral grains shed by the comet enter our atmosphere and glow as they interact with the gases in our atmosphere.  They’re called the Leonids because they appear to emanate from a region of the sky in the direction of the constellation Leo.  But, you’ll see them streak across the sky, sometimes glowing quite brightly and other times just small flashes of light.  It won’t be a “shower” in the sense of a water shower, but more like a succession of bright flashes and streaks across the sky.

Of course, for those viewers who are already getting winter weather, the Leonids presents a challenge: see shooting stars while keeping warm. It reminds me of the time I went out to see the Leonids and was wearing warm-weather gear, had blankets, etc. I sat on my car hood for about four hours, and it never ONCE occurred to me to turn the car ON and let the hood warm up.  But, I got to see some great bolides and smaller meteors, so it was worth it.

If you’re planning to go out and catch sight of some stray falling stars, plan now.  Get your warm-weather gear together, find a nice sight to view them from, and bring along some warm drink, maybe some nice music on your music player of choice, and settle in for some streaky action.

One big challenge for Leonid-watchers this year is that there’ll be a nearly full Moon to brighten up the sky. If you don’t mind the glare, it’ll give a chance to study the Moon while you’re waiting for Leonids to flare across the sky. So, it’s a win-win, provided you don’t get clouded out. All part of the fun of astronomy!