Credit: NASA.

When the LCROSS satellite, nicknamed Centaur, smacks into the south pole of the moon in late October, it is expected to produce a plume of dust 37 miles high, which may be visible from Earth with a good backyard telescope. It will be visible in an arc from Hawaii to Texas.

If you'd like to catch the impact, the Chabot Space and Science Center in Oakland is hosting a Shooting the Moon star party on the night of impact. Morrison Planetarium in San Francisco may host a star-gazing event, as well, but it hasn't been announced yet. And you could check in on other observatories in the Bay Area, as well: Lick observatory in the Santa Cruz mountains, Foothill observatory in Los Altos Hills, Sonoma State observatory in Rohnert Park, and the Fremont Peak observatory in the East Bay.

Not all of them will be open to the public; for instance, Foothill Observatory will be closed to the public, because they’ve been asked to take photographs of the event.

If you know anyone with a 10-inch telescope (that's the diameter of the lens), you can bet that telescope will be lined up to look skyward when the LCROSS probe hits the moon.

If the impact goes well, then the plume above the moon's surface could hover there for hours. It will make its own crater on the moon about 6 feet deep and 30 yards wide, so the plume of dust will not be visible to the naked eye, or even through binoculars.

The exact date, time and even the exact location of the impact have not yet been determined. Keep your eye on NASA's site for more information.

And one aside: This impact will not hurt the moon, or send it off its orbit. That may seem apparent to many people, but NASA Ames officials say those are the most-asked questions about the project.

Listen to the Crash Landing radio report online.

NASA/Mars Reconnaissance Orbiter; Fans of dark dust on Mars'
southern ice cap, apparently blasted from beneath the ice
by thawing carbon dioxide."

It's spring again, that time of year when my thoughts return to…blasts of carbon dioxide gas jetting up from beneath the frigid layer of dry ice below, carrying rusty red dust in plumes that jet toward the pale skies….

At least, that's what happens at the polar ice cap on the planet Mars. I'd sure love to be there to see it, even if there are no flowers in bloom. Still, there seems to be plenty of "blossoming" going on….

NASA's Mars Reconnaissance Orbiter—the spacecraft with that high powered camera that could spot a beach ball on Mars' surface—has captured images of the aftermath of some of Mars' springtime polar action. Appearing as dark fan-shaped bursts strewn across the thinning springtime polar ice, these features are explained as plumes of Martian dust that have settled after being blasted into the air by releases of gas pressure from under the surface of the ice.

To describe what's going on, let me paint a picture of the Martian polar region as it emerges from the deep freeze of winter into spring.

Mars' year is almost twice as long as Earth's—and so too are its seasons. Winter at the southern pole of Mars lasts almost six months. In that time, the normally freezing temperatures on the Red Planet plummet to as low as -225 degrees Fahrenheit at the pole. During this time, Mars' permanent water ice cap acquires a layer of frozen carbon dioxide (dry ice) on top, formed from carbon dioxide freezing directly out of the atmosphere.

This seasonal dry ice cap also forms around the edges of the water ice cap, covering adjacent ice-free surfaces as well. The carbon dioxide ice cap may grow to as much as a meter thick.

Then, as spring approaches and the ice cap gradually comes out of the dark and receives more and more sunlight, it begins to warm up (though don't get the impression that it is ever "warm" anywhere on Mars' surface! Air temperatures recorded by the Viking landers in Mars' more temperate latitudes was barely ever higher than 1 degree Fahrenheit). Spring Equinox in Mars' southern hemisphere was on December 26th.

As the layer of solid carbon dioxide heats up, its ices turn to gas, both at the top of the layer and beneath it as well. The gases forming underneath build up pressure, which seeks a path to escape. Evidently the pressurized carbon dioxide gas can actually carve channels in the Martian soils under the ice as it flows—said channels have been seen in the past after the seasonal ice cap dissipates entirely.

When the gases find a weak point in the ice, they can erupt upward, bursting into the air, sometimes carrying dust with it. The dust rockets skyward and is blown by prevailing winds, settling out on the ice in great dark fans—which is what Mars Reconnaissance Orbiter has shown us.

Ah, to be on Mars in springtime….