Mercury is Cooling Down?

Like the proverbial moth to the candle flame I am drawn to the sky and some interesting space exploration news emerged last week. The Messenger spacecraft may have detected water on Mercury. Many sources reporting that the January ‘fly-by’ found water, here’s the BBC News:

“The Fast Imaging Plasma Spectrometer (FIPS), onboard the craft also revealed details of the planet’s atmospheric composition … silicon, sodium and even water ions around Mercury.”

But this BBC News story also reports that the planet has actually become smaller since Mariner’s viewing in 1975.

“Scientists believe the shrinkage is due to the planet’s core slowly cooling.”

And Scientific American notes that:

“… the planet’s iron-rich core seems to be shrinking, causing its crust to buckle and crack.”

Amazing to think that this planet so close to the sun may actually have water on it. Some explanations suggested in the Columbus Dispatch story:

“There are a few theories. Hydrogen spewed from the sun might strike oxygen on the surface of Mercury and form water, said Thomas Zurbuchen, a professor of aerospace engineering and space science at the University of Michigan.

Or asteroids that struck the surface in the past might have brought water to the planet.”

And the Houston Chronicle reports that,

“… some astronomers have theorized that Mercury harbors reservoirs of ice at the bottom of permanently shaded craters at the planet’s poles, places the sun’s rays would not reach and a prospect that could hold true for the Earth’s moon as well.”

Ice on a planet that reaches temperatures of 400 degrees Celsius! Well it also goes down to -200 degrees Celsius at night.

We’ll know more in a few years when Messenger returns and enters Mercury’s orbit in 2011. Until then, check out these great pics posted at Popluar Mechanics.