Into Saturn’s Rings

378033main_pia07873_fullYesterday, NASA’s Cassini spacecraft began the final stage of its mission — a series of maneuvers that will give the probe a close-up look at the rings of Saturn.

First launched in 1997, Cassini has been knocking around the outer reaches of the solar system for years, exploring Saturn and its moons, and it has made some interesting discoveries.  Cassini’s foray into Saturn’s rings will be its grand finale.  The spacecraft will dive into the gap between Saturn and its rings, loop around the planet’s poles, and take a closer look at Saturn’s idiosyncratic features and study the gas and dust particles that make up the rings.

The mission then will close with Cassini flying close to the planet’s surface and ultimately plummeting into Saturn’s atmosphere in a final suicidal act.  By then, Cassini will be out of fuel, and scientists don’t want to take the chance that the spacecraft could somehow crash into one of Saturn’s moons — moons that might be habitable — so Cassini will be intentionally steered into the planet to go out in a blaze of glory.

Saturn’s rings were first seen by humans in 1610, when Galileo Galilei turned his telescope to the night sky, and they have been the object of wonder and fascination ever since.  The final stages of Cassini’s two-decade mission will give us more information about the rings than we have ever had before.  And it may answer some nagging questions, like whether the rings are the same age as the planet itself, or were they formed later?  And are there small moons embedded in the rings that might explain their shape and configuration?

NASA’s unmanned space exploration program should be the source of pride to all Americans.  Through countless missions to the inner and out solar system, it has added exposed our planetary neighborhood as a constantly surprising place, with potential sources of water, rich mineral deposits, and places that might conceivably harbor other forms of life.  The Cassini mission is just the latest chapter in an ever-encouraging tale that shows that the human impulse to explore and discover still runs strong.

Fun With Physics

If you like physics — and slow-motion footage of science experiments — you’ll enjoy this very cool BBC video that recreates a legendary experiment by Galileo Galilei.

According to the story, Galileo began dropping objects of different weights from the top of the Leaning Tower of Pisa.  Whether heavy cannonballs, lighter musket balls, or objects made of gold, silver, or wood, they all hit the ground at the same time.  Galileo therefore realized that gravity affects all objects and accelerates them at the same rate.

The BBC recreation takes the experiment one step farther, by dropping a bowling ball and some flouncy ostrich feathers.  They do it first in regular atmosphere, where air resistance causes the feathers to drift gently to the ground, and then when the air has been pumped from the room to create a vacuum.  It’s jaw-dropping to watch the feather and the bowling ball fall, in slow motion, at exactly the same rate and then crash to the ground.

There’s an Ohio connection to this story about Galileo, science, and the BBC, too:  the room where the BBC does the experiment at the NASA Space Power Facility in Sandusky, Ohio, which features the largest vacuum chamber in the world.