Science Sunday 04-29-17

Last Call for Cassini

All good things must come to an end, the saying goes, and that applies in equal measure to one of the best space missions ever, the Cassini mission to Saturn.

After 20 years of service, Cassini is checking out because it is running out of fuel.  It has started dangerously diving (at an average speed of 21,500 mph) between Saturn and its rings, shielding itself from possibly deadly particulate matter using its large antenna.

In 2013, Cassini graced us with a postcard from space, of us no less:

But now time is short, and like the Wedding in Cana, Cassini’s mission crew has saved the best for last, with a hara-kiri dive (scheduled for September 15th) into Saturn’s atmosphere, broadcasting live all the way down, until it is crushed into oblivion.

How Deep Is The Ocean

Although Cassini is 790 million miles away, I dare say we know more from Cassini about Saturn than we do about own oceans, of which only 5 to 10% by volume have been explored.

In researching how much a liquid can actually be compressed, I was surprised to find that near freezing sea water volume was diminished by nearly 6% due to hydrostatic pressure at a depth of 36,000 feet, in the Challenger Deep portion of the Marianas Trench.

But life is teaming down there.  The submersible Kaiko found roughly 350 new marine species, including worms, shrimp, and 180 new types of high pressure loving (barophilic) bacteria.

It is estimated that there are thousands more marine species to be discovered in the depths of our mysterious oceans.

And if the title of this posting reminds you of a song, here it is, an Irving Berlin classic, as sung by a young Judy Garland, in 1938:

Enjoy the animation above, courtesy of wise wanderer.

Plastic Eating Worms

Speaking of worms, A researcher recently discovered that waxworms likes to eat polyethylene plastic bags, excreting the biodegradable ethylene glycol in the process.

Scientists are hoping that they will be able to find the digestive enzyme the caterpillar larvae use to perform this miracle transformation, and thereby help solve a seemingly intractable waste problem.  Each year, humans discard about 80 million tons of plastic bags.

You can read more about these hungry caterpillars here.

Dark Matter, Served Hot or Cold

It continues to astound me that we know so little about what makes up our Universe.  Although the last 50 years have produced mind boggling insights into the structure of ordinary matter, relatively recent microwave anisotropy probes (COBE, WMAP, PLANCK) have revealed that the nature of 96% of the Universe is a complete mystery to us.

That 96% is divided into two parts: dark energy (about 68%) and dark matter (about 27%).

Courtesy of Scientific American’s Space Lab you tube channel, Sophie (above) lists the pros and cons of the five current best hypotheses regarding the nature of dark matter.

Author: Bob Mahoney

Physics teacher

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