Sunday, November 25, 2007

The Expanding Nothingness Part I

11/25 - 12/1
by C. Zaitz

In the late 1980's I learned there was a good possibility that we could know the fate of the Universe. There were three choices, and cosmologists were hard at work narrowing it down to one. We knew the Universe was expanding. In 1929, Edwin Hubble had made that clear by showing us the red shifts of countless galaxies. Red shifts meant they were receding, and the farther away they were, the faster they were going. Hubble deduced this meant that space was expanding.

Armed with this information, cosmologists ran the expansion back like a movie to figure out how it began. That’s where the Big Bang Theory came from. And then they ran it forward to see how it would end. Knowing the fate of the Universe seemed within reach. But the fate of the Universe depended on how much stuff there was in it. If there was a lot of mass, gravity would stop the expansion and bring everything together into a Big Crunch. If there was not enough mass, the Universe would expand forever, growing dark and cold into a Big Freeze. Some thought that one day the Big Bang might come together in a Big Bounce, which was an elegant extension of the Big Crunch, wherein the Universe would oscillate forever.

It turns out that the visible Universe, namely the stars that make up galaxies, has only a small percentage of the mass needed for such a fate. The Universe was too light for a Big Crunch or Bounce, and it looked like we were headed toward the Big Freeze. But this is not a happy ending, so cosmologists looked around the Universe for more mass.

We live in the Milky Way, a spiral galaxy home to hundreds of billions of stars. It looks like a big spinning pinwheel. The Milky Way is spinning so fast that the stars in the arms of the galaxy should have wound up around the center a long time ago, like cotton candy winding around a paper cone. But they didn’t; our Milky Way has spun about 20 times in the past 5 billion years and it still looks as pinwheely as it did as a baby galaxy. This doesn’t make sense with the amount of mass calculated from all the stars. There must be mass that we can’t see. Aha!

Cosmologists call it dark matter, and though it is invisible and nothing like regular matter, it accounts for most of the mass in the Universe. The galaxies are embedded in it, and it shapes spacetime. Its existence has changed how we think about the fate of the Universe. In Greek mythology, the three Fates were Clotho, the spinner of the thread of life, Lachesis who measured the thread of fate, and Atropos, who cut the thread to end a life. As the universe spins out its history, it’s easiest to study the past and present. The thread of information left over from the Big Bang is fairly strong. When we look to Atropos, to the end of the Universe, things have gotten cloudy. The fate of the Universe has become uncertain. As we struggle to understand the nature of dark matter, hopefully the answers will become clearer. But there is another piece to the puzzle, an even more enigmatic discovery: dark energy. To be continued…

Until next week, my friends, enjoy the view.

Tuesday, November 13, 2007

The Helium Rush

11/20 - 11/27

by C. Zaitz

I was five years old when Apollo 17 astronauts Gene Cernan and Harrison Schmidt took their last steps on the surface of the moon. They paused to place a plaque that read, “Here man completed his first explorations of the Moon, December 1972.” We never imagined that it would be the final exploration of the moon, but 35 years later, we seem completely earth-bound. The twelve brave astronauts who traversed the dust of the lunar maria have no successors as of yet.

Noise is beginning to be made, however, of a new race to the moon. In the late 60’s, the main concern for space travel was political. The Soviet Union had launched the first satellite into space, that famous beeping sphere called Sputnik, and had also beaten us into orbit. The only way to save face in the world domination game was to land men safely on the moon, which we did six times. The threat eventually passed, the cold war ended and the motivation to go to the moon lay sleeping for decades.

New motivation has risen, and has shifted to economics. So what’s on the moon that anyone would want? We know the dusty surface is pulverized regolith, mostly a basalt powder blasted out of craters from the moon’s pummeled surface. We have lots of basalt here on earth from volcanoes. But the moon harbors a mineral called ilmenite, which is iron titanium oxide. It’s not important for its own chemical make-up, but for its ability to retain helium-3, a product of the solar wind. The sun streams high energy particles in all directions. Earth’s magnetic field deflects most of this material, but the moon has no such deflector. The particles slam into the moon and are trapped in ilmenite. It is said that 220 pounds of the lunar rock could yield $140 million worth of helium-3. At $40,000 per ounce, helium -3 would be 26 times more expensive than platinum.

But what is it? Helium-3 is a lighter form of regular helium, the stuff that makes balloons float. Helium-3 is valuable because it could provide a cheaper, safer and more efficient way to produce energy. Nuclear power plants currently use nuclear fission to break apart heavy atoms like uranium to get energy, but they leave behind toxic nuclear waste. Fusing atoms creates much less waste, and is more efficient. Unfortunately, there is very little helium-3 on earth to fuse.

When President Bush announced his decision to send us back to the Moon by 2018, a committee was formed to research the feasibility of such a project. Sitting on the committee were none other than Neil Armstrong and Harrison Schmitt, the Apollo 17 astronaut, one of the biggest proponents of mining the moon for helium-3. The committee built a small reactor to test the theories of the helium-3 fusion, and it produced energy. However, it will most likely take decades to produce and test commercial reactors. Meanwhile, we aren’t the only country interested in the moon’s supply of helium-3. China, Russia and India all have sights on the supply, and are working toward getting there first. It seems the race is heating up.

Plans are underway to build the new Apollo-like rockets to get us back to Luna, but unless we hurry, we may have to wait in line to plant an American flag on the moon once again.

Until next week, my friends, enjoy the view.

Wednesday, November 07, 2007

Hairy Stars

11/12/07 – 11/19/07
by C. Zaitz

We have a comet in the sky! By now you’ve heard that Comet Holmes has exploded into a naked eye comet and has been haunting the northeastern sky near the constellation Perseus for weeks now. Even in ancient times, comets have appeared in the sky, only to disappear weeks later, leaving folks wondering what they were. Labeled “hairy stars” due to their fuzzy appearance in the sky, the Latin word “coma” literally means “hair” and this comet has quite a head of it! Now said to be over 7 times the diameter of Jupiter, the coma of comet Holmes is an amazingly giant, diffuse ball of fluorescent gas and dust, visible to the naked eye.

Comets are made of ice, gases, and dust. The nucleus, which is the main part of a comet, can be a mile or several miles in diameter, but it is the coma, or the cloud of gas and dust surrounding the nucleus, that becomes huge as the ice melts. The melting is more like dry ice turning straight into a gas rather than an ice cube melting into a puddle. As the gas is released, dust grains are also released, and depending on their size, they will travel a certain distance from the nucleus, puffing out into the coma and tail. Comet Holmes has had more of an explosion than a mere melting, it seems, as it has grown an enormous coma. It doesn’t have much of a tail, though. Usually comets grow two tails, one made of gases and the other made of heavier dust grains. The comet drags the tails around the sun, but they are always driven away from the comet by the pressure of the sun’s own radiation, so no matter where the comet is going, the tails always point away from the sun. Comet Holmes is too far from the sun to grow much of a tail.

Many comets come from a distant place in our solar system, beyond any of the known planets. Far beyond the orbit of Pluto, the Oort cloud is thought to extend halfway to the closest star to us and is home to trillions of comets. Some comets live closer to us. Comet Holmes orbits every 7 years, and was discovered in 1892. Orbiting between Mars and Jupiter, it usually passes unnoticed. This time around, some of the ice must have broken off like our melting glaciers of earth, releasing an enormous amount of dust and growing its huge coma. We get to enjoy its brilliant hairy appearance for as long as it continues to glow.

People are often surprised that comets can be seen night after night, because they associate them with shooting stars, or meteors. It’s a common mistake, most likely because of their streamlined, zippy appearance. With the tail blasting out, looking like a rocket to Mars, comets definitely are the speedsters of the solar system. They do move swiftly, clocking over 100,000 mph, but are so distant that you cannot detect their motion over the course of one night. They seem to hang in the sky for weeks, giving us a view of the mysterious, changing nature of the universe, or at least the solar system. Soon comet Holmes will die down and once again become an icy, dirty snowball, one of many silent, small members of our solar system.

Until next week, my friends, enjoy the view.