Wednesday, July 25, 2007


7/22/07 - 7/29/07
by C. Zaitz

This year marks the 400th anniversary of the first permanent English settlement in the Americas. Jamestown, Virginia is known as the birthplace of the country, where the first boatload of eager colonists landed. They arrived in May, and I can imagine that the summer was filled with building, hunting, cooking and fending off human and animal enemies. By July I imagine that the colonists were wondering what they had been thinking, coming to a new world so far from home. They must have been hot, hungry, riddled with mosquito bites and maybe a few arrow wounds. But enough of them survived the terrible famines and attacks from the Spanish and Natives to build homes, churches and official buildings, to flourish and become farmers and businessmen.

400 years later, we can wonder what happened to that colonizing spirit. When you first heard that we’d gone to the moon, didn’t you think Mars was next? What happened? Yes, space travel is very dangerous, expensive and time consuming, but was not also crossing the Atlantic to the New World?

Old colonizing risks: Running out of food and water. Disease and pestilence. Getting speared by someone already living there. Death.

New colonizing risks: Running out of food, air and water. Disease and pestilence. Getting lasered by someone already living there. Death.

So why haven’t we planned a mission to Mars? Are the risks any greater? Are the costs heavier? If we really wanted to travel to Mars, we would. America has not been frugal when its will was strong. Why do we not establish a mission to Mars, to walk the rusty sands and build a human presence on that nearby planet? Perhaps we need an outside menace to motivate us. The mission to the moon was a response to immediate threat of Soviet superiority. Without that threat, it’s not obvious that we would have endured the expense and the risk. But being motivated by threat is not the best case scenario, since the threats that would motivate us to travel to other planets usually involves the destruction of our own planet.

But it’s not all gloom and doom. Economic incentive seems to be what drives us today, rather than fear of asteroid collision, irreversible global warming, or even nuclear holocaust. Some say our governments should pool resources and offer incentives to private companies to innovate. Private companies can often get the job done with less bureaucracy, more efficiency, and less waste than governments. That requires widespread cooperation, however, and economic motivation. Companies need to know what they will gain from the endeavor. On the other hand, did the Jamestown colonists really know what they were getting into before they left England? They surely weren’t making a profit during the first years of starvation.

I don’t think our will is weak. We are fascinated by space travel, by UFOs and aliens. Maybe we are just yearning for proof that it can be done. Whatever our ultimate motivation, I hope that it includes our will to survive and our curiosity to know the universe. And I hope we don’t wait too long to get started. Who knows where we’ll be in 400 more years. I hope it doesn’t take a threat of Jupiterian superiority to get us motivated, because by then, it may be too late.

Until next week, my friends, enjoy the view.

Tuesday, July 17, 2007

Night Watchmen

7/15/07 - 7/21/07
by C. Zaitz

There are a lot of things floating above us, circling the planet all day long, all night long. While we are all sleeping, there are flocks of satellites gliding silently overhead. If you’ve been out this summer even for ten minutes of star gazing, you’ve seen them. I love it when you can see more than one at a time. They look like a flotilla of space ships, and I imagine a future where they are just commuters coming to and from work.

Meanwhile I looked into what is really up there. Mostly, it’s derelict satellites, parts of old rockets, debris from collisions and even frozen space sewage. It seems the astronauts launch it out into space to get rid of it. Unfortunately, the bags of waste have the same orbit as they do, so it is not unheard of that someone might meet up with it in a future orbit.

There are many different types of orbits for satellites. The International Space Station and most of our weather satellites are in LEO’s, or low earth orbits. They are speeding along at nearly 20,000 mph because they are so “close” to earth, at only 200-500 miles. They circle the earth every 90 minutes. If they went any slower, earth’s gravity would overcome them and they would tumble to earth, burning streaks of incinerated satellite parts as they fell.

A common LEO, especially for satellites that need to see the whole earth over time, is a polar orbit. As the satellite travels from pole to pole, the earth rotates underneath. Over time, the satellite will have passed over the entire planet, just by maintaining its orbit. They can map the entire earth. Remote sensing and long term weather satellites are often in these polar orbits. These are very common to see. I saw three the other night, all at slightly different speeds, but traveling along the same trajectory like silent watchmen.

A GEO is a much higher orbit. GEOs are geosynchronous orbits, meaning they are up so high and going just the right speed so that they appear to be stationary over a certain spot on earth. You can imagine what use these orbits would be, especially if you were curious about a certain spot on earth. Unfortunately, at 22,000 miles up, the view is not as sharp as a lower orbiting satellite's. Their advantage is that they have a large coverage area. We use them for relaying a signal for communication or broadcasting. Our telecommunications satellites are in GEO orbits. The problem with this kind of orbit is that the satellite must be directly over the equator to maintain the orbit. That leaves out the polar regions, and those folks want their satellite TV, just like we do. So we have another orbit, a highly elliptical one, which can come close to earth at one point, even a polar region, and then wander father out.

If you’d like to know exactly when satellites are passing over your head, you can go to the Heavens Above website and enter your town. You’ll be surprised at what you can see. And it’s just the tip of the iceberg of the night watchmen. You’ll be surprised at who’s seeing you!

Until next week, my friends, enjoy the view.

Tuesday, July 03, 2007

The Heavens

7/8/07 – 7/14/07
by C. Zaitz

I have a collection of old astronomy books. Sometimes the author will refer to the sky as “the Heavens.” What a lovely way to think of the regions above our heads. It gives the sense of the vastness and beauty of the sky, but the term does tend to lump everything together. “The Heavens” is a more encompassing term than saying the singular “heaven” but it doesn’t truly capture the layered and complex nature of what lies above.

For example, during the day, the sky is all around us, and we rarely ever look at it, just as we rarely look at the ceiling in our house. But the sky is much more interesting, even on a bland day, than the ceiling. The sky has magnificent layers of intrigue, layers of depth and color. Blue skies aren’t just blue, and grey skies are even more colorful. My favorite, of course, is the black sky of night, when all the subtle, distant and concentrated light from the stars can penetrate the atmosphere and be seen here on earth.

But sometimes when you look up, you see what looks like “heaven” from what we’ve seen in paintings and drawings. We can see rays of light coming down from the frothy, fluffy gold-edged clouds with a bright sun lighting them from behind. It’s a beautiful scene, which is probably why it was chosen to represent heaven. Those rays have a technical name. They are called crepuscular rays, which certainly isn’t as poetic a term as “heavenly rays,” but describes the rays of light that seem to spread out from behind back lit clouds, especially at twilight. Crepuscular means, “twilight,” though the effect can happen anytime there are enough particles of dust or vapor in the air to scatter light well. The cause of these rays is a combination of light and shadow. The light is always there when the sun is out, but the shadow created by an object like a cloud that gives the light a “ray” appearance.

From our perspective, the parallel rays from the sun actually look like they diverge from behind the cloud, giving them that spread out “ray from heaven” look, as if a heavenly body shone a great golden flashlight to illuminate our little patch of earth. It’s the same trick of perspective that the brain plays to make parallel railroad tracks look like they converge at a distance.

There certainly are other beautiful effects of light and shadow, scattering and perspective to be seen in the sky, but I think crepuscular rays are some of the most evocative. Perhaps it’s because they do seem to be flooding the earth with golden light, almost like a curtain opening up onto earth’s stage, as directed by something bigger than ourselves. Next time you see them, you’ll know that they are caused by natural circumstances, but you can always let those pretty rays take your gaze up into the sky. I assure you there will always be something interesting to see in “the heavens.”

Until next week, my friends, enjoy the view.