Let's Reminisce: New telescope will reveal more
Recently, the James Webb Space Telescope took a slow boat from Los Angeles, spent a few days traversing the Panama Canal, and arrived at a spaceport in French Guiana. The telescope has been twenty-five years and ten billion dollars in the making. Thousands of scientists and engineers from fourteen countries have worked on it.
The telescope will be put into Ariane 5, a European rocket named for a mythical princess who helped a man she loved defeat a monster called the Minotaur. Ariane 5 will carry the telescope some ten thousand kilometers in thirty minutes. The J.W.S.T. will then continue on its own, for twenty-nine days, toward a lonely, lovely orbit in space, about 1.5 million kilometers from Earth, where it will stay in constant communication with us.
On its way, the telescope will slowly unfurl five silvery winglike layered sheets of Kapton foil, about as large as a tennis court. These sheets, each thinner than notebook paper, will function as a gigantic parasol, protecting the body of the telescope from the light and the heat of the sun, moon, and Earth. In this way, the J.W.S.T. will be kept nearly as dark and as cold as outer space, to insure that distant signals aren’t washed out.
Then eighteen hexagons of gold-coated mirror will open out, like an enormous, night-blooming flower. The mirrors will form a reflecting surface as tall and as wide as a house, and they will capture light that has been travelling for more than thirteen billion years.
It’s easy to forget that light takes time to travel. But when we see the moon we are seeing it as it was 1.3 seconds earlier; Jupiter we see as it was forty minutes ago; the Andromeda galaxy—the nearest major galaxy to ours, and the most distant object we can see without a telescope—2.5 million years ago. “My students are often frustrated to think that they can’t see the things in space as they are today,” David Helfand, an astronomer at Columbia University, said. “I tell them it’s this great advantage. It means that the universe is laid out like a book. You can turn to any page you want. If you want to see ten billion years into the past, you look out at ten billion light-years away.”
Most of the light spectrum is not visible to the human eye. When we look up at the night sky, it’s as if we were listening to Rachmaninoff’s Second Piano Concerto with ears able to hear only the occasional middle C and maybe a tinny D. We have no biological receptors for radio waves, or microwaves, or ultraviolet radiation, or infrared radiation.
If an object is moving away from us—and most everything in the universe is, because the universe is continuously expanding—the wavelength of its light is, in effect, stretched out, eventually rendering it infrared. On Earth, there are a number of telescopes larger than the J.W.S.T., but they can’t see the range of infrared light with the level of resolution and sensitivity that the new telescope will achieve.
“It will have many capacities, but the two big ones are ‘Very Far Away’ and ‘Very Close,’ ” Helfand said. The Very Far Away component will look back about 13.5 billion years, to when the universe was some quarter of a billion years old. “If you compare the universe’s life to that of a human, that’s like seeing the universe as a baby,” he said.
After the big bang, the universe was a nearly uniform soup of matter and radiation. But by the mysterious epoch that the telescope will examine—sometimes called the Dark Ages—gravity had managed to amplify tiny irregularities in that soup, causing a kind of clumping. “So what we are on is the quest for the very first stars.”
“The Very Close capacity is in some ways the most exciting,” Helfand said. “It’s about looking at planets that are not too different from Earth.” The J.W.S.T. will study exoplanets, or planets outside our solar system. Exoplanetology is a young field. The first exoplanet was discovered only twenty-five years ago. By 2005, about two hundred exoplanets had been found. Today, more than forty-four hundred are known.
Jerry Lincecum is a retired Austin College professor who now teaches classes for older adults who want to write their life stories. He welcomes your reminiscences on any subject: firstname.lastname@example.org.