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 beryllium 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.
For me, the J.W.S.T.’s most interesting capacity is its ability to study exoplanets, i.e., planets outside our solar system. Galchen says, “The J.W.S.T. will be able to describe the atmospheres of these planets, possibly detecting free oxygen or other gases—potential signs of life.”
Galchen’s similes are delightful, e.g., “The Hubble telescope was finally launched in April, 1990, and it sent back fuzzy images of spiral galaxies that looked like melted glaze on a galactic cinnamon roll.” I enjoyed “The Youthful Universe” immensely.
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