Plastic: The lens of the next generation

Astronomers at UA's Steward Observatory are planning to use telescope mirrors made from ultra-thin sheets of reflective plastic to study our extra-terrestrial neighbors. The scientists predict success within the next 50 years.

"This is not a Buck Rogers thing, that's 25th century - it's more like the middle of the coming century," said UA astronomer Neville Woolf.

The study of exoplanets, planets that orbit other stars, became a high priority at NASA. Finding these faint, distant objects requires huge orbiting telescopes made of glass or metal.

Woolf, with astronomy professor Roger Angel and optical sciences assistant professor James Burge, are proposing ways to make these telescopes lighter and cheaper by using mirrors made of enormous sheets of stretched plastic.

These plastic mirrors would be used to look for radiation from gases on the atmospheres of exoplanets.

"We're basically looking for the greenhouse gases of another planet," Angel said. "Even the most primitive life leaves a detectable change in the atmosphere."

Woolf said that telescopes with flat plastic mirrors, each about 10 square meters in size, would be able to detect the fine details of the gases to find out if they are like Earth's.

"We could see if they show traces of materials like refrigerator gases, which are a sign of semi-intelligent life. In other words, they're advanced enough to have screwed up the atmosphere," Woolf said.

Angel said the construction of these plastic mirrors would be difficult, but not beyond the scope of technology.

"We're going to have to work like crazy to figure out how to stretch the plastic and get it right," Angel said. "The good news is, we can surely do it. The bad news is it's going to be another 20 years at least before it happens."

Woolf said the idea to use plastic as a material instead of glass or metal came out of a proposal written by Angel, Woolf, and Burge for the National Institute for Advanced Concepts.

"It's an organization NASA set up to study not-quite-crazy ideas," Woolf said.

The major obstacles being studied by the team involve getting the plastic surfaces smooth enough to accurately reflect light and then devising a system to keep the mirrors in place. This could be done by mounting the mirrors on a frame or by attaching ion propulsion rockets.

The scientists must also take into account the hazards that come with orbiting thousands of miles from the Earth.