Some NIST scientists think they have an simpler way of detecting extraterrestrial life remotely. They note that many molecules have a handedness called chirality. Like human hands, mirror images of chiral molecules can not superimpose. (Try to put a left glove on a right hand.)

A planet with no life would tend to have an even distribution of chiral molecules, detectable by its effect on light. A planet with life would change that balance since life replicates itself. Things containing molecules like amino acids and DNA create like-handed amino acids. The scientists think they could outfit space-borne telescopes to make this measurement.

Writing assignment: invent a chirality ray gun to make sure those aliens don't come here, say, on July 4th.

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