Once again, it's time to take a look at the Moment of Science mailbag. A listener writes:

Dear A Moment of Science,

I was watching a Star Trek marathon recently--the original Star Trek, not the newer versions. And I began to wonder if any of the technology imagined on Star Trek actually exists today in the real world?

Great question. Of course, most of the technology on Star Trek doesn't exist for real. But at least one cool bit of Star Trek science has been made real. Remember tricorder? It was a scanning device that, among other things, was used by the show's doctor to diagnose disease and assess the health of a patient. Today, real-life scientists are making similar devices.

For example, NASA is developing a sensor to monitor the health of astronauts. It's a device worn on the skin that uses near infra-red light to measure an astronaut's metabolic rate, or the rate at which the oxygen in the blood is consumed by the body's tissues. This is important because it could help astronauts pace themselves while working on the surface of the moon or Mars. It could also help them exercise more efficiently.

And the sensor could be used to help people on earth. Monitoring the metabolic rate of patients could give doctors an early warning of when a patient is about to go into shock or have a heart attack. So, Star Trek gizmos like phasers and transporter beams are still the stuff of science fiction, but tricorders could be for real.