From across a room, a tiny box beaming out low-power radar can tell how fast your heart is beating. The technology–initially developed as a concept at NASA to locate victims in a disaster–is coming to market as a monitor for elderly people living on their own, and eventually could be used by anyone as a tool to predict future health.

The startup making the technology thinks of it as an early version of a “tricorder in your home.” Like Star Trek’s fictional medical tricorder, it measures vital signs (for now, it monitors heart rate and breathing, but in the future, the team plans to develop devices that can do everything science fiction writers imagined, including diagnose disease) from a distance. The Welbi, the company’s first product, will connect to a cloud and mobile app that families can access to monitor an elderly relative’s health in real time.

“There are several elderly people in my family who get calls at 7 a.m. just to make sure they woke up,” says Jeff Nosanov, CEO and cofounder of V-Sense Medical, the startup making the device. “I’m sure that’s true of many families. The problem with those situations is that people who are elderly or medically vulnerable, in many cases, don’t like being called every day–they don’t like being reminded that they are fragile or ill. They don’t want to feel like a burden. But at the same time, they do need someone, and with increasing numbers of people at home rather than in nursing homes or other long-term care facilities, there’s this gap connecting people with their families who are also their caregivers.”

Nosanov, who previously worked at NASA, became interested in commercializing the technology after his children spent time in intensive care as newborns. The tiny monitors attached to each baby kept falling off. Nosanov saw the potential for remote monitoring. With venture capital funding, he acquired the rights to develop NASA’s technology, and founded a startup in 2015. His team spent months miniaturizing an early prototype, shrinking it from the size of a carry-on suitcase to roughly the size of a smartphone. But as he explored the market for baby monitors, he realized that it was a crowded space; a tool for elderly people made more sense as a first product (both the baby monitor and adult monitor would work the same way). Around 12 million Americans over age 65 live alone.

“The more we thought about it, we realized that at the other end of life, basically there’s a much larger market, far fewer options, and really a much more pressing need that we could address,” he says. “Seniors are typically an underserved market in many ways, already, because in our society we sort of have a private respect but publicly don’t want to acknowledge aging.”

After the device is plugged in and connected to Wi-Fi, it doesn’t have to be maintained. Unlike a wearable like a Fitbit, users don’t have to directly interact with it or charge it. The monitor continuously scans the room with radar.

“It’s just like radar that police use to see how fast you’re going, when the signal bounces off a car and can tell you how fast it’s moving,” he says. “That’s what we’re doing, but with the surface of the body.” As the radio frequency signal shines on someone’s body, it reflects back differently depending on how the body is expanding and contracting with each breath or heartbeat. Because the body expands much more for each breath than a heartbeat, it’s easy for the system to tell the data apart.