National Geographic : 2015 Dec
Teeth Tongue Palate Airflow Sound waves Pitch is adjusted by varying tongue and jaw position. PHOTO: NASA. GRAPHIC: SAMANTHA WELKER. SOURCE: CHRISTINE SHADLE Science EXPLORE HOW WE WHISTLE What makes the high-pitched sound when lips pucker? Precise aerodynamics, says George Mason University physicist Ernie Barreto. Raising the tongue constricts airflow, producing a pattern of air vortices inside the mouth. When the position of the lips creates a certain geometry, he says, a whistling sound results. Professionals in the art develop advanced skills, such as whistling through their teeth, to produce intricate tunes. To keep lips supple and toned, champion whistler Chris Ullman says he has a “no-kissing policy ” 24 hours before competing. Also, plenty of Chapstick. —DS If you can’t go to the moon, the closest you can get—while still on Earth—may be the Haughton Crater on Devon Island, Canada. Because the site resembles the desolate, cratered surface of the moon and Mars, NASA uses it as a planetary stand-in. On a 2010 “mission” there, the space agency mimicked a long trip in the southern polar region of the moon. Space researchers frequently look for such celestial replicas, known as analogs, on Earth. Antarctica’s cold, windswept landscape has helped engineers design a housing structure for use on Mars. An underwater “low gravity” lab off Florida’s coast has been used to assess navigation and communication systems. “We wouldn’t want to be out in space testing technology for the first time,” says NASA’s Kathryn Hambleton. The analogs help researchers peer into the future. Engineers have used Hawaii’s Mauna Kea volcano to test equipment that may help tomor- row’s explorers drill into the moon for evidence of water or ice. —Daniel Stone Backyard Universe Near Flagstaff, Arizona, and at other sites, astronauts train in simulated conditions.