On a desolate coastline in Patagonia, astronomer Alan Stern huddles behind a semitrailer to block his telescope from the wind. It’s not long after midnight on July 17 — the peak of southern winter — and 40 mph gusts howl across the landscape.
Stern, who heads NASA’s Pluto-visiting New Horizons mission, is one of 56 scientists with two dozen small telescopes spread for 30 miles along Argentina’s Atlantic coast. Some evade the telescope-shaking wind behind 15-foot-tall steel-framed tarps, built with supplies raided from local hardware stores. A few find shelter in natural alcoves on the beach.
“The conditions were generally miserable for observing,” Stern says. But above, the heavens were crystal clear.
Their celestial quarry: the roughly 14-mile-wide shadow of a world 4 billion miles away, one just discovered a few years earlier. When this ancient object passes in front of a background star, the star’s light dips — like a mini-eclipse — allowing the astronomers to tease out the mystery world’s size, shape and reflectivity. The data can tell the New Horizons team how to position the spacecraft and calibrate its camera when it actually visits next year. Most crucially, the light dip might reveal spaceship-killing debris nearby.
But catching the star as it dims isn’t easy. The shadow passes over Patagonia at 60,000 mph, and the team already failed in their two previous attempts to see this shadow, called an occultation. “This was our last chance,” Stern says.
