Rare clouds drift behind a telescope at the ALMA Observatory in Chile.

After fulfilling the main purpose of our trip—to build relationships with universities in Santiago, the capital city of Chile—we headed north to the Atacama Desert, the driest non-polar desert in the world.  The small town of San Pedro de Atacama serves as a starting point for adventure travelers looking to experience all this beautiful landscape has to offer. It is also the closest town to the Atacama Large Millimeter/submillimeter Array (ALMA)—a multi-national space observatory that seeks to understand our cosmic origins.

My colleagues and I boarded a public tour bus to the ALMA operations center. The on-board safety video once again put physiology front and center as it discussed a reality that locals here deal with every day: the effects of altitude on the human body.

San Pedro, and most of the Atacama Desert, is located at around 8,000 feet above sea level. The ALMA control center sits above the town at around 10,000 feet. Most impressively, the radio telescopes that make the observations are located on a plateau at 16,000 feet high. For comparison, Mount Whitney, the highest mountain in the continental U.S., is 14,505 feet above sea level.

A warning to ALMA visitors about prolonged UV exposure.

Spending time at high altitudes can have an impact on the cardiovascular and respiratory systems. The increased ultraviolet exposure is significant, and ALMA visitors (even just to the control center) are cautioned against spending prolonged periods in the sun and are advised to wear sunscreen and protective clothing. The extremely arid Atacama Desert also challenges the body’s ability to maintain proper hydration, so water is frequently provided to visitors.

The safety video explained that at 10,000 feet, the control center is considered “moderate” altitude that most people can tolerate well. However, we learned that any visitors to the actual telescopes—which the general public is not allowed to visit—must go through a medical screening that includes taking vital signs (heart rate, blood pressure, blood oxygenation) and assessing signs and symptoms of altitude sickness (dizziness, headaches, nausea). Telescope visitors must also spend a minimum of one night getting used to the high elevation (acclimatizing) in Calama (the town where the nearest airport is) or San Pedro to prepare the body for this challenging environment. They are also given supplemental oxygen to help prevent any altitude-related issues and to allow them to perform physical tasks that might otherwise be too difficult.

All of these physiological challenges of visiting and working at ALMA ultimately are what makes it perfectly suited for its main purpose, observing our skies. Dryness, high altitude, no clouds and minimal light or radio pollution from nearby sparsely populated towns (it’s not easy to live in the Atacama!) are perfect conditions for the ALMA scientists to try to solve important astronomical mysteries.

Crecelius puts safety first during her visit to the ALMA Observatory.

This post is part two of a three-part series by physiologist Anne Crecelius, PhD, chronicling her summer of research and travels through South America. (Read part one here.) Crecelius is assistant professor at the University of Dayton.