Chile is a very slender country about 4300 km long from south to north. The northern region extending over 1000 km is an area called Atacama Desert, which is the driest area in the world. Its extremely dry climate is due to its location between Humboldt Current coming up along the Pacific side and the 6000-meter Andes Mountains on the eastern side. Photo 1 shows northern Chile photographed from a space shuttle on a mission to repair Hubble Space Telescope. This photo shows the geography of Chile very clearly as explained above. VLT (Very Large Telescope) of ESO (European Southern Observatory) is located only 25 km from the coast, while ALMA is in an interior area at a high altitude about 300 km from the coast.
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Photo 1: Northern Chile photographed from a space shuttle |
Japanese team started site testing in this area from 1992 ahead of other nations (Photo 2), focusing on advantages of northern Chile: high altitude and vast extent of land. At an altitude of 5000 m, the atmospheric pressure and amount of oxygen decreases to a half of that at sea level. At such high altitudes, some people suffer hypoxia due to decreased blood oxygen level and sometimes severe acute altitude sickness. I also experienced early symptoms of altitude sickness when I caught a cold at 4200 m where the temperature was minus 10 degrees Celsius and high fever continued for two days, but I could recover from such severe condition by drinking an infusion of coca leaves given by a local supporter.
On another occasion, I got lost in a desert. I was driving a car along the southern side of the Atacama Salt Lake toward Antofagasta, accompanied by another car with two staff persons of the National Radio Astronomy Observatory (At that time, there was no airport in Calama and we had to travel between Antofagasta Airport and the candidate site in a four-wheel-drive vehicle). Since we spent too much time to drive through off-road tracks on the way, the sun went down and we were in the darkness. We had a GPS device but we couldn’t find the way only with the information of latitude and longitude. The “road” on which we were driving was a mere track marked by wheels of other cars, and it was very difficult to find it in a dark desert. After repeating the GPS measurement many times, we could finally find the way to San Pedro de Atacama.
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Photo 2: Author using a satellite cell-phone at site testing in northern Chile |
When we arrived at San Pedro de Atacama, it was already past 10:30 p.m. and the gas station that we were driving for was closed. The fuel level gauge of our cars indicated a near-zero point; however we decided to go to Calama without fueling the car. The road to Clama is a paved road but it was obvious that we would run out of gas on the way. To save the fuel, we began to coast our cars in neutral on downward slopes after passing the hill (Photo 3). Even in such a critical situation, human curiosity is irresistible and endless; we enjoyed wonderful starry sky in darkness by turning off headlights.
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Photo 3: Downhill way from San Pedro de Atacama to Calama |
When we finally arrived at the present ALMA site through these difficulties, I felt like standing on the surface of Mars and confirmed my belief that we can complete ALMA here. Remembering the long way to reach here, I feel a surge of pleasure to see the ALMA Project under construction at the site discovered after years of relentless effort.
