I've stood on the summit of Mount Whitney in California, the highest mountain in the contiguous United States at 14,500 feet.  Looking out over that vista, I wondered if that would be the highest place I would stand on this planet.  I wasn't aware of it at that time, but there is a complex in Chile called the Atacama Large Millimeter/submillimeter Array (ALMA) that is the highest observatory in the world at an elevation of 16,400 feet.  Yes, it looks like a satellite dish farm, but those are really radio telescopes located in the driest location on Earth, and they help us uncover some amazing mysteries of the universe.  Which ones? Read further on for the answer to that question and what it's like to move around where the air is thin.

This is our launching point to ALMA, and is a delightful town with a population just shy of 4000 people, and a countless number of dogs.  Constructed of adobe, the Church of San Pedro is the town's center and lifeblood.  We were blessed to be there for the dedication of an organ that hasn't been played in 100 years. Actually, no one really knows when the organ first came to the church or who made it.  The performance was in synch with the festival for St Peter which included dances and a parade in the street.  Different groups in masks performed in various places as they assembled for their parade along the main dirt street. The shopping and restaurants were fantastic and the culture and the ambiance were divine. In short, when I think of Chile, this is the town I will fondly remember.  The area surrounding the town is rich in tourist adventures providing everything from geysers to hot springs, pink flamingos, sand dunes, odd "lunar-like" landscapes, and ALMA.

Valle de la Luna                                                                          Los Flamencos National Reserve

Only viewing the universe in visible light is like only playing the piano with only several keys.  To appreciate the full richness of our cosmos we need to "see" it in all wavelengths.  ALMA provides us with "radio eyes" that can view the universe in millimeter and submillimeter wavelengths.  To do this it uses 66 antennas, 54 of them are 12m in diameter and the other 12 are 7m in diameters.  These antennas can be placed in a wide variety of configurations with the longest baseline reaching 16 km,  and working together can give the same resolution as the Hubble Space Telescope.  The site is operated by a partnership that spans the globe including North America, Europe, and East Asia, along of course with Chile.  The observatory is located at the high site at 16, 400 feet.  It is operated from the low site which is at 9,500 feet. 

The low site facility has the control room, offices, conference rooms, labs, dormitories, cafeteria, and displays for the public.  It is here that you can get a feeling of scale when you see some of the real antennas next to one of the vehicles that move them into their various configurations.

photo courtesy of Tim Spuck                                                                                                           
photo courtesy of Tim Spuck                                                                                                                                

 The general public is not allowed at the high site.  The site was chosen because it is high above the atmospheric moisture in the driest desert on the planet.  It is a perfect environment for studying the universe in microwaves.  It is not so perfect for people.  Dangerous altitudes, extreme ultraviolet wavelengths, and wild donkeys are some of the adventures that await those who are privileged enough to  ascend.  First, you have to have a medical exam where they check you blood pressure, temperature, heart rate and oxygen level.  Passing this hurdle you are cleared for the high site, but can only stay for two hours.  You begin your half hour journey to the summit in a van holding onto a canister of oxygen.  I've been to high altitudes before and know that my body starts to feel the effects of altitude around 13,000 feet.  That wasn't the case here.  We drove to the top and I didn't experience any shortness of breath or head pounding throbs of pain.  Then I realized we drove up- I didn't have to exert any energy by walking with a heavy pack.  I stepped out of the car and felt light headed.  I smiled.  Remember the rule.  Take it slow and think twice.  I remember descending from Long's Peak in Colorado and my brother asked if I was alright.  I said I was fine.  I just needed to take it slow and make certain that where I was putting my feet was really where I wanted to put my feet.  This is no place for mistakes.  

                                                                                                          photo courtesy of Tim Spuck

                                                                    photo courtesy of Ryan Hannahoe                    photo courtesy of Ryan Hannahoe

I've never been at altitude with such luxuries.  There is a building at the high site where we had bathroom facilities, a kitchen, a viewing area, and the correlator.  The correlator is the fastest computer at an astronomical site.  Its 32,768 chips perform an amazing  17,000,000,000,000,000 operations per second.  We were driven to an area where we could walk among the radio telescopes accompanied by an ambulance.  Two hours goes by fast and soon we were heading back to the low site.  

The process of observing at ALMA is somewhat similar to that at an optical observatory.  You fill out an online application and it goes through a selection process. If accepted, the next step is to have a member of the Software Team write a script to have the telescopes perform your research based on the antenna configuration you need.  The Software Team is now involved in the observing run making certain everything goes according to plan.  You may travel to Chile and go to the low site and collect your data or it can be performed by their telescope operators and you receive the data remotely.

Correlator photo courtesy of ALMA                                                                                                             

Due to its sensitivity ALMA can observe galaxies in minutes rather than hours. It works off a different kind of science by looking at  molecular gas, and from this has discovered complex molecules in space, ALMA's primary targets include looking for carbon and carbon monoxide in Milky Way type galaxies, and  protoplanetary disks around newly forming stars.  But it is capable of doing much more than this. ALMA is truly a revolution in astronomy, and a case study model of where this science is going.

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