ACEAP 2019: ALMA Radio Telescope

Where do we come from? What are we? Where are we going? Questions as old as mankind. The search for answers impels many quests including the painter Gauguin’s voyage to Tahiti. Today, it draws astronomers to the remote Chajnantor plateau in the Chilean Andes. The Atacama Large Millimeter/sub-millimeter Array, ALMA, Array Operations Site hosts the most powerful telescope on earth.

ALMA 12 meter antennas, Credit: R. Pettengill (NRAO/AUI/NSF)

With 16,500 feet of altitude at the AOS, supplemental oxygen is required. Nearby in a more sheltered location, at 10,000’ high is the ALMA Operations Support Facility in the Atacama Desert. OSF hosts the couple hundred scientists, engineers, and staff needed to operate and maintain the telescope. The massive amount of data produced by ALMA requires reduction, archive, and distribution centers on four continents to deliver observational data to investigating scientists.

The dedicated staff of a couple hundred at the OSF with the dozen or two essential personnel at AOS during the day, must cope with isolation and separation from family and comforts of home. Most commute from Santiago and face about about a 6 hour commute, including the two hour flight. A common shift is 8 work days and 4 days off. Staff with families far away may spend 6 months apart. Pride, intelligence, and sense of purpose shone in everyone we spoke with from the director Sean Dougherty to the casino staff. Don’t get excited, casino is Chilean for cafeteria!

All together, including the thousands needed at supporting locations, ALMA is a knowledge factory helping answer these profound questions. The ACEAP 2019 cadre were thrilled to have the rare opportunity to stay overnight at the OSF and make the 45 minute trip for a two hour stay at the AOS high site. In exchange we all are sharing our experiences.

The day before included a tour of the OSF and presentations including one about ALMA’s role in the Event Horizon image of the M87 black hole shadow. New capabilities for signal polarization measurements will enable understanding of the motion of targets.

Paulo Cortes, Credit: R. Pettengill (NRAO/AUI/NSF)

Paulo Cortes, the ALMA operations astronomer, dreamed of being a truck driver in a Chilean public school. His high school physics teacher prepared Paulo and a few others for university entrance exams. Now the whole world benefits from his talents and many others like him. Thank teachers! Just one small example of the human capitol available to answer questions and solve problems that have proven too difficult for developed world alone.

The lights of this large engineering and residence complex did nothing to dim the spectacular Atacama view of the Milky Way and Jupiter

Jupiter above the Milky Way from ALMA OSF, Credit: R. Pettengill (NRAO/AUI/NSF)

In the morning, not only did the ACEAP 2019 team have to pass a medical exam before proceeding, but drivers to the high site must pass one before every trip. Visitors are allowed a maximum of a 2 hour visit. Essential staff are limited to 6 hours. No one is permitted to stay overnight. The day before our visit, staff was evacuated due to high winds.

We were fitted with our oxygen, then crammed into two trucks for the 45 minute trip. The road is straight and wide for a mountain road, because it used to transport the giant dish antennas. A majestic snow capped volcano dominated the view to our left. We also encountered several groups of wild vicuña. Near the AOS the ground looks remarkably like rover images of Mars with the blue sky the only hint that we are still on earth.

Road to ALMA AOS with vicuña and the Licancabur Volcano. Credit A. Borja: (NRAO/AUI/NSF)

After a brief stop at the small engineering building with the correlators that combine signals from the antennas, we begin touring the array.

ALMA includes both smaller antennas for sub-millimeter signals and larger ones for longer wavelengths. There are a total of 66 antennas: 54 twelve meter and 12 seven meter dishes. Antennas made in the US, Europe, and Japan have distinctive looks and parts, but function identically.

Japanese 7m dishes and European 12m dish in the compact array, Credit: R. Pettengill (NRAO/AUI/NSF)

We were lucky with a calm sunny day, but looks are deceptive. My roommate Art discovered his oxygen line was pinched when his fingertips started to become numb.

Huge antenna transporters position the dish antennas on mounting pads with sub-millimeter precision. A visit with Otto the transporter was a highlight worthy of a group picture.

The ACEAP 2019 team with Sonia Daffau and our ALMA driver in front of Otto the transporter and an American dish. Credit: V. Foncia (NRAO/AUI/NSF)

The ACEAP team went from ALMA to visits at the wonderful Tata Mallku Park and Valley of the Moon near San Pedro. Back in Santiago we were introduced to the powerful ESO observatories that will have to wait for others visits. The big picture of astronomy and economic development in Chile was given by Luis Chavarria, Director of Astronomy at Chile’s CONICYT.

I left with profound admiration for those who have created one of the great scientific enterprises of history in Chile. Thanks to the NSF, AUI, and National Optical and Radio Astronomy Observatories for making this trip possible. Learn about ACEAP and meet the 2019 and previous cadres at I’m entranced by the warmth of the people of Chile and the wonderful food and wine. The Texan in me may smuggle in a little hot sauce on the next visit, because the astrophotographer in me has to go back.

Even the familiar Moon takes on a new look in the Atacama. Earthshine on the crescent moon takes on colors of the desert as it sinks behind a ridge, from the ALMA OSF Residencia. Credit: R. Pettengill (NRAO/AUI/NSF)

For more about this trip, more images, and press articles see: ACEAP 2019 or #ACEAP2019 #AstroAmbassadors #NSFfunded on social media.

Content created: 2019-08-04




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Moon Phase