On Friday, 05^th July, we went to ALMA (Atacama Large Millimeter/Submillimeter Array), our last stop on our #MeetESO tour. ALMA is located close to San Pedro de Atacama at about 3,000 m and over 5,000 m altitude. A visit of the radio telescopes on the Chajnantor plateau is normally not possible. Luckily our group was allowed to drive the 32 km long road from the ALMA OSF (Operations Support Facility) to over 5,000 m altitude on the Chajnantor plateau. But before going up, everybody had to undergo a medical test to measure blood pressure & saturation. If the values were not met, you were not allowed to go up to the plateau. ESO is very strict on this, as the principle safety first applies.

All #MeetESO members and most of the ESON members passed the test and together we travelled by bus into high altitudes. After arriving on the plateau, you do really feel the height. You walk much slower, you do breathe more consciously and somehow you do feel a little bit dizzy. So, instead of running around to take as many photos as possible, you need to stay calm.

The Chajnantor plateau just looks amazing. You’re surrounded by many chilean volcanos, but there is no vegetation. Moreover, you don’t hear any noise. Even the radio telescopes move very silently. We had fantastic weather luck, it was warm (probably about 2-3°C) and no wind. I felt like I was walking on a different planet.

Why is ALMA built in this high altitude?

Well with ALMA radio-astronomy is conducted. That means the antennas don’t observe in the optical spectrum, but use radio frequencies (wavelengths between 0.3 and 9.6 mm) to observe the universe. That also means, with these antennas you don’t get back pretty pictures from galaxies or nebulas, instead you get wonderful data. And these data then can be converted into “nice” pictures.

Water vapor is the natural enemy of radio-astronomy. But in high and dry altitudes you get less of it. A big advantage of radio-astronomy is that you don’t need a night sky to observe, instead you can do science 24/7. The astronomers at ALMA report, that they do work in shifts.

ALMA is searching for our cosmic origins and revealed for example new born solar systems. Moreover, the radio antennas are also part of the Event Horizon Telescope, which just recently released the first ever photo of a Black Hole (to be more precise it was a photo of the Black Hole shadow).

I would like to say a very big thank you to ESO, to enable me to go on this extraordinary & fascinating trip. As one of my #MeetESO colleague spot on said, it was an “extreme social” and imho absolutely beautiful and highly interesting.

Weitere Informationen:
https://www.eso.org/public/germany/teles-instr/alma/
https://www.almaobservatory.org/en/home/

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