The extreme terrain and arid environment near the northern Chilean town of San Pedro de Atacama meant there was little in the way of human development, making it the perfect spot for travelers like us anxious to get off the beaten track. Months before leaving on our South America adventure, we had made reservations to discover the Atacama's Desert otherworldly landscapes, the clear blue salt lakes teeming with flamingos and the largest group of geysers in the southern hemisphere.
All that would have to wait for a bit as our first exploration in the area took us to the Atacama Large Millimeter/submillimeter Array and known as ALMA. Though neither Steven nor I are science buffs, we both figured the tour of the largest ground-based astronomical project in existence certainly deserved four hours of our time. Plus, the free tour included transportation to and from the ALMA site located 45 minutes outside of town. After registering months in advance on the ALMA website, we were relieved to know we had confirmed tickets as spaces on the tour were very limited.
All that would have to wait for a bit as our first exploration in the area took us to the Atacama Large Millimeter/submillimeter Array and known as ALMA. Though neither Steven nor I are science buffs, we both figured the tour of the largest ground-based astronomical project in existence certainly deserved four hours of our time. Plus, the free tour included transportation to and from the ALMA site located 45 minutes outside of town. After registering months in advance on the ALMA website, we were relieved to know we had confirmed tickets as spaces on the tour were very limited.
The ALMA, meaning 'soul' in Spanish, is the largest land-based observatory ever built and consisted of 66 enormous antennas which simulate a telescope 16km in diameter! More powerful than the Hubble telescope, it looks out to some of the most distant galaxies and observes the very first stages of formation of planets and stars.
Isabella, our tour guide, pointed out the mandatory on-site lodging for all the workers which included many recreational opportunities but a ban on all liquor.
The following is a far better description about why ALMA is considered so important than I could ever write. "For four centuries, telescopes of all kinds have delighted us with images of the Universe that are intriguing, amazing and humbling, given the immensity that surrounds us. We have seen exploding stars, the birth of planets and many other objects and phenomena.
With ALMA, the mysterious light of the coldest, most hidden parts of the Universe is now appearing. We can clearly observe what no human eye has ever seen, study the first stars and galaxies that emerged from the cosmic Dark Age, determine the chemical composition of the atmosphere of planets in formation, and perhaps even detect the first traces of life."
Even though much of the tour was indoors, there was enough standing outside that we were glad we had heeded the warnings to wear sunscreen as the Operational Support Facility or OSF was at an altitude of 2,900 m or 9,514 feet above sea level. The UV Rays Indicator measured the maximum amount of exposure at the site depending on whether a person had 'white tone skin' or 'matte tone skin' and what precautions needed to be taken at each level.
We learned that European, North American and Japanese experts studied the potential for building large telescope arrays. It soon became evident that such ambitious projects couldn't be developed by a single country so they decided to collaborate. As a result, ALMA's construction and operations have been led by the European Southern Observatory (ESO) on behalf of its member countries, the National Radio Astronomy (NRAC) of the US and the National Astronomical Observatory of Japan (NAOJ). ALMA began on September 1st, 2003.
I wondered how many pieces there were in the LEGO model of the antenna equipment mover or transporter! You'll see the actual transporter further in the post.
Of course, the big question was why Chile had been chosen to host ALMA. Isabella said over the last few decades her country had become a world leader in astronomy and many international partnerships had developed there. Other critical factors were Chile's clear skies, the dryness of the Atacama Desert, the altitude of the site where the antenna array would be installed. In addition, because of its relative proximity to the equator, ALMA is able to observe most of the sky providing an exceptional view of the Milky Way.
Did you know that cool objects in space radiate much less light than hot objects such as stars? I sure hadn't. Detecting these cold objects requires instruments with an exceptional power to sense light. Each of the ALMA telescopes has a diameter of 12 meters which is bigger than the largest visible light telescope on earth. Isabella stated that ALMA works because it can point all of its 66 antennas with great precision at a single astronomical source. Together, the antennas observe the same point in the universe requiring that their electronic components work with an unseen precision.
The signal captured by each antenna is sent to the Correlator, a supercomputer located 15 kms north of the Operational Support Facility on the Chajnator Plateau at a dizzying altitude of 16,400 feet. The Correlator combined the signals provided by all the antennas to generate astronomical data. A specialized team of astronomers calibrates and processes the data, which is sent to the astronomers who have been assigned observation time with ALMA.
The ALMA Correlator processes all the antennas' signals and transforms them into images. Isabella mentioned that required colossal computing and processing power which is exactly what the ALMA Correlator has. As one of the fastest supercomputers in the world, about three million laptop computers would be needed to perform the number of operations that the Correlator carries out! Everyone working at the Correlator is required to use oxygen because it was found that people working at 5,000 masl or 16,404 feet altitude were making mistakes because of the lack of oxygen.
On September 17th, 2009, one of two ALMA transporters - named Otto and Lore - brought the project's first antenna to the Chajnator Plateau and positioned it at its final location. Traveling at around 5 kilometers per hour, the transporter started out from the OSF after the antenna had passed all its tests with flying colors. The journey took nearly nine hours of hard work and anxiety. Since then, the other 65 antennas were installed on Chajnator to observe the universe.
Astronomers from around the world don't have to travel to Chile to perform observations with ALMA, since highly efficient connectivity infrastructure has been built for data transmission. Astronomers must apply for observation time, which is granted based on the scientific and technical merits of each proposal. Once the data is collected, those astronomers have exclusive access to the findings for one year. After that, the data becomes public in a vast library that, when it reaches its maximum capacity, will grow at a rate of 800 gigabytes a day!
Despite its similarity with the martian landscape, the Atacama Desert was home to native flora and fauna, which over centuries have developed techniques to adapt to the rugged living conditions. ALMA workers frequently spot vicuñas, foxes and other animals that inhabit this incredible landscape.
All of ALMA's operations are carried out in territory provided as a concession by the government of Chile in the Atacama Desert, one of the driest places on earth. Although the landscape is stark, it is home to long-established communities. The Atacameño people, the third largest indigenous community in Chile and known as Likan Antai, have raised llamas and alpacas for hundreds of years and still do along with weaving and crafting.
When locals lived at the Estancio Barrio ranch until the 1960s, the animals were moved among 20 ranches in the gorges to feed them, depending on the time of year and availability of water. The ranch was restored by ALMA and converted into a museum on the road between the OSF and the Chajnator Plateau to show its commitment to the environment and local history.
A representation of an antenna made out of LEGOS! FYI: There is a fascinating discussion online about whether the correct spelling is all caps or capital 'L' and the other letters being lower case; also about whether the plural word is LEGOS vs LEGO bricks! How much I discover when writing these blog posts!
Following the indoor display, there was a brief film about ALMA and its initial findings. You can tell when we were there from the time stamp!
What a sight it would have been to view the antennas atop the plateau, instead of just the photo!
ALMA started scientific operations on September 30th, 2011 with a quarter of the final number of antennas. Called Cycle O, the first phase of ALMA operations identified 112 highest-priority proposals out of 919 submitted by astronomers from all over the world to start using the cutting edge facility.
For Cycle 1, there were 1133 proposals submitted. 78 science assessors from all over the world evaluated the expected scientific value of these proposals. As a result, the 196 highest-priority projects were chosen to use 32 ALMA antennas in 2013. They were carried out simultaneously with the ongoing construction, commissioning and verification of the entire ALMA system. Isabella explained that there is no charge to any scientist to request a project to be done.
We had a chance to walk past many of the labs.
The OSF Control Room normally comprised of four people: two array operators and two engineers. I was surprised that we were welcomed into the main control room for a few minutes and had an opportunity to meet one of the scientists in charge and ask questions. I found it very impressive that ALMA has really made an effort to be accessible to the public and to open its doors to teach people about what it does.
One scientist explained that they are only able to see radio waves but the ALMA office in Santiago, Chile's capital, converts those to optical lines.
We next walked past some of the labs where maintenance was being performed on the equipment.
Outside, Isabella pointed to three slices of one of the 24 American antennas. She stressed each component of the antenna had to be perfectly aligned to work properly. That was why it could take up to seven hours to transport the antennas to the Correlator located at 5,000 km altitude. The antennas had traveled from the Chilean port on the coast 300 kms or 187 miles to the ALMA site.
In the distance was Otto, the massive antenna mover! We had seen the LEGO display of the German-made vehicle at the beginning of the tour so we were excited to see the real thing as it wasn't always at the ALMA site but up at the Plateau instead!
See the donkey on the rocks in the middle below?
It wasn't a flamingo, a fox or a vicuña but at least we saw one animal!
Watching the humongous vehicle ever so slowly turn around on the parking lot really was pretty interesting as I imagine none of us on the tour had ever seen a vehicle of that size before.
Again, I was flabbergasted when we were permitted direct contact with Otto even if the drivers didn't take us for a spin! The 130-ton machine, had 7 axles and 28 wheels!
The drive back to San Pedro de Atacama took us through the Chan Desert. As I said at the outset, neither of us are science geeks but we were both glad we took advantage of the incredible opportunity to tour the most powerful telescope for observing the cool universe. Our overseas adventures are a way of being exposed not just to what makes us comfortable but to stretch our knowledge and appreciation of this wonderful world beyond our doorstep.
Next post: Moon Valley & Death Valley!
Posted on March 29th, 2018, from Littleton, Colorado.
No comments:
Post a Comment