On days 6-7 I stayed at the APEX base. The APEX base is fabulous - it is essentially a tiny village consisting of buildings constructed from adobe clay - much the same as the buildings in the nearby San Pedro. Here are some pictures from the base:

Adobe dorms - this is where the APEX staff and visitors stay. Everyone gets their own hut.
I especially loved the main offices and canteen - there is something of the Flintstones about the design of these two buildings especially. The adobe really works well in keeping the buildings cool naturally - no fans or airconditioners required. Which in over 30 degree heat is an extremely welcome feat.

The main offices and control tower, which is used to control the telescope.

The all-important canteen.
Interestingly even though it is peak summer time in the southern hemisphere at the moment the APEX telescope is actually not in full operation as it is “Bolivian winter”. It does seem counterintuitive that while the rest of the continent is in peak summer the Bolivian altiplano is experiencing winter. Apparently the weather system changes in January and February allowing wet winds to come in from the east bringing winds, rain and even snow. The enhanced moisture this brings mean radio observations aren’t possible.
Visit to the Chajnantor plain
Once we’d had a generous Chilean lunch, my very kind guide and APEX engineer, Juan, drove up to the APEX telescope. The drive was fantastic - we went past the base of the ALMA (Atacama Large Millimeter/ submillimeter Array) project, where a contingent of 60-80 telescopes are being assembled. We also saw the Gran Salar (the giant salt lake bed) and at enormous cactuses (cacti?) sprouted up out of nowhere. They only seem to grow over a small range of altitudes just over 3500m.

Chajnantor plain with a storm brewing in the background.
Finally we arrived at the Chajnantor plain - this consists of a few control buildings and one telescope for the moment. Ultimately it will be covered by about 80 telescopes - all essentially updated versions of the APEX telescope. For the moment it is rather a stunning vast empty plain surrounded by even higher peaks. You don’t appreciate how high you are because of this. The main clue is that your brain feels woolly - there are clear indications that your thought processes are a bit slow. Kind of how you feel if you haven’t slept in a really long time.
The first ALMA antennas have already been constructed and are scheduled to start operations in 2010.
Until the ALMA antennas arrive, APEX holds pride of place. APEX, the Atacama Pathfinder EXperiment, is a prototype of the antennas that will make up ALMA. So eventually this whole plain will be covered in 80 telescopes that look more or less like this.

APEX telescope & Juan.
You can see a picture of the surrounding peaks below: a few of these are actively volcanic. Indeed one of them just to the left of this picture was quietly smoking away the whole time.

On Cerro Chico - a small peak near APEX. The mountain behind me hosted a sulphur mine - hence the strange colour.
On our return I had to catch up on a massive backlog of work. Luckily it’s such a tranquil place I cleared a lot of things out of the way. I also vamped up a talk on my research that I had to give a couple of days later.
The APEX base is a great place to work. If ESO ever want to make money they could market the APEX dorms as a writers’ retreat. Quiet, beautiful, insanely sunny and with a great internet connection. What more could you want?
The following day I headed back to Santiago for a few days and into the arms of the extremely genteel ESO guesthouse. More on that anon.
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