A few days ago, Neil and I went for an adventure out to the Martin A. Pomerantz Observatory, or MAPO as everyone here knows it. MAPO contains the Keck Array telescopes (formerly known as SPUD, which is how most folks here know the telescope) and support gear, and our machine shop.
MAPO is located in the “dark sector”, which is an area near station devoted to various telescope-type experiments (including IceCube). The dark sector is on the opposite side of our skiway from the main station, so we have to be careful to avoid airplanes when going between here and there. To help with that, the “crossing beacon” – red lights on posts – is lit up when a plane is landing or taking off. We had to wait a few minutes behind the sign, while a Herc took off for McMurdo, so I got a photo!
The Keck Array is designed to look at the cosmic microwave background. Essentially, it’s a telescope designed to look at the early stages of our universe, and verify some predictions about the big bang. This summer, the telescope is getting a couple upgrades, which require it to be taken apart and put back together. I thought it would be neat to see the insides of a telescope, and ended up getting to help take one of the cryostats apart!
Working on a telescope array like this one is an interesting process – the sensors in each of the 5 cryostats (a sciency way to say super-refrigerator) are cooled to about half a degree Kelvin. To get the sensors that cold, cryostats are nested affairs, with an insulating vacuum between them. Practically speaking, that means lots of screws are involved in taking apart the telecopes, and the folks working on it didn’t mind a hand with unscrewing some of them.
Some of the other folks working on here are dealing with the machines that cool down the cryostats – dealing with pumps and shiny braided hoses. The cryogenics equipment makes some really bizarre sciency noises. The sounds are caused mostly by fluid whooshing through the inside of these hoses, which are shaped like a vacuum cleaner hose (or one of those kids toys that I can’t remember the name of) on the inside.
The five Keck Array telescopes are refractor telescopes, and it turns out that plastic makes very good lenses for their purposes.