Wow, what progress can be made in a week! We have gone from unpacking to on the pump in one week- a new record for the SPIDER team. Being on the pump is a big milestone for us because pumping all of the gas out of our cryostat takes a fixed amount of time, and no amount of will power or hard work can make it go any faster. Therefore, we use up all of our will power and work ethic in the time leading up to that stage and then relax just a little bit while the pump does the work for us once we’re all closed up.
We finished buttoning Theo up and started pumping a couple hours ago, and now Ed and I are monitoring it over night. We have to be very careful with the speed at which we pump down the cryostat, since we have very thin filters that can tear if they are subject to a big pressure differential. They are kind of like thin balloons- we don’t want them to pop. So we slowly open a needle valve bit by bit until sometime early tomorrow when we’ll have only a small fraction of an atmosphere left in there. We’ll repressurize with nitrogen a few times (this, in theory, helps dislodge water molecules that adhere to the surfaces inside the cryostat) and then leak check the system.
While we twiddle our thumbs (and occasionally the needle valve), I figured I would post some pictures. First of work done over the past few days, and then of the environment here at LDB, since I have heard a request for shots of buildings. I haven’t spent a lot of time in town lately, but I’ll take pictures of those buildings soon!
Loading up a telescope, ready for insertion into the cryostat.
Telescope coming up the tube.
All inserts installed! From the back.
Sean tapes up some seams at the front of Theo. With six telescopes inserted, we’re in business!
Johanna and John inspect waveplates. These are single crystal sapphire plates that rotate the polarization of the light that enters our telescopes. By turning them, we can change which polarization of light our detectors see.
Ed spent a long day taping baffles around filter stacks. This has been a lot of the sort of work we’ve been doing in the assembly stage of the experiment.
Sasha performs delicate MLI (multi-layer insulation) configuring. We got new MLI for this run, and needed to customize it with holes and slots where feature in our system go. It was just a little bit of a reach to do all that…
You know something has gone wrong when the PI (my advisor, Bill) has his head in the cryostat. Here, he is soldering a connector that we broke during assembly.
Cynthia tapes up a baffle around the final filter stack.
VCS2 (the outermost vapor-cooled shield) is finished being installed with filter stacks.
Many layers of aluminized mylar blanket the two vapor-cooled shields to insulate them from the warmer parts on their exteriors. Here, the last of the MLI is installed. This is my favorite stage of the assembly, since it is the shiniest stage.
Bottom dome installation.
ON THE PUMP!
Ed tightens some screws on the top of the cryostat as we begin the pumpdown.
To get to and from LDB, there are a variety of vehicular options. Most mornings, we take the Cress, but I don’t have a picture of that just now. It’s basically a semi whose trailer is a big passenger compartment. It is cold and slow and I don’t like it all that much. On Sundays, when the number of people heading to LDB is drastically reduced, we take these awesome vehicles called deltas. Those are the first ones pictured below. They are nice because you can see out the windows, sit across from each other, and are reasonably fast. My most common means of transport (and also the least cool) is shuttle van, shown in the last photo. It is just a big van with big tires.
Deltas, my favorite mode of transportation.
Bill and Jon in the delta.
Ziggy and Cynthia in the delta.
Stickers in the delta.
The shuttle van, which is often what takes us home at the end of the day.
Today I walked around and took some pictures around LDB.
It was a very foggy day in the mountains. Here, a flag past which you can’t go or else risk falling in a crevasse, and a very faint Mt. Erebus.
It’s important to stay organized with this big of an experiment.
The three payload buildings. The tent on the left was just completed, and is where COSI will be assembled. ANITA has the next high bay, and we have the one to the right of that.
Rigging and telemetry buildings.
The galley is just a long arched tent, more or less.
Sunday is most people’s day off in McMurdo. This includes the LDB chef. So this Sunday, the LDB site coordinator, Dave, cooked us lunch. This was his menu.
The galley, which is packed at lunch time, but not on Sundays at dinner time.
Menus are posted on white boards. So far, the food has been fantastic.
Very soon we will know if we have managed to make our system helium leak tight. This is a very difficult thing to do, and we have failed numerous times in the past, so send some positive thoughts our way!