Science in the Middle

doing 6th grade science – outside the box!

The VIP Instrument Lab Tour

on September 21, 2015

The almost windowless NASA building we drove to everyday is known as “703” and its contents and people riveted me daily, whether we were flying or not. We were happy to learn that it had a little gift shop! We would proudly wear and spread joy to our loved ones back home with the SOFIA logo! I purchased a polo shirt, a couple of mugs, some patches and stickers. Being able to wear the SOFIA shirt (and NASA jacket!) will hopefully invite questions that I will be thrilled to answer!

Zaheer with Jeff, Mike, Susan, and April with the GREAT instrument.

Zaheer with Jeff, Mike, Susan, and April with the GREAT instrument.

Zaheer Ali gave us a tour of the instrument lab and MCF (mirror coating facility). SOFIA uses 7 different instruments of which the FORCAST is only one.  The telescope mirror is used for all. The lab has sticky mats at all entrances to get any dust or debris which could get airborne off of our shoes. One door even had an electric rolling brush machine which you had to put your feet into! The mirror is made of specially ground glass and has a super thin coating of aluminum, about 150 nanometers thick. 

Compare that to the aluminum foil in your kitchen – which is about 0.5 millimeters thick! The mirror is about 100 inches in diameter and it must be completely uniform in its aluminum leaf coat. The process of coating the mirror involves a detailed chemical evaporative process in a special chamber.  The reflective coat should last about 5 years but has lasted longer. It would put the telescope out of operation for about six weeks if it needed to be recoated or replaced.

The giant mirror coating chamber

The giant mirror coating chamber

I'm looking into the coating chamber!

I’m looking into the coating chamber!

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A cryogenic tank must use specially designed and layered hoses as the ultra-low temps would rupture conventional connectors.

I was especially interested in the cryogenics.  This is a branch of low temperature physics. When I say low, I mean REALLY low – almost the point at which all molecular movement ceases! The telescope must be cooled to a very low temp, otherwise the heat given off “pollutes” the faint radiation data given off by the target space objects. The cooling is done in two stages.

First, liquid nitrogen cools the outer shell to 77 Kelvins*  This is way colder than even dry ice!  However, it is not cold enough!  The instruments are operating in the stratosphere where the temp is about -50 degrees F. Liquid Helium is used to further cool the assembly to 4.2 Kelvins. One reason Helium is not used for the full range of cooling is that it is much more expensive than liquid Nitrogen and evaporates more easily. *Kelvins

With the FiFI instrument, German scientists were working on it and explained its workings to us. SOFIA is in partnership with DSI, Deutche SOFIA Institute, and we learned that some would be on board to calibrate and  test the instrument.

German scientists at work with FIFI

German scientists at work with FIFI

That evening, before dinner, we went to a spot by the side of the road to watch SOFIA take off from the ground.  Since every schedule is precise to the minute, we could plan on being there for take off and not waste a lot of time waiting and watching. 

Coral Clark of USRA, our enthusiastic and tireless escort this week, is with me at SOFIA's takeoff, just barely seen under my left ear!

Coral Clark of USRA, our enthusiastic and tireless escort this week, is with me at SOFIA’s takeoff, just barely seen under my left ear! Photo credit: Coral Clark

At the appointed moment, she started moving down the runway and we all waved, shouted, and tried to take selfies with the plane in the air over our shoulder. Off for another scientific voyage without us, but we would be on board the next evening.

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Photo credit: Coral Clark

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Photo credit: Coral Clark

Off we went to Lancaster, home of the Aerospace Walk of Honor, which we would check out on our way to dinner at BEX.

If you’re interested, here is a quick clip on how big a nanometer is!

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