NASA Logo, National Aeronautics and Space Administration

What’s This? #4 – The big reveal!

In our latest entry in the What’s This? series, we posted a mysterious image and asked for people to guess what they were looking at.

So what is this tall thing in NASA Goddard’s cleanroom?

We had a lot of great guesses – a number of people guessed it was a stand of some sort. Or a Russian rocket gyro nose piece. Or the secondary mirror boom for JWST. Or a UV lamp. Or a “nose-picker.” Or where the NASA 8-ball team stores their pool cues. We even had someone ask if it was cheating if it was his budget that pays for what goes on top of it. (Yes, Scott, it is!)

But the only person to get it right (though we don’t know how much inside info they had), was Anthony Cotto, who said it was a “massive theodilite stand.”

What's This?

The full answer is that it’s a metrology tower. (Metrology, simply put, is the science of measurement.) In this case, techs put theodolites (which are precision instruments for measuring angles) on the towers and then measure positions on hardware, much like surveying, but with more emphasis on all three dimensions rather than just two. The red object nearby is another metrology tower, just shorter. Many towers are height-adjustable. With several theodolites on different towers, positions on things like science instruments and mounting points on space hardware can be measured with pretty amazing precision, down to thousandths of an inch.

Many thanks to Paul Geithner for this explanation.

And congrats to Anthony for guessing the correct answer!

Categories: What's This?


  • Anthony Cotto says:

    Alright I confess I had some inside info. I interned at GSFC in 2011 and had to move some Theodolites around and while looking into JWST clean room I noticed those mega versions of what I saw in our lab. I’m back here for the summer and having a great time! Keep up the great work on the blog and podcast!

    • Sara Mitchell says:

      Anthony – We were impressed by the accuracy of the answer, and wondered how you knew! Glad you enjoy the blog and podcast (some awesome new episodes coming out soon), drop us a line while you’re around Goddard if you’d like an in-person look at some of the astrophysics stuff going on.

NASA Logo, National Aeronautics and Space Administration