Friday, July 8, 2011

Always an Attitude Analyst: Shuttle Musings from Columbia to Atlantis

Launch of Columbia on April 12, 1981
When Columbia lifted off on the first shuttle mission on April 12, 1981, I was still at the start of my career as an attitude analyst.  It is a title that I am proud of to this day.

Many following these notes know exactly what I am talking about, as some of them were working side-by-side with me even then.  Straight out of graduate school in 1978 with an MS in astronomy and a specialization in celestial mechanics and astrometry, I needed a job.  A friend showed me a full-page ad in the Washington Post for a company called Computer Sciences Corporation (CSC) in Silver Spring, MD, that was looking for people with physics and astronomy backgrounds who happened to know a bit about programming.

I soon found myself in the Attitude Systems Department, home in those days to the legendary Malcolm Shuster, working on the fine attitude system for a scientific spacecraft called Magsat.  We wrote the entire ground system, which we lovingly called Magfine, on computer cards in Fortran 77 to be run on a big IBM 360-95 mainframe.  We spent many long hours in Bldg. 3/14 at Goddard Space Flight Center (GSFC) preparing for launch and then actual mission operations.  Magsat was launched on October 29, 1979, which, as we liked to point out, was the 50th anniversary of the 1929 stock market crash.  Magsat, the first NASA mission I worked on, will always stand out as an early highlight of my career.  It was a resounding success for all who worked on it, both scientists and engineers.

Pitch, Roll, and Yaw
Oh yes, I still haven't explained what I mean by "attitude."  Well, it's simply the orientation of a spacecraft in three dimensional space.  That orientation can be described in many ways.  One common way is to use three angles:  pitch, roll, and yaw that define the spacecraft's orientation relative to reference axes.   Another way is by matrices.  Yet another -- the one that is most frequently used in spacecraft operations -- is via quaternions.  "What in the world is a quaternion," you ask?  Simply put, it's four numbers that define a pointing vector (eigenvector) and a rotation angle about that vector.  A quaternion accomplishes in four numbers what a matrix accomplishes in nine.  It's a nifty formulation that was first developed by Hamilton in the 19th century.  Quaternions fell into disuse, but they were rediscovered in the early days of the space program when, given the limited memory of early computers, a compact form of defining a spacecraft's orientation was needed.

If you still wonder why one would care about attitude, just think of those wonderful photos from Hubble Space Telescope (HST).  Without a way of defining attitude, controlling it, and moving from one orientation to another via attitude slews, there would be no photos.

Working in attitude does have its amusing side.  At GSFC in the late 1970s and early 1980s we had an office called Attitude Operations.  If the phone rang in that office, we picked it up and said, simply, "Attitude."  I often wondered what a caller who reached that number in error would think.  Also, we had a large, sharpened stick mounted to the wall that we said was the fall-back attitude determination method if all computer systems failed.  We would also joke that we "spoke quaternion."

By the time Space Shuttle Columbia lifted off in April 1981, I was on to other missions such as Solar Max and a couple of GOES weather satellites.  We had finally graduated from computer cards to TSO (time sharing) terminals.  I remember setting the alarm for early that April 12 to make sure my spouse-to-be and I would be able to watch it on our little portable TV.

So much of the rest of my CSC career centered around shuttle launches.  I never worked on the shuttle program itself, but I came to work on HST in the mid-1980s and rarely left that project until I finally left CSC in 2004.  HST was launched on April 25. 1990, on Shuttle Discovery.

Coincidentally, it was shortly after HST launch in 1990 that I tried to talk openly about being transgender for the first time in my life.  For my efforts, I spent a week in a psychiatric ward, was placed on antidepressants, and was released back to home and work as though nothing had ever happened.  I went back into the closet for another twenty years.

Fixed Head Star Tracker
Then there were the HST servicing missions in 1993 (Endeavor), 1997 (Discovery), 1999 (Discovery), and 2002 (Columbia).  Through all those years I continued as an attitude analyst, having all sorts of fun with Fixed Head Star Trackers (FHSTs), gyroscopes, star catalogs, and pointing control algorithms for high gain antennas.  And it really **was** fun.  I will always look back on those years as the must fun, wonderful work years of my life.  Living and working overseas for State has been wonderful, but nothing will ever compare with a launch, mission operations, and solving problems when a satellite doesn't function the way it is supposed to.

My love of the night sky, astronomy, and the space program goes all the way back to the early 1960s.  I remember living every minute of those early Mercury flights, marveling at the stars and the very idea of space.  It is hard to say, in fact, which came first in my consciousness, my love of space or my sense that something was very wrong with me in the gender department.  They existed in parallel, and for decades to come I would throw myself into the one because I could not even bring myself to speak of the other.

Space Shuttle Atlantis
With the launch of Space Shuttle Atlantis scheduled for today, July 8, 2011, it is appropriate to note the passing of an era.  I mean that both for human exploration of space and for myself personally.  For me, the first and last shuttle launches are the bookends for a marriage that endured but failed.  As we move forward beyond July 8, 2011, I seem to be moving into the most free, honest expression of a life that for 50+ years I had to keep in the shadows.  I wonder what direction my life will take?  What direction will we all take?

According to the liftoff clock, just 4 hours and 17 minutes remain until launch.  I will be sitting glued to the screen just as I was glued to the TV for the launch of John Glenn in 1962.  I expect many of you will be as well.

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