presents this overview of the Flight Dynamics Officer.

The Flight Dynamics Officer (FDO, pronounced "fido") is responsible for the overall trajectory, or flight path, of the Space Shuttle and all related payloads or other space-bound vehicles associated with the Shuttle.

The FDO is a Mission Control Center Flight Control position at NASA's Johnson Space Center. There, along with other talented and dedicated individuals, the FDO ensures that the "big picture" mission objectives are obtained.

If you have any questions about anything presented here, feel free to contact me.



There are several distinct phases of a Space Shuttle mission, specifically Ascent, Orbit, and Entry. Each one of those phases has a specific FDO specialization and certification level associated.

What's "The Trench"?

"We call the first row in the control center 'The Trench.' There's a debate about how it really got its name but it's the lowest row of consoles in the control center and we called it 'the first line of defense in manned space flight.'

We were the guys in the trench: the Retrofire Officer, the Flight Dynamics Officer and the Guidance Officer. We were the ground pilots, if you will, who tracked the spacecraft, calculated the maneuvers and told the astronauts what time to burn, what maneuvers to do and where to go. So, we were a proud bunch."

Jerry Bostick
Flight Dynamics Branch
1965-1973

The Ascent FDO

During the most exciting 8.5 minutes imaginable, the Ascent FDO makes decisions that are literally life-and-death.

In the hours leading up to any Shuttle launch, the Ascent FDO is a study in preparation for things he hopes never happens. Planning for all possible contingencies and aborts, the Ascent FDO is ready for a variety of failures that could lead to anything from a slightly lower final orbit to a complete Return To Launch Site (RTLS).

These aborts, from the RTLS to a Trans-oceanic Abort Landing (TAL) somewhere in Europe or Africa, are planned, simulated, reviewed, and simulated again, until both the flight crew and the Mission Control team know them backwards and forwards. Then, on launch day, they hope to never put into practice that for which they've all spent so many stressful hours preparing.

As the Shuttle stack clears the launch tower, the Ascent FDO is monitoring the trajectory, as other MCC positions monitor the physical systems that provide the thrust required to take this massive vehicle stack from a standstill at the Kennedy Space Center to orbiting the Earth faster than a bullet shot from a gun.

If all goes well, the FDO provides well-rehearsed calls that the CAPCOM relays to the crew, letting them know when certain "performance gates" have been passed. Each of these discrete points in the trajectory represent a particular "abort capability"

You've heard the calls "Negative Return" (meaning the Shuttle can no longer perform an RTLS back to KSC), "Single Engine Press 104", "Press to MECO", and other fairly cryptic phrases during a launch. Each of those originate from the Ascent FDO!

The Orbit FDO

In some of the simplest terms, the Orbit FDO determines where the shuttle is, where it is going, and where it has been.

With the trajectory defined, the FDO also generates, executes, and confirms all translational maneuvers (maneuvers that change the orbit size) to meet specific payload requirements. Once these maneuvers are defined, the FDO is responsible for determining landing opportunities and just as important, evaluate the weather conditions at landing sites around the world. Further, the FDO coordinates with the United Space Space Command at the Cheyenne Mountain Air Force Station in Colorado Springs to determine if orbital debris poses a threat to the shuttle. Other real time activities that the FDO performs include providing shuttle sighting opportunities (which you can view on the shuttle web site) and state vector postings for a variety of satellites (including Mir) so other people can plot the shuttle ground track on home computers.

I have provided the contents of a presentation that was given by the Orbit Flight Dynamics Officers whenever the question "What is a FDO?" is asked. There is quite a bit of detail in this pitch, and I have purposely left it in its original wording.

I will be updating this and the other sections soon, but in the meantime, you can see the "old version" at this link. Please use your browser's "back" button to return to -THE TRENCH-!!


The Entry FDO

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