Anything that leaves the Orbiter gets the FDO’s attention!
- Upper Stage-assisted satellites (Inertial and Spin-stabilized)
- RMS-deployed spacecraft
- GAS can deployables or other “mini-ejectables”
- “Inadvertent” releases (i.e., EVA tools, non-stowable HST solar arrays, etc.)
The additional nominal and contingency coordination, planning, and operations for Upper Stage deployments required extra training and the Deploy FDO certification.
The FDO maintains an ephemeris of all deployed spacecraft for relative motion monitoring and for predicting tracking coverage in the post-deploy timeframe. This was useful during separation maneuvers for safety concerns (both orbital recontact as well as positioning the Orbiter at a safe stand-off distance prior to and during the upper stage ignition).
Inertial Upper Stage (IUS)
The CSTC (IUS – Sunnyvale) performs a Gamma-Guidance simulation and supplies the FDO with the deploy time.
Transfer Orbit Stage (TOS)
The TOS POCC (at KSC) performs a TOS guidance simulation and supplies the FDO with SRM TIG, from which the FDO computes the deploy time.
In both cases, the FDO is responsible for state vector maintenance, transfer of specified trajectory information to the customer, and separation maneuver computations, including the Deploy and SEP PADs.
Payload Assist Module Deployment (PAM-D)
Deployed with the spin axis coincident with the Orbiter -Z axis
Syncom (or “frisbee”-type)
Deployed with spin axis coincident with Orbiter +X axis
The FDO is responsible for computing the deploy time and separation maneuvers.
Typically, two sets of deploy computations are performed:
- The preliminary computations are made early in the deploy timeline and are reviewed by the customer.
- The final computations are made based on updated target information supplied by the customer to the FDO from the preliminary computations.
Typically, the deploy time is specified by some trajectory event such as orbital noon to allow proper crew viewing of the payload or by payload pointing, communication, or sunlight requirements.
The FDO is responsible for computing deploy time, separation maneuvers, and, if applicable, station-keeping and rendezvous maneuvers.
GAS-can ejectables or other “mini-satellites”
The FDO computes deploy time and monitors post-deploy relative motion
Inadvertent release… or “oops!”
The FDO helps recommend best course of action for object retrieval or collision avoidance maneuver
Upper stage deploys:
All upper stage deploys require a “final” separation maneuver that places the Orbiter “above and behind” the upper stage prior to SRM ignition.
In addition, IUS and TOS deploys also require a “backaway” separation maneuver to insure adequate clearance prior to the final separation maneuver.
The magnitude of the final separation maneuver is selected to protect for Orbiter tile erosion and payload explosion limits.
The typical separation provides a small backaway maneuver (0.5 to 1.0 FPS) followed by a 0.5-3.0 FPS in-plane maneuver.
The exact separation profile will also depend on the payload requirements (e.g., whether the payload will be retrieved later, etc.).
Generic Separation Maneuver (aka 1-2-3 SEP):
Pg. 11-2 Orbit Ops Checklist contains the crew procedures.
Sep sequence consists of a 1 FPS backaway maneuver followed 2 minutes later by a 2 FPS out-of-plane maneuver. A final 3 FPS posigrade maneuver is executed 15 minutes after the out-of-plane maneuver.