1. National Aeronautics and Space Administration July 2015 POIWG Face-to-Face: Thruster Constraints Planning and Coordination Ben Honey ADCO Specialist Flight Operations Directorate – CM5 Johnson Space Center Public Release Statement: This document has been reviewed for Proprietary, SBU, and Export Control (ITAR/EAR) and has been determined to be nonsensitive. It has been released to the public via the NASA Scientific and Technical Information (STI) Process DAA #33751

2. This presentation is not Export Controlled, see cover for full disclosure. Purpose To explain the current state of how ADCO manages thruster constraints to the payloads community To solicit two-way communication so that ADCO is aware of all parties that are impacted by thrusters To start a dialogue with interested payload representatives, especially those ADCO may not be aware of To discuss improvements to thruster constraint planning and coordination that would benefit payload operations ADCO / Ben Honey2

3. This presentation is not Export Controlled, see cover for full disclosure. 3ADCO / Ben Honey Outline Overview of thruster constraints Overview of planning coordination Discussion of efficiency gaps Possible process improvements Solicitation of input for future work

4. This presentation is not Export Controlled, see cover for full disclosure. Helpful Jargon MCC-M = Mission Control Center Moscow LoAC = Loss of ISS Attitude Control ATL = Attitude Timeline TRTL = Thruster Reconfiguration Timeline MCS = Motion Control System FDIR = Fault Detection Isolation & Recovery; refers to software that could recover from thruster inhibit w/out manual action CMG = Control Moment Gyroscope (provides non-propulsive attitude control) LoAC recovery procedure = Warning Procedure 2.702 Loss of ISS attitude Control Desat = a small thruster firing to “desaturate” CMGs. These are thruster firings that can occur during “non-propulsive” attitude control. Are automatic and can be unexpected. Thruster inhibit required to prevent them. ADCO / Ben Honey

5. This presentation is not Export Controlled, see cover for full disclosure. Thruster Coordination Overview All thruster inhibit requests are coordinated with MCC-M flight controllers All planned thruster inhibit periods appear in ATL, TRTL, and OSTPV ADCO is aware of several ISS systems, operations, and payloads which have restrictions on thruster firings The only operations for which thruster inhibits are put in place are those with documented Flight Rules tracked by ADCO team When thrusters are inhibited, the ISS requires manual action to configure for thruster attitude control – ISS will go LoAC (free drift) before it will allow thruster firings. IE, all FDIR is inhibited. In such a contingency, all hardware and operations that require safing prior to thruster firings are checked in the LoAC recovery procedure ADCO / Ben Honey5

6. This presentation is not Export Controlled, see cover for full disclosure. Thruster Planning Overview How does ADCO coordinate with the team for a constraint period? ATL shows changes in attitude as well as mode, including thruster inhibit TRTL shows which specific thrusters on the Russian Segment would fire ADCO tries to have ATL updated with pending events at E-30 days Thruster inhibits can be added later if necessary (up to ~E-7 days) Systems constraints: US or JAXA robotics flight controllers, mechanism flight controllers, or Russian planners submit inputs for the ATL Payloads: Payloads can request thruster inhibit period via a RAC (Request Attitude Change) form per Operations Interface Procedure (OIP) 7.5.4 Note: No RAC has ever been received for a payload thruster inhibit ADCO / Ben Honey6

7. This presentation is not Export Controlled, see cover for full disclosure. Where are there gaps? ADCO must verbally inform the team (Flight, POD, Crew, etc) when thruster firing recovery is pending. Because RACs are not used, ADCO not aware who might be doing thruster restricted ops all the time. Not all thruster constraints are documented in places ADCO traditionally tracks (ie, Marangoni, SOLAR). ADCO / Ben Honey7

8. This presentation is not Export Controlled, see cover for full disclosure. Why increase communication? If planning around the flight plan has been working, why complicate operations coordination by adding ADCO? 1.To understand all impacts in event of LoAC, unplanned thruster firing, or late addition of a new flight event. 2.To add safing steps to contingency procedures. 3.To know who to inform of new types of attitude control. 4.To inform you if thrusters aren’t planned, but desats may fire. 5.ADCO is in MCC reviewing upcoming plans 24/7. We can serve as a double-check on the plan. 6.By being aware of who is planning around us, we can make our plan for the MCS more accommodating. ADCO / Ben Honey8

9. This presentation is not Export Controlled, see cover for full disclosure. Ideas to improve efficiency 1.Innovative Operations: ISS MCS can operate in a mode that reports a Caution for “CMGs Near Saturation” if thruster firings are pending in a thruster inhibit period* 2.Consolidate thruster constraint documentation: ADCO would like all known constraints to be Flight Rules, or we can start tracking existing documentation that has all payload thruster constraints 3.Communicate throughout planning process: Even if a RAC is not to be submitted, ADCO would like to know if a payload is running which would be impacted by thruster firings 4.Your idea goes here *This idea has pros and cons which require further discussion: – Would allow teams to take safing action prior to desat firing – Could reduce the risk of LoAC during thruster inhibit periods – Safing actions can be documented in a formal procedure to respond to the Caution – Other control centers can train to respond to the Caution – However, if safing can’t be performed in time a desat thruster firing would automatically occur (potentially violating thruster constraints in some cases) ADCO / Ben Honey9

10. This presentation is not Export Controlled, see cover for full disclosure. Help us focus future work We want to hear your feedback about ISS MCS and how you are impacted. For the possible new innovative operations: How would you be impacted by the new FDIR-enabled ops concept? Are there payloads/operations for which safing prior to thrusters is highly desired but not essential? Are there payloads/operations that require quick safing steps from ground or crew to be ready for thrusters (could respond to Caution)? Also, let me know: If your existing or future payload would lose science or be damaged by thruster firings If you have existing constraints but they aren’t Flight Rules If you currently “plan around” the ATL to avoid thrusters If your team has a hard time understanding ATL/OSTPV ADCO / Ben Honey10

11. This presentation is not Export Controlled, see cover for full disclosure. ADCO wants to hear from you! We are looking for input by September to move forward with any new operations or processes Contact info: – Phone: 281-244-7140 – Email: Benjamin.Honey@Nasa.govBenjamin.Honey@Nasa.gov – At JSC: Building 30A, office 2060 Also presenting “ADCO Ops Overview” at the Externals Splinter on Wednesday Also at “genius bar” after Externals Splinter ADCO / Ben Honey11

12. This presentation is not Export Controlled, see cover for full disclosure. Q&A ADCO / Ben Honey12

13. This presentation is not Export Controlled, see cover for full disclosure. Backup ADCO / Ben Honey13

14. This presentation is not Export Controlled, see cover for full disclosure. RAC description from OIP 7.5.4 ADCO / Ben Honey14 “It may be necessary for payload customers and IPs to request changes to the ISS agreed-to attitude plan. Additionally, this form should be used to request periods of microgravity. While the justification for these changes will come through the Program Office or relevant management decisions, the process for implementing these changes is documented below. The output from this procedure will flow into the Attitude Change Request (ACR) process between the MCC-H FCT and ГОГУ (OIP Volume A: NASA/Roscosmos, Section A7.5.4). Request for Attitude Change (RAC) forms should be submitted no later than 4 weeks prior to the activity if the requested attitude is outside the approved attitude envelope. This will allow time for the CHIT to be processed. If the requested attitude is within the approved attitude envelope, the RAC form should be submitted no later than 3 weeks prior to the activity.”