CII Mechanical Interface Guidelines
CII Mechanical Interface Guidelines
Randy Hein NASA CII Team
General Background The mass and envelope as identified in the Guidelines were based upon an Instrument survey for similar class missions. These parameters are still being finalized. The Mechanical Guidelines were generated with reference from General Interface Requirements Documents (GIRD) for payload development. The Mechanical Guidelines were generated with reference from interface guidelines developed on the JWST for the science payloads. The Mechanical Guidelines were generated with reference from standard observational instruments development for the science payloads.
2
Mechanical Interface Goals Minimally intrusive to spacecraft provider. The interface should allow the spacecraft provider to move out on the design process independent of the Instrument provider. The interface should allow the instrument provider to move out on the design process independent of the spacecraft provider. Implementation details should be worked out between Spacecraft and instrument once paired in an ICD.
3
Mechanical Interface Assumptions Instruments are nadir pointing Location on spacecraft would accommodate a typical rectangular volume. The mass and envelope as identified in the Guidelines were based upon an Instrument survey for similar class missions. The instrument should be designed as a self contained assembly with on board electronics and thermal control. The Spacecraft Provider is responsible for the mounting interface. The Instrument provider is responsible for, if needed, the kinematic mounting and degrees of freedom. 4
Mechanical Interface Assumptions The Spacecraft Contractor will provide shims or other mounting hardware as required to attain the required alignment accuracy. The Spacecraft Contractor will determine the location of the instrument on the spacecraft. The spacecraft bus will provide clear (i.e., no blockage) fields-ofview (FOV) that equal or exceed the Instrument science and radiators, as defined in the MICD. MICD (Mission Interface Control Document) generated once instrument and spacecraft are paired.
The spacecraft contractor will provide a model and optical properties of hardware in close proximity for instrument stray light analysis. The spacecraft contractor will be responsible for the combined structural dynamics analysis of the spacecraft bus and the instruments. The spacecraft contractor will provide the combined structural dynamics analysis results to the respective Instrument Provider.
5
LEO EOS Example Secondary payload example and possible locations.
VELOCITY NADIR
6
Mechanical Interface Drivers Parametric studies of a variety of similar class instruments drove mass guidelines Guideline payload volume was determined by engineering analysis based on mass guidelines and comparisons to spacecraft envelopes in the NASA RSDO catalog.
7
Key LEO Guidelines ID
Function
7.4a
Instrument Instrument components in the launch and on‐ Instrument survey Envelopes orbit configurations should be contained within the detailed instrument envelope of 0.7m x 0.7m x 1.0m (HxWxL) for a 200kg (max) instrument or 0.5m x 0.5m x 0.73m for a 75kg instrument.
7.5a
Instrument The Instrument mass should be less than or Mass equal to 200 kg.
Instrument survey
7.7a
Instrument The Instrument should be mounted to the Mounting Spacecraft via 4 point semi‐kinematic mount unless the Instrument Provider demonstrates that kinematic mounts are not required.
To prevent perturbation between instrument and spacecraft
7.7b
Guidelines
Rationale/ Comment
The method by which the instrument is mounted to the spacecraft should be as defined in the MICD. 8
Guideline Envelope
75kg Interface
200kg Interface 9
Mounting Plate (200kg or 75kg Instrument)
10
CII Volume (and mass) Comparisons
CII Volume (and mass) Comparisons
12
Key LEO Guidelines
ID
Function
Guidelines
Rationale/ Comment
7.11a
Access, Handling, & Servicing Accessibility
The Instrument should be capable of being installed/removed in it's launch configuration without disturbing the primary payload.
To prevent damage or misalignment of primary instrument
7.12c
Test Points & Instrument mechanisms, thermal control, Test or any exclusions to testing and operations Guidelines related to orientations should be documented in MICD.
13
Key LEO Guidelines
ID
Function
Guidelines
7.17a
Mechanisms
Instrument mechanisms that require restraint during launch should be caged during launch without requiring power to maintain the caged condition.
7.18
Captive Hardware
All items planned to be installed, removed, or replaced during integration should use captive hardware except Instrument mounting hardware and MLI.
Rationale/ Comment
Safety to Instrument and spacecraft
14
Key LEO Guidelines ID
Function
Guidelines
Rationale/ Comment
7.19a
Structural Characteristics
Minimum Fixed‐Base Frequency ‐ mass of less than 200 Kg
Instrument survey
The instrument component with a mass of less than 200 Kg, configured for launch, should have a fixed‐base frequency of > 50 Hz TBR. Fixed‐based is defined as follows: Each mounting point should be constrained in those degrees of freedom which are rigidly attached to the Spacecraft, and should be free in those degrees of freedom for which kinematic mounts or flexures provide flexibility.
15
Key LEO Guidelines ID
Function
Guidelines
Rationale/ Comment
7.19c
Design Limit Loads
The design limit loads should be multiplied by a factor of 1.4 to obtain the ultimate design loads, and by 1.25 to obtain the yield design loads for a tested interface.
NASA‐STD‐ 5001
7.20b
Handling Fixtures
Handling and lifting fixtures should be designed Safety to the to 5 times limit load for ultimate and 3 times limit instrument load for yield. Handling fixtures should be tested to 2 times working load.
7.21d
Interface Alignment Cube (IAC) & Alignment Parameters
The Instrument Provider is responsible for measuring the alignment angles between the IAC and the Instrument boresight and it should be documented in the MICD.
16
Key Deltas to Guidelines for GEO There are currently no listed deltas to the mechanical guidelines for GEO. The CII team would prefer to define Mechanical Guidelines for GEO based upon input from all of our potential hosts…
17
Responses to CII Workshop 1 Input The following changes were made to the mechanical guidelines based upon the feedback received from the CII Workshop 1: ID 7.4a was revised to show two mass categories (200kg and 75kg), including corresponding volume envelopes. Values were added for constant torque limits (7.19f) and allowable angular momentum (7.19g). ID 7.7a was revised to include non-kinematic mounts
18
Randy Hein NASA CII Team
General Background The mass and envelope as identified in the Guidelines were based upon an Instrument survey for similar class missions. These parameters are still being finalized. The Mechanical Guidelines were generated with reference from General Interface Requirements Documents (GIRD) for payload development. The Mechanical Guidelines were generated with reference from interface guidelines developed on the JWST for the science payloads. The Mechanical Guidelines were generated with reference from standard observational instruments development for the science payloads.
2
Mechanical Interface Goals Minimally intrusive to spacecraft provider. The interface should allow the spacecraft provider to move out on the design process independent of the Instrument provider. The interface should allow the instrument provider to move out on the design process independent of the spacecraft provider. Implementation details should be worked out between Spacecraft and instrument once paired in an ICD.
3
Mechanical Interface Assumptions Instruments are nadir pointing Location on spacecraft would accommodate a typical rectangular volume. The mass and envelope as identified in the Guidelines were based upon an Instrument survey for similar class missions. The instrument should be designed as a self contained assembly with on board electronics and thermal control. The Spacecraft Provider is responsible for the mounting interface. The Instrument provider is responsible for, if needed, the kinematic mounting and degrees of freedom. 4
Mechanical Interface Assumptions The Spacecraft Contractor will provide shims or other mounting hardware as required to attain the required alignment accuracy. The Spacecraft Contractor will determine the location of the instrument on the spacecraft. The spacecraft bus will provide clear (i.e., no blockage) fields-ofview (FOV) that equal or exceed the Instrument science and radiators, as defined in the MICD. MICD (Mission Interface Control Document) generated once instrument and spacecraft are paired.
The spacecraft contractor will provide a model and optical properties of hardware in close proximity for instrument stray light analysis. The spacecraft contractor will be responsible for the combined structural dynamics analysis of the spacecraft bus and the instruments. The spacecraft contractor will provide the combined structural dynamics analysis results to the respective Instrument Provider.
5
LEO EOS Example Secondary payload example and possible locations.
VELOCITY NADIR
6
Mechanical Interface Drivers Parametric studies of a variety of similar class instruments drove mass guidelines Guideline payload volume was determined by engineering analysis based on mass guidelines and comparisons to spacecraft envelopes in the NASA RSDO catalog.
7
Key LEO Guidelines ID
Function
7.4a
Instrument Instrument components in the launch and on‐ Instrument survey Envelopes orbit configurations should be contained within the detailed instrument envelope of 0.7m x 0.7m x 1.0m (HxWxL) for a 200kg (max) instrument or 0.5m x 0.5m x 0.73m for a 75kg instrument.
7.5a
Instrument The Instrument mass should be less than or Mass equal to 200 kg.
Instrument survey
7.7a
Instrument The Instrument should be mounted to the Mounting Spacecraft via 4 point semi‐kinematic mount unless the Instrument Provider demonstrates that kinematic mounts are not required.
To prevent perturbation between instrument and spacecraft
7.7b
Guidelines
Rationale/ Comment
The method by which the instrument is mounted to the spacecraft should be as defined in the MICD. 8
Guideline Envelope
75kg Interface
200kg Interface 9
Mounting Plate (200kg or 75kg Instrument)
10
CII Volume (and mass) Comparisons
CII Volume (and mass) Comparisons
12
Key LEO Guidelines
ID
Function
Guidelines
Rationale/ Comment
7.11a
Access, Handling, & Servicing Accessibility
The Instrument should be capable of being installed/removed in it's launch configuration without disturbing the primary payload.
To prevent damage or misalignment of primary instrument
7.12c
Test Points & Instrument mechanisms, thermal control, Test or any exclusions to testing and operations Guidelines related to orientations should be documented in MICD.
13
Key LEO Guidelines
ID
Function
Guidelines
7.17a
Mechanisms
Instrument mechanisms that require restraint during launch should be caged during launch without requiring power to maintain the caged condition.
7.18
Captive Hardware
All items planned to be installed, removed, or replaced during integration should use captive hardware except Instrument mounting hardware and MLI.
Rationale/ Comment
Safety to Instrument and spacecraft
14
Key LEO Guidelines ID
Function
Guidelines
Rationale/ Comment
7.19a
Structural Characteristics
Minimum Fixed‐Base Frequency ‐ mass of less than 200 Kg
Instrument survey
The instrument component with a mass of less than 200 Kg, configured for launch, should have a fixed‐base frequency of > 50 Hz TBR. Fixed‐based is defined as follows: Each mounting point should be constrained in those degrees of freedom which are rigidly attached to the Spacecraft, and should be free in those degrees of freedom for which kinematic mounts or flexures provide flexibility.
15
Key LEO Guidelines ID
Function
Guidelines
Rationale/ Comment
7.19c
Design Limit Loads
The design limit loads should be multiplied by a factor of 1.4 to obtain the ultimate design loads, and by 1.25 to obtain the yield design loads for a tested interface.
NASA‐STD‐ 5001
7.20b
Handling Fixtures
Handling and lifting fixtures should be designed Safety to the to 5 times limit load for ultimate and 3 times limit instrument load for yield. Handling fixtures should be tested to 2 times working load.
7.21d
Interface Alignment Cube (IAC) & Alignment Parameters
The Instrument Provider is responsible for measuring the alignment angles between the IAC and the Instrument boresight and it should be documented in the MICD.
16
Key Deltas to Guidelines for GEO There are currently no listed deltas to the mechanical guidelines for GEO. The CII team would prefer to define Mechanical Guidelines for GEO based upon input from all of our potential hosts…
17
Responses to CII Workshop 1 Input The following changes were made to the mechanical guidelines based upon the feedback received from the CII Workshop 1: ID 7.4a was revised to show two mass categories (200kg and 75kg), including corresponding volume envelopes. Values were added for constant torque limits (7.19f) and allowable angular momentum (7.19g). ID 7.7a was revised to include non-kinematic mounts
18
