ICD

The following drawing set shows the critical dimensions of LISSA with respect to the ISISPACE dispenser. Please refer to ISIS Advised Envelope, 6-Unit CubeSat Dimensions, ISIS.STS.0.1.006 Rev D.

The structure is designed to contact the dispenser on the +/-Z faces of the CubeSat through the CubeSat feet. Separation switches are position through the -Z face of the CubeSat through the CubeSat feet. More information can be found in the Separation Switch Section.

Sufficient clearance exists in order for there to be a minimum of 6 mm along the X and Y axis on the CubeSat corner rails to contact the ISISPACE dispenser. A minimum of 0.3-0.4 mm of clearance is possible if the corner rails (link) and main crossbar hinges (link) are manufactured according to the tolerances specified in the drawings. Note the centre rails have a nominal 1 mm clearance measured from the top of the corner rails at both ends (+/-Z).

LI Bus - Payload Interface

The following information specifies how the payload developed by Bornea Dynamics Limited interfaces with LI Bus to form LISSA.

LI Bus - Payload Connection Points

The following drawing set defines the connection points required on the payload in order to integrate with LI Bus. Additionally, a tolerance analysis is performed in order to verify that the payload can integrate with LI Bus. The payload developed by Bornea Dynamics Limited connects to LI Bus via socket head screws and helicoils installed within the shell of the payload structure.

Harnessing Interface

Harnessing cutouts required to interface with LI-Bus is shown below.

Tolerance Analysis

CDR RID UPDATE (2025): As per Bornea, all dimensions on the payload structure have a tolerance of +/- 0.1 mm. Appropriate tolerances are now incorporated into the corner rails which interface with the SWIR payload.

Stray Light Analysis

CDR RID UPDATE (2025): The LI-Bus structure lead and Bornea are looking into stray light and the rail geometry. (Last Updated: 2025-01-30)

LISSA - Assembly

The following assembly procedure shows how the entire LISSA nanosatellite can be assembled with each module (payload included) independent from each other. Each module can be worked on independently and then connected to the rails as the final step. Thus, the current satellite structure facilitates concurrent testing and assembly of all of the modules (including the payload). For detailed assembly procedures specific to each module and for the deployable wings refer to the following links:

ADCS-CDH Module (link)
POW-COM Module (link)
Reaction Wheel Module (link)
Thruster Module (link)
Deployables (link)

Note all structural components are to be electrically bonded per SSP 30245. Note that proper torque specifications shall be used when installing any fasteners.

Key components not captured in the module assembly drawings are summarized below:

UMS-0761: Retroreflector (link)
UMS-0793: S-Band Patch Antenna

CDR RID UPDATE (2025): Concerning stainless-steel to aluminum interfaces: There are no stainless-steel to aluminum pressurized interfaces between thruster components. The stainless-steel to aluminum interfaces in our design are limited to mounting points and fasteners. Considering the satellite's mission lifetime and operating temperature range, we do not anticipate any issues with galvanic corrosion.

CDR UPDATE NOTE: S-Band Antennas are now being procured from EnduroSat. Procurement is currently in progress (2025-01-30). The relative location will be the same as shown in the drawing below. Please refer to ITEM NO. 18.

LISSA - Reflective Surface

The drawing below outlines the proposed polished aluminum surface used for specular reflection.

Blank Shells

The following drawing set is dedicated to the 1/2U modular structural shells (UMS-0585 Blank Structural Shell). Drawings related to shells specific to a single module can be found below in subsequent sections. All module specific shells are modified based off of the blank structural shells, and therefore, the overall structure as a whole accommodates bulk ordering of structural components. Please note that the following drawings under this section and the associated CAD model should be referenced when designing any avionics boards that mount using the standoff tabs located within the shell. No components should be placed within the standoff tabs areas.

Note that the blank structural shell has wall thicknesses of 2 mm (along the side walls), 5 mm (along the bottom base), and 12 mm (at the internal standoff locations). Nominally the thickness of the blank structural shells and module specific shells exceed 2 mm. For more information please refer to the module specific structural shell drawings.

UMS-0585: Blank Structural Shell

UMS-0585: Avionics Board Clearance Areas

Corner Rails

The following drawing set is dedicated to corner rails (UMS-0598 Corner Rail 1, UMS-0599 Corner Rail 2, UMS-0662 Corner Rail 3, UMS-0663 Corner Rail 4).

UMS-0598: Corner Rail 1

UMS-0599 : Corner Rail 2

UMS-0662: Corner Rail 3

UMS-0663 : Corner Rail 4

Centre Rails

The following drawing set is dedicated to centre rails (UMS-0597 Centre Rail 1, UMS-0610 Centre Rail 2).

UMS-0597: Centre Rail 1

UMS-0610: Centre Rail 2

ADCS-CDH Module

The following drawings outline the assembly procedure for UMS-0719 ADCS-CDH Module). Key components within this module are summarized below:

UMS-0586: CDH CCA
UMS-0641: ADCS CCA
UMS-0626: Star Tracker
UMS-0053: Torque Rods
UMS-0596: S-Band Transceiver
UMS-0099: Separation Switch (X1)
UMS-0766: Burnwire Hold and Release Mechanism

UMS-0719: ADCS-CDH Module Assembly

UMS-0701: S-Band TMTC & Star Tracker Adapter

The S-Band TMTC and Star Tracker Adapter (UMS-0701) is used to mount the EnduroSat S-band transceiver and Rocket Lab star tracker. This adapter connects to the side faces of the module shell through helicoils.

Magnetorquers (Torque Rods)

UMS-0754 - Torque Rod Core

POW-COM Module

The following drawings outline the assembly procedure for UMS-0718 POW-COM Module). Key components within this module are summarized below:

UMS-0587: POWER CCA
UMS-0750: COMS CCA
UMS-0036 & UMS-0023: Battery Cells and Saddle (Note there is an updated saddle design documented here (link)).
UMS-0651: GNSS Antenna
UMS-0632: GNSS Receiver
UMS-0099: Separation Switch (X1)
UMS-0770: S-Band Hybrid Coupler

UMS-0718: POW-COM Module Assembly

Reaction Wheel Module

The following drawings outline the assembly procedure for UMS-0720 Reaction Wheel Module). Key components within this module are summarized below:

UMS-0630: Reaction Wheel Cluster
UMS-0660: Thruster CCA
UMS-0775: Remove Before Flight (RBF) Switch
UMS-0381: Sun Sensors
Note: That a charging port can also be placed on the top of UMS-0670 as per the drawing "LI-BUS Potential Charging Connector Location" (Drawn: 2024-08-29).

UMS-0720: Reaction Wheel Module Assembly

UMS-0775: Remove Before Flight RBF

UMS-0381: Sun Sensor

Thruster Module

The following drawings outline the assembly procedure for UMS-0772 Thruster Module). Key components within this module are summarized below:

UMS-0656: Thruster Fuel Tank
UMS-0743: Pressure Transducer
UMS-0657: Fill Valve
UMS-0658: Solenoid Valve
UMS-0659: Thruster Nozzle

UMS-0772: Thruster Module Assembly

Thruster Nozzle Orientation

The following drawing outlines the position of the thruster nozzle (UMS-0659) with respect to the entire LISSA structure. The nozzle is orientated away from both the general bus structure. The nozzle also points in a direction away from the payload FOV and the star tracker FOV.

In the open configuration (solar wings deployed) the moment arm between the center of mass of the satellite and the thruster nozzle is approximately 4.2 mm.

UMS-0099 - Separation Switches

The separation switches activate the satellite when the deployer is no longer in contact with the CubeSat feet. The separation switches in LISSA are implemented through each of the four corner rail feet. The ADCS-CDH module (link) contains a single separation switch. The POW-COM module (link) also contains a single separation switch. The separation switches are placed in different modules in order to satisfy the requirement specifying that the switches must be triggered thorugh the CubeSat feet.

The selected springs are from McMaster-Carr (2006N183 - 302 Stainless Steel Compression Springs). The selected springs (UMS-0752) have a maximum load of 0.22 lbs (0.978 N). Additionally, the springs have an uncompressed length of 8.2 mm and a compressed length of 2.2 mm. At maximum compression, the traveled length is 6 mm which exceeds the minimum recommended travel from the pressed configuration to the released (switching) configuration according to the ISISPACE documentation (which is 5 mm).

Note that the following separation switch has been adapted from the IRIS CubeSat mission. Modifications made to the separation switch are to allow the asembly to be connected directly to the module shells instead of the battery saddle. Additional changes were made to adjust the amount of force exerted by the springs due to the overall dimensional changes made from changing the mounting location (to the module shells) method.

UMS-0099: Separation Switch Assembly

UMS-0098 - Separation Switch Alignment Bracket

UMS-0751 - Separation Switch Shim

UMS-0100 - Separation Switch Shim

Retroreflector

A custom retroreflector based off the THORLABS mounted retroreflector is proposed to be developed and integrated into the LISSA structure. An existing optic (either THORLABS PS974-C or THORLABS PS977-M01) will be selected based on requirements R-LIB-STR-026 and R-LIB-STR-028 and other additional requirements to be determined based on performance. The current THORLABS retroreflector mounts contain O-rings which are not suitable for space. The plan is design a similar optic mount which contains materials compatible with R-LIB-STR-026 and R-LIB-STR-028.

CDR RID UPDATE (2025): The THORLABS retroreflectors cover SWIR band.

3U Solar Panels

3U Solar Panel Board 1

3U Solar Panel Board 2

Deployables

There are two deployable 6U wings (UMS-0716 & UMS-0717) planned to be incorporated on LISSA. The previous version of LISSA presented at PDR had a small 1U deployable array located at the top of satellite. This smaller 1U deployable array has since been removed after revaluating the relative risk of improper deployment versus power gain from having an extra two solar cells.

The proposed hold and release mechanism strategy is adapted and modified from the previous IRIS mission. Spring loaded hinges (UMS-0191) are used to open the two solar wings (UMS-0716 & UMS-0717) to their deployed state. Both wings are held in place by a burnwire hold and release mechanism that is mounted on the ADCS-CDH module (link).

Solar Wing Assembly

The drawing below outlines how the solar wing and spring loaded hinges are installed on LISSA. Two corner rails on the opposite end of the payload are designed to allow solar wings to be installed after the primary satellite structure has been assembled. For more information please refer to the LISSA assembly drawings (link).

Spring Loaded Hinge Assembly

The drawing below illustrates how the spring loaded hinges are assembled. At the receiving end of (6) are rivet nuts installed on the module shells that allow the spring loaded hinges and solar wings to be installed as one of the last steps during the entire LISSA assembly procedure. Two changes were made from the final model used in the IRIS mission. First, the main crossbar was modified to accommodate M3 screws. Second, solar wing hinge (7) allows for the main body of the solar wing to be installed independently of the spring loaded hinge mechanism.

Solar Wing Frame and Board

The following set of drawings are for the 6U solar wing frame. The solar wing frame was designed to maximize the amount of solar cells that could be fit on the accompanying 6U solar wing PCB (UMS-0628). Additionally, the design of the solar wing frame accommodates several different components that either are mounted on or protruding out of the exterior surface of the satellite such as the S-band patch antennas (UMS-0793), thruster fill valve port (UMS-0657), thruster nozzle (UMS-0659), retroreflector (UMS-0761), and burnwire hold and release mechanism (UMS-0766). Two different 6U solar wing frames are required, however, both are mirror structures about the wing's longest axis. The 6U solar panel board (UMS-0628) interfaces with both frames but is required to be rotated 180 degrees to align the mounting holes.

On sheet 4 of 6 of the following drawings are two holes which are designed to allow a fishing line to be looped through both the aluminum frame (UMS-0666 and UMS-0667) and 6U PCB board (UMS-0628). The fishing line can be tied down and secured at this location with the other end tensioned at the burnwire hold and release mechanism. Other holes dimensions on the drawing allow for the 6U board to be screwed in via helicoils installed in the frame or for a bolted connection at the location of the UMS-0191 and the overall solar wing structure.

Burnwire Hold and Release Mechanism

The following drawing shows the current structural model of the burnwire hold and release mechanism. A suitable fishing line will be held down and tightened using a wire-lockable socket head screw. For more information on fishing line testing please refer to the IRIS documentation (creep test: link, melt wire test: link, burn resistor test: link). After being tightened and secured , the fishing line is then passed across the burnwire PCB (UMS-0799) resistors. The burnwire PCB is designed to have resistors in parallel for redundancy. The burnwire clamp (UMS-0800) clamps down and holds the burnwire in place when screwed into the ADCS-CDH module shells. Two cutouts are made on the burnwire clamp to allow the fishing line to pass through once burned. As mentioned above the other end of the burnwire is tied down on the solar wing. Thus, no debris is expected to generated with this burnwire hold and release mechanism. Additionally, the length of the remnant fishing line is not long enough to cross the star tracker or payload FOV. Testing and verification of the proposed design is to be conducted as soon as Phase D begins.

UITR

UMS-0719 - ADCS-CDH Module

UMS-0982 - Star Tracker Assembly

Assembly Procedure

Step 1: Attach Star Tracker Mount to Adapter

Place the bottom face of the Star Tracker Mount [1] onto the top face of the Star Tracker Adapter [2], aligning the screw holes.
Insert three screws [9] upward through the bottom face of the tracker adapter into the mount.
Secure the connection using nuts [11] on the top face of the tracker mount.

Step 2: Insert Helical Inserts

Thread helical inserts [7] into:
- The three holes on the angled face of the Star Tracker Mount [1].
- The four holes on the vertical tabs of the Adapter [2].

Step 3: Mount the Star Tracker

Place the Star Tracker [4] onto the angled face of the Star Tracker Mount [1], aligning it with the pre-inserted helical inserts.
Secure the Star Tracker using screws [8], threaded into the helical inserts [7] on the angled face.

Step 4: Stack Transceiver, Stand-offs, and Comms Board

Align the Star Tracker Adapter [2] with the top face of the Transceiver [5].
On the bottom face of the Transceiver, align the Comms Board [6], separated from the transceiver by the Comms Stand-offs [3].
Feed two long screws [10] from the top of the adapter [2], through the transceiver [5], down through the stand-offs [3], and into the comms board [6].
Secure the entire stack using nuts [11] on the bottom of the comms board.

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