4.3 Typical Requirements and Design Considerations

Sources for requirements may be generated from external constraints or internally generated needs from all parts of the spacecraft lifecycle, from manufacturing to spaceflight operations. The basic requirements or design drivers for any subsystem are the allocated size, weight, and power, which apply to structures and mechanisms. Requirements specific to the structures and mechanisms system related to the spacecraft mission include:

• Components requiring a certain orientation within the spacecraft frame (facing away from the spacecraft center)
• Components requiring a certain placement within the spacecraft frame (radiation shielding or protection)
• Observing payloads that need an unobstructed view into the space environment (most optics)
• Accommodation of specific size within spacecraft volume and weight distribution affecting moment of inertia
• Required active mechanisms or deployable (like an extendable boom) to achieve mission objectives
• Total mass and size of the spacecraft
• Mechanical interfaces between spacecraft components and primary structure

Sources of internal requirements during manufacturing and assembly could include handling fixtures, container interfaces, or stresses induced by manufacturing processes. The Artemis CubeSat Kit does not have handling fixtures, has rails to interface with the P-POD deployer, and inserts to deal with manufacturing fatigue from assembly and disassembly.

Sources of internal requirements during manufacturing and assembly could include handling fixtures, container interfaces, or stresses induced by manufacturing processes.

Artemis Kit Specific

During transport and handling, requirements may include crane or dolly interfacing (especially for large spacecraft) and considerations for land/sea/air transport environments (like shipping containers for freight boats or trucks). The Artemis CubeSat Kit does not have any handling interfaces but will arrive fitted snugly in fitted foam within a Pelican case, which offers protection during shipment.

Artemis Kit Specific

During testing, external requirements from the launch provider commonly include environmental testing from vibration or acoustic profiles. These tests may require a fixture to the testbed that also must withstand vibration loads. During pre-launch, requirements could include handling during stacking sequence and pre-flight checks.

Artemis Kit Specific

During launch and ascent, the structure must withstand steady-state booster accelerations, vibroacoustic noise during launch and transonic phase, propulsion system engine vibrations, pyrotechnic shock from separation events, transient loads during stage separations, etc. Generally, spacecraft are designed to launch loads as these loads are the most intense out of any phase.

Artemis Kit Specific

During mission operations, the spacecraft structure must withstand thruster acceleration, transient loads from pointing maneuvers, docking events, pyrotechnic shock from separation or deployment, and thermal expansion.

Artemis Kit Specific

In the final phase of reentry and landing, the spacecraft may experience aerodynamic heating and transient winds or landing loads. These phenomena are particularly relevant for the astronaut return or for Mars entry, descent, and landing operations.

Artemis Kit Specific

From the CubeSat Design Specification Rev. 14, the CubeSat dimensions and features are outlined in the CubeSat Specification Drawings (Appendix B). Note: The CubeSat Inspection and Fit-check Procedure (CIFP) can be used to aid in verifying that the CubeSat meets the dimensional requirements specified in Appendix B. The CIFP can be found on cubesat.org. These requirements are applicable for all dispensers not utilizing the tab constraint method. CubeSats designed with tabs can find those specific requirements on the PSC website. Within the CubeSat Design Specification Rev. 14, the structural requirements fall under section 2.2 CubeSat Mechanical Specifications, which start on page 10.

Artemis Kit Specific

3.6	The CubeSat structure shall be contained within 1U and offer flexibility in mounting components internally
	3.6.1	The CubeSat kit structure shall remain inside a 10 x 10 x 11.35 cm +/- 0.1mm volume while undeployed
	3.6.2	All four protruding corners on the top and bottom of the main body of the CubeSat shall not exceed a height of 6.75mm, shall have a minimum length and width of 6mm, and shall have a surface area of 6.5mm x 6.5mm, per NASA CLSI requirements
	3.6.3	There shall be a minimum of 20mm from the CubeSat surface to the top of the corners along the Z direction per NASA CSLI Requirements
	3.6.4	The four edges of the CubeSat along the Z direction shall have a hardness greater than or equal to Rockwell C 65-70 per NASA CSLI Requirements
	3.6.5	The overall structure shall withstand 1200N between two XY planes applied in the Z direction, per NASA CSLI Requirements
	3.6.6	The maximum mass of the entire CubeSat Kit shall not exceed 1.33 kg per NASA CSLI Requirements
	3.6.7	The center of gravity shall be within 2cm of its geometric center relative to the Z direction, per NASA CSLI Requirements
	3.6.3	The CubeSat kit shall be easy to assemble with the provided instructions

Requirements Compliance Matrix

In a NASA Technical Standard to establish NASA structural design and test factors [NASA-STD-5001], this document’s appendix provides a listing of requirements for selection and verification of requirements by programs and projects. You may use the entire appendix table to decide which requirements apply to your program and by entering “Yes” to describe the requirement’s applicability to the program or project; or entering “No” if the intent is to tailor and enter how tailoring is to be applied in the “Rationale” column. For all the requirements that you’ve deemed applicable, you should read the corresponding sections in NASA-STD-5001. The figure below is just a snapshot of the 8 pages of potential requirements.