CubeSTEP’s CubeSat features an innovative two-bus structure, dividing the 3U spacecraft into two 1.5U sections — one dedicated to payload integration and the other to avionics and support systems. This modular architecture improves accessibility, simplifies testing, and allows rapid payload replacement without disturbing critical flight hardware.

The upper 1.5U section houses the additively manufactured oscillating heat pipe (OHP) payloads, while the lower section contains the power, communications, and control subsystems. The two halves connect through internal fasteners and precision alignment features, maintaining structural integrity while maximizing usable internal volume.

This split-bus approach enhances modularity, reusability, and integration efficiency — enabling the lower “controlling half” to serve as a common platform for future payloads and technology demonstration missions.

CubeSTEP’s CubeSat incorporates an isogrid structural pattern within its additively manufactured aluminum frame to maximize strength while minimizing mass. The triangular lattice geometry efficiently distributes loads and resists bending and buckling under launch stresses, providing an optimal strength-to-weight ratio.

Because the structure is 3D printed, the isogrid pattern can be precisely customized—allowing engineers to add or remove material in specific areas to fine-tune the center of mass and balance the spacecraft. This flexibility supports accurate attitude control and structural optimization throughout design and integration.

By integrating the isogrid directly into the printed walls, CubeSTEP achieves lightweight efficiency, enhanced manufacturability, and tunable mass distribution—a key advancement for modular, high-performance CubeSat platforms.

The payload integration assembly houses the Data Acquisition (DAQ) board, which monitors temperature and power data from the Oscillating Heat Pipe (OHP) payloads during flight. The board connects to the spacecraft’s On-Board Computer via a PC-104 interface and collects readings from 27 thermocouples and three patch heaters.

To ensure reliable operation in orbit, the DAQ board is thermally isolated and mechanically reinforced using aluminum and Kapton tape, epoxy, and stainless-steel fasteners. It is mounted to a 3D-printed isogrid bracket with aluminum spacers for thermal isolation and wrapped in Multi-Layer Insulation (MLI) to reduce heat transfer. This configuration provides stable thermal and structural performance, allowing precise data collection throughout launch and on-orbit testing.

The CubeSTEP CubeSat is designed to integrate seamlessly with standard CubeSat deployers through precision-engineered Type III hard-anodized aluminum rails. These rails are the only structural elements that make direct contact with the deployer, ensuring a controlled and reliable release during launch and deployment.

The x- and y-face rails interface with the deployer’s internal guidance tracks, while the rail ends are clamped between the deployment wagon plate and the dispenser’s door-end mechanism. This configuration restrains the CubeSat both vertically and laterally, preventing vibration-induced wear and cold welding under launch loads.