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A Primer on Cubesats

CubeSats are a class of nanosatellites, defined by their standardized size units (U), where 1U is a cube of 10cm x 10cm x 10cm. Initially developed for academic purposes, CubeSats have become popular in various space missions due to their low cost, modularity, and ease of deployment. A typical CubeSat can range from 1U to 6U or more in size.

Realization of Cubesat

Actuators in CubeSats

The development of miniaturized, high-efficiency actuators is crucial. For example, a new generation of micro-electromechanical systems (MEMS) based thrusters are being tested, offering precise control with significantly reduced size and power requirements.

Reaction Wheels

A 1U CubeSat may include a set of three miniature reaction wheels, each weighing approximately 50 grams. These reaction wheels can provide a torque of about 0.001 Nm, sufficient for attitude adjustments in a low Earth orbit (LEO).


For propulsion, a 3U CubeSat might use a cold gas thruster system, with each thruster capable of providing around 1 mN of thrust. This modest thrust is enough for minor orbit corrections and maneuvering in space.

Control Moment Gyroscopes (CMGs)

A larger 6U CubeSat might incorporate CMGs. A single CMG in such a satellite can generate around 0.5 Nm of torque, enabling it to rapidly change its orientation, which is especially useful for imaging missions.

Sensors in CubeSats

Advancements in sensor technology have led to the integration of LIDAR and hyperspectral imaging systems in CubeSats. A hyperspectral sensor in a 6U CubeSat, for instance, can have over 200 spectral bands, each with a spatial resolution of 30 meters, enabling detailed environmental monitoring.

Star Trackers

A 2U CubeSat dedicated to earth observation might include a miniaturized star tracker with an accuracy of 5 arcsec. This high precision is crucial for aligning the satellite's camera accurately for imaging.


A common magnetometer in a 1U CubeSat might have a resolution of around 10 nT, used mainly for coarse attitude determination in conjunction with a sun sensor.

Sun Sensors

In a basic 1U CubeSat, sun sensors can be as simple as photodiodes, providing an accuracy of about 1 degree, sufficient for solar panel alignment and basic attitude control.

Case Studies

QB50 Satellite

QB50 Project

This initiative involved launching a network of 36 CubeSats (2U and 3U) equipped with standardized sensor payloads to study the lower thermosphere. Each satellite carried sensors like ion-neutral mass spectrometers and flux-probe experiments, demonstrating the feasibility of using a constellation of CubeSats for scientific research.


A 6U CubeSat developed by JPL and MIT, ASTERIA was designed to study exoplanets. It featured a precision-pointing system using miniaturized star trackers and reaction wheels, achieving pointing stability within 0.5 arcsec, a remarkable feat for a satellite of its size.

Structural Considerations for CubeSats

The structural design of these satellites is crucial, as it needs to withstand the rigors of launch and the harsh conditions of space.

Fundamental Structural Components


The CubeSat's frame is typically made of lightweight, high-strength materials like aluminum alloys. For example, Al 7075 is commonly used due to its high strength-to-weight ratio.


The external panels must protect internal components from space radiation and thermal extremes. Using aluminum or composite material with thermal coatings is standard practice.

Fastening Elements

Screws and bolts, often made from titanium due to its strength and corrosion resistance, are used for assembly.

Design Considerations

Size and Modularity

CubeSats are designed in 'U' units; a 1U CubeSat has dimensions of 10cm x 10cm x 10cm. The modular design allows for scalability - for instance, a 3U CubeSat is simply three times longer.

Mass Constraints

The mass of a 1U CubeSat typically should not exceed 1.33 kg. This necessitates a meticulous design to balance structural integrity with weight.

Vibration and Shock Resistance

During launch, CubeSats endure severe vibrations and shocks. Reinforced frames and shock absorbers are often incorporated. For example, a CubeSat might include a deployable shock absorption system that reduces the impact forces by up to 40%.

Thermal Considerations

Thermal Expansion

Materials like aluminum that have low thermal expansion coefficients are preferred to minimize structural warping due to temperature fluctuations.

Thermal Protection

Multi-layer insulation (MLI) blankets are commonly used for thermal control, reflecting solar radiation and retaining internal heat.

Deployment Mechanisms


The Poly-Picosatellite Orbital Deployer (P-POD) is the most common deployment mechanism. It’s crucial for the CubeSat structure to be compatible with P-POD dimensions and ejection mechanics.

Spring Systems

Springs in the deployment mechanism need to be precisely calibrated to ensure successful ejection without causing damage.

Case Studies

BIRDS-3 CubeSats

Launched in 2019, these CubeSats featured an aluminum frame with solar panels doubling as structural elements, showcasing an innovative approach to material utilization.

LightSail 2

This mission used a 3U CubeSat to deploy a solar sail. The structural design had to accommodate the sail, its deployment mechanism, and ensure stability during and after deployment.

Power Systems in CubeSats

In CubeSat missions, power systems are a critical component, as they directly affect the satellite's operational capabilities and longevity.

Common Wattage and Power Generation

Solar Panels

The primary source of power for CubeSats. A standard 1U CubeSat may have solar panels generating around 2 to 4 watts of power under ideal conditions.

Power Density

Advanced solar cells can achieve a power density of about 29 mW/cm². For a 3U CubeSat with an external area of approximately 0.3 m², this translates to about 8.7 watts.

Power Consumption by Subsystems

Communication Systems

One of the most power-intensive subsystems, a transceiver in a CubeSat can consume up to 2-3 watts during operation.

Onboard Computers

The satellite’s computer, or OBC, usually consumes around 1-2 watts.

Sensors and Payloads

Depending on their complexity, sensors can consume between 0.5 to 3 watts.

Attitude Control Systems

Systems like reaction wheels and magnetorquers can consume about 1-2 watts.

Power Management

Power Management Unit (PMU)

Responsible for distributing, monitoring, and controlling the electrical power. It ensures optimal charging of batteries and power supply to different subsystems.

Battery Storage

Lithium-ion or Lithium-polymer batteries are commonly used for energy storage. For example, a 1U CubeSat might have a battery capacity of around 20-40 watt-hours.

Energy Budgeting

Ensuring that power generation meets or exceeds consumption is crucial. This involves balancing high-power activities, like data transmission, with periods of lower power usage.

Case Studies and Examples

QB50 Project

This project involved several CubeSats, each equipped with solar panels capable of generating up to 10 watts, powering sensors and communication systems efficiently.

AAUSAT-4 Satellite


A 1U CubeSat with power consumption carefully managed by a PMU, with solar panels providing around 3 watts, sufficient for its operational needs.

Onboard Computers in CubeSats

The onboard computer (OBC) is the brain of a CubeSat, orchestrating various subsystems and processing data. Its capabilities and limitations play a crucial role in determining the satellite's overall performance.

Capacity and Capabilities

Processing Power

OBCs in CubeSats have evolved from simple microcontrollers to complex systems. A typical CubeSat may use an ARM-based processor capable of operating at hundreds of MHz, comparable to early smartphones.


Memory capacity varies but is often limited due to space and power constraints. A standard CubeSat OBC might have a few hundred MBs of volatile (RAM) and non-volatile memory (Flash).

Data Handling

Data Storage

For data-intensive missions like Earth observation, CubeSats need substantial data storage. A 3U CubeSat might include solid-state drives (SSDs) with storage capacities of 32 to 64 GB.

Data Processing

Advanced CubeSats carry out significant data processing onboard, like image compression, to reduce the data volume for transmission.

Software and Operating Systems

Real-Time Operating Systems (RTOS)

CubeSats often employ RTOS like FreeRTOS or RTEMS, providing reliable and efficient task management.

Custom Software

Many CubeSats run custom-designed software tailored to their specific mission requirements.

Reliability and Redundancy

Fault Tolerance

Given the harsh space environment, OBCs are designed for high reliability. This includes radiation-hardened components and error-correction mechanisms.


Some CubeSats incorporate redundant OBC systems to ensure mission continuity in case of a failure.

Case Studies

Spire's Lemur-2 CubeSats

These CubeSats use advanced OBCs capable of handling complex algorithms for weather data processing and ship tracking.

BIRDS-3 CubeSats

These satellites feature OBCs managing multiple payloads, demonstrating multitasking capabilities in a compact form factor.

Roadmap for Designing CubeSat AOCS

1. Define Mission Requirements

  • Understand mission objectives (e.g., Earth observation, scientific measurement).

  • Determine required attitude control precision and stabilization needs.

2. Conceptual Design

  • Choose between passive or active control systems based on mission needs.

  • Decide on the type of sensors (e.g., sun sensors, star trackers) and actuators (e.g., reaction wheels, magnetorquers) required.

3. System Modeling

  • Develop mathematical models of the CubeSat dynamics and environmental disturbances (like magnetic field, solar pressure).

  • Model sensor and actuator characteristics.

4. Control Algorithm Development

  • Implement control algorithms like PID (Proportional, Integral, Derivative), B-dot for magnetorquers, or more advanced techniques like adaptive or robust control for active systems.

  • Simulate the control algorithms using the system model.

5. Sensor and Actuator Integration

  • Integrate sensors and actuators with the CubeSat's onboard computer.

  • Ensure compatibility and proper communication between components.

6. Software Implementation

  • Develop software for the onboard computer to process sensor data, execute control algorithms, and command actuators.

  • Implement fault detection, isolation, and recovery algorithms.

7. Testing and Validation

  • Perform ground-based tests such as air-bearing table tests for attitude control.

  • Conduct environmental tests, including thermal vacuum and vibration tests.

8. Launch and Operational Testing

  • Monitor and analyze AOCS performance post-launch.

  • Adjust and fine-tune control parameters as required.

Designing the AOCS of a CubeSat is a multidisciplinary process, requiring a balance between mechanical design, electronics, control theory, and software engineering. The choice of sensors, actuators, and control algorithms depends heavily on the specific mission requirements and constraints inherent to CubeSat platforms.

Cite this article as: Kumar, Yajur “A Primer on Cubesats” Space Navigators, 26 November 2023,


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