CubeSats are small satellites designed to comply with specific standardized criteria for size, weight and shape. The basic CubeSat unit, known as a 1U CubeSat, is a cube that measures about 10 cm on each side and weighs up to 1.33 kg.

CP1, a 1U CubeSat, was the first satellite developed at Cal Poly to qualify a reliable bus system, sensors and attitude control devices (left); CP10, a 3U CubeSat, was also designed at Cal Poly with space weather sensors from NASA’s Goddard Space Flight Center(right). Source: Cal Poly

CubeSat design specifications were developed by the CubeSat Program at California Polytechnic State University. Standard specifications are also available for 1.5U, 2U, 3U and 6U CubeSat sizes. For deployment, CubeSats are loaded into standard dispenser hardware that can interface with a wide range of launch vehicles to fill spare payload space.

The standardized CubeSat form factor reduces the cost of satellite development and deployment, lowering the barrier to entry for educational projects, scientific research, technology demonstrations and commercial applications.

Every year through its CubeSat Launch Initiative (CSLI), NASA selects several projects that align with its research goals and covers all launch costs to deliver the satellites to space.

Not all CubeSats launch through NASA’s CSLI program, but the development process is similar regardless of mission details.

A typical CubeSat development timeline follows the steps below and takes 18-24 months from concept development to completion.

An example timeline of a CubeSat project. Many phases can occur concurrently if development resources allow. Source: NASA

1. Concept development (1–6 months)

This step outlines the primary objectives and basic details of the CubeSat project. To maximize the probability of a successful project, design a concept aimed at attracting potential funding sources. Mission goals should support at least one objective in NASA’s Strategic Plan for a chance at winning CSLI funding.

Identifying collaborators with similar goals and establishing partnerships can be a fruitful tactic for gaining additional resources and expertise to ensure that difficult projects succeed.

2. Securing funding (1–12 months)

ARMADILLO (Attitude Related Maneuvers and Debris Instrument in Low (L) Orbit) is a 3U CubeSat under development at the University of Texas at Austin. Source: University of Texas at Austin

Occurring concurrently with step 1, funding is a critical part of CubeSat projects. Without money to pay for development costs, a CubeSat will never reach the finish line.

Projects awarded CSLI funding will only have launch costs covered. Funds still must be raised to cover other costs of development which include materials and components, labor, environmental testing and travel.

Sources of funding may include:

• Organizations like the National Science Foundation and NASA’s Earth Science Technology Office that send out requests for proposals (RFPs) for external teams to perform research projects for them
• Government agencies or commercial organizations looking for contractors to perform technology demonstrations to prove the viability of new technologies
• University sponsorships
• Crowdfunding sites like Kickstarter

3. Merit and feasibility reviews (1–2 months)

Before submitting mission proposals to CSLI, CubeSat teams must organize merit and feasibility reviews of their projects conducted by external reviewers of their choice. The merit review evaluates the quality of a mission’s science and technology objectives and determines whether it is aligned with NASA’s Strategic Plan. The feasibility review assesses the project’s likelihood of success taking into account technical viability, mission risks and the team’s ability to succeed.

4. CubeSat design (1–6 months)

An exploded view of the basic modules that comprise a typical CubeSat. Source: NASA

Designs must comply with the basic requirements stated in the CubeSat Design Specifications. But that leaves a lot of room for customization including component selection and internal layout of command and data handling, radio frequency (RF) communication, attitude determination and control, power and other systems.

Commercial off-the-shelf CubeSat components are increasingly common, although many teams design and fabricate their own parts in an effort to reduce expenses and provide an educational experience.

CubeSat components can be found using the following resources:

• A list of suppliers of CubeSat components, buses/platforms and launch services available at Cal Poly’s CubeSat Program website
• A searchable database of components available thanks to NASA's Small Spacecraft Systems Virtual Institute (S3VI) which indexes the SmallSat Parts On Orbit Now (SPOON) database and other spacecraft parts and technologies databases

Design specifications and requirements on which to base CubeSat design prior to receiving the official CubeSat-to-dispenser Interface Control Document (see step 7) include:

• Cal Poly’s 1U – 3U CubeSat Design Specifications [PDF]
• Cal Poly’s 6U CubeSat Design Specifications [PDF]
• NASA Launch Services Program’s Program Level Dispenser CubeSat Requirements Document (LSP-REQ-317.01 B) [PDF]
• NanoRacks LLC’s NanoRacks CubeSat Deployer (NRCSD) Interface Control Document [PDF]

5. Development and submittal of proposal in response to CSLI call (3–4 months)

The annual CSLI Announcement of Opportunity (AO) is usually posted on NASA’s website and the Federal Business Opportunities (FBO) website in early August with proposals due in November.

Proposals typically require:

• Demonstration of the benefits to NASA based upon the NASA Strategic Plan
• Identification of a project focus area, i.e. science, technology or education
• Description of the merit review process and outcome including review committee membership
• Description of the feasibility review process and outcome including review committee membership
• Full compliance with the Launch Services requirements or identification of any potential waivers
• Completed Mission Parameters Table
• Completed Project Details Table
• Schedule for remaining CubeSat development that supports a launch within a certain timeframe
• Funding commitment information

6. Selection and manifesting (1–36 months)

NASA’s CSLI Selection Recommendation Committee evaluates proposals and produces a prioritized list of CubeSat projects. NASA’s Launch Services Program (LSP) will assign CubeSats at the top of the list to available slots on upcoming rocket launch opportunities.

When a CubeSat has been selected to be manifested on a mission, developers must enter into a contract with NASA known as a Cooperative Research And Development Agreement (CRADA) defining legal liabilities, risks, data sharing rules and other requirements.

7. Mission coordination (9–18 months)

The CSSWE (Colorado Student Space Weather Experiment) CubeSat (left) next to its dispenser, the Poly-Picosatellite Orbital Deployer (PPOD) (right). Source: University of Colorado at Boulder

CSLI-sponsored missions typically include a mission integrator in charge of coordinating integration schedules, deliverable documentation and communications between the launch vehicle provider and the CubeSat developer. The integrator’s schedule sets a timetable for the rest of the mission by providing developers with deadlines for hardware and documentation delivery.

The mission integrator creates the CubeSat-to-dispenser Interface Control Document (ICD) which serves as the official rulebook for the CubeSat by defining all requirements for the interfaces between the CubeSat and the dispenser, and the dispenser and the launch vehicle, as well as environmental testing requirements.

8. Regulatory licensing (4–6 months)

All CubeSats that transmit radio signals or contain an imaging instrument must obtain licenses from the government before launch.

RF communications licenses are issued by:

• The Federal Communications Commission (FCC) for all satellites not operated by the government (see the FCC’s “Guidance On Obtaining Licenses For Small Satellites”)
• The National Telecommunications and Information Administration (NTIA) for government-operated satellites (see the NTIA’s “Manual of Regulations and Procedures for Federal Radio Frequency Management”)

Imaging licenses for all non-government owned U.S. CubeSats are issued by the National Oceanic and Atmospheric Administration (NOAA). Read more at NOAA’s Commercial Remote Sensing Regulatory Affairs website.

The licensing process can be lengthy, so it is recommended to submit applications within 30 days after the CubeSat is manifested. If licenses are not obtained by the launch date, the CubeSat will not be deployed to space.

9. Flight-specific documentation development and submittal (10–12 months)

Students Sergei Posnov, David Einhorn, Thompson Cragwell, and Maria Kromis work on ANDESITE (Ad-Hoc Network Demonstration for Extended Satellite-Based Inquiry and Other Team Endeavors), a 6U CubeSat, at Boston University. ANDESITE will deploy a constellation of picosatellites to measure current densities at different spatial resolutions in the near-Earth magnetosphere. Source: Boston University

The mission integrator will specify the documentation that CubeSat developers are required to provide to prove that the CubeSat meets all safety and launch requirements of the mission. These deliverables include:

• Orbital Debris Assessment Report (ODAR) – includes a mission description, a list of all components and materials, and verifies the CubeSat will not pose a hazard to orbiting spacecraft or the ground
• Transmitter surveys – includes information about the CubeSat’s communication system and assists the launch vehicle provider in performing EMI/EMC analysis
• Materials list – identifies every material in the CubeSat and verifies that no dangerous or prohibited items are part of the CubeSat design
• Mass properties report – includes the CubeSat’s total mass, center of gravity, moments of inertia, etc., to be used by the launch vehicle provider for load calculations
• Battery report – includes battery manufacturer, part number and specifications to verify that the CubeSat has proper battery circuit protection
• Dimensional verifications – includes a dimensional checklist, or CubeSat Acceptance Checklist (CAC) and ensures the CubeSat will fit into its dispenser
• Electrical report – includes a diagram of electrical power systems and identification of important components like the Remove Before Flight (RBF) pin, and verifies several requirements in the CubeSat-to-dispenser ICD
• Venting analysis – identifies ventable and non-ventable volumes and venting area locations, and verifies the CubeSat has adequate venting to prevent explosive decompression of containers on the CubeSat as it transitions from standard atmosphere to vacuum
• Testing procedures and reports – includes a report for each test performed on the CubeSat including Day-In-The-Life (DITL) testing, Dynamic Environment (Vibration/Shock) testing and Thermal Vacuum Bakeout testing to verify CubeSat-to-dispenser ICD requirements
• Compliance letter – signed by the CubeSat principal investigator and guarantees the CubeSat is compliant with the CubeSat-to-dispenser ICD
• Safety package inputs – depends on CubeSat mission model, e.g. Missile System Prelaunch Safety Package (MSPSP) or Flight Safety Panel (for International Space Station missions), and includes all hazards the CubeSat could pose to anything around it, such as the launch vehicle and dispenser, and supports launch vehicle provider analyses to verify that the CubeSat is safe to fly

10. Ground station design, development and testing (2–12 months)

Ground stations allow communications between the CubeSat and Earth. Among other components, they require a radio and antenna, often sourced from off-the-shelf amateur radio components.

Amateur radio club members are a great source of expertise for setting up a ground station. Find local clubs at the National Association for Amateur Radio (ARRL).

CubeSat developers can practice tracking and even uplinking to existing satellites (given permission by the current operator). The 470 MHz (70 cm) band is a common CubeSat communication frequency. NOAA weather satellites are also good test subjects and operate on the 140 MHz (2 m) band.

Rules governing amateur radio service are included in Part 97 - Amateur Radio Service Rules of Title 47 of the Code of Federal Regulations.

11. CubeSat hardware fabrication and testing (2–12 months)

Denise Thorsen and Jesse Frey from the University of Alaska Fairbanks perform Day-In-The-Life (DITL) tests (functional tests under typical operating conditions) on the Alaska Research Center (ARC) CubeSat. Source: University of Alaska, Fairbanks

If the budget allows, a best practice is to build multiple units of the CubeSat. These include an Engineering Test Unit (ETU) and a FlatSat (in which all components are mounted on a flat board without integration into the structure) used for testing purposes, as well as two flight units in case of a launch failure.

Document all progress and challenges, including detailed photos, to ensure continuity of the project if team members leave before completion.

CubeSat testing includes development tests during hardware fabrication and verification tests to prove that the CubeSat meets ICD requirements and is safe to launch. Verification tests include vibration, shock, thermal vacuum, EMI/EMC and static load tests. NASA’s GSFC-STD-7000 General Environmental Verification Standard contains guidelines for these tests.

12. Mission readiness review (half-day)

During the Mission Readiness Review (MRR), the CubeSat developer will present a summary of all evidence to CSLI and the mission integrator demonstrating that the CubeSat meets all requirements in the ICD.

13. CubeSat to dispenser integration and testing (1 day)

The CubeSat developer delivers the flight unit to an integration site determined by the mission integrator to be inserted into the dispenser. The dispenser/CubeSat system will then undergo a final vibration test as a single unit before being shipped to the location where it will be integrated into the launch vehicle.

14. Dispenser to launch vehicle integration (1 day)

CubeSats can be mounted in relatively small unoccupied space aboard a launch vehicle. The image on the left shows the location of CubeSats for a typical United Launch Alliance (ULA) mission. The images on the right show where a Naval Postgraduate School Cubesat Launcher Lite (NPSCul-Lite), housing eight 3U P-PODs, would be attached to the launch vehicle via an Aft Bulkhead Carrier (ABC) plate. Source: ULA

Two to four weeks before launch, launch vehicle technicians will attach the dispenser holding the CubeSat to the rocket. CubeSat developers are typically not invited to this event due to launch vehicle provider security restricting access to essential personnel including NASA Launch Services Program representatives, the mission integrator and the launch vehicle technicians.

15. Launch (1 day)

The launch date is established by the primary mission, so CubeSat delivery, whether on-time or late, will not affect the launch; the rocket will leave without a CubeSat if it is not ready by the launch date.

CubeSat developers are generally invited to the launch site at their own expense, but launch day delays due to weather and other issues are not unusual, so it is wise to plan for extra days.

16. Mission operations (variable, up to 20 years)

The first task following CubeSat deployment is the identification of which new object in space is the satellite. The launch provider typically provides preliminary state vectors before launch day and actual state vectors immediately after the CubeSat is ejected into space. State vectors indicate an object’s position and velocity relative to Earth’s center of mass and can be converted into two-line elements (TLEs), which is a data format used to predict any satellite’s location in orbit.

Volunteer satellite trackers in the amateur radio community are often very good at identifying CubeSats. Observations among this community are usually shared first on the CubeSat Internet Relay Chat (IRC) channel, which can be joined by any IRC client directed to irc.freenode.net #cubesat.

Further reading

CubeSat 101: Basic Concepts and Processes for First-Time CubeSat Developers [PDF] | NASA

CubeSat Launch Initiative Resources | NASA

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