What are Cubesats?
To answer that, let’s first define a U. A U is 10x10x10 cm cube of space from which cubesats derive their name. Cubesats are made up of multiples of these U’s put together and can have 1.33Kg of weight for every U in their structure. Cubesats can range from a simple 1U cube to 24U “behemoths”, but they are all made to fit in an area traced out by the same standardized cube. If cubesats are just a standard of sizing, why do we hear about them so often? Because standardization opens up a world of possibility
A 1U Cubesat
Standardization is the Key
Cubesats are quick and cheap to build. They can be built and launched for around $150,000 US and can go from initial concept to launch in under a year. Traditional satellites often take years and millions of dollars to develop. Standardization is the key to cubesats low costs and quick turnaround. Because most cubesats are one of 3 sizes (1U, 3U, 6U) manufacturers can design components generally. Components don’t need to be tailor made. These general cube-sat components are also augmented by many commercial off the shelf (COTS) pats which further drive down the cost and time in development. Applicable knowledge also spreads quickly. When a team building a 1U cubesat finds a component that works in their satellite, any other 1U cubesat team knows that that competent is now a possibility.
Democratizing Space
Because Cubesats are so cheap to build, they have massively reduced the barriers of entry to space. If you’re a group that want to collect data from space on a specefic item (rainfall, arctic ice, exoplanets, etc…) but you cant afford a dedicated satellite you no longer need to hope that you can be mounted as a secondary payload on another satellite. It’s now cheap enough that you can build your own cubesat. Solar sails are one great example of using cubesats to demonstrate new technology. Both the planetary society and NASA are using cubesats (Lightsail-1 and Nanosail-D respectively) to experiment with solar sails. These missions are being carried out for fractions of a price of a traditional space based platform. They are cheap enough that even high schools are able to launch cubesats as a way of getting people interested in STEM.
A 3U cubesat with it’s dispenser in the background
Satellite Subsystems
If there’s interest, I may go over the main subsystems in more details in the future post but here are the main subsystems I’ve seen on cubesats
- Guidance Navigation and Control- They are responsible for knowing where the satellite is, where it’s looking, and re-orienting the satellite to where it should be looking.
- Structures- Designs, simulates, and fabricates the main structure of the satellite. Responsible for ensuring that the satellite can survive the forces from launch.
- Thermal- Ensures that none of the components go outside their operation temperature ranges while in orbit.
- Payload/Science- This is subsystem ensures that the satellite will be able to carry out it’s mission once in space. (I lead the payload/science team for a 6U cubesat for 3 years at the University at buffalo nano-satellite lab (Link) )
- Command and Data Handling – They handle the satellites “brain” and all the data in it. How data’s stored, sent back to earth, how the spacecraft monitors other subsystems, etc…
- Power- They ensure that the satellite has enough power to run all the components and some custom board design.
- Integration & Testing- They assemble and test all the components in the satellite. (I got my start on cubesats on an integration and testing team)
- Software – They write the code that both controls the satellite as well as code for the ground station and mission support.
- Propulsion – This is an uncommon subsystem because few cubesats use propulsion currently.
A 6U Cubesat with deploy-able solar panels
If you are interested in reading more about the engineering details of designing a satellite or are in a university cubesat team this is a great reference. I’ve seen it at every space systems group I’ve been to, from UBNL to Lockheed martin to NASA.
Future of Cubesats
The future of cubesats are bright. With companies like spaceflight and rocket labs we now have dedicated rides to space just for cubesats. They fill an important niche in low earth orbit and demand from private companies for cubesats has finally outstripped demand from academia for cubesats. We have everything from imaging companies like planet labs to pharma companies who want to develop new drugs in a zero-g environment developing their own cubesats.
Additionally, Cubesats have also started to push past the boundaries of earth’s orbit and into deep space. Two Cubesats MarCO-A and MarCO-B accompanied the insight lander to mars late last year. They allowed the first images and landing data to be sent back to earth almost instantaneously instead of having to wait for NASA’s Mars Reconnaissance Orbiter to be able to transmit. Even more deep space cubesats are still being developed by NASA like NEA Scout, a cubesat designed to use a solar sail to visit a near earth asteroid. Much like their current cousins in earth orbit, deep space cubesats have the potential to revolutionize deep space exploration. Their low cost will allow us to probe areas of our solar system that previously could not afford a traditional mission.
Artists impression of MarCO-A and B, the Two NASA cubesats that went to Mars
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