We are a team of students from the French engineer school ECE Paris.
We are designing and building a 1U CubeSat.
Follow our journey on this website.
Context
Education
Since the beginning of the space race in 1957, the number of objects sent into orbit is continuously growing, as does the amount of space debris orbiting the Earth. This is becoming a real threat for operational space missions around the Earth. Space debris can be the result of:
- A collision between two satellites, two debris or a satellite and a debris/meteoroid
- A battery which became unstable and exploded
- Fuel leftovers in a satellite or a launcher stage which became unstable and exploded
- A planned destruction
- An out of control satellite or a launcher stage
Today, the population of space debris is estimated to be more than 500 000 trackable objects where 20 000 of them are bigger than a tennis ball. In addition, there are millions of pieces too small to be detected.
The vast majority of space debris is located in Low Earth Orbit (LEO) where most space missions are located or planned. Figure 1 illustrates the distribution of debris around the Earth in 2013.
Even with the direct threat to space missions that space debris represents, the real threat comes in the long-term management of the Earth orbit. Indeed, the Clean Space department of ESA calculated that the population of debris would keep on growing in an exponential way if the space industry does not change or if every space activity stops (Figure 2); thus preventing any orbital activity. The same forecast considered the limitation of debris creation, End of Life (EOL) management, debris removal and the limitation of orbital objects.
One part of the implementation of the space debris mitigation is made through the development of solutions to give the tools to the new satellites to perform deorbiting maneuvers to either cemetery orbits where the satellite is passivised (batteries and tanks emptied) or toward Earth to disintegrate upon re-entry into the atmosphere. Several types of deorbiting systems are currently being developed such as the aerodynamic sail, chemical engine, and electric/ionic engine.
A CubeSat (1U-class spacecraft) is a nanosatelite satellite for space research that is made up of multiples of 10x10x11.35 cubic units, with a weight less than 1.33 kilograms. CubeSat are most commonly put in low Earth orbit by deployers on the International Space Station (ISS), or launched as secondary payloads on a lunch vehicle. Thus, in 1999 CubeSat specifications were developed by California Polytechnic State University and Stanford University to help universities worldwide to perform space science and exploration. The goal is to enable graduate students to be able to design, build, test and operate in space a spacecraft with capabilities similar to the first spacecraft, Sputnik
Application
In terms of applications, CubeSats are generally used to demonstrate spacecraft technologies that are targeted for use in small satellites or that present questionable feasibility and are unlikely to justify the coast of a larger satellite. In our case, the CubeSat will be used to test a new deorbitation system.
Design
Many CubeSat’s specifications have several high-level goals. Miniaturizing satellites does reduce the cost of development and especially the launching cost. Standard CubeSats are called 1U made up of 10x10x11.35 cm units designed to provide 10x10x10cm of useful volume while weighing no more then 1.33 kilograms. Those are the characteristics of the standard size 1U used in our ECE CubeSat’s project. It is possible to increase the size of a CubeSat by adding units. For example, CubeSat composed of two units (2U) and 3U CubeSat for 30cm3 availible volume permitting more advanced missions and more are obtained this way.
Structure
Materials used in the structure must feature the same coefficient of thermal expansion as the deployer to prevent jamming. Specifically, allowed materials are four alluminium alloys: 7075, 6061, 5005 and 5052. Aluminium used on the structure which contracts the P-POD must be anodized to prevent cold welding, and other materials may be used for structure if a waiver is obtained. Furthermore, further consideration is put into material selection as not all materials can be used in vacuums.
The ECE3SAT project is a student project developed at the french engineer school, ECE Paris . The goal of the project is to send a CubeSat in space to verify a physical theory permitting a fast deorbiting. The project started in September 2015 after the ESA authorization.
The ECE3SAT is composed of five modules named
- Energy Power Supply (EPS)
- Telecommunication System (TCS)
- Attitude Determination Control System (ADCS)
- OnBoard Computer (OBC)
- Payload (Payload)
The CubeSat development is divided in five different phases, 0, A, B, C & D and E & F. Each phase is supposed to be realized in 1 Year.
The goal of the project is to succeed in the mission, but also to enable students to overcome a physical theory through the realization of a satellite.
A space project needs a big management to be successful. That’s why all space projects are divided into various logical stages, called Phases. Each phase is designed to end with a major milestone in the development, such as proof of concept, equipment delivery, launch, etc.
The text in bold and italics describes the phases specifics for CubeSats.
Typically the phases are:
Phase 0
Phase 0 is sometime already ready but in a project like a CubeSat it needs to be done. So this includes focusing on the technical aspects of the project, the management plan, the group project agreement and building partner’s interest.
The Phase 0 is very important for CubeSat Projects because everything needs to be thought from scratch. (Done in 2015-2016)
Phase A
Phase A is a relatively low cost paper exercise, designed to expand the basic idea and confirm that the project is feasible.
During Phase A, the Principal Investigators (PI) shall define the overall experiment plan. Co-Investigators (CoIs) may be necessary to avoid experiment duplication, share the work loads, or be responsible for the development of sub-systems, algorithm’s, data interpretation packages etc.
Includes: Technical Specifications, Coordination Board, Simple Simulations. (Done 2016-2017)
Phase B
The main purpose of Phase B is to convert the conceptual idea into a prototype model upon which further investigations can be performed to confirm the feasibility of the concept, before going to the expense of building space qualified hardware. The initial prototype models sometimes referred to as Engineering Models (EM), can use non-space qualified materials or procedures. They are not constrained by either weight or size restrictions, but they should prove the functionality of any special components or materials that would eventually be incorporated into a flight model. Following testing and acceptance of the hardware or software, the project is ready to move onto the next phase.
Includes: Technical Modeling, Designing, Simulations, Low level Feasibility. (In process 2017-2018)
Phase C & D
Phases C and D are usually combined. The purpose of Phase C & D is to convert the outcome of Phase B into a fully space qualified model that would be suitable for either space activities on board the actual flight or as ground equipment or software to control a particular activity.
Includes: Technical Specifications, Management Project, Technical Tests & Validations, Partners Financial investments.
Phase E & F
Phases E & F are associated with the launch campaign and the post launch activities, tests, preparation.
Includes: Launch preparation, Ground Relay, Start of launch, Partners implications
Data analysis phase
The ultimate stage of a project is the analysis of the data to reach a scientific conclusion. Analysis of data may take place at any stage of the experiment, prior to flight, in-flight and post flight.
The interesting part starts ! Will the mission be a success ?