Gaining practical experience is a key part of any engineer’s studies. At EPFL, Lausanne’s Swiss Federal Institute of Technology, the EPFL Spacecraft Team aims to provide just that. Founded in 2019 by a group of passionate students, the team began working towards designing and building two CubeSats from scratch. Today, the team has already launched a payload, and the satellites are in the works.
“We have students from the first year of bachelor until the last year of master, so we really have the whole range. They don’t need to have the technical skills when they join, so we also take first-year students. Then they start to work on a more educational program, CanSat. The people who are the most motivated and are good at working in a team also stay in the association for a longer period of time, and that’s what we want.
Normally the people that join us don’t have a space background, but they are motivated to learn. That’s what we have the association for, to give people this knowledge”
told us Lina Kuhlmann, president of the association, whom we had the pleasure to talk to.
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CHESS
The team’s flagship project is CHESS, a fleet of CubeSats designed to study Earth’s exosphere. CHESS, or Constellation of High-Performance Exospheric Science Satellites, is a joint project between many Swiss universities. The project is scheduled to launch several satellites over many years. Launches will start with a test spacecraft, and will eventually see an entire constellation orbiting the Earth.
The first mission will be CHESS Pathfinder 1, due to launch at the end of 2026. The spacecraft will carry two scientific payloads: CubeSatTOF, a mass spectrometer, and a GNSS receiver. The two instruments, provided by the University of Bern and ETH Zürich respectively, will determine the chemical composition and density of the exosphere.
The first one will detect the neutral atoms and ions found around the satellite. The second one will receive signals from navigation satellites to precisely track the spacecraft and estimate the density of the air by measuring the drag.
The first satellite has already found a launch opportunity, being awarded one on a Chinese launch vehicle. This came as the prize for winning the IAF-CSA Space Universities CubeSat Challenge 2.0 in 2023.
The platform
The payloads will be installed on a 3U CubeSat platform built by EPFL Spacecraft Team. It will provide essential functions such as power generation, attitude control, and communications. The On-Board Computer will be the brain of the satellite. Its task will be to accommodate the flight software and control all other systems.
The communication system will be composed of two modules: an off-the-shelf one operating in UHF, and a custom-built one transmitting over the X-band frequency. The former will be used for sending telemetry and receiving commands, and as such the reliability offered by a commercial component will be crucial. The latter will be used to transmit the scientific data back to Earth.
Power will be provided by four solar panels, which will then be distributed throughout the satellite. The Electrical Power System will incorporate many protective features as well as complete redundancy. To minimize risks, the system will be demonstrated in orbit in January 2025. The Attitude Control and Determination System will be CUBESPACE’s CubeADCS Gen 2. Once again, the choice fell on a commercial option to ensure reliability on a crucial system.
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Ensuring reliability
Multiple in-orbit demostrations are planned to meet both the reliability and educational requirements of the program.
“When you’re building a CubeSat theoretically you could buy all the components off-the-shelf, but then you don’t have the educational value. That’s why we decided to build most of the components in-house. This then naturally comes with a higher risk, and that’s why we will do these in-orbit demonstrations. That’s one reason to reduce risk, but also having these frequent launches allows students to be part of actual space launches.
Our final launch is at the end of 2026 and most of the students that are involved now will have graduated by then, so doing this allows them to work on a subsystem that will actually fly, go through testing and integration, and allow them to gain knowledge”
Kuhlmann explained.
In-Orbit Demonstrations
Bunny is a flight computer launched in January 2023 as a rideshare payload along a Starlink satellites batch. Its purpose was to demonstrate the use of commercial-grade electronics for spaceflight applications. It was hosted on D-Orbit’s ION Satellite Carrier and was the first time EPFL launched something in space since 2009.
X-Band is a communication system designed by the team since no satisfactory commercial solution was found. Its aim is to provide robust communications with satellites and to enable the transmission of scientific data. It is a Software Defined Radio operating in the 10.45 – 10.50 GHz, an X-Band amateur frequency. Twocan is another piece of hardware developed to support future endeavors. It is a new flight computer, developed thanks to the lessons learned with Bunny. It incorporates more computational power and more redundancy.
Both Twocan and X-Band are planned to fly in 2024 on a demonstration mission. This will allow the team to validate their design and reduce the risk of failure on CHESS. Before that, all systems are thoroughly checked on the ground as well.
“We have many available facilities. We have a shaker for vibration testing at the University of Bern, a vacuum chamber, and clean rooms at EPFL. We’re lucky that we have access to these facilities. Especially at the University of Bern, we can benefit from working together with the Space Science & Planetary Sciences Institute, which has extensive experience in space missions and provides us with valuable knowledge” Kuhlmann said.
CanSat
Some members of the EPFL Spacecraft Team also work on CanSats, in collaboration with EPFL’s Rocket Team. These are small satellites designed to fit into a soda can that are launched by amateur rockets. Even if they don’t reach space, they are still a valuable opportunity to gain experience. At EPFL Spacecraft Team a few small subteams compete with each other to build the best one.
“They work in groups on their own CanSats, and they are in competition with each other. We have a launch in May with the Rocket Team where hopefully all goes well. They design the CanSats all by themselves and they decide what they want to measure. The most successful CanSat there wins. We have one slot for a rocket that will go to EuRoC, the rocketry competition in Portugal, so our best CanSat will fly on the rocket that will go to EuRoC”
Kuhlmann told us.
The team has ambitious goals and a long list of planned missions. There are already ideas for missions beyond CHESS Pathfinder 1. “Then we will have CHESS Pathfinder 2, which is an identical CubeSat that will go to a different orbit. Once we have a platform we can rebuild this CubeSat and we can look for another launch opportunity again” added the president.
The next few years will surely be full of activity for the EPFL Spacecraft Team, so let’s wish them to be very successful.
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