Internship Diaries: Interning at Cosine, a leading company in the space sector

Image Credit: Cosine

Lluís Martínez Fortuño shares his experience coding for a future ESA mission, NewAthena’s observatory

In the summer of 2024, I did an internship at Cosine, a company based in Sassenheim, the  Netherlands. My internship focused on modeling the performance of a future ESA mission, NewAthena’s observatory, which is being developed by Cosine.

Cosine is a leading company in the space sector that combines physics and technology to deliver state-of-the-art products. Cosine has two business units: high-energy optics and remote sensing. The high-energy optics unit has been contracted by the European Space Agency to build the mirror assembly for the NewAthena mission. Cosine has developed the Silicon Pore Optics technology, which has been chosen as the ideal technology for this mission. NewAthena will be launched in 2037 and will be the largest X-ray observatory ever built, studying some of the hottest and most energetic phenomena in the universe. Some of the objects studied will be supermassive black holes, active galactic nuclei, and plasma located in the intergalactic medium. By studying these objects, astrophysicists will learn more about the origin and evolution of galaxies. The context of this internship motivated me to pursue it, as I would be working on an observatory that will shape the future of astrophysics. As an astrophysics graduate, this was an opportunity I felt I could not miss.

During my internship, I was part of the Data Synthesis and Software team; we were responsible for creating software that analyzes and models the performance of the mirrors used in the observatory. The current design consists of 600 mirrors distributed in 15 rows, each with different effective areas and azimuthal positions. Each mirror has a Point Spread Function (PSF), which tells us how each mirror will respond to incoming light. The overall PSF of the observatory needs to fulfill a few specifications. Resolution requirements and simulations are needed to ensure that the current design is compliant with these specifications.

My internship involved modeling the overall PSF of the NewAthena observatory by adding the contributions of each of the 600 mirrors. I also modeled how this PSF is affected by possible misalignments and potential resolution distributions for the different mirrors. At the end of the internship, I had the chance to present my findings to the company in the weekly Thursday meeting and commit my code to the company’s general database.

This internship was computationally intensive, but it helped me strengthen my skills in Python and software architecture. There were days when my code would not stop giving errors; sometimes, I spent the whole day coding only to get unrealistic results. However, one needs to understand that results will not come on day one; you need to keep working towards your goals little by little, and eventually, the solution will come to you. The highlight of my day was when the code I had been working on for weeks finally worked and gave me accurate results! Even if you are stuck and things seem hard, you can always ask for help. All my colleagues at Cosine were extremely helpful and offered great advice. The internship taught me the importance of collaboration and how working in a large team can accelerate your personal and professional growth. It was amazing to work on a meaningful project that will eventually be extremely valuable to the company.

There were several reasons I decided to intern at Cosine. I have always wanted to contribute meaningfully to the field of astrophysics and have been endlessly fascinated by the discoveries made by the Hubble Space Telescope and XMM-Newton. I knew I would learn a lot during this internship, especially regarding software and coding skills, as they are extremely valuable in the space sector. Not only did I improve my coding skills, but I also wrote the best code I have ever written! Coding at Cosine was unlike anything I had done before. In university, I did coding assignments as part of my coursework; back then, as long as the code produced the correct output, I did not put much effort into making it neat and easy to read. On the other hand, the coding I did for my team was serious and will be used in ESA’s next mission, so the stakes were very high. The fact that I worked on a mission that future generations of astrophysicists will learn from is... extremely cool. Cosine is a global company with significant built-in diversity. My teammates came from many different countries, and I learned a lot about their experiences and career trajectories during our lunch and coffee chats. Even though I was a student intern, I was welcomed into the team as a professional and was very much an integral part of it from day one.

I have many good memories from the internship. I particularly enjoyed our biweekly team meetings, where we discussed our individual projects, gave progress updates, and asked for advice. I also enjoyed getting to know my team outside of work at the company’s social events. One event was a Formula One racing competition, where two Formula One simulators were brought to work, and short races were held between two contestants. The winner received VIP tickets to the Dutch Grand Prix with the managing director of the company. I managed to win the competition and attend! The seats were located on the main straight of the circuit, giving us perfect visibility of the race start, pit stops, and podium ceremony. That is definitely an experience I will never forget.

This internship has skyrocketed my career and set a strong foundation for my future. I would recommend all UCD students take internships as part of their undergraduate and graduate studies. In my case, I learned a lot from my internship and improved the skills I had learned in college. I advise students to contact their professors and local companies about internships. You will learn a lot from what you have studied, and an internship will help you decide whether you want to pursue a similar job in the future or something different. It will help you take baby steps toward discovering what you enjoy doing.