Thermo-Mechanical Engineer

Location: Sassenheim

Your (space) mission
As the Thermo-Mechanical Engineer at cosine you help shape the next generation of space-borne optical instruments that push the boundaries of Earth observation and planetary science. Working from the cosine headquarter, you contribute to missions that will fly on satellites and asteroid explorers, where performance, precision, and reliability are critical for success in orbit. You join an international team with a start-up mindset, where engineering decisions directly influence hardware that will operate in the most demanding environment imaginable: space.

From early design choices to final qualification testing, your work ensures that our instruments survive launch and perform flawlessly in orbit, enabling new scientific discoveries and commercial applications in the rapidly evolving New Space sector.

Tasks & responsibilities
In this role you will:

Lead and contribute to the thermo‑mechanical design of high‑precision optical instruments for space applications

Perform thermal and structural analyses to ensure performance under launch and orbital conditions

Support the full development cycle from concept design through to assembly, integration, and qualification testing

Collaborate closely with optical, mechanical, and system engineers in an international multidisciplinary team

Contribute to solving complex engineering challenges in a fast‑paced, project‑driven environment

Your profile
We are looking for candidates with the following qualifications:

A Master's degree in Mechanical Engineering, Aerospace Engineering, or a related field

Experience in thermo‑mechanical design and analysis, ideally within space, aerospace, or high‑tech precision engineering

Strong understanding of thermal and structural behavior of complex systems under extreme conditions

Hands‑on mindset with experience in hardware development, integration, and testing

Ability to work effectively in small, international teams with a proactive and collaborative attitude

Strong communication skills in English, both written and spoken

What we offer
At cosine, we highly value our employees, and we will support your professional and personal development. We also provide our employees with:

A unique, international working environment at the intersection of physics and engineering

The opportunity to deliver end‑to‑end solutions in autonomous project teams, in close collaboration with customers

27 days of annual leave (based on full‑time employment)

Annual bonus based on personal and company performance

Hybrid working options, including the possibility to work partially from home

Company bicycle‑and fitness plan

A personal development budget

Initial one‑year contract with the intention of a long‑term collaboration based on mutual satisfaction

About cosine
Founded in 1998, cosine is a world‑leading developer of space instrumentation and measurement systems, making the invisible measurable and the complex actionable. Its expertise spans High‑Energy Optics, including optics developed for ESA's future New Athena X‑ray observatory, as well as remote sensing solutions for Earth Observation and planetary science. With over 25 years of experience and advanced cleanroom and assembly facilities across the Netherlands, Germany, and Italy, cosine brings deep scientific and engineering expertise to some of the most demanding missions in space and on Earth.

What makes cosine a unique place to work is that your work goes end‑to‑end: from concept and design to building, testing, and delivering hardware that actually flies in space. You work in small, highly skilled teams where you have real ownership and impact, alongside experts in optics, physics, nanofabrication, and systems engineering. cosine is committed to providing an inclusive and equal opportunities work environment where everyone can thrive.

As a proud member of the Women in Aerospace community, we recognise the importance of diversity, inclusion, and equal opportunity in the workplace.

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