Meet the Team

We have a highly skilled team working on inspiring projects with the aim of moving technology forward and conducting cutting-edge science.

Roel Eerkens
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Being on the frontline of development and research is very important to Roel Eerkens. Space is part of this frontline

One of his strong suits is combining people's skills and being creative in both business and engineering. The space industry is not directly linked to creativity, yet solving complex problems is.

Roel's focus within the T-Minus team is to make sure that the customers get what they require and to make sure that new projects are the best solution for the customer.

Hein Olthof
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Hein Olthof's field of expertise are rocket propulsion, systems engineering, and rocket operations. 


He acquired his M.Sc. title in Aerospace Engineering at Delft University of Technology in 2013 with a thesis on solid rocket motor design and solid propellant development.


During his internship at Esrange Space Center as a test engineer and ground safety engineer he worked amongst others on the Mapheus-2 sounding rocket and the D-SEND balloon campaign

Eric Smit
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Eric Smit has a Master’s degree in Electrical engineering, with a specialization in aerospace systems. He was introduced with space systems during his bachelor’s study, where he worked on the transmitter for the Delfi-C3 satellite.

 As T-Minus Engineering co-founder, Eric started working on the Delfi-n3Xt satellite, where his work mainly consisted of building the flight versions of many subsystems.

Mark Uitendaal
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Mark Uitendaal is an aerospace engineer with a master degree from the Technical University of Delft. Mark was project manager and chief engineer of the STRATOS I project launched in 2009. This rocket achieved the European altitude record for amateur rockets.


He co-founded T-Minus Engineering, since he is a firm believer of making the sounding rocketry and space business cheaper and more efficient via miniaturisation and commercialisation, a goal which he tries to achieve via T-Minus Engineering.

Ron Wierdsma
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Ron Wierdsma is a skilled manufacturer and the first full-time employee of T-Minus. After completing his internship he has been a core driver of the manufacturing process at T-Minus.

His eye for quality and all round capabilities are essential to the company.

His work has flown on almost all our missions and his hands-on approach is valued during operations.

Lars Pepermans
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Lars Pepermans is an Aerospace Engineer with a masters degree in Space Engineering from Delft University of Technology.


During his studies, he was chief recovery of the Stratos III project and chief engineer of the Supersonic Parachute Experiment Aboard REXUS (SPEAR).


His primary interest lays in the field of sounding rockets and Entry Descent and Landing systems.

Paul Beckers
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Paul Beckers has studied Electrical Engineering at Delft University of Technology.

He worked on the Delfi-C3 and Delfi-n3Xt nano-satellites as part of a graduation project, with the focus on Ground Support Equipment and Attitude Determination and Control.

Paul is also an alumnus of the university's solar racing team, known for their solar car "Nuna" that has participated in the World Solar Challenge since 2001 winning multiple editions.

Laura Koelemij
Graduate student
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Laura Koelemij is a graduate student, working on a thesis with both T-Minus and Delft University of Technology. This thesis focusses on developing a novel flight termination system. Her earlier internship consisted of performing trajectory simulations and launch site wind analyses.


She is currently in the final phase of the Space Flight master’s programme at Delft University of Technology. Prior to this, she obtained a BSc in Applied Physics at Eindhoven University of Technology.

Maartje Zaalberg
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Maartje Zaalberg is doing an internship at T-Minus from the Leidsche Instrumentenmakersschool

Oscar den Buurman
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Oscar den Buurman is doing an internship at T-Minus Engineering from the Haagse Hogeschool