People of PACE: Jeroen Rietjens Followed His Passions to SPEXone and PACE

A man stands to the left of the image, seen from the waist up. He is wearing glasses, blue latex gloves, a white mask covering his nose and mouth, and a white clean suit that covers his arms, torso, and head. He gestures to the right of him, holding both hands out towards a large box-shaped item - the PACE spacecraft. The spacecraft is covered in wires, other mechanical sensors and items, and a silver-colored foil-like material.

Jeroen Rietjens is an instrument scientist at the Netherlands Institute for Space Research (SRON) and worked on the SPEXone polarimeter. PACE’s SPEXone instrument is a multi-angle polarimeter. It measures the intensity, degree and angle of linear polarization of sunlight reflected back from Earth’s atmosphere, land surface, and ocean.

What is your favorite atmosphere or ocean related book or movie?

I like “Cloud Atlas” by David Mitchell a lot. It doesn’t have anything to do with clouds except for the title, but it counts. And it concludes with an ‘oceanic’ wisdom when the impact of actions by individuals are compared to insignificant small drops in a limitless ocean: “Yet what is any ocean but a multitude of drops?”

The image is focused in on a man to the left of the image wearing glasses and a blue and red short sleeved polo short. He wears a headset, where the wire is hanging down past the far side of his head. He is pointing at a computer screen which is in the background of the image. In front of him, but out of focus in the iamge are two other people, one sitting next to the man and one sitting across from him, closer to the camera. At the table they are sitting at are computers, coffee mugs, and water bottles.
Jeroen looking at instrument telemetry in the PACE I&T control room shortly after the integration of SPEXone onto the PACE observatory. Image Credit: Dennis Henry

What is your background?

I have a background in applied physics, and I worked with polarization sensitive instrumentation for my master’s and PhD research. At SRON, I work as an instrument scientist. We are the people who fill the gap between the scientists who have great ideas about what they want to measure, and the engineers who build the hardware that perform these measurements. We specify the instruments and do the analysis and make sure that the hardware will survive in space and perform as the scientists desire.

What are you most looking forward to during launch?

It concludes a long period of tremendous work and I hope that we can experience that with all the people who contributed to PACE.

The focal point of the image is the bright sun, centered. Two reflections of the sun are seen to the left and right of the main bright spot. Below the sun is a grassy landscape with a bush directly below the sun. The sky is a dark blue color.
An image of a sundog, one of the most common types of ice halos. Image Credit: Adam Voiland

What is your favorite color and why?

My favorite color is green. The why is more difficult. My second favorite color would be blue, so I think it’s colors from nature that I like.

The image looks down from a plane, looking at an expanse of fluffy clouds. Centered in the image is a glory, a faint circular rainbow.
A glory photographed from 11 km altitude somewhere between Greenland and Canada as Jeroen was coming into the US to watch the 2017 solar eclipse. Image Credit: Jeroen Rietjens

Do you have a favorite atmospheric phenomenon?

I like rainbows a lot! And any other scattering phenomena, such as a glory, or a sundog. The latter occurs in the presence of high clouds with ice crystals: due to refraction by horizontally aligned ice crystals, you can see two additional ‘suns’ at specific angles left and right of the sun.

A man and a woman are standing side by side, the man to the left with his arm around the woman's shoulder. They both have glasses on and their faces are covered in a glittery face paint. They wear green, yellow, and red striped shirts and black vests that have colorful puns on them. They both have large hats upon their heads with green, yellow, and red spirals on them. The lighting in the room is dim and there are streamers hanging on the walls behind them.
Jeroen and his wife in their parade costume of 2020. Image Credit: Jeroen Rietjens



What is a fun fact about yourself?

Outside of work, and mainly during the winter period, me and my family participate in the “Vastelaovendj”-activities in my home-village. This is the Limburgse (a Dutch province) carnival, consisting of, among other things, a yearly music contest, open stage, presentation of the Prince Carnival, a ‘peasant’s wedding’ and a parade. It is a lot of fun and I particularly like the role-reversal aspect of this tradition.

What advice would you give to aspiring scientists or engineers who are looking to get where you are today?

Follow your passion. I had a weakness for space. I was playing with a Space Shuttle and Lego rockets when I was young and was always interested in space. Along the way, I lost track of it but it’s not really a coincidence, I think, that I still ended up working at a space research institute. So, follow your passion and try to make work your hobby and I think you have awesome life.

What is one catch-all statement describing the importance of PACE?

PACE will yield unprecedented data sets that will enhance research into climate modeling, understanding clouds and aerosols and their impact on the Earth climate.

The image shows a landscape of a neighborhood with grass areas, streets, and some houses to the left at the horizon. There are som trees in the center as well as a lamp post. The sky is cloudy and a gray color. The featured part of the image isa double rainbow, spanning from the entire left to right of the image. The inner rainbow is brighter while the outer rainbow is faint.
An atmospheric treat for Jeroen during a bicycle-ride coming home from work. Image Credit: Jeroen Rietjens

Header image caption: “Very proud to have had the opportunity to pose in the Goddard cleanroom with the fully assembled and tested PACE satellite, which hosts our small SPEXone instrument,” said Rietjens. Image Credit: Dennis Henry

By Erica McNamee, Science Writer at NASA’s Goddard Space Flight Center