In Search of the Next Earth

It’s one of the great questions: Are we alone in the universe or are there other planets like ours out there? What about other solar systems that are organized like ours? Scientists and astronomers are looking for the answers in an unexpected place. It turns out that starlight holds the key to finding Earth-sized exoplanets (planets outside of our universe.)

Exoplanets orbit stars just like the planets in our own solar system do. A satellite can observe the light coming from thousands of stars at once and record any small dips in the intensity of the starlight. These dips happen when the exoplanet passes in front of the star, blocking its light. By observing these dips over time, scientists can determine how big the exoplanet is, how long it takes to orbit around its star, and whether it’s in the star’s habitable zone. They can even determine whether it’s a rocky, gaseous, or icy planet, how far it is in its lifecycle, and if its atmosphere has clouds.

This is exactly how PLATO, an upcoming European Space Agency satellite, is going to search for exoplanets. PLATO will spend several years patiently observing the stars waiting for those little blips that mean that an exoplanet is passing in front of its star. Scientists across Europe are working on the equipment that will be used in the satellite to observe the starlight. One of those scientists is Lorenza Ferrari, an instrument scientist at the Netherlands Institute for Space Research (SRON) and a project leader for the PLATO AIT phase.

“In the beginning, I enjoyed that I was developing something new that was also advancing the detector. Nine years later, while I still enjoy that I’m working on something new, I also like that it can go to space and be part of a new science.”

Lorenza wasn’t the kind of kid who always dreamed of working in space research when she grew up. Her path to space and SRON was through physics. Lorenza did a PhD in particle physics at the University of Genoa. Following her interest in neutrinos, she worked with a group that was developing a neutrino detector. It was while she was doing the modelling and fabrication of what is called a transition edge sensor that she first heard of SRON. SRON was working with the University of Genoa on the same type of detectors, but for an x-ray mission.

After graduating and becoming frustrated by the lack of permanent university jobs, Lorenza took her detector expertise to SRON. There weren’t many other groups doing this type of research and development at the time and SRON was closest to her family in Italy. “In the beginning, I enjoyed that I was developing something new that was also advancing the detector,” she says. “Nine years later, while I still enjoy that I’m working on something new, I also like that it can go to space and be part of a new science.”

The PLATO space mission is part of the new science Lorenza is working on. PLATO will contain 26 cameras each with a different, yet slightly overlapping, field of view to observe a large portion of the sky at once. Right now Lorenza and her colleagues are developing the space simulator to test these cameras. They have to think about how dark it will be, how cold it will be, and how clean it has to be (since there’s no way to clean a dirty camera from earth.) They also need to make sure that the telescopes and cameras are extremely stable so that any recorded changes in light intensity can be attributed to exoplanet movement, not telescope movement. Lorenza and her team will analyze every aspect of the camera’s performance so that any potential problem can be resolved before the cameras are mounted on the spacecraft.

PLATO is scheduled to launch in 2026 and it will be the first mission Lorenza has worked on to launch. Athena/X-IFU, an x-ray mission she is also part of, will launch in 2031. Big missions like these take 10 to 20 years to prepare for. Most of that time is spent on what Lorenza calls the perfecting stage. “You have to ensure that you reach a level of trust and understanding that what you’ve built can really fly,” she explains. “Because, of course, once it launches you have no opportunity to change it.” Besides these long term projects, her job with SRON has also allowed her to work on a project with a shorter timeline. A few years ago she travelled to a ground telescope in Chile to install and take data with a kinetic inductance detector array that she built and helped to develop. She was thrilled to see something that she worked on gather data to help improve our understanding of the universe. Just wait until PLATO starts sending data!