Why Do We Need to Test Our Sensors in Space?

So why do we want to perform an experiment on the International Space Station (ISS)? Why can’t we do it on Earth? And why is it so important to us?

Thomas and I have been developing new concepts and technologies for measuring radiation for a couple of years now. We started working on it while we were still studying at the Technical University of Munich. Then we made it our PhD projects. So we already invested quite a part of our life into developing instruments that we believe can help make humanity’s voyage deeper into space possible.

During these years of work, we performed many tests—in the lab, at particle accelerator facilities, and aboard stratospheric balloons—that were designed to demonstrate the working principle of our sensors. These tests also helped us understand the properties and characteristics of the components we use to a great level of detail. Only with this knowledge can we build the sensors that we want to test in the 3D-DOS experiment.

Yet, none of the tests we can perform on Earth can validate the full set of capabilities of our sensors. The principle reason for that is that it is almost impossible to re-create the space environment in a laboratory on Earth. Most relevant for us is the radiation environment. In space it is isotropic, so radiation particles can hit you from random directions without any possibility to predict where the next one will come from. Space radiation also consists of many different kinds of particles that have randomly distributed velocities.

On Earth, we need to re-create the radiation environment using large machines called particle accelerators. These machines can accelerate one kind of radiation particle at a time to a certain velocity. The particles all travel in one direction, much like photons in a laser beam. If you want to reproduce the space radiation environment, you would need to distribute many of these machines around the sensors you want to shoot radiation at. Since particle accelerators are typically tens of meters long and weigh hundreds of tons, this solution is impractical and a lot more expensive than bringing a small experiment to the ISS.

So, for us, 3D-DOS is about bringing some of our sensors to space for the first time to validate that they work as we designed them to. And it is also about concluding years of development work with a final and hopefully successful test.