A doctoral student in the Department of Physics at the Hebrew University (32) breakthrough PhD research of Dan Cohen will help realize one of the most important questions in nuclear physics of today: What is the size of particles called protons, which are in the nucleus of every atom. Various experiments to measure the radius of the proton, some of them in recent years have yielded different results without a satisfactory explanation; the trial of Cohen, led by Prof. Guy Ron, offering innovative technique and guarantees. Cohen is part of an international group which integrate and work at the particle accelerator PSI, Switzerland. this year he is expected to complete at the Hebrew university the construction of his special detector, which is a screen like detector, the two types of particles will scatter on it: electrons are elementary particles in nature, and muons are similar to electrons but heavier than them. the experiment will be carried out at a particle accelerator in Switzerland, which is the only site in the world where this can be done. the accelerator will shoot at the protons the two particle types (separately) from the information collected on the interaction between the protons and the particles using their dispersion on the detector, it will be possible to calculate the size of the proton. One can imagine this ball doused in water and then with oil, and from the different distribution of the oil and water drops splashing from the ball, we can calculate its size. The experiment is expected to be completed within three years. Cohen, who dreamed of being an astronaut from an early age, realized that the way to realize the dream goes through learning sciences. He is alumnus of Space Studies Program 2014, from the International Space University and volunteer as the head of landing site selection team at SpaceIL. This is a non-profit organization founded in 2011 by three young Israeli engineers, and aims to launch the first Israeli spaceship on the moon, and a way to inspire the next generation of scientists and engineers. After completing his doctorate one can assume that Cohen will do postdoctoral at the United States which leads the field, and then he wants to come back and to be a researcher at Israel. The dream of being an astronaut is still vivid in his blood.