Paxi was placed in a Large Diameter Centrifuge gondola which normally housesresearchers' and students' experiments at ESA's ESTEC establishment.
As the centrifuge starts spinning, the relative g-levels within the gondola increase and this causes Paxi's weight to increase. At 20 g, Paxi weighs 20 times what he normally does on Earth. As the centrifuge spins down, the g levels decrease and eventually when the centrifuge stops, return to normal.