Astronauts aboard the International Space Station (ISS) opened the hatches to the SpaceX Dragon capsule Saturday, marking the start of several days of unloading supplies from the vessel. \"The hatch between the newly-arrived SpaceX Dragon spacecraft and the Harmony module of the International Space Station was opened by NASA astronaut Don Pettit at 5:53am EDT as the station flew 253 miles [407km] above Auckland, New Zealand,\" NASA announced in a statement Saturday. SpaceX\'s Dragon is the first-ever private spacecraft to supply the ISS. The spacecraft is transporting supplies to the ISS including food, water and clothing for the astronauts and it will haul back trash left at the station. During a press conference Saturday, Pettit explained the load of materials that can be delivered and taken out is \"about as much stuff in here as I could put in the back of my pickup truck.\" He also hailed Friday\'s historic docking of the unmanned Dragon spacecraft at the ISS. \"We all remember the transcontinental railroad ... it was commemorated by pounding in a golden spike. This is kind of the equivalent of the golden spike,\" Pettit said. He said after the retirement of NASA\'s space shuttle fleet, there was \"little opportunity to do this.\" The docking and supply delivery is \"a great first step to move us forward,\" Pettit added. NASA said Pettit entered the Dragon Friday with Station Commander Oleg Kononenko, both wearing protective masks and goggles. \"The goggles and masks will be removed once the station atmosphere has had a chance to mix air with the air inside the Dragon itself,\" NASA said. Upon opening the hatch to the SpaceX Dragon Saturday, Pettit said it had the \"smell of a brand new car.\" Pettit and Kononenko were then joined at the entrance to the hatch by European Space Agency astronaut Andre Kuipers and Russian cosmonaut Gennady Padalka, SpaceX said in a statement. Before docking, the capsule was \"captured\" by a robotic arm extending from the ISS. SpaceX is a private California company owned by entrepreneur Elon Musk. The company hopes to allow the US access to the ISS following NASA retiring its shuttle fleet last year.