Washington: The strength of the astronauts increased to six on the International Space Station (ISS) as three Expedition 48 crew members on Sunday joined the orbital laboratory to facilitate key research. NASA astronaut Kate Rubins, cosmonaut Anatoly Ivanishin of Roscosmos, and astronaut Takuya Onishi of the Japan Aerospace Exploration Agency (JAXA) joined their Expedition 48 crew members aboard the space station when the hatches opened between their Soyuz MS-01 spacecraft and the ISS. Expedition 48 Commander Jeff Williams of NASA and Flight Engineers Oleg Skripochka and Alexey Ovchinin of Roscosmos welcomed the trio aboard their orbital home. In the coming months, the astronauts are scheduled to receive multiple cargo resupply flights delivering several tons of food, fuel, supplies and research, the US space agency said in a statement. SpaceX's ninth commercial resupply services mission under contract with NASA is scheduled to launch to the space station no earlier than July 18 aboard the Dragon cargo spacecraft. It will include experiments to test the capabilities for sequencing DNA, understand bone loss, track heart changes in microgravity and regulate temperature aboard spacecraft. The first of two international docking adapters is also headed to station in Dragon's unpressurized trunk which will allow commercial spacecraft to dock to the station when transporting astronauts in the near future as part of NASA's Commercial Crew Programme. Williams and Rubins are scheduled to install the adapter during a spacewalk later this summer. Rubins, Ivanishin and Onishi are scheduled to remain aboard the station until late October. Williams, Skripochka and Ovchinin will return to Earth in September.