Miami - An unmanned SpaceX spaceship carrying food and equipment to the astronauts living at the International Space Station is poised to blast off from a historic Nasa launch pad on Saturday.The Falcon 9 rocket launch of the Dragon cargo ship will be launched from Cape Canaveral's launchpad 39A, which was built and used for the US space agency's pioneering missions to the moon in the 1960s and 1970s.It was also the blastoff point for sending American space shuttles into orbit, until the shuttle program came to an end in 2011.SpaceX, headed by billionaire internet entrepreneur Elon Musk, negotiated a lease with Nasa for the launchpad in 2013, beating out its competitor Blue Origin, which is headed by Amazon founder Jeff Bezos.By the time the launch pad is completely outfitted for sending astronauts to space in 2018, the company will have spent over $100m to adapt it for modern day spaceflights, said SpaceX chief operating officer Gwynne Shotwell."I wouldn't say we saved a bunch of money here," she told reporters, but added that the launchpad's singular place in American space lore made the price tag worthwhile."My heart is pounding to come out here," she told an outdoor media conference near the launchpad on Friday, recalling how she watched the Apollo 11 mission's July 1969 lunar landing on television with her father as a child. SpaceX has endured two costly disasters in the past two years - a launchpad blast that destroyed a rocket and its satellite payload in September and a June 2015 explosion after liftoff that obliterated a Dragon cargo ship packed with goods bound for the space station.The Hawthorne, California-based company has already made one successful return to flight in January of this year, from Vandenberg Air Force base in California.SpaceX on Friday discovered what Shotwell described as a "very small" helium leak in the second stage of the Falcon 9 rocket.After engineers spent the day narrowing down the cause of the issue, Musk said on Twitter that the countdown to launch would proceed."Looks like we are go for launch," he wrote late on Friday, adding that the launch could be aborted within a minute of liftoff if signs indicated a problem with the helium in the upper stage of the rocket.Saturday's launch is meant to carry more than 2 267kg of gear into orbit.If delayed, another opportunity opens up on Sunday morning.