<span>SpaceX pressed ahead with its second attempt to launch astronauts for Nasa — a historic first for a private company — but stormy weather has threatened more delays.</span> <span>Elon Musk’s company came within 17 minutes on Wednesday of launching a pair of Nasa astronauts for the first time in nearly a decade from the US, before the threat of lightning forced a delay.</span> <span>Nasa Administrator Jim Bridenstine said managers were debating whether to again delay the next launch attempt from Saturday to Sunday to take advantage of a slightly improved forecast at Kennedy Space Center.</span> <span>At an outdoor news conference on Friday, Mr Bridenstine stressed the need for safety for astronauts Doug Hurley and Bob Behnken — no matter how many times it takes to launch them in a SpaceX Dragon capsule to the International Space Station.</span> <span>“We cannot forget this is a test flight. This — is — a — test — flight," he repeated. </span> <span>“We will go when everything is as safe as we can possibly make it."</span> <span>Forecasters put the odds of acceptable weather conditions on Saturday at 50-50, with the outlook improving to 60 per cent favorable on Sunday. Rain and clouds were the main concerns for both days.</span> <span>Hurley and Behnken, veterans of two space shuttle flights, said they’ve both faced launch delays before. </span> <span>In a tweet Friday, Hurley said his first shuttle flight was scrubbed five times for weather and technical issues.</span> <span>“We’re ready for the next launch opportunity!” Behnken tweeted.</span> <span>While Nasa urged spectators to stay home on Wednesday because of the pandemic, prime viewing spots at area parks and beaches were packed. </span> <span>A weekend launch could draw even bigger crowds. </span> <span>The Kennedy Space Center Visitor Complex reopened on Thursday, after a 2 1/2-month shutdown, and within a few hours, all 4,000 tickets were snapped up for Saturday’s launch attempt.</span> <span>President Donald Trump and Vice President Mike Pence were expected to return on Saturday to watch from inside Kennedy. </span> <span>Whether an attempt is made Saturday or Sunday, “There will be no pressure. We will launch when we’re ready,” Bridenstine added.</span> <span>The last time astronauts launched to orbit from the US was in 2011 when Atlantis closed out the 30-year space shuttle program. Hurley was on that mission as well.</span> <span>Nasa hired SpaceX and Boeing in 2014 to get the ball rolling again — kicking off a commercial revolution for getting people to low-Earth orbit, according to officials. </span> <span>In the meantime, Nasa has spent billions of dollars to buy seats on Russian Soyuz capsules for US astronauts, in order to keep the space station staffed.</span> <span>Boeing's first astronaut flight, on the company's Starliner capsule, is not expected until next year.</span> <span>On Friday, a prototype of its Starship exploded while undergoing a routine engine test at the company’s Texas site. </span> <span>The ship vented large amount of gases and was engulfed in a tremendous fireball.</span> <span>SpaceX did not respond immediately to a request for comment.</span> <span>Nasa, which has a contract with SpaceX to develop Starship for its lunar landing program, has no problems going ahead with this weekend’s unrelated launch of astronauts from Cape Canaveral, agency spokesman Bob Jacobs.</span> <span>“That’s a test program. That’s why they test," Jacobs said.</span>