The successful voyage of SpaceX’s unmanned Crew Dragon to the International Space Station this weekend put the US one tantalizing step closer to the day when American rockets will again ferry the nation’s astronauts into space.Sometime this summer, both Elon Musk’s Space Exploration Technologies Corp. and Boeing Co. are scheduled to launch crews toward the ISS, ending a long drought in which the US has had to hitch rides in Russia’s Soyuz capsules. NASA awarded them contracts worth as much as a combined $6.8 billion in 2014 to fly US astronauts to the ISS, splitting what’s known as the Commercial Crew program to avoid a monopoly.Saturday’s launch of the crew cabin from Florida and Sunday’s docking at the ISS mark “a major milestone for SpaceX and for the nation,” said Taber MacCullum, chairman of the Commercial Spaceflight Federation, in a statement. “This mission puts us a step closer toward re-establishing American access of American astronauts, on American rockets, from American soil to the ISS for the first time since the Space Shuttle retired in 2011.”SpaceX may get there first, in July based on how the test schedules are shaping up, with Boeing following just a few weeks later. In addition to the lucrative launch business, both companies see space tourism as a future source of revenue. Boeing CEO Dennis Muilenburg congratulated Musk in a tweet for reaching the testing milestone.“This is a huge milestone and shows how far NASA and the industry have come together,’ said Lori Garver, a former deputy NASA administrator, via email. “Lots more important milestones ahead, but the team can be very proud of this accomplishment - I know I am!”For SpaceX, the next big test comes later this week. Crew Dragon, which carried some supplies to the ISS along with a sensor-laden mannequin, is slated to undock from the space station at 2:31 a.m. New York time on Friday, then return to Earth and splash down into the Atlantic Ocean with the help of four parachutes.Crewed FlightsThough dates can shift, the latest schedule from NASA has SpaceX conducting an in-flight abort test in June and then following up in July with Demo-2, a flight that will take NASA astronauts Bob Behnken and Doug Hurley to the ISS. That’s the final hurdle before the system would be certified to enter the official rotation of crew-carrying flights.NASA says that Boeing’s CST-100 Starliner continues to undergo testing in preparation for its Orbital Flight Test, slated for no earlier than April. If all goes well, Boeing would then have a launch-pad abort test no earlier than May and a crewed flight test no earlier than August.Beyond the test flights, Boeing and SpaceX could use their vehicles to offer space rides to tourists and others with the means to pay. SpaceX is interested in flying Crew Dragon passengers other than government astronauts but hasn’t begun prospecting for customers, Musk said Saturday at a news conference at the Kennedy Space Center.