When, seconds after liftoff on October 28, an Antares rocket built by the Orbital Sciences Corp. fell back and exploded over its launch pad at a NASA facility in Wallops Island, Va., much more than its payload of small satellites and International Space Station cargo may have been lost.   The rocket did not carry a crew, and no one was injured, but damage to the surrounding launch infrastructure was significant. A cursory inspection revealed shattered windows, imploded doors and broken equipment around the launch pad that will require extensive repairs. How much damage has been dealt to Orbital Sciences’s reputation, and perhaps even NASA’s quest to outsource orbital flights, is less certain.   Orbital Sciences is one of two companies NASA now relies on to fly supplies to the space station. Four previous Antares flights, including three to the station, had launched successfully, and five resupply flights remain in the company’s $1.9-billion NASA contract. Orbital Sciences’ stock price has fallen by some 15 percent in recent days and the rocket mishap potentially complicates its planned merger with another aerospace company, Alliant Techsystems. “This is a big problem for NASA,” says Roger Handberg, a space policy expert at the University of Central Florida. “They are now dependent on the commercial sector to lift payloads to the space station, and their own rocket, the Space Launch System, is at least three years out and is intended for other purposes. So what happens if Orbital Sciences can’t get its rockets fixed? Then what do you do?”   The space agency does have some options. NASA officials said the station’s crew was in no danger of running out of supplies for several months, and on Wednesday a Russian Soyuz rocket launched a resupply mission that docked with the station to deliver even more. SpaceX, the other company NASA uses to resupply the station, is slated to launch its fourth delivery in December and has eight more scheduled. Orbital Sciences’s next Antares launch, previously set for April, is likely to be delayed for several months.   According to John Logsdon, a space policy expert at The George Washington University, if Orbital cannot return its Antares rockets to flight in time to fulfill the remaining resupply missions in its contract, NASA could buy additional flights from Russia—or SpaceX, if the company proves to have sufficient “surge capacity.” In “extreme cases,” Logsdon says, NASA could even buy launches from the space agencies of Europe, India or Japan. “This just reinforces NASA’s good judgment in having two providers, both Orbital and SpaceX,” says Eric Stallmer, president of the Commercial Spaceflight Federation, an industry association. If Orbital was the only provider, there might be a six-month or even a year before a return to flight. But SpaceX looks ready and will probably launch [its next resupply mission] in early December, so this redundant system will work.”   This is not Orbital Sciences’s first high-profile launch failure. In 2009 a malfunction in the fairing separation of its Taurus XL rocket destroyed NASA’s Orbiting Carbon Observatory satellite; in 2011 a similar problem doomed NASA’s Glory spacecraft. Even so, in the aftermath of the Antares failure a variety of NASA officials, congressional representatives and senators, and industry experts have issued statements in support of Orbital Sciences and the company’s ongoing service to the space agency.   The cause of this latest failure is not yet known but investigators will be closely examining the Antares rocket’s twin main engines as a possible culprit. Russia designed and built hundreds of the liquid-fueled engines in the late 1960s and early 1970s for a giant rocket to send cosmonauts to the moon but shelved them after NASA’s successful Apollo missions. An American company, Aerojet Rocketdyne, purchased many of the engines in the late 1990s, refurbishing them and offering them to private companies. Orbital Sciences bought 20, some of which were discarded after test-firings revealed flaws.   In a conference call with investors, Orbital Sciences’s CEO David Thompson said that if the Russian main engines were found to have contributed to the accident, the company could attempt to accelerate the estimated two-year development time for an already planned replacement engine.   The fact that Orbital Sciences chose to purchase the old Russian engines for Antares, Logsdon says, “is symptomatic of the fact that the United States has underinvested in its space program and failed to develop a modern propulsion engine.” The Atlas 5, a workhorse U.S. rocket, also uses Russian engines that, albeit newly manufactured, were designed in the 1960s. Another American rocket, the Delta 4, uses domestic-built engines designed in the early 2000s. These Delta 4 engines were the sole large liquid-fueled engines designed in the U.S. since the 1970s until the recent debut of SpaceX’s all-American engines, which the company designs and builds in-house.   The gap in U.S. engine development, Handberg says, was a product of wishful thinking in a post–cold war world. “We’re keeping Russian technologists working, building these things, but we’re not doing the same for ourselves. We can do better, obviously, since the Deltas are flying and SpaceX is building engines. We have the technology and the people, but we don’t seem to have much political will.”   According to Lori Garver, a former NASA deputy administrator who helped mastermind the agency’s outsourcing strategy, political support for more commercial space development is on the upswing, particularly as NASA ramps up its efforts to use private companies not only to transport cargo to the space station, but also crew. In September the agency revealed its selection of SpaceX as well as the aerospace giant Boeing to each ferry astronauts to the space station in coming years. “There are just so many people supporting commercial space now,” Garver says. “It’s really seen as the Russians versus American companies like Boeing and SpaceX. I don’t think there’s a single member of Congress who would vote for the Russians in that matchup.”