It has been a tough year in spaceflight. The disintegration Sunday of an unmanned SpaceX Falcon 9 rocket bound for the International Space Station (ISS) was a first for that vehicle, but not for NASA, which has now seen three of the four spacecraft that ferry supplies to orbit fail in the past eight months.

In October an Antares rocket built by SpaceX rival Orbital ATK crashed and burned seconds after liftoff. Then in April Russia lost control of its Progress 59 cargo spacecraft shortly after launch, causing it to fall out of orbit and disintegrate in the atmosphere. Both unmanned freighters were carrying food, equipment and scientific research projects to the space station, just as SpaceX’s Dragon was on Sunday morning before the rocket carrying it broke apart during its climb from Florida's Cape Canaveral Air Force Station.

All three accidents appear to be completely unrelated, and space industry insiders have been repeating their usual mantra in the wake of the latest incident: Rocket science is rocket science, and a certain level of failure is unavoidable. “The astronauts are safe aboard the station and have sufficient supplies for the next several months,” NASA Administrator Charles Bolden said in a statement. “We will work closely with SpaceX to understand what happened, fix the problem and return to flight.”

Yet the rash of mishaps has many worried, especially those in Congress who are footing NASA’s bill and have lately been stingy in allocating funds for NASA’s partnership with commercial companies such as SpaceX. “We would be remiss to underestimate the gravity of the situation right now,” Florida Sen. Bill Nelson, who flew on the space shuttle himself in 1986 and is now the ranking member of the committee that oversees NASA, said in a statement.

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