SpaceX is eleven years old, has six successful launches on the books, and forty-one missions scheduled between now and 2017. Their next mission, CRS-2, for NASA is scheduled for launch on March 1. This launch is the second of twelve contracted between NASA and SpaceX to completed by 2015.
The Falcon 9 and Dragon last flew in October 2012. The Dragon docked successfully with the International Space Station (ISS) and came back to earth safely. What seemed to get the most press coverage during the mission was an issue being reported as an engine explosion. About a minute and nineteen seconds into the CRS-1 launch there was what looked like an engine explosion. This was not an explosion but an example of Falcon 9 redundancy in action. The Falcon rocket detected a sudden loss in pressure in Merlin engine 1 and issued a command to shutdown. The burst, debris, and plume of smoke were the pressure relief panels being ejected to protect engine 1 and surrounding engines. The flight computer then recalculated a new ascent profile and the Dragon continued on to the ISS.
The secondary payload aboard the Dragon, an Orbcomm satellite, did not make it to the designated orbit and fell back to earth burning up in the atmosphere. But here’s what didn’t happen—the Falcon 9 and Dragon did not explode due to this anomaly. The Falcon 9, which uses liquid propellant, can reignite its engines (NASA did not permit that in this case) and has a dual redundant engine setup. Not only can it loose power to two engines and still reach planned orbit, it actually turns off two engines as method of deceleration to limit speed to 5 g’s during a normal flight. The Falcon 9 also has dual redundant avionics systems.
There are other safety features built in like the Falcon being tested to 140% of maximum expected payloads instead of the 125% NASA requires. Or the launch pad grips that keep the Falcon in place allowing all nine engines to fire to full power before being released from the launch pad. This “hold-before-release” feature, similar to what we experience on an airline runway, allows propulsion and vehicle systems to be confirmed before the rocket lifts off.
And that’s just the Falcon. The Dragon is a showoff when it comes to redundant features. The Dragon’s Draco thrusters also use liquid propellant and have dual redundancy. The flight computers are up to quad fault tolerant, the telemetry and video transmitters are single fault tolerant, and the drogue and main parachutes are each dual redundant. The thermal control and power systems also have multiple redundancies. The spacecraft has the most powerful heat shield in the world and a coating of SPAM on its backshell, SpaceX’s Proprietary Ablative Material. Not too shabby for a spacecraft with Puff the Magic Dragon as its namesake [page 26].
So how much does this über safe, redundancy filled showboat cost us for a round trip to the ISS? About $133 million per flight. That may seem like a shocking number but the Space Shuttle was about $1.2 billion per flight. One Space Shuttle flight equals the amount of money spent to develop the Falcon 9 and Dragon, $300 million each, and almost five round trips to the ISS. SpaceX has been able to to keep costs low by rethinking the recipe for space vehicles and then cooking from scratch. They buy raw materials and build most of the Falcon and Dragon in house.
UPDATE: I transposed my information about the Soyuz in the last sentence of the article. I deleted it and will update soon with a cost and cargo comparison of the other cargo spacecrafts that dock with the ISS.