Management of the ISS unanimously agrees that the Dragon’s propulsion system is operating normally along with its other systems. Therefore they cleared the Dragon for rendezvous for early Sunday. From 30 feet below the complex Kevin Fordm, the present ISS station commander will use the robotic arm to grapple Dragon at 6:3 1 a.m. EST (11.31 GMT), berthing of the Dragon at ISS will occur at about 8:40 am EST (1340 GMT)
Dragon missed its opportunity to rendezvous as planned for Saturday after problems with the craft’s thruster system arose 11 minutes into the launch on Friday. The problem consisted of failure of three of the four pods of thrusters to pressurize. For the first two hours of the mission Dragon was operating with only one set of functioning thrusters. The pods are positioned to provide complete control of the spacecraft’s direction of motion (X, Y and Z axis), as well as orientation (roll, pitch and yaw). This meant the spacecraft could not conduct the needed burns to initiate its approach to the space station. Again the SpaceX team proved that Dragon is resilient as they were able to bring all four of the thrusters online Friday afternoon. They apparently think they figured out why the thrusters at first did not pressurize as SpaceX announced that it is confident that the thruster problem will not reoccur during rendezvous. Dragon will deliver more than a ton of cargo (2,300 pounds) on this $133 million mission to the ISS.
When he heard of the problems of the Dragon spacecraft Space station commander Kevin Ford responded: “That’s space exploration for you. We sometimes have problems and work through them, and that’s how you learn.”
At T+plus 9 minutes, 40 seconds. Falcon 9 had reached orbit with a perigee of 199 kilometers and an apogee of 323 kilometers. The orbital inclination was 51.66 degrees. Moments after the capsule deployed from its Falcon 9 booster controllers at Hawthorne, California, noticed a problem in the Dragon spacecraft’s propulsion system. Computers automatically put the capsule in a safe mode and stopped the craft from extending its power-generating solar arrays. [br]At 4:07 pm EST Elon Musk told the world via social media that all four thruster pods were operational again. A minimum of three pods is required to approach the space station. The Dragon spacecraft’s Draco thrusters are mounted on four pods. Two of the pods contain five thrusters and the other two contain four thrusters, making for 18 Draco rocket jets in total. [br]SpaceX engineers spent Friday evening evaluating data from Dragon’s propulsion system to establish the cause of the malfunction.
Falcon 9 lifted off as planned at 9:10 am EST and experienced a nominal flight. After Dragon achieved orbit, the spacecraft experienced an issue with a propellant valve with just one thruster pod running as the system inhibited three of the four pods from initializing. When the Dragon came over Australia a command inhibit override was given to the spacecraft which brought up its second thruster. When at 11:40 am EST the second pod (pod three) pressurized the Dragon did extend its power-generating solar panels 10 minutes later, while the engineers kept working on pressurizing pod 2 and 4.
Basically SpaceX demonstrated again that glitches do not deter her from completing a mission. And as mission will have glitches no matter how perfect you plan, the resilience to overcome them is actually more telling about your capabilities to handle a space mission than perfect launches would demonstrate. Lets hope this last glitch does not deter the Dragon from being used as a human rated carrying system as having more than one system (besides the Russian Soyuz) to taxi astronauts to the ISS would definitely be a good thing.