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SpaceX launch Dragon to the ISS, Dragon has on orbit issues
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Friday March 1st 2013 saw the SpaceX Falcon 9 v1.0 rocket blast off from SLC-40 at Cape Canaveral Florida at 1510 UTC / 10:10am EST, intending to rendezvous with the International Space Station on Saturday.

After a textbook launch and perfect ascent from the Falcon 9, Dragon separated from the second stage of the Falcon 9 when an issue occurred on Dragon, the computer went into passive abort during Draco thruster initialization. The abort cut the computer from being able to deploy the solar arrays and left Dragon on a limited battery life, but in its target orbit.

Elon Musk, head of Space X, tweeted that they were taking steps to override the computer and complete the start up of Dragon. As Dragon passed over the Australian ground station, SpaceX issued a override command to the Dragon to bring the Draco thruster pods online, needed to correctly orient the spacecraft when docking with the ISS.

A little later Elon tweeted that they had positive data for Draco pod 3, showing that the system was responding to the attempts to bring the thrusters online, and went for solar array deployment. Shortly after that, Elon confirmed that solar arrays had been deployed before continuing to try and bring thruster pods 1 and 4 online. The US Air Force stepped in to help SpaceX by giving them access to the TDRS network as Dragon was having issues communicating with ground stations due to not having the ability to point its antenna at the ground.

At 19:57UTC pods 1 and 4 were online and Dragon had transitioned from free drift orbit into active control. During a teleconference with SpaceX and NASA, SpaceX stated that thruster pods 1 and 4 were operational and that pods 2 and 3 were looking good for a full recovery.

The cause of the passive abort on thruster initialization is currently being attributed to a blockage in the helium lines to the oxidizer tanks causing the pressure in three of the tanks to be lower than needed for operation. “We think there may have been a blockage of some kind or stuck check valves going from the helium pressurant tank to the oxidizer tank,” Elon Musk said, also adding that conclusion was just one possibility based on a preliminary investigation. “Whatever that blockage is seems to have alleviated.”

Elon and SpaceX tweeted late on Friday that all four thruster pods were online and fully operational, performing the first orbital burn to bring Dragon into a stable orbit. They then started orbital checkouts of the Dragon, performing manoeuvres to bring Dragon into a favourable position to be able to approach the ISS during Saturday.

The orbital maneouvre sequence was pretty complex, taking dragon into a higher orbit than the ISS to allow the ISS to “overtake” Dragon (objects in higher orbit around a planet move more slowly than those at lower orbits) before Dragon dropped down behind the ISS and slowly increased its speed to approach and eventually dock.

Dragon arrived at the station on Sunday March 3rd at an earlier than planned time, but ISS mission control and crew aboard the ISS were ready to receive their new supply craft. NASA astronauts Kevin Ford, current ISS commander, and Tom Marshburn with support of Canadian astronaut Chris Hadfield, used the CanadaArm2 to grapple the Dragon spacecraft at 1031 UTC marking the arrival of Dragon as part of the ISS. Dragon was originally suppose to arrive on Saturday, 18 hours after launch but due to Dragons initial issues SpaceX missed their original orbital burns causing Dragon to overtake the station in her lower orbit. The arrival of Dragon was only 1 day 19 hours and 22 minutes after launch, barely a day later than the original arrival time.

For the first time, Dragon was moved via ground controllers on the CanadaArm2 rather than the ISS crew, over the next 3 hours the Dragon was checked out for any damage to the Common Berthing Mechanism used to hard mate the spacecraft with station. After ground controllers agreed there was no danger to continue Dragon was moved into per-berthing position and slowly moved into position for berthing. At 1341 UTC Dragon and Station showed that all four Ready To Latch indicators were green allowing for the first part of the berthing to commence. Three minutes later at 1344 UTC the first stage of berthing was completed allowing Kevin Ford to continue into the second stage. The Second stage of berthing is the driving of four sets of bolts that create the hard mate between the Dragon and ISS, installing the spacecraft as a fixed part of the station for her stay.

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At 1356 UTC NASA and ISS confirmed that second stage berthing had been completed and that Dragon was now installed as part of the ISS, firmly attached to the Earth-facing Harmony node, completing the arrival to ISS.

This launch is the second contracted resupply mission and third visit to the space station of the Dragon spacecraft. The commercial resupply service consists of two contracts given to private commercial companies to use their cargo ships to resupply the ISS from US soil under NASA’s Commercial Orbital Transportation Services scheme. The two active contracts are for SpaceX, who are contracted for a minimum of 12 flights of their Falcon 9 and Dragon spacecraft; and Orbital Sciences, who are contracted for eight flights of their Antares rocket and Cygnus cargo ship.

This flight of the Falcon 9 marks the end of life for the original Falcon 9 design, being replaced by a upgraded rocketed called the Falcon 9 v1.1. The new rocket uses the new Merlin 1D engines that provide an additional 2073 kN of thrust at sea level for a total lift off thrust of 5880 kN at liftoff. The tail also looks different going from the 3 by 3 grid layout to having a ring of 8 engines inside the circumference of the rocket with one engine in the middle of that providing a more structurally strong booster and removing the need for extra fairings and casings on the engine cluster of the booster. The upgraded booster allows for more payload to LEO and GTO while also being the first major step towards the Falcon Heavy that uses three Falcon 9 v1.1 cores on its first stage at liftoff.

The Dragon is a unique spaceship as it is currently the only spaceship in service that has the ability to return cargo from the ISS now that the Shuttle was retired. The only other spaceship that returns to earth currently is the Soyuz decent capsule for crew and it has very limited cargo capabilities and all other, including the new Cygnus, operate under a destructive re-entry to dispose of rubbish from station.

The Dragon took 1,493 lb (677 kg) of cargo, 1,268 lb (575 kg) without packaging. Included is 178 lb (81 kg) of crew supplies, 766 lb (347 kg) of scientific experiments and experiment hardware, 298 lb (135 kg) of hardware for the station, and 822 lb (373 kg) of cargo in the unpressurised trunk and other miscellaneous items such as crew care packages, that include a “more healthy option” as Gwynne Shotwell said on Thursdays briefing, also stating that the items come from an employee’s fathers’ orchard.

This is the first time that the Dragon’s trunk will be used for taking cargo to the station. The trunk will be carrying some grapple bars that will be attached to station to allow EVA access to the stations radiators, so if they need access to them for maintenance it is readily available. These grapple bars are a in part designed by SpaceX for the ISS. Gwynne Shotwell said on Thursdays briefing that SpaceX are happy to have some of their hardware permanently attached to ISS.

The Dragon will return 3,020 lb (1,370 kg) of cargo, 2,668 lb (1,210 kg) without packaging. Included is 210 lb (95 kg) of crew supplies, 1,455 lb (660 kg) of scientific experiments and experiment hardware, 884 lb (401 kg) of space station hardware, 84 lb (38 kg) of spacesuit equipment and other miscellaneous items.

SpaceX, is a space transport company headquartered in Hawthorne, California. It was founded in 2002 by former PayPal entrepreneur Elon Musk. With the help of NASAs CRS contracts, SpaceX independently developed the Falcon 9 v1.0 rocket and Dragon cargo spacecraft.

Recently the company has been focusing on its new launcher, the Falcon Heavy, designed to be the most powerful rocket in service today. Also under development is Dragon 2.0, which will include a crew variant as well as propulsive landing capabilities; Project Grasshopper, that is exploring the technologies needed to make rockets rapidly reusable like a fleet of intercontinental airliners, as well as final preparations of the new launch facility at Vandenberg Air Force Base. The new facility, Space Launch Complex 4,  is being designed to accommodate the new Falcon 9 v1.1 and the Falcon Heavy and is expected to be online in the next month or so, according to Shotwell during the Thursday briefing, with a Falcon 9 v1.1 launch happening shortly after.

Image of Falcon 9 from SpaceX on Facebook and SpaceX.com
Images of Dragon at the ISS from NASA.gov 

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About The Author
Chris Trudgen
I am a Freelance Photographer from the South West UK with a passion for space, particularly the rockets that take us there. When I am not doing my day job I am reading up on the engineering used in rocket design and most likely playing Kerbal Space Program while doing so.

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