Falcon 9 launches Dragon on CRS-1 mission to the ISS
Launched on 22 May, C2+ completed the Dragon spacecraft’s demonstration as part of the Commercial Orbital Transportation Services program with a mission culminating in rendezvous, capture and berthing with the International Space Station.
Six days after berthing, Dragon C2+ departed the space station and successfully returned to Earth.
The mission is also designated SpaceX-1 and CRS SpX-1 in some NASA technical documentation, and has been known as Dragon C3 or C4 by some enthusiasts; although this does not appear to be an official name.
Dragon C2+ was the Dragon’s second flight, following its maiden flight on the brief Dragon C1 mission on 8 December 2010. During that mission, the Dragon orbited the Earth twice, before successfully returning to Earth less than four hours after launch.
Designed and built by SpaceX as part of NASA’s Commercial Orbital Transportation Services (COTS) programme, development of the Dragon spacecraft began in 2005, with a COTS contract being awarded in 2006.
Rocketplane Kistler was also awarded a contract for its K-1 spacecraft; however this was cancelled in October 2007 following RPK’s inability to meet its targets.
Orbital Sciences have since been awarded a replacement contract under which the Cygnus spacecraft, scheduled to make its first flight next year, and Antares rocket, have been developed.
Dragon can carry both pressurised and unpressurised cargo; the former being carried in a recoverable capsule with 6.8 cubic metres (240 cubic feet) of storage space, and the latter in the disposable “Trunk” section at the rear of the spacecraft, with a volume of 14 cubic metres (494 cubic feet).
For the CRS-1 mission, no unpressurised payloads are being carried in the Trunk, however it will serve to encapsulate the launch’s secondary payload; Orbcomm’s O2G-1 communications satellite, during the initial stages of its flight.
Dragon is 5.9 metres (19.3 feet) long, with a diameter of 3.66 metres (12 feet). The 2.9-metre (9.5-foot) long capsule can transport up to 3,310 kilograms (7,296 lb) of cargo to the ISS, and return 2,500 kilograms (5,500 lb) to Earth, while the trunk can carry 3,310 kilograms to the station, and hold 2,600 kilograms (5,732 lb) of non-recoverable payload for the return to Earth; the Trunk section is expected to burn up in the Earth’s atmosphere during reentry.
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Power to the spacecraft is provided by a pair of solar arrays, affixed to the Trunk section. Manoeuvring, attitude control and the deorbit burn are performed using eighteen Draco thrusters on the spacecraft.
These thrusters each provide 400 newtons (90 lb) of thrust through the reaction of monomethylhydrazine with dinitrogen tetroxide. A Common Berthing Mechanism, or CBM, will be used to berth the spacecraft with the International Space Station.
Dragon is named after the 1963 song “Puff, The Magic Dragon” by US folk band Peter, Paul and Mary. According to a press release accompanying the launch, the name was chosen as a response to criticism that SpaceX’s goals were unrealistic.
The Dragon spacecraft will launch atop a Falcon 9 1.0 carrier rocket. Also developed by SpaceX, the Falcon 9 is a two-stage carrier rocket which first flew in June 2010.
The launch of the CRS-1 mission was the Falcon 9’s fourth flight, following the two previous Dragon missions, and its maiden flight which carried a mockup Dragon spacecraft; the Dragon Spacecraft Qualification Unit. All three previous Falcon 9 launches have been successful.
The first stage of the Falcon 9 1.0 is powered by nine Merlin-1C engines, with a vacuum-optimised Merlin-1C powering the second stage. Both stages are fuelled by RP-1 propellant, which is oxidised by liquid oxygen.
All Falcon 9 launches to date have used the 1.0 configuration; however the Falcon 9 1.1, which features stretched stages and Merlin-1D engines, is expected to replace it next year.
Two more Falcon 9 1.0 launches are currently scheduled; the next CRS mission, and a launch in 2014 to deploy the Jason-3 satellite; a contract which could not be awarded to the unproven Falcon 9 1.1.
The launch of SpaceX CRS-1 was the ninth launch of a Falcon rocket; in addition to the Falcon 9s, five smaller Falcon 1 rockets were launched between 2006 and 2009, with two successes and three failures.
The Falcon 1 has since been retired from service in favour of flying smaller satellites on Falcon 9 rockets with excess capacity; such as the Orbcomm satellite on Sunday’s launch. An improved version, the Falcon 1e, was proposed, but has now been abandoned.
Seven and a half hours before launch, the Falcon 9 and Dragon spacecraft were powered up. Oxidiser loading will begin about three hours and fifty minutes ahead of launch, and ten minutes later fuelling will start. The loading of both propellant and oxidiser was completed by three and a quarter hours before launch.
Controllers then worked through the countdown, reaching the terminal count phase at T-10 minutes. During this phase, an automated sequence controlled the countdown, and final preparations for launch were made, including arming the rocket’s flight termination system, and transferring to internal power.
Final clearances for launch was given by the launch director and the Eastern Range at T-150 seconds and T-120 seconds respectively. The “Niagara” pad water system was activated a minute before launch.
About forty seconds before liftoff, the rocket’s propellant tanks were pressurised, with engine start being commanded at T-3 seconds. Once the countdown reached zero, the Falcon 9 rose from the pad, and begin its ascent, and after manoeuvring to the necessary trajectory for its target orbit, it passed through the area of maximum dynamic pressure 85 seconds after launch.
The first stage burned for 180 seconds, however about 30 seconds before the end of the burn; two engines shut down to limit the vehicle’s acceleration.
There was – at around MaxQ – an engine 1 failure, as observed in video footage, with more information to be noted in an article on Monday.
Once first stage flight was complete the vehicle coasted for five seconds, allowing residual thrust and vibrations to dampen down; the third Falcon 1 launch failed due to residual thrust causing recontact between the first and second stages. After the brief coast, the first stage was jettisoned, and seven seconds later the second stage ignited.
The first burn of the second stage lasted five minutes and 59 seconds, ending nine minutes and 11 seconds after liftoff. Dragon separation was on schedule, thirty five seconds after the end of the burn.
About forty five minutes after the Dragon separates, the Falcon 9’s second stage may make a short second burn to raise its orbit ahead of deploying the Orbcomm satellite.
This burn is, however, contingent on the stage being deemed healthy enough to make the burn; the backup plan being to deploy the satellite into the upper stage’s parking orbit.
Built by Sierra Nevada Corporation, the Orbcomm spacecraft is the first Orbcomm Second Generation, or O2G, satellite to be launched. It is also the first satellite based around the SN-100 bus to fly. With a mass of 142 kilograms (313 lb), it is expected to operate for five years.
As the first O2G satellite, it will serve as a prototype for future missions; the next two spacecraft are scheduled for launch together next year, aboard a Falcon 9 flying from Vandenberg.
Sunday’s launch took place at Space Launch Complex 40 at the Cape Canaveral Air Force Station. The launch complex was originally part of the Titan III Integrate-Transfer-Launch complex, along with Space Launch Complex 41, and supported fifty-five launches of Titan carrier rockets, including twenty six Titan IIICs, eight Titan 34Ds, four Commercial Titan IIIs, five Titan IVAs and twelve Titan IVBs. The first launch from the pad was the June 1965 maiden flight of the Titan IIIC.
Following the final Titan IV launch from Cape Canaveral in April 2005, the complex fell into disuse. It was leased by SpaceX to support Falcon 9 launches in 2007, with the Titan launch facilities being demolished shortly thereafter. This is the fourth Falcon launch from the pad, making it the fifty-ninth launch in total from SLC-40. Another Falcon 9 launch complex is under construction at Vandenberg Air Force Base, however to date all Falcon 9 launches have occurred from SLC-40.
The next Falcon 9 launch is scheduled to occur in January, with the next Dragon CRS mission to resupply the ISS. The next mission to the space station is scheduled for launch on 23 October, with a Soyuz-FG carrier rocket launching the manned Soyuz TMA-06M mission. This will be followed a week later by a Soyuz-U launching the next resupply mission, Progress M-17M. Both of these launches will occur from the Baikonur Cosmodrome, using launch pads 31/6 and 1/5 respectively.
The next scheduled US launch will be conducted by United Launch Alliance, using an Atlas V 501 to deploy the X-37B Orbital Test Vehicle for its third flight; a mission which will reuse the spacecraft which flew the vehicle’s first mission in 2010.
(Images: via SpaceX, NASA, Orbcoom and L2’s SpaceX Dragon Mission Special Section – Containing presentations, videos, images (Over 800mb of unreleased hi res images from the C2+ mission alone), space industry member discussion and more).
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