The SpaceX Dragon spacecraft launched on its maiden flight Wednesday, beginning a series of demonstration missions as part of NASA’s Commercial Orbital Transportation Services (COTS) programme. The mission, known as Dragon C1, launched from Cape Canaveral atop a Falcon 9 rocket at 10:43am Eastern, before the spacecraft splashed down around 19:00 UTC.
The opening target of a T-0 at 15:09 UTC was enjoying a smooth count heading into the terminal count. However, at T-2 minutes 50 seconds an abort was called. The second opportunity being aimed for is at 10:43am Eastern (15:43 UTC).
Sources note the abort was caused either by an issue with intermittent drop outs in range-critical telemetry, an off-nominal condition with the Dragon computer was also noted. SpaceX are currently classing the abort as related to a false abort on the Ordnance Interrupter (OI) ground feedback on the Flight Termination System (FTS) showing relation to the range critical note.
Following countdown for the second window was faultless, as was all the major milestones of the launch and ascent into orbit, with nominal first stage, staging, second stage flight and deployment of the Dragon all appearing to be flawless.
On orbit, Dragon appears to be very stable. One of the Draco thrusters has failed, sources note, which is within tolerance. All cubesats were deployed and have communicated good status. Deorbit burn was stable, with Dragon heading towards Entry.
Dragon – as expected – deployed its Drogue and three Main parachutes, ahead of a splashdown in the Pacific ocean at around 19:00 UTC.
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SpaceX Falcon 9/Dragon Preview:
The Dragon spacecraft has been developed by SpaceX to transport cargo to the International Space Station. In June 2006 it was selected, along with the Rocketplane Kistler K-1, for development under the COTS programme.
The contract with Rocketplane Kistler was subsequently cancelled in October 2007 after the company had been unable to meet targets, and a replacement contract was awarded to Orbital Sciences Corporation in February 2008, to develop the Cygnus spacecraft.
Development of the Dragon spacecraft began in 2005, and in March 2006 it was submitted for the COTS programme. The spacecraft was designed to be able to transport crew eventually, as well as cargo, however a number of modifications would be required before it could be flown manned.
Its pressurised cargo module has a volume of ten cubic metres, whilst its “trunk” section, which can be used to transport unpressurised cargo or deploy small satellites, has a volume of fourteen cubic metres. In terms of mass, three tonnes of payload can be transported in each section.
Attitude control will be provided by 18 Draco thrusters, burning monomethylhydrazine oxidised by dinitrogen tetroxide. These thrusters will also be used to deorbit the spacecraft at the end of its mission. The Dragon spacecraft, excluding the unpressurised trunk section, is 2.9 metres long, with a diameter of 3.6 metres. It carries a Common Berthing Mechanism, and on flights to the International Space Station it will be berthed at the station using Canadarm2, in a similar way to the HTV spacecraft.
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Unlike the existing unmanned spacecraft used to resupply the International Space Station, Dragon is designed to return to Earth and be recovered at the end of its mission.
To do this, it is equipped with a heat shield made of PICA-X, or Phenolic Impregnated Carbon Ablator, which can reach up to 2,200 degrees Celsius. The heat shield has a diameter of 3.6 metres, covering the bottom of the spacecraft, and took four years to develop. SpaceX believe that it will not be damaged by reentry, and will be able to be reused for many flights. Following reentry, the spacecraft will descend into the Pacific Ocean under parachutes.
If successful, this will be the first time a commercial organisation has recovered a spacecraft from orbit. The only previous attempt was made in 1995 by Space Systems Incorporated using the Multiple Experiment Transporter to Earth Orbit and Return, or METEOR, spacecraft.
This was launched from Wallops Island on the only flight of the Conestoga 1620 rocket, and ended in failure when the rocket was destroyed by range safety after its guidance system malfunctioned.
One or two more missions will be conducted to test the Dragon spacecraft. Dragon C2 (large amount of NASA presentations available on L2) is expected to rendezvous with the International Space Station, whilst Dragon C3 is planned to become the first commercial spacecraft to dock with the outpost.
SpaceX are reported to be considering merging the C2 and C3 missions into a single flight, however they will need approval from NASA to do so. SpaceX has also been awarded twelve Commercial Resupply Systems (CRS) missions to transport cargo to the ISS, which will be conducted once the demonstration missions are complete. Two free-flying DragonLab missions, carrying scientific payloads, are also planned.
Dragon C1 will be launched by a Falcon 9 rocket. The Falcon 9 made its maiden flight earlier this year carrying a mockup of the Dragon spacecraft, and this will be its second flight. Falcon 9 is a two stage rocket, with both stages burning RP-1 propellant with liquid oxygen oxidiser. The first stage is powered by nine Merlin 1C engines, whilst the second is powered by a single Merlin Vacuum engine. The previous launch was considered successful, however several problems occurred during the flight which SpaceX are hoping to resolve, including roll problems during the second stage burn.
The countdown for the launch of Dragon C1 will begin two hours and thirty five minutes before launch, with flight controllers being polled to begin the fuelling of the rocket. The strongback, a structure used to transport the rocket to the pad, raise it to vertical, and support it, will be lowered 100 minutes before launch. Fuel and thrust vector control bleeding on the second stage will be performed at T-1 hour. At T-13 minutes, a final flight readiness poll will be conducted, which will be followed by the final hold point at T-11 minutes.
The terminal count will begin ten minutes before launch. Four minutes and forty six seconds before launch, the rocket will transfer to internal power. The flight termination system, used to destroy the rocket in the event of a problem, will be armed three minutes and eleven seconds before launch, and seven seconds later oxidiser topping will end. The flight computer will be started sixty seconds before launch, and the pad water system will be activated. Forty seconds before launch, the propellant tanks will be pressurised.
Ignition of the first stage engines will occur three seconds before launch. Assuming checks are nominal, the rocket will then lift off at T-0, and begin its climb towards orbit. Seventy six seconds into the flight the rocket will experience max-Q, the portion of the flight when maximum aerodynamic pressure is exerted on the vehicle. At around 155 seconds after launch, two of the first stage engines will be shut down to limit the load on the rocket due to acceleration. About twenty three seconds later, the remaining engines will also cut off. Stage separation will occur four seconds later, followed after another seven seconds by ignition of the second stage.
The second stage will burn for five minutes and fifty one seconds before cutting out. At this point, the vehicle should be in its target orbit; a circular low Earth orbit at an altitude of 300 kilometres, and an inclination of 34.5 degrees. Thirty five seconds after the end of the second stage burn, and 665 seconds after launch, Dragon C1 will separate from the rocket.
The first stage of the Falcon 9 was designed to be reusable, however on the previous launch it was discovered that it could not survive reentry. Some modifications have been made to try and improve its chances of survival; however it is not expected to be recoverable. Despite this, recovery will be attempted, with the M/V Freedom Star, one of NASA’s SRB recovery ships, on standby to collect the spent stage should it come down intact.
Following launch, the Dragon C1 spacecraft is expected to complete a single orbit of the Earth, before being deorbited during its second orbit. If a problem prevents reentry on the second orbit, it can be waved off until the third orbit. Whilst in orbit the Dragon will manoeuvre to test its propulsion system. Assuming the flight proceeds nominally, then about two hours and thirty two minutes after launch, the spacecraft will jettison its trunk section, and fire its Draco thrusters to deorbit.
The deorbit burn will last six minutes, and will be followed 20 minutes later by entry interface. Eleven minutes after entering the atmosphere, with the spacecraft at an altitude of 13.7 kilometres, the drogue parachutes will deploy to begin slowing the spacecraft down.
The main parachutes will be deployed a minute later, as the spacecraft passes through an altitude of three kilometres. Three hours and 19 minutes after launch Dragon C1 will land in the Pacific Ocean. The target landing site is about 800 kilometres off the coast of Mexico.
Dragon C1 will be launched from Space Launch Complex 40 at Cape Canaveral. SLC-40 was built in the 1960s as a Titan IIIC launch complex. The first launch from the complex, in June 1965, was the maiden flight of the Titan IIIC. During the late 1960s, the complex was converted to support the MOL programme, with the mobile service structure being modified to include an environmental shelter. When MOL was cancelled, LC-40 resumed normal operations.
The last Titan IIIC launch occurred from LC-40 in 1982, and shortly afterwards by the Titan 34D began using the complex. It was then used by the Commercial Titan III before the complex was completely rebuilt for the Titan IV. In 1997 the Cassini spacecraft was launched from LC-40 on its mission to Saturn.
The final Titan launch from the complex occurred on 30 April 2005. In April 2007 SpaceX leased the site and began to convert it to accommodate the Falcon 9. The complex was used for the first Falcon 9 launch earlier this year.
The next Dragon mission, Dragon C2, is currently scheduled for launch on 12 April next year; the fiftieth anniversary of the first manned spaceflight and the thirtieth anniversary of the first Space Shuttle launch. This will also be the next Falcon 9 launch. Dragon C1 is also the fifteenth and final orbital launch of the year to be made by the United States.
If the launch of Compass I2, currently believed to be scheduled for 20 December, goes ahead as planned then China will have conducted as many launches as the United States for the first time. The next American orbital launch is expected to be that of NRO L-49 on a Delta IV, which is currently scheduled for 11 January.
(Images: Larry Sullivan, MaxQ Entertainment. Space X).