SpaceX has launched the second Dragon mission of 2014, with a Falcon 9 v1.1 lofting the cargo spacecraft into orbit on a resupply mission to the International Space Station (ISS). Following a weather-related scrub on Saturday morning, liftoff from SLC-40 at Cape Canaveral occurred without issue at 1:52am Eastern early on Sunday.
It was the company’s sixth launch of the year, doubling the number they achieved in 2013, their previous record year for launches.
SpaceX’s Dragon spacecraft is a recoverable unmanned logistics spacecraft designed to deliver both pressurised and unpressurised cargo to the space station.
Developed as part of NASA’s Commercial Orbital Transportation Services (COTS) program, Dragon was awarded twelve missions to carry supplies to the International Space Station under the Commercial Resupply Services (CRS) program.
Prior to this launch Dragon had completed two COTS demonstration missions and three operational CRS flights.
The Dragon which was carried into orbit by this mission, SpaceX CRS-4, is the sixth Dragon mission and the second of the year.
CRS-3, the previous mission, launched in mid-April and spent a month in orbit before a successful recovery in May. It is the fifth Dragon mission to the International Space Station.
Dragon is part of a varied array of ships used to deliver supplies to the ISS. Russia’s Progress spacecraft, which was originally developed to serve the Soviet Union’s Salyut 6 space station in 1978, has made the majority of unmanned supply missions to the outpost, but since 2008 they have been joined by an international fleet of supply vehicles.
Europe’s Automated Transfer Vehicle (ATV) has made five supply missions, with the final craft, Georges Lamaitre, currently docked at the outpost. Japan’s Kounotori, or HTV, spacecraft has made four missions and launches are continuing.
(ATV-3 Docking Animation created from 70 hi res ATV-3 docking images acquired by L2 – LINK).
The United States’ contribution to the program is a pair of commercial spacecraft, of which the Dragon is one member. The other, Orbital Sciences Corporation’s Cygnus, was also developed under the COTS program and has been awarded eight CRS missions, of which it has already completed two.
The Dragon can transport up to 3,310 kilograms (7,300 lb) each of pressurised and unpressurised cargo into orbit, and return up to 2,500 kilograms (5,500 lb) of pressurised cargo to Earth at the end of its mission.
The spacecraft consists of two sections, a pressurised capsule which returns to Earth, and an unpressurised trunk section which is jettisoned prior to reentry and will be destroyed when it enters the Earth’s atmosphere.
For this launch, a total mass of 2,216 kilograms (4,885 lb) of cargo is aboard the Dragon. Of this, 1,627 kilograms (3587 lb) is pressurised while the remaining 589 kilograms (1298 lb) is accounted for by NASA’s RapidScat instrument, an ocean research payload to be mounted on the outside of the space station’s Columbus module.
The pressurised cargo consists of provisions and equipment for the crew, spares and replacement parts for the space station’s systems and scientific equipment, including replacement lithium ion batteries for use in the US Extravehicular Mobility Unit (EMU) spacesuits used to perform EVAs from the American segment of the station.
The scientific experiments being carried include a low-temperature 3D printer intended to demonstrate whether replacement components for the space station could be produced in orbit when required, bioscience research payloads studying the effects of microgravity on the growth of seedlings, the behaviour of fruit flies and the bone density of twenty mice.
Ten of these mice will be returned to Earth at the end of the Dragon’s mission, with the remainder following on a later flight.
Other payloads include Cyclops, a new dispenser for deploying small satellites from the station, an experiment to find ways to improve techniques for feeding astronauts and a materials research experiment.
The RapidScat instrument will be used to collect wind velocity data over regions of ocean on the Earth’s surface. It replaces the SeaWinds instrument on NASA’s QuikSCAT satellite, which failed in 2009.
Built as an interim spacecraft following the loss of a NASA-operated instrument on Japan’s Midori satellite in 1997, QuikSCAT was launched by a Titan II rocket in June 1999 and was intended for a two year mission to ensure continuity of data until a permanent replacement could be constructed. Instead, the satellite was NASA’s front line ocean monitoring satellite for ten years.
RapidScat was built from an engineering backup of the SeaWinds instrument constructed as part of the QuikSCAT program. NASA currently expects it to operate attached to the International Space Station for two years.
A small satellite is also being carried aboard the Dragon in order to be deployed from the space station.
The Special Purpose Inexpensive Satellite (SPINSat) will be used by the US Naval Research Laboratory and Space Test Program to study thruster operation and provide a target for tracking and atmospheric drag experiments. The satellite will be deployed using the Cyclops system via an airlock in the Kibo module of the station.
The Falcon 9 conducted its thirteenth flight, with more than half of those launches having occurred in the last twelve months.
A two-stage vehicle, the Falcon’s first stage is powered by nine Merlin-1D engines arranged in an octagonal, or ‘Octaweb’ formation with eight of the engines clustered around the ninth in the centre of the stage.
The engines burn RP-1 propellant, oxidised by liquid oxygen. With nine engines on the first stage, the Falcon is designed to offer an engine-out capability allowing it to make orbit even in the event of an engine failure.
This capability was called into use during the type’s fourth launch, which carried the CRS-1 spacecraft.
Despite the failure of a first stage engine eighty seconds into the mission the rocket was still able to deploy its Dragon payload for a successful mission to the ISS, however the launch as a whole was a partial failure as a second payload, an Orbcomm communications satellite, could not be placed into its target orbit and reentered the atmosphere shortly after launch.
The second stage of the Falcon 9 is powered by a single Merlin, which is optimised for performance in Vacuum conditions. Using the same propellant mixture as the first stage, the second stage will complete the Dragon’s ascent into orbit after the first stage boosts it out of the atmosphere.
The launch used the Falcon 9 v1.1 configuration, which features elongated first and second stages compared to the earlier configuration which has become known retrospectively as the v1.0.
The v1.1, which has been used from the sixth flight onwards, also introduced the octagonal engine arrangement in place of the square used on previous flights, and the Merlin-1D in place of less powerful Merlin-1C powerplants.
The launch took place from Space Launch Complex 40 at the Cape Canaveral Air Force Station. A former Titan launch pad, SLC-40 was constructed in the 1960s for the Titan IIIC, seeing subsequent use by the Titan III(34)D, Commercial Titan III and Titan IV rockets.
Following the last Titan launch from Cape Canaveral in April 2005 the pad was mothballed, and its towers were demolished in 2008 to make way for the Falcon 9’s Clean Pad complex.
The maiden flight of the Falcon 9 was made from SLC-40 in June 2010, and eleven of its twelve flights before this launch have been made from the pad.
SLC-40 was last used for the AsiaSat-6 launch earlier this month, making this one of the fastest turnarounds for a US launch complex between two orbital launches, and the fastest in recent years.
The Falcon 9’s other launch complex is Space Launch Complex 4E at Vandenberg Air Force Base, which was used for the September 2013 launch of Canada’s CASSIOPE satellite. Another former Titan pad, this complex facilitates launches to polar and retrograde orbits which are unattainable from Cape Canaveral due to geographical restrictions.
In addition to these two complexes, SpaceX has recently been awarded use of the Kennedy Space Center’s Launch Complex 39A, which it intends to use for the Falcon 9-derived Falcon Heavy rocket. The Heavy is scheduled to make its first launch from Vandenberg next year.
Ahead of the launch, the Falcon 9 underwent a successful static firing on Thursday.
The final countdown towards launch began with the Falcon being powered on Friday, ten hours in advance of liftoff – and again on Saturday for the Sunday attempt. The Dragon had already been powered up sixteen hours previously to begin its own final preparations.
Fuelling of the Falcon began at the four hour mark in the countdown with the commencement of propellant tanking. Oxidiser loading began forty minutes later, with propellant and initial oxidiser loading completed five minutes later. Topping off of the oxidiser tanks continued throughout the countdown as the liquid oxygen boils off.
The terminal countdown began ten minutes before liftoff, with the Falcon entering its automated sequence. The Dragon followed suit at the six minute mark.
The Strongback structure, used to erect the vehicle at the pad and support it during preparations for liftoff began to be retracted from the vehicle at around T-4 minutes, 40 seconds and the Flight Termination System switched to internal power with three and a quarter minutes to go – the system was armed 15 seconds later.
The final ‘go’ calls for launch was given by the Launch Director and Range Control Officer, at approximately 150 and 120 seconds before launch respectively.
The rocket switched to internal control and entered startup configuration sixty seconds before liftoff. In the final minute of the countdown the rocket performed its final automated checkout, with tank pressurisation also completed. The launch pad’s water sound suppression system, or Niagara, was activated around this time.
Ignition of the nine first stage engines occurred at T-3 seconds, with the engines building up thrust and undergoing checkout in the three seconds before liftoff occurred at T-0.
After clearing the tower the Falcon transitioned to put the Dragon on course for its rendezvous with the International Space Station, reaching the speed of sound after seventy seconds and also passing through the area of maximum dynamic pressure, or Max-Q, during the second minute of flight. The first stage burned for 161 seconds before cutting out and separating three seconds later.
Second stage ignition began a six-minute, 48-second burn to reach the Dragon’s deployment orbit. Dragon separated from the Falcon 9 thirty five seconds after the end of the burn; beginning its independent flight ten minutes and fifteen seconds after lifting off.
Shortly after separation the Dragon deployed the solar arrays which will provide it with power throughout the mission.
The spacecraft opened its guidance, navigation and control bay door two and a half hours after launch, and at five hours and twenty three minutes elapsed time it performed a circularisation burn to begin a series of manoeuvres necessary to reach the ISS.
Dragon’s arrival at the ISS is planned for Tuesday at around 11:30 UTC, when the Expedition 41 crew aboard the outpost will use the station’s Canadarm2 Remote Manipulator System (SSRMS) to capture the freighter and berth it to the Nadir port on the Harmony module.
After about a month at the station the Dragon will be loaded with 1,486 kilograms (3,276 lb) of cargo for return to Earth, after which its hatch will be sealed and the RMS will be used to remove it from Harmony and release it back into free flight.
After performing a series of separation manoeuvres, the spacecraft will be deorbited for recovery at sea by SpaceX.
The launch was the nineteenth US launch of 2014 and the fifty-seventh of the year overall.
SpaceX are planning to conduct several more missions before the year’s end, with another Falcon 9 launch with the CRS-5 Dragon mission scheduled for the start of December.
A commercial launch with eleven Orbcomm satellites is currently scheduled for November, with a Turkmen communications satellite also slated for the end of the year at present.
The next launch for the United States, and for NASA’s CRS program, is scheduled for next month when Orbital Sciences’ Antares will deploy the next Cygnus mission to the ISS. Before then a Russian Soyuz mission, TMA-14M, will fly to the outpost and return its crew complement to six.
The station is currently commanded by Roskosmos cosmonaut Maksim Surayev, with Gregory Wiseman and Alexander Gerst also aboard the outpost. They will be joined by Aleksandr Samokutyayev, Yelena Serova, and Barry Wilmore with the arrival of TMA-14M, which is expected to occur during the Dragon’s stay at the facility.
(Images: SpaceX, NASA and via L2′s SpaceX Special Section, which includes over 1,000 unreleased hi res images from Dragon’s flights to the ISS.)
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