SpaceX have launched their Falcon 9/Dragon duo – the latter of which is aiming to complete the spacecraft’s remaining COTS demonstration objectives, and culminate in a visit to the International Space Station. The launch suffered from no problems, lifting off from Cape Canaveral at 3:44am Eastern. The key milestone of solar array deployment was also successful.
SATURDAY’S LAUNCH SCRUB:
The countdown for Friday’s attempt suffered from no major issues ahead of the engines firing, with only a few minor range issues noted with several hours to go. These were all cleared ahead of the business end of the count.
With the Range green and the weather acceptable for launch, the countdown clocks continued to tick down smoothly, as the Falcon 9 and Dragon were put through their terminal count events. However, at T-0.5, with the engines firing, an abort was called.
The issue was initially understood to be related to the redline limits being breached by Engine 5’s chamber pressure readings on the Falcon 9, causing the flight computers to abort the launch. Vehicle safing was conducted without issue.
Due to the near-instant launch window for this mission, a scrub was called for the day, with the next attempt No Earlier Than (NET) May 22 (03:44am Eastern), as pre-arranged. An opportunity also exists on May 23 (03:22am Eastern) if arrangements can be made with the Eastern Range.
Additional post scrub information noted that all nine engines ignited as advertised, prior to engine 5’s chamber pressure tending high, triggering the abort. A similar, but not identical, issue was observeed with the first flight of the Falcon 9 – an issue that was resolved ahead of launch due to an extended launch window for that opportunity.
After the Falcon 9 was detanked, engineers arrived at the pad to inspect the engine, inspect the chamber and potentially borescope the hardware.
SpaceX noted an option exists to swap the engine with another unit located on the next Falcon 9 set to launch, a vehicle that is already at the Cape. They added that they should still be able to head back to the pad in time for the May 22 launch date option, depending on the work required on the engine resolution.
The latest update came via SpaceX CEO and Chief Designer Elon Musk, who tweeted “Engine pressure anomaly traced to turbopump valve. Replacing on engine 5 and verifying no common mode.”
SpaceX then released a statement, noting repairs are expected to be completed on Saturday night, with checks to follow on Sunday, hopefully allowing for the next attempt to be on May 22.
“Launch was aborted when the flight computer detected slightly high pressure in the engine 5 combustion chamber. We have discovered root cause and repairs are underway,” noted a SpaceX statement.
“During rigorous inspections of the engine, SpaceX engineers discovered a faulty check valve on the Merlin engine. We are now in the process of replacing the failed valve. Those repairs should be complete tonight. We will continue to review data on Sunday. If things look good, we will be ready to attempt to launch on Tuesday, May 22nd at 3:44 AM Eastern.”
NEW LAUNCH DATE:
The valve – relating to the nitrogen purge – was replaced on the engine at the pad, allowing for evaluations to take place to confirm the next launch opportunity. On Monday morning, SpaceX confirmed they are in a stance to carry out a second launch attempt at 3:44am Eastern on Tuesday morning.
Launch was nominal, as were all the milestones through to solar array deployment – the latter a first for SpaceX.
Follow the live update thread for additional information. Further key updates will be added to this article.
Dragon Mission Overview – New article post launch coming shortly:
The Dragon C2+ mission is a combination of the C2 and C3 missions which were originally planned to be conducted separately. The second flight of a Dragon spacecraft, it follows on from the successful Dragon C1 flight in December 2010.
C2+ will be the first flight of a complete Dragon, however; as C1 flew without the unpressurised “Trunk” section and solar arrays. Launched at 15:43 UTC on 8 December 2010, Dragon C1 made two orbits of the Earth before being deorbited.
Following reentry, splashdown occurred at 19:02 UTC, with the spacecraft being recovered successfully from the Pacific Ocean, having completed all of its planned mission objectives.
The C2+ mission is more demanding; SpaceX need to prove that the spacecraft can be used to deliver cargo to the International Space Station safely. As a result, the spacecraft needs to demonstrate its ability to remain in orbit for several weeks, test its manoeuvring and navigation systems, and perform a rendezvous with the space station.
If the initial rendezvous is successful and the spacecraft is operating well, SpaceX will then be cleared to perform the next stage of the demonstration, which will see the spacecraft approach to within ten metres of the ISS before being grappled by the station’s Canadarm2 remote manipulator system, and berthed at the nadir port of the station’s Harmony module.
In anticipation of being cleared to perform the berthing test, the Dragon spacecraft has been loaded with 520 kilograms (1,146 pounds) of cargo for delivery to the ISS.
Provisions for the crew account for most of this mass, with 306 kilograms (675 lb) of food, clothing and equipment present. This includes 18 bags of crew rations (13 standard and five low sodium), each of which contains nine meals for the crew.
In addition, Dragon C2+ will deliver 123 kilograms (271 lb) of bags to be used to store cargo on future flights, 10 kilograms (22 lb) of computer equipment, including a laptop computer and associated batteries and cables, and finally 21 kilograms (46 lb) of material for experiments; consisting of ice bricks to cool samples, and the NanoRacks CubeLabs Module 9 research package which contains a crystal growth experiment for Ohio State University.
Unlike the Progress, ATV and HTV spacecraft currently used to resupply the ISS, the Dragon’s capsule is designed to survive reentry and be recovered. With the Space Shuttle retired and Soyuz spacecraft not large enough to accommodate large amounts of cargo, this will provide the only means of returning equipment from the space station to Earth.
After its cargo has been unloaded, Dragon C2+ will be loaded with 143 kilograms (315 lb) of crew equipment, 93 kilograms (205 lb) of research equipment, 39 kilograms (86 pounds) of spacesuit equipment and gloves, and 345 kilograms (760 pounds) of station hardware.
The research equipment being returned includes several different experiments; 24 kilograms (52 lb) of hardware used in the “Plant Signalling” experiment, is being returned; this experiment studied how plants reacted to changes of environment, at a molecular level. Another 36 kilograms (79 lb) of downmass is equipment used for the Shear History Extensional Rheology Experiment, or SHERE, which studied the responses of liquid polymers to stress and strain in a microgravity environment.
Sample cartridges from the Materials Science Research Rack, or MSRR, make up nine kilograms (20 lb) of the cargo, including samples from the SETA-2 and MICAST/CETSOL experiments. In addition, equipment from the Combustion Integrated Rack (CIR) and Active Rack Isolation (ARIS) is being returned, along with cold bags and MSG tapes. The station hardware to be returned includes a multifiltration bed, a fluid pump, water containers and a multiplexer from the Japanese Kibo module.
Click here for other Dragon News Articles: http://www.nasaspaceflight.com/tag/dragon/
Dragon was developed by SpaceX as part of NASA’s Commercial Orbital Transportation Services, or COTS, programme. Initial development began in 2005, with the spacecraft being selected for COTS in June 2006, along with the now-cancelled Rocketplane Kistler K-1.
Following the K-1 being dropped from the programme in October, 2007 – after its developers were unable to keep up with programme targets, Orbital Sciences Corporation was awarded a contract to develop the Cygnus spacecraft.
This vehicle is expected to make its first demonstration mission late this year or early next, following the opening test flight of the Antares launch vehicle later this year.
The Dragon spacecraft consists of two sections; a pressurised cargo module, or capsule, which houses the supplies to be delivered to the station, and a “trunk” section which can house unpressurised cargo, or additional payloads such as microsatellites.
The pressurised module has a volume of ten cubic metres (353 cubic feet), of which 6.8 cubic metres (240 cubic feet) can be used to store cargo, whilst the trunk has a volume of 14 cubic metres (494 cubic feet). The trunk section also accommodates the two solar arrays which will provide power to the spacecraft.
The pressurised module is 2.9 metres (9.5 feet) long, and can carry up to 3,310 kilograms (7,296 lb) of cargo to the space station. It can also accommodate 2,500 kilograms (2,500 lb) for return to Earth. The trunk section can carry the same mass of cargo to the station; however it is not recovered, so it cannot be used to return cargo to Earth. Instead, it can hold 2,600 kilograms (5,732 lb) for disposal.
The thrusters use monomethylhydrazine as propellant, and dinitrogen tetroxide as an oxidiser. Each one delivers 400 newtons (90 pounds) of thrust. The nose of the pressurised module houses a Common Berthing Mechanism (CBM), which will be used to connect it to the International Space Station.
Like Japan’s HTV, and unlike the Progress and ATV spacecraft, Dragon cannot dock to the space station itself. Instead, it will rendezvous with the station, and the crew will capture and berth the spacecraft using the station’s remote manipulator system, Canadarm2.
Dragon spacecraft are launched by SpaceX’s Falcon 9 carrier rocket, which will be making its third flight to deploy C2+.
A two-stage rocket which is in theory partially reusable, the Falcon 9 first flew on 4 June 2010, carrying an inert demonstration payload, the Dragon Spacecraft Qualification Unit. Its second flight then came in December 2010, with the first Dragon test flight, C1. Both previous launches were successful.
The third launch of the Falcon 9 is the eighth overall for SpaceX, and its Falcon family of rockets. The other five launches were made using the smaller Falcon 1 rocket, which has since been retired from service.
The first three launches failed; the maiden flight in March 2006 because of a fuel leak, the second flight a year later due to fuel sloshing causing a premature second stage cutoff and the third in August 2008 due to residual thrust causing recontact between the first and second stages.
The first flight carried the FalconSat-2 spacecraft, the second carried a DemoSat, and the third carried the Trailblazer, NanoSail-D and PreSat spacecraft, along with a Celestis “space burial” payload.
A reflight of the Celestis payload, named “New Frontier”, was carried as a secondary payload on Tuesday’s launch. It contained cremated remains from over 300 people, including astronaut Gordon Cooper – one of the Mercury Seven; and actor James Doohan who played Scotty in Star Trek.
The first successful Falcon launch occurred in September 2008, when the fourth Falcon 1 orbited a demonstration satellite known as RatSat. That was followed by the successful launch of RazakSat-1 in July 2009.
The Falcon 1 is no longer in use; it was originally intended to be replaced by the more powerful Falcon 1e, however SpaceX have abandoned this plan for now, opting instead to fly smaller satellites as secondary payloads on Falcon 9 launches.
Countdown And Launch – Now May 22:
Seven and a half hours before launch, the Falcon 9 and Dragon spacecraft will be powered up. Loading of liquid oxygen, which is used as an oxidiser by both stages of the Falcon 9, will begin three hours and fifty minutes ahead of launch.
Loading of RP-1 propellant, a highly refined form of paraffin (kerosene), is scheduled to begin ten minutes later. Fuelling is expected to be completed by three and a quarter hours before launch, although the liquid oxygen will require topping during the countdown; this will continue until three minutes and four seconds before launch.
The terminal countdown will begin ten and a half minutes before liftoff, with the Dragon’s computer entering its automated terminal count sequence five and a half minutes before launch. At around T-4 minutes, 46 seconds, the rocket will switch to internal power, with the flight termination system being armed around three minutes and eleven seconds ahead of liftoff, and oxidiser topping ending a few seconds afterwards.
The Launch Director will give a final “go” for launch at T minus two and a half minutes, with the USAF Range Control Officer confirming that the range is go for launch at T-2 minutes. At T-60 seconds, the flight computer will be started, and the launch pad’s “Niagara” water deluge system will be activated. Twenty seconds later, the Falcon 9’s propellant tanks will be pressurised.
At T-3 seconds, the first stage’s nine Merlin-1C engines will ignite, and at T-0 the Falcon 9 will lift off, and begin its ascent. The vehicle will pass through the area of maximum aerodynamic pressure, or max-q, eighty four seconds after liftoff.
Around two and a half minutes into the flight, two of the first stage engines will shut down, reducing the rocket’s acceleration to limit the load upon the vehicle and its payload. The remaining engines will cut off three minutes after liftoff; an event designated main engine cutoff, or MECO.
Five seconds after MECO, the first and second stages will separate, with the second stage’s single Merlin Vacuum engine igniting seven seconds later to begin a six-minute, 14-second burn.
Forty seconds after second stage ignition, the protective nose cone will be jettisoned from the front of the Dragon. Unlike a payload fairing, this cone only covers the front of the spacecraft, where the berthing mechanism is housed; the remainder of the spacecraft is not enclosed.
The Falcon 9 will complete its powered flight with second-stage engine cutoff, or SECO, nine minutes and fourteen seconds after launch. Spacecraft separation will occur thirty five seconds later.
Two minutes and four seconds after separating from the Falcon 9, the Dragon will begin to deploy its solar arrays.
Testing will begin almost immediately, with a demonstration of its absolute Global Positioning System planned for around 55 minutes after launch. This test will ensure that the position and velocity reported by GPS correspond to measurements made during launch, within an acceptable error margin. Two hours and twenty six minutes into the mission, the navigation bay door will be opened, with sensor checkout beginning fourteen minutes afterwards.
With this checkout complete, the Dragon will begin a series of tests known as far-field demonstrations. These will begin with two approach abort simulations, with the first, which simulates a full abort situation, occurring about eight and three quarter hours after liftoff. The second will be performed about 70 minutes later, testing the spacecraft’s ability to use smaller, pulsed, burns to abort.
According to documentation available via L2, the full abort will consist of a continuous, on-axis, burn of the Draco thrusters, whilst the pulsed abort will use short off-axis pulses. After each test, SpaceX will verify the correct delta V has been imparted upon the spacecraft, and that its attitude is within expected constraints.
About forty minutes after the second abort demonstration, the third and final far-field test will be conducted. The spacecraft will be placed into a free-drift state, to ensure that it can operate in, and recover from, this condition, whilst staying within attitude limits. The spacecraft will need to be able to enter free drift for grappling and berthing with the ISS.
The second day of the mission will be dedicated to orbit phasing; the Dragon first circularising its orbit, and subsequently raising itself towards the orbit of the International Space Station in preparation for rendezvous.
On flight day 3, the Dragon will make a flyby of the ISS at a distance of 2.5 kilometres (1.3 nautical miles, 1.6 statute miles). During this flyby, tests of the Relative Global Positioning System (RGPS) and COTS UHF Communications Unit (CUCU) will be conducted.
According to L2 documentation, the RGPS test consists of comparing the distance between Dragon C2+ and the space station as calculated by the RGPS system to the absolute positions of the two spacecraft, and ensuring the value is within acceptable limits.
The CUCU system, which was delivered to the International Space Station by the Space Shuttle Atlantis during STS-129 in November, 2009, enables communications between the space station and Dragon, while the Crew Command Panel allows the crew of the ISS to send commands to the Dragon.
A GNC Mission Readiness Review presentation, available on L2, shows that in preparation for the Flight Day 3 flypast, the station’s Solar Alpha Rotary Joints will be feathered and rotation stopped, and the US Orbital Segment thrusters will be used to manoeuvre to a better attitude for communications.
Once the flypast is complete, Dragon will make a series of burns first taking it away from the station, before flying around and above it, and eventually approaching again from behind and below.
On flight day 4, it will again pass 2.5 kilometres below the outpost, and conduct another CUCU test. It will then make a burn to close its approach to 1.2 kilometres (0.65 nmi, 0.75 mi). Another burn will then be made to enter the approach ellipsoid of the station, closing to 250 metres (820 feet) below the station, on an R-bar approach trajectory.
Once inside the station’s approach ellipsoid, the Dragon’s Light Detection and Ranging, or LIDAR, system will be tested. The LIDAR system aboard the Dragon spacecraft is known as DragonEye, and is used for ranging and direction finding during Dragon’s approach to the ISS.
The DragonEye system has twice been tested during Space Shuttle missions; Endeavour carried a Detailed Test Objective payload on STS-127, and Discovery carried a final test article during STS-133.
With the LIDAR tests complete, Dragon C2+ will hold 250 metres below the station, before performing a series of R-Bar Demonstration manoeuvres. These consist of the spacecraft being commanded to approach from the hold position, closing to around 220 metres (722 feet), before being commanded to retreat by the crew aboard the station.
It will then return to 250 metres and hold automatically before being commanded to approach the station, this time holding at 220 metres rather than retreating. A final decision will then be made on whether to proceed with the C3 objectives, which will see the spacecraft deliver its cargo to the space station.
If all test objectives have been completed successfully, and approval has been given to proceed, Dragon C2+ will then be cleared to enter a 200-metre (656-foot) keep-out sphere around the station.
A final hold will be made 30 metres (98 feet) from the station, before the Dragon will make its final approach to 10 metres (33 feet) from the station.
The space station, and shortly afterwards the Dragon, will then be placed into free-drift mode. The station crew will then use the Space Station Remote Manipulator System (SSRMS), Canadarm2, to capture the Dragon.
A Mission Robotics Overview presentation on L2 gives an overview of how the crew will use the SSRMS to capture the spacecraft.
During early approach, the arm will be placed in a “high hover” position, and the crew will configure robotics work stations to monitor the Dragon’s approach, before reviewing contingency procedures in case the capture should need to be aborted.
Once mission control gives a go for capture, the RMS capture command will be armed, the arm will be aligned with the Dragon’s grapple fixture, and brought to within 1.5 metres (5 feet) of the spacecraft. At this point, both spacecraft will enter free drift, and the SSRMS end effector will be brought into place over the grapple fixture, and the capture command will be sent.
Once capture is complete, the space station’s attitude control will be restored via the thrusters on the US Orbital Segment. Canadarm2 will then be used to move the Dragon to within 3.5 metres (11.5 feet) of the nadir port of the Harmony module; a Common Berthing Mechanism port which has previously been used for the attachment of H-II Transfer Vehicles and the Multi-Purpose Logistics Modules which were carried on some Space Shuttle missions.
An inspection of the Dragon’s CBM will be conducted by the ISS crew, by means of a camcorder pointed out of a hatch window on the Harmony module. The Dragon will then be moved to 1.5 metres from the port, and finally onto the port. Four indicators will show when the spacecraft is in position, at which point stage one capture will be complete. The RMS will be placed into a limp state for stage two capture, and then its brakes will be applied, and the Dragon released.
Dragon C2+ is the 52nd unmanned resupply mission to the International Space Station; the previous missions consisting of 47 Progress spacecraft, three Automated Transfer Vehicles, and two H-II Transfer Vehicles. One of the Progress missions, Progress M-12M, failed before reaching the space station.
In addition, there have been sixty seven manned missions to the outpost, and four unmanned launches of modules. In total, and including the launch of the first module, Zarya; Dragon C2+ is the 123rd spacecraft to launch to the ISS, and the first commercial mission.
During docked operations, which are expected to last between two weeks and 18 days (the latter being the planned duration when the launch was scheduled for late April), the crew will enter the Dragon for cargo unloading and loading.
L2 documentation suggests that the station RMS, with the Dextre attachment, will be used to study the trunk section of the Dragon in preparation for future missions where it may be necessary to unload cargo from the unpressurised section.
Once docked operations are complete, and the Dragon has been loaded with cargo to return to Earth, the crew will again grapple it with the SSRMS, and it will be released from the Harmony CBM. It will be backed about 1.75 metres (5.75 feet) away from the port, before being manoeuvred to a release point below the station. The SSRMS will be commanded to release the spacecraft, and it will then be withdrawn by about 4.5 metres (14.8 feet), before the Dragon is commanded to depart from the station.
The Dragon will make three burns to leave the vicinity of the International Space Station, with integrated operations ending once it leaves the space station’s approach ellipsoid. Once departure is complete, the navigation bay door will be closed in preparation for reentry. The spacecraft will be deorbited using its Draco thrusters, and once the deorbit burn has been made the trunk section will be jettisoned to burn up in the atmosphere.
Following deorbit, Dragon C2+ will reenter the atmosphere over the Pacific Ocean. It will be protected by a heat shield composed of Phenolic Impregnated Carbon Ablator, or PICA-X, which can withstand temperatures of up to 2,200 degrees Celsius (4,000 degrees Fahrenheit).
The spacecraft will subsequently deploy drogue and main parachutes, and descend into the ocean. It is expected to land several hundred kilometres west of southern California.
Cape Canaveral Air Force Station’s Space Launch Complex 40 will be used for the launch of Dragon C2+. Constructed in the 1960s for the Titan IIIC rocket, SLC-40 was first used for the maiden flight of the Titan IIIC in June 1965.
The complex was later modified for use in conjunction with the Manned Orbiting Laboratory programme, however following that programme’s cancellation the complex resumed normal operations, allowing Complex 41 to be modified for the Titan IIIE.
In total, twenty six Titan IIIC rockets were launched from SLC-40, the last of which flew in May 1982, carrying a Defense Support Program satellite. In October 1982, the first of eight Titan 34D launches from the pad was conducted, with a pair of DSCS communications satellites. After the last Titan 34D launch in September 1989, four commercial Titan III rockets were launched, including one which carried NASA’s ill-fated Mars Observer spacecraft; one of two planetary probes to have launched from SLC-40.
Between 1992 and 1994, the complex was completely rebuilt, and in February 1994, SLC-40 supported its first Titan IV launch, when a Titan IV(401)A deployed the first Milstar satellite. 17 Titan IVs were launched from the pad; five in the Titan IVA configuration and twelve in the Titan IVB configuration. Amongst these launches was the October 1997 deployment of the Cassini and Huygens spacecraft bound for the planet Saturn.
In April 2005, SLC-40 supported its last Titan launch, the final east coast Titan IV launch carrying a Lacrosse radar imaging satellite for the US National Reconnaissance Office. The site was leased by SpaceX in April 2007, its service towers were demolished, and it was converted to accommodate the Falcon 9.
To date, all Falcon 9 launches have been made from SLC-40, however another ex-Titan IV pad, SLC-4E at Vandenberg Air Force Base, is now being converted to support launches to polar orbits.
Assuming the C2+ mission is successful, the next Falcon 9 launch will carry the first operational Dragon mission, as part of the Commercial Resupply Services contract. Twelve Dragon missions are currently planned under the CRS programme.
The next ISS resupply mission scheduled for launch is the third H-II Transfer Vehicle, or Kounotori 3, which is currently expected to launch on 21 July. The next scheduled US orbital launch is expected to be a Pegasus-XL with the NuSTAR satellite; scheduled for launch on 13 June.
(Images: NASA, SpaceX, CSA and via L2’s SpaceX Dragon C2/C3 Mission Special Section- Containing presentations, videos, images, interactive high level updates and more, with additional images via NASA, SpaceX).
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