SpaceX’s Falcon 9 rocket – forced to delay its opening attempts to launch the SES-9 communications satellite – finally launched on Friday evening. The mission, which also involved a sporty – and ultimately unsuccessful – attempt to recover the rocket’s first stage at sea via an Autonomous Spaceport Drone Ship, occurred from SLC-40 at Cape Canaveral at 18:35 pm Eastern.
The launch has suffered from numerous delays, with the opening attempt halted ahead of propellant loading due to unfavorable upper level winds.
The winds were deemed a problem for both fly out and onboard LOX temps for the rocket’s overall performance.
The next attempt managed to get under two minutes to launch, prior to a hold being called. Despite a long launch window, engineers opted to scrub for the day.
Based on the scrub rules for that point in the countdown, it was an automatic 48 hour turnaround. However, after a few days of evaluations, it was decided that Sunday was to be the next launch attempt.
Sunday’s launch showed an increased ability with the hold rules as the countdown was once again halted just prior to launch. This time a ship in the Range was an issue. The launch team continued to hold the Falcon 9 until the ship was cleared.
However, the launch was scrubbed when another hold was called – this time by the flight computer – during ignition of the Merlin 1D engines.
“Launch aborted on low thrust alarm,” noted SpaceX’s Elon Musk. “Rising oxygen temps due to hold for boat and helium bubble triggered alarm.”
The next launch attempt was to take place on Tuesday, following a data review of the abort that was conducted on Monday via a Delta Launch Readiness Review (DLRR). The 90 minute launch window was to open at 6:35pm Eastern.
However, due to projected high upper level winds, Elon Musk opted to move the launch to Friday night, which is aiming for the same launch window.
The launch was SpaceX’s second for SES, following on from December 2013’s successful deployment of SES-8.
The first geosynchronous satellite to be launched by SpaceX, SES-8 is now on station at 95 degrees East, providing communications to India and South-East Asia.
SES-9 is the eighth satellite launched by SpaceX in seven missions to geostationary transfer orbit – including the dual launch of the ABS-3A and Eutelsat 115 West B satellites last March.
If a mission allows, the first stage of the Falcon 9 is designed to perform a powered descent and landing following its separation. Depending on the flight plan, this can either be made at sea using a modified barge named the Autonomous Spaceport Drone Ship (ASDS), or by returning to land at the launch site.
SpaceX has made three unsuccessful attempts at a barge landing; with the first landing hard and at an angle, the second toppling over due to residual motion after landing, and the third – during last month’s launch of Jason 3 – toppling over after the landing gear failed at touchdown.
December’s Orbcomm mission was the first to attempt a return to the launch site, with the stage successfully touching down at Landing Zone 1 – the former Launch Complex 13 – a few miles south of its launch pad.
The SES-9 launch was the first geosynchronous launch to make use of the upgraded Falcon 9 which was used in December’s mission.
As a result of the enhancements, SpaceX was able to attempt to recover the rocket’s first stage for the first time on a geostationary mission; on previous missions, the rocket did not have sufficient excess performance for such an attempt.
The rocket was not able to make it back to Cape Canaveral, so an ASDS was positioned downrange to receive the stage. However, SpaceX was cautious about the chances of success.
The recovery attempt was experimental and unsuccessful – however its result did not impact upon the success of the overall mission.
At 5,271 kilograms SES-9 is the heaviest geosynchronous payload yet carried by the Falcon 9 – surpassing the AsiaSat 8 satellite which was deployed in August 2014.
Both SES-9 and the AsiaSat spacecraft individually exceed the combined masses of the ABS and Eutelsat spacecraft which launched together last March.
Constructed by Boeing, SES-9 is built around the BSS-702HP satellite bus and is designed for fifteen years’ service.
It carries 81 Ku-band transponders which will be used to provide direct-to-home video, satellite broadband and backhaul for mobile communications to Northeast Africa, the Middle East, Southern and Eastern Asia and parts of Oceania.
From an orbital slot at 108.2 degrees East, SES estimate that the satellite will broadcast to 22.29 million households.
SES-9 is a replacement for the NSS-11 satellite which was acquired by SES when it purchased GE Americom in 2001. Launched by a Proton-K/DM3 rocket in October 2000 with a design life of fifteen years, the satellite was initially named GE-1A, but following its acquisition by SES and the rebranding of GE Americom to SES Americom, it became Americom Asia-Pacific 1, or AAP-1.
The satellite was transferred to a new subsidiary, WorldSat, in January 2004 as WorldSat-1 and returned to SES Americom about a year later. In 2007, the satellite was transferred to another division, SES New Skies, as NSS-11.
Over the next few years, SES underwent corporate restructuring, with SES New Skies and SES Americom merging in 2009 under the banner SES World Skies. This was absorbed by the parent company, along with the European division, SES Astra, in 2011.
Following replacement by SES-9, NSS-11 will be relocated to a different orbital slot for further operation.
The SES-7 satellite, which was purchased by SES in May 2010 following the bankruptcy of its previous operator ProtoStar, is co-located with NSS-11 and will remain on station alongside SES-9. SES-7, which was originally named ProtoStar-2, was another satellite acquired by SES while already in orbit having been launched by a Proton-M/Briz-M in May 2009.
The launch was the second flight of the “Full Thrust” or “Upgraded” Falcon 9 which debuted with December’s successful launch of eleven Orbcomm communications satellites, and the twenty-second mission overall across all Falcon 9 versions.
The “Full Thrust” is an enhanced version of the Falcon 9 v1.1 which made its final flight last month with the Jason-3 satellite; with modifications including a stretched second stage, uprated engines and colder oxidiser.
Like the v1.1, the rocket’s first stage is powered by nine Merlin-1D engines arranged in an octagonal, or “OctaWeb” pattern as opposed to the square grid layout flown aboard the Falcon 9’s first five flights – now retrospectively known as the v1.0.
The propellant, RP-1 refined petroleum which is oxidised by liquid oxygen. The Full Thrust Falcon 9 uses supercooled liquid oxygen, reducing the oxidiser to an even lower temperature than its predecessor. As it is cooled, the oxygen condenses allowing it to be loaded more densely within the available tank volume.
The Falcon departed from Space Launch Complex 40 (SLC-40) at the Cape Canaveral Air Force Station in Florida.
SLC-40 was constructed in the 1960s for the Titan III rocket, with 26 Titan IIIC and III(23)C, eight Titan III(34)D and four Commercial Titan III vehicles departing the complex between 1965 and 1992.
Following modifications, the pad was then used from 1994 to 2005 by seventeen Titan IV vehicles – including both the Titan IVA and IVB – which included the October 1997 launch of the Cassini mission to Saturn.
The former Titan complex was torn down following the lease of the launch complex to SpaceX by the US Air Force in 2007; with the mobile service tower being felled with explosives in April 2008.
Checkout of the first Falcon 9 at the pad occurred in January 2009, with the first launch in June 2010. The launch is the twentieth flight of a Falcon from the complex, with the Falcon 9’s two other launches having departed Space Launch Complex 4E at Vandenberg Air Force Base.
An additional launch complex – the former Saturn and Space Shuttle pad at Kennedy Space Center’s Launch Complex 39A – is currently being converted for the Falcon.
Ahead of the launch the Falcon underwent a successful static firing on Monday.
Fuelling of the Falcon began thirty minutes before launch, with oxidiser loading continuing up until the propellant tanks are pressurised about a minute before launch. The final ten minutes of the count made up the terminal phase, during which time an automated sequence was in control of operations.
Transfer of the rocket to internal power occurred six minutes before liftoff, with the Strongback, a structure used to transport the rocket, erect it at the launch pad and provide a point of attachment for umbilicals and cables, retracting away from the vehicle.
Three and a half minutes before launch the flight termination system (FTS) – or self-destruct – was powered on and armed. The FTS would be used to destroy the vehicle should it go off course or if the range safety officer deems it a danger to populated areas.
Final authorisation to launch was given by the launch director and range control officer in the final two minutes of the countdown. Startup and pressurisation of the vehicle began at the one-minute mark, along with activation of the launch pad’s “Niagara” water deluge system.
The nine first stage engines ignited two seconds before liftoff, allowing for automated checkout as they built up to full thrust. In the event of a problem during startup on the ground, the engines can be shut down and the liftoff aborted. Following an abort the launch may be scrubbed, however in the past SpaceX have been able to retry launches within the same window following a post-ignition abort.
After lifting off, the Falcon climbed to the East, aiming for a geostationary transfer orbit. Around a minute after launch it reached Mach 1, or the speed of sound, and passed through the area of maximum dynamic pressure (Max-Q). First stage flight lasted two minutes and 36 seconds, after which the nine engines shut down.
The stages separated four seconds after cutoff, with ignition of the second stage Merlin Vacuum engine seven seconds later. Following separation, the first stage began its descent for the landing attempt.
The second stage continued to orbit with SES-9. Around 55 seconds into the first of two-second stage burns, the payload fairing which protected the satellite during its climb through the atmosphere separated from the nose of the vehicle.
The burn lasted six minutes and 14 seconds, following which the mission entered a coast phase.
The first stage, meanwhile, conducted a ballistic return back to the Autonomous Spaceport Drone Ship (ASDS), as opposed to a usual tactics of restarting a subset of its engines for a series of three burns to facilitate the experimental recovery attempt.
The first of these, a boostback manoeuvre, did not occur with this mission. However, the stage aimed to slow down and conduct a multi-engine landing burn to provide a controlled descent onto the deck of the barge.
Timings for the landing and the actual burns involved, had not been fully confirmed ahead of the launch. However, previous ASDS landing attempts have occurred around eight minutes after launch for low Earth orbit missions.
The barge upon which landing was attempted is named Of Course I Still Love You. It hit the ASDS hard and did not survive.
Replacing the previous ASDS, Just Read The Instructions, which supported the CRS-5 and CRS-6 Dragon missions early last year, Of Course I Still Love You put to sea to receive the first stage of the Falcon 9 used in the launch of CRS-7.
However, the launch failed with the rocket disintegrating prior to stage separation. The only Falcon launch from Cape Canaveral since has been December’s Orbcomm mission for which the ASDS did not put to sea.
The barges are named after fictional spacecraft in Culture, a series of works by author Iain M. Banks.
The final phase of the mission was a forty-eight second restart of the second stage, beginning 27 minutes and seven seconds after liftoff, to place SES-9 into its target transfer orbit.
Three minutes and 29 seconds later the satellite separated from the Falcon 9 to begin its mission. SES-9 will use its own electric propulsion system to raise and circularise its orbit as it heads towards its geostationary slot.
The launch was the second of the year for SpaceX and the Falcon 9, following January’s successful deployment of Jason-3 from Vandenberg.
SpaceX’s next launch is currently scheduled for 1 April, carrying the CRS-8 Dragon mission to the International Space Station.
CRS-8’s cargo includes the Bigelow Expandable Activity Module, an experimental inflatable compartment which will be attached to the station’s Tranquillity module for around two years.
The next launch for SES is expected to be of the SES-10 satellite in September, which will be followed by SES-11 – a spacecraft which will be operated jointly by SES and American company EchoStar – in October. Both of these launches will also use the Falcon 9.
(Images: via SpaceX, SES and L2 – including work via L2 artist Nathan Koga – The full hi-res gallery of Nathan’s (SpaceX Dragon to MCT, SLS, Commercial Crew and more) L2 images can be *found here*)
(Click here: http://www.nasaspaceflight.com/l2/ – to view how you can support NSF’s running costs and access the best space flight content on the entire internet)