SpaceX launched their sixth mission for telecommunications giants SES. The launch, using a flight-proven Falcon 9 rocket to deploy the SES-12 satellite into a geostationary transfer orbit, occurred at 00:45 Eastern on Monday, departing from SLC-40 at Florida’s Cape Canaveral Air Force Station.
The launch of SES-12, SpaceX’s eleventh mission of the year, continues a partnership with Luxembourg-based SES, who was the first customer to launch a communications satellite on Falcon 9 back in 2013. SES was also the customer for SpaceX’s first mission with a previously-flown – or flight-proven – first stage last March.
SES-12 also launched aboard a reused Falcon 9, whose first stage was previously part of the rocket that deployed one of the US Air Force’s X-37B spaceplanes last September.
The payload – SES-12 – is a 5,400-kilogram (11,900 lb) communications satellite carrying a total of seventy-six Ka- and Ku-band transponders. Constructed by Airbus Defence and Space the satellite is built around a Eurostar E3000e platform – a variant of Airbus’ Eurostar 3000 product line that relies solely on electric propulsion for orbit-raising maneuver.
Now Falcon has deployed it into geostationary transfer orbit, SES-12 will use its SPT-140D thrusters – manufactured by Russia’s OKB Fakel – to raise itself to geostationary orbit. This process is expected to last six months. The satellite is expected to operate for at least fifteen years.
SES commissioned the SES-12 satellite from Airbus in mid-2014. A replacement for the fifteen-year-old NSS-6 satellite, SES-12 will be stationed in geostationary orbit at a longitude of 95 degrees East – from where it will provide direct-to-home broadcasting and high-throughput satellite services to Asia, the Middle East and Australia, as well as parts of Eastern Europe, the Mediterranean and East Africa.
The NSS-6 satellite, which SES-12 will replace, was launched on the penultimate flight of Europe’s Ariane 4 rocket in December 2002. NSS-6, which was built by Lockheed Martin, was designed for a fifteen-year service life which it passed at the end of last year. The spacecraft was originally built for Dutch firm New Skies Satellites (NSS), which was acquired by SES in late 2005. New Skies Satellites became SES New Skies shortly afterward and was merged with SES Americom in 2009, with the resulting subsidiary being named SES World Skies. SES amalgamated World Skies and its other subsidiary, SES Astra, back into the parent company two years later.
SES-12 is more powerful than NSS-6: carrying sixty-eight Ku-band transponders – including both spot beams and wide beams – to its predecessor’s fifty. It is also equipped with eight Ka-band transponders. SES-12 will be co-located with SES-8, a smaller direct-to-home broadcasting satellite that was launched in December 2013.
SES-8 was the payload for SpaceX’s first geostationary launch, and the first communications satellite to fly aboard Falcon 9. Since then, SpaceX also launched the SES-9 satellite in 2016, SES-10 last March via the first flight-proven Falcon 9, SES-11 in October and GovSat-1 – also known as SES-16 – this January.
SES-12 had originally been slated to launch aboard an Ariane 5 rocket, with SES-14 flying aboard Falcon 9 instead. Last year SES opted to swap the two launches around in order to get SES-14 on-orbit sooner. SES-14 was launched in January. However, the Ariane 5 went off course and placed it into a more highly-inclined orbit than had been planned. Like SES-12, SES-14 uses electric propulsion and is still in the process of maneuvering into its final geostationary orbit.
The launch was SpaceX’s eleventh of 2018 – a total that includes ten flights of the single-core Falcon 9 and February’s test flight of the Falcon Heavy rocket. A two-stage liquid-fuelled rocket, Falcon 9 was designed to fulfill SpaceX’s ambition of developing a reusable rocket.
The company has achieved success with recovering and reusing the first stage of the Falcon 9, while efforts to make the vehicle’s payload fairing reusable are underway. The second stage is not currently recovered – however SpaceX is hopeful that this can also be returned to Earth and reflown in the future.
The SES-12 mission used Core 1040, a previously-flown or “flight-proven” first stage that first flew last September. Core 1040 was the first stage of the Falcon 9 rocket that launched the X-37B OTV-5 mission for the US Air Force last September.
After separating from the vehicle during September’s launch the first stage executed three planned burns to return to its launch site, touching down in a powered landing at Cape Canaveral Air Force Station’s Landing Zone 1 – a Falcon 9 landing pad built on the site of the former Launch Complex 13.
With SES-12, Core 1040 was making its second flight. As it is a Block 4 booster, a previous generation of Falcon 9 hardware that was superseded by the new Block 5 version of the rocket that debuted last month, it was only qualified to make two launches. Because of this, SpaceX did not attempt to recover the booster again following its role in the launch.
Although Falcon’s first stage was not recovered, SpaceX continued to take steps towards recovering the rocket’s fairing. The fairing – the nose cone of Falcon 9 that protects the satellite while the rocket climbs out of Earth’s atmosphere – costs about six million dollars per launch and separates into two parts once the rocket reaches space. During recent missions from Vandenberg Air Force Base, SpaceX has attempted to catch the two halves of the fairing in a giant net as it descends under parachute.
While they have not yet managed to catch a fairing using the net – which is mounted aboard the boat, Mr. Steven – SpaceX has demonstrated that the structure can survive reentry and deploy parachutes. During the recent Iridium and GRACE launch, SpaceX recovered both parts of the fairing intact from the water, after they missed the recovery ship. Catching the fairing before it hits the water will help to protect it from contamination.
SpaceX does not currently have a ship on the East coast equipped with a net-like Mr Steven’s. However, their recovery ship GO Pursuit departed Port Canaveral on Monday. The ship will likely attempt to pick up one or both parts of the rocket’s fairing from the water – allowing SpaceX to gather more data as it descends.
The SES-12 launch took place from Space Launch Complex 40 (SLC-40) at the Cape Canaveral Air Force Station. This is one of two launch pads SpaceX use on Florida’s Space Coast – the other being Launch Complex 39A (LC-39A) at the nearby Kennedy Space Center. SLC-40 was originally built as Launch Complex 40 (LC-40) – part of the Titan III Integrate-Transfer-Launch (ITL) Complex – in the 1960s.
Along with its sister pad LC-41, LC-40 initially supported Titan IIIC rockets. LC-40 was later used by Titan III(34)D and Titan IV rockets – becoming the Cape’s last active Titan pad after Complex 41 began conversion for the Atlas V rocket in 1999. The last Titan launch from SLC-40 was made in April 2005, after which the complex became inactive.
SpaceX leased Complex 40 from the US Air Force in 2007, demolishing the Titan launch towers in favor of a clean-pad approach. Falcon 9 is integrated horizontally in a hangar close to the launch pad, before being transported to the pad atop a strongback structure shortly before launch.
SLC-40 was heavily damaged in September 2016 when a Falcon 9 exploded during fuelling ahead of a static fire test. The pad remained out of action for over a year while refurbishment was conducted, returning to duty last December.
The launch was to occur two days after the Eastern Range had been due to enter a planned period of downtime for maintenance. Such periods are scheduled to allow the US Air Force to catch up with work that is difficult to schedule while launches are taking place.
The outage was due to extend from 29 May to 8 June. However, neither SpaceX nor the US Air Force has confirmed whether this has been rescheduled, or whether enough assets have been left online to support the Falcon launch. Falcon 9 requires fewer range assets than other rockets, in large part due to its autonomous flight termination system (AFTS), which allows the rocket to monitor its own flight and issue a self-destruct command if necessary instead of relying on tracking and a command from the ground.
Regardless of this issue, the launch was moved to June 4 due to work relating to the rocket.
Standing down from Friday’s launch attempt to run additional tests on Falcon 9’s second stage. Rocket and payload are in good health. Currently working toward a June 4 launch of SES-12 from Pad 40 in Florida.
— SpaceX (@SpaceX) May 31, 2018
The launch of SES-12 was the fifty-sixth flight of Falcon 9. The rocket has completed fifty-three of its previous missions with complete success – with one outright failure and a further mission during which a first stage engine failure left the rocket with insufficient fuel to reach the deployment orbit for one of two payloads on board. The primary payload of that launch – a Dragon spacecraft – was still deployed successfully.
Not included in Falcon’s total number of flights is September 2016’s mission to launch Israel’s Amos 6 satellite, which resulted in the loss of both the Falcon 9 and its payload after an explosion during a static fire test, two days before launch.
Falcon’s flight began with first stage ignition, about three seconds before the countdown reached zero. The rocket’s first stage is powered by nine Merlin-1D engines, manufactured in-house by SpaceX, which burn RP-1 kerosene propellant and liquid oxygen. They are laid out in an octagonal pattern – termed an OctaWeb – with a center engine and eight more clustered around it.
The OctaWeb was introduced with the Falcon 9 v1.1 upgrade in 2013, a stretched and enhanced version of the rocket that replaced the original design. For the first five Falcon 9 missions, using what has retrospectively become known as Falcon 9 v1.0, the engines were arranged three-by-three in a square.
Falcon 9 v1.1 was superseded by another improved design, Falcon 9 v1.2 – also known as Falcon 9 Full Thrust – in December 2015. Amongst the changes were a move to supercooled oxidizer – which is more dense, allowing a greater mass of liquid oxygen to be carried – and uprated engines. Within this version, SpaceX has continued to refine the rocket’s design with incremental production blocks, culminating in the Block 5 that represents the final major revision of the Falcon 9.
Once the countdown reached zero, Falcon 9 lifted off to begin its mission. Around Seventy-eight seconds after liftoff the rocket passed through the area of maximum dynamic pressure – Max-Q – which is the point at which the combination of aerodynamic forces and the rocket’s velocity combined to put it under the highest mechanical stress that it experienced during the ascent.
The first stage – Core 1040 – burned for the first two minutes and 44 seconds of flight. Separation of the spent first stage took place four seconds after its cutoff, with the second stage igniting its single Merlin Vacuum (MVac) engine a further seven seconds after staging.
Although Core 1040 was not recovered, SpaceX has sometimes used these missions to demonstrate techniques to aid future recovery operations – such as different landing burn profiles – before the stage falls into the Atlantic Ocean. The company has not announced whether any such tests will be conducted with Core 1040.
The second stage made two burns during the launch. The first of these placed the stage, with the SES-12 satellite attached, into an initial parking orbit. This saw the Merlin Vacuum engine burn to T+8 mins and 25 seconds. The Merlin Vacuum is a version of the Merlin-1D engine optimized to be more efficient in the vacuum of space than in the Earth’s atmosphere. It burns the same propellants as the engines on the first stage.
— Michael Baylor (@nextspaceflight) June 3, 2018
About 32 seconds after second stage ignition, with the rocket clear of Earth’s atmosphere, Falcon’s payload fairing separated. Splitting down the middle into two halves, the fairing fell away from Falcon. It is likely that at least one side of the fairing is carrying recovery hardware – including a parachute – to allow SpaceX to gather further data to support its fairing reuse project.
After the second stage’s first burn concluded, Falcon will coast to T-26 minutes before a second burn carried the satellite to its planned geostationary transfer orbit. The second burn, which will last about 55 seconds, will raise the orbit’s apogee and places SES-12 into its targeted deployment orbit. Spacecraft separation is expected about five minutes after the end of the burn.
The launch followed two successful launches for SpaceX last month – with the deployment of the Bangabandhu-1 communications satellite by the first Block 5 Falcon 9 on 11 May and a California launch with a payload of five Iridium-NEXT satellites and the twin-satellite GRACE-FO Earth science mission. The next Falcon mission is expected to fly at the end of June, with SpaceX’s Dragon spacecraft beginning its CRS-15 resupply flight to the International Space Station.