SpaceX has static fired their Falcon 9 rocket tasked with lofting the CRS-11/SPX-11 Dragon resupply mission to the International Space Station on Sunday ahead of a planned launch on Thursday afternoon at 17:55 EDT (21:55 UTC). The company had intended to conduct the static fire on Saturday before remarkably advancing that forward to Friday. Technical obstacles then prevented the Friday test and ultimately moved the event to Sunday.
Advanced static fire – a testament to the teams and pad:
Rarely does one get to boast about the advancement of a major milestone in spaceflight; but that’s exactly what SpaceX had aimed to do with the static fire of the Falcon 9 rocket tasked with launching the CRS-11/SPX-11 Dragon resupply mission to the International Space Station.
The mission was already notable for being the first to reuse a Dragon spacecraft for an uncrewed resupply flight to the Station, but SpaceX also aimed to gain bragging rights of advancing their static fire by a day.
Since the commencement of Falcon 9 operations from LC-39A earlier this year, the SpaceX team has proven time and again their capability to maintain a relatively smooth flow for their Falcon 9 rockets – with payload customers themselves (notably the National Reconnaissance Office) largely responsible for gaps longer than two or two and a half weeks in the launch manifest.
Moreover, a great deal of credit for the possibility of a static fire advancement belongs with the engineers overseeing historic pad 39A – who have done a tremendous job of maintaining the pad in excellent condition such that the last two missions from the pad have resulted in no major issues of note and no waivers for pad systems that SpaceX has needed to accept prior to the next flight.
In fact, in the final day of the Inmarsat-5 4F launch campaign earlier this month, workers at the Kennedy Space Center noted in documentation available on L2 that the Inmarsat-5 4F flow was the smoothest flow to launch they’d experienced, with no line items, no waiver requests, and no action items in the Launch Readiness Review (LRR).
That same type of report post-Inmarsat-5 4F noted that Pad-A came through launch “without major issue” – which is truly the best post-launch pad report one can hope for a given that there will always be minor things that need to be repaired or refurbished after millions of pounds of thrust inundate the launch pad surfaces.
Following the Inmarsat-5 4F launch, the AECOM ISC (Institutional Support Contract) support plan flight sheet for the Kennedy Space Center and the Cape Canaveral Air Force Station listed the static fire for CRS-11 – the next mission in the flight manifest – as scheduled for Saturday, 27 May with a T0 of 12:00 EDT at the opening of a six-hour static fire window that extended to 18:00 EDT.
The same AECOM ISC support plan also noted that “Readiness has been requested and is due Wednesday, 5/24” – a readiness summary that surprisingly indicated that not only was everything on track from a mission integration standpoint with the Falcon 9, its Dragon spacecraft, and the assortment of internal and external cargo supplies for the Space Station, but also that the static fire could be advanced by one day to Friday.
So subdued was the announcement of the advancement that NASASpaceflight.com learned of it not through SpaceX but from a standard advisory sent to all Kennedy Space Center employees Thursday afternoon announcing that “SpaceX will be conducting a static fire test of their Falcon 9 rocket at LC-39A on Friday, May 26.”
Unlike the originally planned Saturday test, which carried an entire test window of six hours, Friday’s static fire would have been contained to a four-hour window opening at 16:00 EDT and closing at 20:00 EDT.
Furthermore, unlike some previous – though not all – static fires, SpaceX would not have had the ability to extend beyond the 20:00 EDT end of the static fire window, with Friday morning documentation from Kennedy noting “Planned T-0 1600L, with a four hour duration (hard cut-off for T-0 at 2000L).”
However, by early afternoon Friday, an issue with an umbilical between the rocket and the TEL (Transporter/Erector/Launcher) forced the static fire back to Saturday before eventually pushing the crucial pre-flight test to Sunday.
Static Fire milestone, launch plan:
As with all SpaceX missions, the journey of the core stage – Core 1035 – began with construction in Hawthorne, California, before shipment to the company’s McGregor, Texas, test site.
Core 1035 arrived at McGregor on 17 March and was spotted on the S1 (Stage 1) test stand on 20 March (L2 McGregor Photos).
The hot fire test at McGregor is a critical step for all Falcon 9 core stages – new or flight-proven – to confirm that every element of their avionics, electrics, engines, and Main Propulsion Systems are in perfect working order before they are shipped to the Kennedy Space Center (or Vandenberg), where they are then brought inside the Horizontal Integration Facility (HIF) for final preparations for flight.
By 5 April, the S1 test stand at McGregor was empty, and on 22 April, Core 1035 was seen arriving at the LC-39A HIF.
Since its arrival, Core 1035 has undergone receiving inspections and final checkouts ahead of mating to its second stage a few days ago.
Per the static fire timeline, SpaceX anticipated having the Falcon 9 vertical atop LC-39A in time to allow engineers to target the opening of Sunday’s window – which opened at 12:00 EDT and stretched for six hours.
Prior to the static fire, Kennedy Space Center security establish roadblocks to LC-39A three hours before the opening of the static fire window, thereby blocking access to Pad-A while allowing any work that might be taking place this weekend at Pad-B to continue.
An hour and a half before the opening of the static fire window, the Kennedy Space Center Emergency Operations Center (KSC EOC) activated to monitor the static fire and – in the unlikely event of an anomaly – “assist in the response and communicate any necessary actions to the appropriate personnel.”
A now-standard statement from KSC EOC reads that “even if there were a catastrophic anomaly at LC39-A, it would pose no danger or threat to KSC Spaceport personnel.”
The static fire itself allows the launch teams to practice every single aspect of the countdown as it will occur on launch day, culminating with a 3.5 second run of all 9 Merlin 1D engines at the base of the Falcon 9 core stage.
After this run, the engines are shut down and the vehicle and pad safed – giving the launch team a chance to practice this type of scenario in real-time should it occur on launch day.
After a successful static fire, the vehicle was detanked, lowered to horizontal, and taken back into the HIF where final preparations continued for the launch of CRS-11.
These final preparations include mating of the Dragon spacecraft to the top of the second stage of the Falcon 9 as well as the critical LRR two days before launch.
The LRR will review every piece of data gathered during the static fire, and the various teams (including NASA) will provide final recommendations regarding the vehicle and launch windows before granting final engineering approval to proceed toward launch.
The LRR is also the meeting during which any waivers – if they exist – will be discussed and either accepted or a forward plan developed.
Current timelines show that all elements for the mission – including the rocket, the Dragon capsule itself, and all of the various supplies, experiments, and equipment – are on track to meet the 1 June launch target, even taking into consideration the prolonged three-day holiday weekend in the United States for Memorial Day.
Despite the delay of the static fire by one day, there are no plans at this time to delay the launch, which is carefully choreographed around the U.S. federal holiday on Monday and the scheduled Friday, 2 June undocking of the Soyuz MS-03 vehicle.
Launch on 1 June of CRS-11 to the ISS is targeted for an instantaneous time of 17:55 EDT (21:55 UTC), the exact center of a five-minute launch window opportunity that day.
Unique to this resupply mission – though something which hopefully will not be unique in the future – is the fact that this Dragon capsule has already been mated into a Falcon 9 rocket and launched into space before.
While it has long been confirmed that CRS-11 will be the first commercial resupply mission by SpaceX to reuse a Dragon capsule, it is now understood that CRS-11 is using Capsule C106, which flew the CRS-4 mission back in September/October 2014.
The reuse of this particular capsule marks an important step in SpaceX’s stated goal to develop reusable technology not just for its rockets but for its spacecraft as well.
The mission will mark the first time that a commercial resupply vehicle to the International Space Station is reused and the first time that a previously flown spacecraft will arrive at the ISS since the final arrival of the Space Shuttle Atlantis in July 2011.
(Images: SpaceX and L2, Jacques van Oene/Spacepatches.nl and L2 McGregor Gary Blair)
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