Falcon 9 conducts Static Fire test ahead of Inmarsat 5 F4 mission

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SpaceX has demonstrated for a second time just how short a turnaround it can accomplish at LC-39A with Thursday’s static fire of the Falcon 9 that is set to launch the Inmarsat 5 F4 satellite Monday afternoon.  As preparations for that mission continue, the flight two slots down on the manifest, the mid-June launch of BulgariaSat 1, has now been announced and confirmed as the next mission to make use of a flight-proven Falcon 9 core stage.

Inmarsat 5 F4 static fire:

Coming an impressive 10 days after the launch of the NROL-76 mission for the National Reconnaissance Office, SpaceX brought fire to LC-39A again for the static fire of the Inmarsat 5 launch campaign.

The static fire ties the shortest turnaround the pad has seen for SpaceX at just 10 days between a launch and a static fire, with an anticipated – and only once seen before – 14 days between two launches.

That record was set with the 14 day turnaround at SLC-40 in September 2014 – between the AsiaSat 6 launch on the 7th and the CRS-4 mission on the 21st.

Documentation in L2 shows that the time between Echostar XXIII and SES-10 could have been even shorter, at just 12 days from launch to launch; however, range shuffling with the continuously-delayed Atlas V for the Orbital ATK OA-7 mission pushed SES-10 out of its range approved 27 March date, with the launch eventually falling on 30 March.

After SES-10, a two week delayed due to the NRO’s secretive payload precluded SpaceX from repeating its rapid turnaround efforts with the NROL-76 mission, though it is understood and documented in L2 that Pad-A and the TEL (Transporter/Erector/Launcher) were ready to support the NRO launch in its original mid-April slot.

Importantly for SpaceX, this soon-to-be repeated two week turnaround between missions is crucial to launching the myriad of satellites currently in the company’s full manifest.

Pointedly, the ability for SpaceX to perform this kind of short turnaround is due in large part to a change in the TEL retract sequence that occurs at T0.

At SpaceX’s other launch pad, SLC-40 at the Cape Canaveral Air Force Station, the TEL retracted from the Falcon 9 at T-3mins, leaving long umbilicals between it and the rocket that were then damaged and/or destroyed from the Falcon 9’s exhaust plume – necessitating timely replacement and repair operations between missions.

For Pad-A, SpaceX adopted a new “throwback” procedure for the TEL, which quickly moves it away from the rising Falcon 9 to protect its umbilicals.

This “throwback” procedure has been praised by the company as immensely successful in eliminating the timely turnaround efforts needed for the TEL between missions – as is now being fully re-demonstrated with the 10 day period between the NROL launch and Inmarsat 5’s static fire.

For Inmarsat 5, the Falcon 9 rocket and its mated second stage was rolled to the launch pad and hoisted to vertical on Wednesday afternoon, after which final connections to Pad 39A’s propellant, electrical, and data systems were made.

As with Echostar XXIII, the Inmarsat 5 Falcon 9 is expected to look slightly different than what we have come to know as the traditional Falcon 9.

Inmarsat 5’s mission profile denotes the need to fly the Falcon 9 in its expendable configuration and the vehicle will therefore not sport any landing legs and will not attempt an ocean landing on the ASDS (Autonomous Spaceport Drone Ship) Of Course I Still Love You.

As with standard static fire procedures, roadblocks and Emergency Operations Command (EOC) were established to prevent access to Pad 39A and to assist with recovery efforts in the unlikely event of a static fire mishap.

As with the previous static fires from Echostar XXIII through NROL-76, Pad 39B remained open to workers at the Kennedy Space Center during the static fire.

The specific window for Thursday’s static fire was targeting an 1200 to 1800 EDT window – though as with previous static fires, that window could be adjusted as required.

For the static fire, the Falcon 9’s first and second stages were completely filled with propellant as the launch team conducted what is essentially a full-up Wet Dress Rehearsal practice countdown, going through every step and procedure that will be used on launch day.

When the count reaches T-3 seconds, the “start” command for the nine Merlin 1D engines at the base of the Falcon 9 first stage was sent, with chamber ignition occurring at T-2 seconds.

The Falcon 9 engines then ran for three seconds, as is standard for static fires, before engine shutdown is commanded and safing of the vehicle occurs. T-0 was – as pre-planned earlier in the day – 12:45 Eastern.

The engine firing and shutdown sequence not only allows SpaceX to gather valuable data about the entire rocket’s performance – guaranteeing it is ready for liftoff – but also gives the launch team the opportunity to practice shutdown and safing operations of the Falcon 9 should that occur during the actual countdown.

Following static fire, the Falcon 9 will be de-tanked, returned to horizontal, and rolled back into the Horizontal Integration Facility (HIF) at Pad-A where it will then be mated with its Inmarsat 5 F4 payload.

At this time, liftoff is slated to occur on Monday, 15 May 2017 during a launch window of 1920 – 2010 EDT (2310 – 0010 GMT – Monday into Tuesday).

BulgariaSat 1 – flight-proven core to take to the skies again:

As Inmarsat 5 prepares for its big day, the mission two slots down in the manifest, the mid-June scheduled launch of BulgariaSat 1, received its own fair share of attention with confirmation and announcement that it will be the second mission of the Falcon 9 to utilize a flight-proven core.

In March, prior to the first flight-proven core mission of SES-10, SpaceX stated that there were “other customers” interested in using flight-proven cores – though SpaceX did not enumerate on which customers those were.

Bulsatcom, the owner of BulgariaSat 1, is now understood to be one of those customers – with the company very recently agreeing to use a flight-proven core.

In a statement regarding the announcement, Maxim Zayakov, BulgariaSat Chief Executive, stated that “Elon Musk and his SpaceX team have convinced me that people like them bring us closer to a new quality of life through providing access to cutting-edge technology.  This is a chance for Bulgaria to join the efforts to develop these new aspects of space industry.”

Unlike the SES-10 mission, which used a core that had flown a full year prior, BulgariaSat 1 will make use of a core that has flown this year – the same Falcon 9 first stage that triumphantly returned the company to flight with the Vandenberg launch of the IridiumNEXT mission in January.

Reuse of the IridiumNEXT 1-10 core will mark just five months between the stage’s two missions, more than halving the total amount of time between reflights of the SES-10 core.

Importantly, however, the total amount of time spent refurbishing the two cores is understood to be roughly the same at about four months.

Interestingly enough, the announcement that Bulsatcom had signed on to use a flight-proven core coincided with a shuffling of the SpaceX manifest that moved the BulgariaSat 1 mission ahead of the Intelsat 35e mission.

Whether or not the decision to use a flight-proven core somehow improved Bulgariasat 1’s placement in the manifest or made it possible for Bulgariasat 1 to move ahead of a delaying Intelsat 35e flight is unknown – though curious nonetheless as it could represent part of SpaceX’s stated desire to introduce flexibility into its launch manifest via the use of flight-proven cores.

Presently, the two-month forward outlook for SpaceX’s launch manifest is as follows:

15 May – Inmarsat 5 F4 (Kennedy – LC-39A)
1 June – Dragon/CRS-11 (Kennedy – LC-39A)
15 June – Bulgariasat 1 (Kennedy – LC-39A)
29 June – IridiumNEXT 11-20 (Vandenberg, SLC-4E)
Late-June – Intelsat 35e (Kennedy – LC-39A)

(Images via NASA, SpaceX, and L2/Jacques van Oene/Spacepatches.nl)


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