SpaceX has conducted a crucial static fire of their Falcon 9 rocket ahead of Dragon’s return to flight mission to the International Space Station. The company transported its Falcon 9 rocket for the CRS-8 mission to its seaside launch pad at the Cape Canaveral Air Force Station on Tuesday for the milestone test ahead of a planned launch on Friday, 8 April.

The road to CRS-8 static fire:

As with all Falcon 9 first stages, the powerful Full Thrust (FT) variant of the Falcon 9 was built and assembled at SpaceX’s Hawthorne, California, facility before it was shipped via road and security escort to the company’s McGregor, Texas, test facility.

Once at McGregor, the first stage was put through a series of tests before it was erected on the test stand and put through a full duration hot fire test.

This hot fire test, designed to evaluate the health of all nine engines at the base of the Falcon 9 first stage and verify that all plumbing, equipment, wiring, and software on the first stage and its engines are functioning properly during powered operations, occurred on Friday, 5 February.

The hot fire test was a success, proving that the first stage was ready for shipment to the Cape Canaveral Air Force Station for use on the CRS-8 ISS resupply mission.

However, following the hot fire test, the first stage suffered an incident on Monday, 8 February, during follow-up testing when a GSE (Ground Support Equipment)-related incident resulted in damage to most of the first stage’s engine nozzles.

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The damage was subsequently repaired and the stage was shipped to Cape Canaveral a week and a half ago.

After its arrival at SLC-40, the Falcon 9 first stage was transported into its integration facility at the pad where teams performed receiving inspections and final preparations for first stage/second stage mate.

The first and second stages were subsequently mated last week ahead of what was scheduled as a static fire test on Tuesday. Static Fire tests traditionally take place in the second half of the day, with this latest test taking place in the Florida evening – around 9:40pm local time.

The static fire – an important step:

For SpaceX, a static test fire in the days prior to launch helps the company ensure the functionality of the propellant and propulsion systems of the Falcon 9 as well as all of the launch pad’s systems prior to the all-important Launch Readiness Review (LRR).

To this end, every static test firing involves a full propellant loading sequence, launch countdown and engine ignition operations, and testing of the pad’s high-volume water deluge system.

Moreover, these static fires provide SpaceX and the launch team with a full dress rehearsal for the actual launch and allows them to identify and fix issues with the vehicle and/or pad prior to the commencement of actual launch operations.

Perhaps no other static fire proved the beneficial nature of this static-fire-for-every-mission approach than the ORBCOMM-2 Return To Flight mission in December 2015.

During that campaign, a series of attempts over multiple days to achieve static fire for the ORBCOMM-2 mission’s Falcon 9 v1.1 FT first stage encountered multiple issues.

Specifically, the issues – as understood – stemmed from the new type of super-chilled oxidizer debuting on that mission.

The repeated delays and lessons learned led to minute procedural changes and increased understanding of how deep cryo liquid oxygen interacts with the vehicle at the pad during loading and launch operations.

Impressively, all of those issues encountered and accounted for during the static fire led to the almost unprecedented on-time on-the-first-attempt launch of a brand new version of the Falcon 9 rocket utilizing a never before used propellant.

Likewise, the CRS-8 Falcon 9 will use the same deep cryo liquid oxygen.

Following the static fire, teams performed an immediate analysis of the CRS-8 Falcon 9’s engine and vehicle data.

The vehicle was then de-tanked, lowered back to the ground by the Transporter Erector (TE), and rolled back to its pad-side integration hanger for final processing.

At the same time, engineers and senior management will meet to conduct the LRR, which will confirm the launch date for CRS-8.

Currently, launch is targeted for NET (No Earlier Than) 8 April 2016 at 16:43 EDT, with a backup opportunity already booked with the Eastern Range for 9 April at 16:20 EDT.

CRS-8 – return to ISS for SpaceX:

In all, the CRS-8 mission will mark a resumption of ISS resupply efforts for the commercial space company.

SpaceX’s last ISS resupply mission ended in failure 2 minutes 19 seconds after liftoff on 28 June 2015 when the second stage of the Falcon 9 rocket failed during first stage flight.

In the resulting six months it took SpaceX to investigate and correct the issues with the second stage, ISS resupply efforts were maintained solely by the Russian Federal Space Agency, Roscosmos, and the Japan Aerospace eXploration Agency, JAXA, via their Progress and HTV-2 resupply vehicles, respectively.

NASA’s other commercial resupply partner, Orbital ATK, which suffered its own failure in October 2014, returned to flight operations via a United launch Alliance (ULA) Atlas V rocket on 6 December 2015 and followed that mission by a second resupply effort, again on an Atlas V rocket, two weeks ago.

For SpaceX, CRS-8 will be the first time in almost exactly one year that a Dragon spacecraft will visit the Space Station.

Dragon’s arrival will also mark the first time both CRS vehicles – Dragon and Cygnus – will be berthed together on the orbital outpost.

The mission will be the fourth flight of the Falcon 9 following the mishap last June, with the return to flight mission being the ORBCOMM-2 flight in December 2015 which resulted in the first-ever successful powered Return To Launch Site (RTLS) landing of a first stage of an orbital-bound rocket.

Likewise, SpaceX will attempt to recover the first stage of the Falcon 9 used for this week’s CRS-8 mission; however, like previous ISS resupply missions, it is understood that the company will use its ASDS barge for the first stage landing attempt.

For this, the ASDS will be placed approximately 210 miles Northeast of the launch site where it will wait to receive the Falcon 9 first stage.

The fact that SpaceX is expected to use the ASDS barge instead of executing a RTLS landing is notable as missions to the International Space Station are not classed as high-performance flights of the Falcon 9 – therefore giving the vehicle the needed performance margins to safely fly itself back to its launch site.

Moreover, with December’s successful RTLS landing of the Falcon 9 first stage, one would assume that the Federal Aviation Administration (FAA) would grant permission to return the first stage to LZ-1 (Landing Zone 1) for CRS-8.

Therefore, either the FAA did not grant permission for a RTLS landing or SpaceX opted to forgo a LZ-1 landing and instead focus on fine-tuning Falcon 9 first stage landing performance on the ASDS barge instead.

(Images: via SpaceX 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*)

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