SpaceX has selected the ORBCOMM-2 (OG2) mission for Falcon 9’s Return To Flight. While no specific launch date has been selected, the company is aiming for lift off to take place in around six to eight weeks, likely resulting in an early December mission. ORBCOMM-2’s trip to LEO will allow for the Second Stage to conduct additional testing ahead of the more taxing SES-9 mission.

Falcon 9 RTF:

SpaceX is into the final leg of its post-CRS-7 failure investigation, with its findings currently being overviewed by the Federal Aviation Administration (FAA).

It is expected the subsequent failure report into the loss of the CRS-7 mission will – as expected – point to a failed strut that released a Composite Overwrapped Pressure Vessel (COPV) otherwise known as a helium pressurization bottle, resulting in it leaking its helium, causing an overpressure event in the tank and the subsequent failure of the stage.

Those struts have since been replaced in the upcoming fleet of Falcon 9’s – both in the first and the second stages, along with additional improvements to aid the reliability of the SpaceX workhorse.

SpaceX utilized the investigation period to conduct a “deep dive” review of all its hardware and processing paths, with engineers reviewing the history of modifications to the evolving Falcon 9, including elements such as the optimization of the Second Stage that have been implemented over recent years.

Inspections of Falcon 9 hardware at SpaceX’s base in Hawthorne, California resulted in the mitigation of small issues, such as one relating to weld points – cited as “inconel tubes” (L2) – associated with a helium line. Engineers have since mitigated the issue on the F9-19, 21 and 22 vehicles.

The path to Return To Flight (RTF) saw the first “Full Thrust” Falcon 9 shipped out of the factory in late August (L2), en route to the company’s test site in McGregor, Texas.

That stage was erected on the “Falcon Heavy Test stand” (L2) – a dual-purpose stand that can be used for both Falcon Heavy and Falcon 9 testing. It is currently the only test stand that can be utilized for the upgraded Falcon 9 while the original stand prepares to be upgraded.

The first task was the check out the stand, while providing the new stage its first test – resulting in a 15-second static fire.

This was a historic milestone for the Falcon 9, as it marked the first time an upgraded rocket’s first stage has fired up its nine engines.

The results of the test weren’t published, although it is understood one engine on the Falcon 9 did endure a long residual afterburn, which has required some additional work to take place ahead of the next milestone.

That next task is to conduct a full-duration static test, which has been scheduled to take place this month. Providing the results are acceptable, the stage will then be transported to SpaceX’s Florida launch site at SLC-40.

Up until recent days it was predicted the SES-9 satellite would be the passenger for the RTF mission. However, SpaceX has since renegotiated its manifest obligations to allow for the ORBCOMM-2 (OG2) mission to ride uphill first.

“As we prepare for return to flight, SpaceX together with its customers SES and Orbcomm have evaluated opportunities to optimize the readiness of the upcoming Falcon 9 return-to-flight mission,” noted SpaceX in a statement on Friday. “All parties have mutually agreed that SpaceX will now fly the Orbcomm-2 mission on the return-to-flight Falcon 9 vehicle.”

The reason for opting to go with the ORBCOMM-2 mission first makes sense per the goal of “risk buy down” on what is a newly upgraded rocket.

The SES-9 satellite launch is a more complex GTO mission that requires two burns from the second stage, while the OG2 mission is to LEO, requiring just the one push from the second stage.

Launching and deploying OG2 successfully will confirm SpaceX’s successful RTF, while allowing the company to conduct an important test involving the refiring the second stage with no risk to the already-separated payload.

“The Orbcomm-2 mission does not require a relight of the second stage engine following orbital insertion. Flying the Orbcomm-2 mission first will, therefore, allow SpaceX to conduct an on-orbit test of the second stage relight system after the Orbcomm-2 satellites have been safely deployed,” SpaceX added.

“This on-orbit test, combined with the current qualification program to be completed prior to launch, will further validate the second stage relight system and allow for optimization of the upcoming SES-9 mission and following missions to geosynchronous transfer orbit.”

The launch date for the OG2 mission is expected to be placed into the early December timeframe, although SpaceX won’t be able to be more specific until the stages have been tested and shipped from McGregor.

“This change does not affect the timeline for SpaceX’s return-to-flight mission which is still targeted to take place in the next 6-8 weeks,” added SpaceX. “The SES-9 launch is currently targeted for late December 2015.”

SpaceX is also working with the International Space Station Program to find an acceptable Visiting Vehicle (VV) slot for the next CRS Dragon mission to the orbital outpost, which will follow the upcoming return of Orbital ATK’s Cygnus spacecraft, set to launch atop the ULA Atlas V rocket on December 3.

SpaceX is also working to find a schedule placement for the Jason-3 mission, which will involve the final launch of the Falcon 9v1.1 variant, set to launch from Vandenberg Air Force Base in California.

A successful launch of the OG2 mission, with acceptable post flight reviews, will allow SpaceX to return to a launch cadence that is expected to result in 2016 being the busiest in the company’s history.

(Images: via SpaceX, NASA, SNC and L2’s SpaceX Section, including Jo Hunter’s aerial overview of SpaceX McGregor)

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