SpaceX appears to have completed an evaluation into potential commonality between a failure on a test vehicle and its Falcon 9 fleet, following its now-approved request to the Eastern Range for Sunday morning launch of the ASIASAT-6 mission. The launch, to be conducted by SpaceX’s Falcon 9 v1.1 rocket, was delayed just ahead of fueling last week, in order to triple-check its fault detection systems.
Last week’s launch appeared to be going ahead as planned, as the SpaceX team entered the Delta Launch Readiness Review (LRR).
The initial LRR had cleared the flow to proceed towards rollout plans, while the Delta review also covered late flow items, such as the replacement of two helium valves ahead of the rocket’s short trip to the SLC-40 pad.
The Delta review was still ongoing as the rocket was being erected on the pad, which explains the “late” call to postpone the launch – a call that came several hours before the approval to begin fueling the vehicle was required.
The decision was based on the small potential of a commonality fault between the hardware on the Falcon 9 v1.1 and the F-9R Dev-1 test rocket that failed during her “hop” at SpaceX’s test facility in McGregor, Texas.
SpaceX CEO Elon Musk – who had e-mailed the SpaceX team to notify them of his decision – later released a statement to the public, admitting he was not aware of any issues with the Falcon 9 v1.1, yet the postponement had been called in order to review all potential failure modes and contingencies.
Notably, the sensor issue that ultimately resulted in the demise of the F-9R is unique to the test vehicle, from a failure standpoint.
“It looks like it was a single point failure that existed on that test article, but does not exist on the Falcon 9. We think it was a failure of a single sensor,” noted SpaceX’s Dr. Garrett Reisman to the recent Future In-Space Operations (FISO) Working Group.
“Falcon 9 has multiple sensors that its algorithm uses, so the same failure on Falcon 9 would not effect the mission in any way. The fact that Falcon 9 had nine engines, even if it had eight engines it could overcome this issue.”
While it is possible a similar issue on the Falcon 9 v1.1 would have resulted in the vehicle aborting during ignition, whilst being held on the pad via the hold down bolts – pad hardware that isn’t available for the test rockets at McGregor – the F9 can continue to rise uphill even with the loss of two engines.
Imagery from the engine failure was dramatic, due to the rupturing of the fairing that protects the engine from aerodynamic loads.
However, the engine did not explode and the vehicle continued on her path to safely insert the Dragon into orbit.
Mr. Musk noted the review of the sensor issue was expected to take “one to two weeks”. This appears to have been the case, with L2 schedule information showing a preliminary target of this coming weekend for the realigned launch attempt.
“SpaceX is currently working toward a 9/6, Launch date with a T-0 of 0050-0404 (Local) and an alternate date of 9/7 with the same 0050-0404 window, pending approval from the Eastern Range,” noted the information.
On Thursday, Cape sources claimed the target was sipping to the 7th. Range documentation later showed the slip to the target date, with the new NET (No Earlier Than) being classed as September 7, with a September 8 place holder – both with the 0050-0404 (local) windows.
However, SpaceX is yet to confirm any date at this time.
This latest mission follows on from the successful mission to loft the ASIASAT-8 satellite into orbit, part of a record year of launches for SpaceX.
For this latest mission, the Falcon 9 v1.1 will be tasked with lofting of the ASIASAT-6 telecommunications satellite into a Geostationary Transfer Orbit (GTO).
ASIASAT-6 is based on the Space Systems/Loral 1300 platform. The bird is designed to provide C-band coverage over Asia, Australasia, Central Asia and the Pacific islands.
The satellite also sports 28 high-powered C-band transponders, with a design life of 15 years.
After being lofted into a Geostationary Transfer Orbit (GTO), she will be positioned at the 120 degrees East orbital slot, with a global beam and a regional beam to offer enhanced power and look angles for video distribution and broadband network services in the region.
Most of the Falcon 9 v1.1 propellant will be required for the reach to spacecraft separation parameters, meaning there won’t be a propulsive landing attempt of the core on this mission.
However, sources note the Falcon 9 v1.1 tasked with this mission may not sport the landing legs required for such a landing attempt.
Even if it is confirmed the CRS-4 Falcon 9 is without legs, a level of continued testing toward SpaceX’s fully reusable launch system aspirations could still be undertaken, as the company refines the returning of core stages for what may soon be a return to terra firma.
(Images: SpaceX, NASA and L2)
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