SpaceX Falcon 9 Full Thrust - Amos 6 - Destroyed September 1, 2016
No screenshot from SpaceX Webcast of the destruction of Amos 6
Mission Rundown: SpaceX Falcon 9 FT - Amos 6
Written: January 30, 2021
Shouldn’t we test without the satellite?
In January 2013, SpaceCom announced that they had signed a contract with SpaceX for the 2015 launch of the Amos-6 satellite on a Falcon 9 launch vehicle. The Amos-6 satellite was intended to replace the Amos-2 satellite, which was planned to be retired in 2016. During 2015 SpaceCom announced the launch date had slipped to mid-2016. A final launch date was set for 3 September 2016.
Under the deal with SpaceCom, state-owned IAI was contracted to build Amos-6 and its ground control systems, as well as provide operating services. SpaceCom estimated that the cost of launching, insuring and one year's operation of Amos 6 would be $85 million.
On 1 September 2016, during propellant loading for a routine test, the Falcon 9 launch vehicle suffered an anomaly that destroyed the vehicle and its AMOS-6 payload. The explosion started near the upper stage LOX (Liquid oxygen) tank.
Because the satellite was destroyed prior to the launch, the cost of the satellite was not covered by SpaceCom's insurance policy, but rather by the manufacturer, IAI - that had its own insurance and filed a claim in order to compensate SpaceCom.
The contract with SpaceX specified that SpaceCom could choose to receive $50 million, or a future flight at no cost. SpaceCom chose the future flight to launch Amos 17.
News reports in early November indicated that SpaceX had determined the root cause for the anomaly, that it was straightforwardly fixable, and that SpaceX would return to flight in December 2016. On 2 January 2017, SpaceX released an official statement indicating that the cause of the failure was a buckled liner in several of the COPV tanks, being the root cause of perforations that allowed liquid and/or solid oxygen to accumulate underneath the lining, which was ignited by friction caused by pressurizing the COPV.
Somebody in SpaceX should have asked a simple question, but since nobody did. It went wrong. SpaceX has since this incident not done static fires testing with commercial or public payloads onboard. They are more lax about inhouse payloads from SpaceX.
The Payload
The primary payload for what was to be the 29th flight of the Falcon 9 rocket was AMOS-6, an earth communications satellite weighing 5.5-tonne (12,100 lbs). AMOS-6 had a total power generating capability of 10 kW, and was meant to replace the aging AMOS-2 satellite.
It was a Israeli Earth communications satellite, one of the SpaceCom AMOS series, that was built by Israel Aerospace Industries (IAI), a defense and aerospace company.The Amos-6 included payload components from various subcontractors including Canada's MacDonald, Dettwiler and Associates, which built the communications payload, and Thales Alenia Space ETCA for the electric propulsion.
AMOS-6 is an geostationary earth communications satellite – primarily built by Israel Aerospace Industries (IAI) and operated by Space Communication Ltd (SpaceCom) – that is part of the SpaceCom AMOS (Affordable Modular Optimized Satellite) series of satellites.
It had a planned mission duration of 15 years.
AMOS-6 was destined for a geostationary orbit, placed at 4° West with a perigee of 35,785 km (22,235 mi) and an apogee of 35,800 km (22,245 mi).
Overall, AMOS-6 was to be the second satellite in the AMOS 4000 platform – the second generation of AMOS satellites – after AMOS-4.
Moreover, AMOS-6 was to be the first in the AMOS series to make use of electric propulsion for station keeping operations in its geostationary orbit; however, its orbit raising maneuvers following its release from the second stage of the Falcon 9 would still have been conducted via traditional, chemical-based propulsion.
AMOS-6 was equipped with 36, 43 Ku band coverage and 36, 43 Ka band coverage – as well as two S-band transponders. What 36, 43 Ku and 36, 43 Ka band means, I don’t know.
The satellite was originally contracted to launch in 2015; however, SpaceCom later announced that launch would not take place until mid-2016.
Subsequently, in October 2015, Facebook and Eutelsat entered into an agreement with SpaceCom to lease 18 of AMOS-6’s 36 Ka-band spot-beams for broadband capability beginning 1 January 2017 through September 2021 for a fixed price of $95 million (USD) over the life of the contract.
The contracts was to serve for spot-beam coverage of sizeable portions of Sub Saharan Africa, significant portions of Europe, and portions of the Middle East (including Israel, Jordan, portions of western Iraq, and a majority of Syria) for Facebook’s internet.org initiative – which aims to provide affordable access to internet services.
Composite Overwrapped Pressure Vessel
COPV are placed in Falcon 9 propellant tanks and deliver the inert gaseous Helium and Nitrogen to backfill the propellant tanks with helium and steer the booster in vacuum so it’s oriented the right way just before ignition. The helium gas is also used to stir the liquid oxygen tank with bubbles which helps with the oxygen evaporation and thereby chills the LOX by removing “the warmer gaseous oxygen”.
The Reaction Control System - RCS thrusters use fast cold gas nitrogen bursts to orient the spacecraft, apply a major burst as a gravity push to press the propellant towards the intake valves, and from where the Merlin 1D+ vacuum engine can start the next burn in outer space. COPV are used to store the necessary Nitrogen gas needed for these maneuvers under extremely high pressure if not in a liquid state.
The forces applied to a COPV are extreme, they are wrapped in carbon fiber composite and reinforced with Kevlar fibers, and they must perform in cryogenic conditions on an ascending rocket. The weakest point on a COPV is the top valve, the pipes and the bolts, that attach them to struts in the propellant tanks. The latter caused the CRS-7 inflight failure where a COPV ripped itself loose, broke a helium pipe and over pressurized the LOX tank to its breaking point. So it was Bye Bye to CRS-7 and Cargo Dragon C109.
The Amos-6 Pad failure found a new never seen before weakness in minor cracks/bubbles in the composite carbon fiber layers. Liquid oxygen penetrates the space between the metal aluminum vessel and the composite carbon fiber layers, freezes and expands the fibers to breaking point. It then snaps and sparks, igniting the oxygen and carbon fiber dust that’s created in an instant. Oxygen expands a 1000 times and breaks more fibers with a cascade of sparks, ignitions and a huge explosion followed within milliseconds.
Carbon dust is the fuel, oxygen is the oxidizer and whether either the friction of or the snap of bursting fibers is the ignition? The BOOOM surely follows. In naval warfare U-boats found that some ships exploded faster and sank faster after being torpedoed. The German Navy took that as evidence that they sank an ammunition ship. But the allies knew who was carrying and wasn’t carrying ammunition.
Passenger Ships like Lusitania, Carpathia and Britannica didn’t carry ammunition, but they sank fast and quickly as if they did carry ammunition. The cause was coal dust blown loose from floors and walls by the torpedo blast and ignited by the flames. The empty coal bunkers, long service tunnels to the boilers and an uninhibited blast wave passing through the bottom of the Passenger Ships sealed their fate. They sank fast.
Fine dust in the air will combust just as fast as a gas/oxygen mixture, so be aware of ignition sources in your surroundings. It might get you killed or burned severely.
