The United Launch Alliance (ULA) is forced to abort its mission again to launch a US spy satellite atop its powerful Delta IV Heavy Rocket, just a few seconds before lift-off on Wednesday, September 30.
Officially designated as NROL-44, the secretive spy satellite for the National Reconnaissance Office (NRO) was set to be carried into orbit through the ULA-built Delta IV Heavy Rocket at 11:54 PM EDT from Cape Canaveral Air Force Station in Florida.
However, with only even seconds left before launch, the much-awaited countdown was immediately stopped. It is reminiscent of the NROL-44's cancelled launch a month ago when ULA Director Lou Mangieri announced the cancellation of the launch - also due to technical issues.
The Delta IV Heavy Rocket, minutes before its now-cancelled attempt to carry NROL-44 into orbit, taken from a tweet by the United Launch Alliance (ULA).
Abort at T-minus 7 Seconds
ULA, through its Twitter account, first announced "HOLD. Abort at T-minus 7 seconds." It was followed by an explanation that the Terminal Countdown Sequencer Rack (TCSR), which controls the last ten seconds of the launch, automatically called for an abort due to a detected issue.
Shortly after the launch was called off, ULA CEO Tory Bruno explained via Twitter. Bruno wrote: "We experienced an automated abort because a sensor reported a fault. Automated Safety System operated as intended." He added that both the rocket and its payload are "safe and unharmed." He added that the radially outward firing initiators (ROFI) were not ignited and the turbo-pumps had not yet started.
The Delta IV Heavy Rocket uses two types of engine ROFI ignitors, the ULA CEO explained in a subsequent tweet in response to a user asking about the use of the term. One type of ROFI is embedded in the injector plate of the rocket engine. This ignites the engine with a cone of spraying hot gas, igniting the engine.
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Bruno explained that the second type is actually called Hydrogen Burn Off Units, responsible for the licking flames filling the base of the expendable heavy-lift launch craft shortly before its engines generate thrust and begin liftoff.
Erring on the Side of Caution
On August 29, the scheduled ULA mission to lift NROL-44 into orbit was also grounded shortly before launch. This earlier attempt saw its launch countdown teaching T minus three seconds before a detected fault pulled the plug on the attempt. The August attempt, like the recent one, was a "hot fire abort" - cancelling a launch at the last possible seconds, when the rocket's engines have begun heating up.
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Another Twitter user raised the possibility of the sensor itself malfunctioning, despite everything else on the launch craft working correctly. User @darkmelmet argued that ULA "has so many sensors on their rockets and launch pads," asking if the aerospace manufacturer's target of 100% reliability is actually "counterproductive."
Bruno accepted the notion of a "false" alarm from the sensor's end, adding that it remains to be known. As for the question on counterproductivity, the ULA chief explained their bias towards aborting a mission with the risks of "critical malfunction."
"Recycle time is always a better trade than the risk of killing a billion-dollar payload that took many years to build," Bruno answered.
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