The record-breaking doubleheader was believed to hinge upon the Saturday morning launch of a United Launch Alliance (ULA) Delta IV Heavy rocket with a classified spy satellite. However, that is apparently no longer the case.
Instead of launching on time, ULA’s infrequently-flown heavy-lift rocket was hit by 72 hours of delays to rectify minor pad hardware bugs. Around 2 am EDT (UTC-4) on August 29th, Delta IV Heavy made it just seconds away from liftoff before the rocket’s autonomous flight computer detected an anomaly with pad hardware and aborted the launch. As a result, the three cores’ three Aerojet Rocketdyne RS-68A engines were forced to shut down after ignition – an uncommon Delta IV launch abort scenario that has historically required at least a week of work to recycle for another launch attempt.
ULA ultimately determined that it was not possible to recycle the countdown for another attempt although enough time remained in the launch window to do so. The launch vehicle was safed and a scrub was announced.
In a statement provided by ULA confirmed that the early shutdown was “due to an unexpected condition during the terminal count at approximately three seconds before liftoff.” ULA also confirmed that “the required recycle time prior to the next launch attempt is seven days minimum.”
ULA has to fly before SpaceX, right?
With a minimum of seven days required to recycle the ULA Delta IV Heavy for another launch attempt, it was unclear what that meant for the fate of the SpaceX SAOCOM-1B mission.
It was previously understood that in order for SpaceX to launch the SAOCOM-1B mission from nearby Space Launch Complex-40 (SLC-40), the ULA Delta IV Heavy would have to successfully launch first. The southern polar launch trajectory of the SAOCOM-1B’s mission is one that hasn’t been flown from Cape Canaveral, FL in nearly six decades. This particular flightpath includes launch hazard zones that inch ever so close to the launchpad of the Delta IV Heavy, which is currently still on its launchpad stacked with a classified payload for the U.S. government.
It was assumed that the Falcon 9 would suffer the same minimum delay of seven days, if not longer. However, on Saturday afternoon, August 29 a SpaceX media representative confirmed that the company was still targeting the historic double header launches on Sunday, August 30.
Double the launches, double the recoveries
If SpaceX can pull it off, Sunday is set to be a stellar day for Falcon 9 launches and landings. The SAOCOM-1B mission will feature a Return To Launch Site (RTLS) landing attempt of the expended Falcon 9 booster while the Starlink Falcon 9 booster is expected to land aboard the autonomous droneship “Of Course I Still Love You” currently stationed off the coast of South Carolina.
In an unusual move, SpaceX split up the fairing catching vessels. Initially, both vessels left Port Canaveral and headed south to a catch zone located between The Bahamas and Cuba in an attempt to catch both fairing halves of the SAOCOM-1B mission. Then, GO Ms.Tree did an about-turn and met up with the booster recovery vessels off the coast of South Carolina.
At the time of publishing, the two Sunday Falcon 9 launches are expected to occur just nine hours apart. The Starlink V1.0-L11 mission is slated to occur at 10:12am ET (1412 UTC) from Launch Complex 39-A at Kennedy Space Center while the SAOCOM-1B mission is set to launch at 7:18pm ET (2318 UTC) from SLC-40 at Cape Canaveral Air Force Station. As usual, SpaceX will host official launch webcasts live, typically beginning around 15 minutes before liftoff.
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