A United Launch Alliance (ULA) Atlas V heavylifter stands ready to kick off a weekend of back-to-back launches Saturday morning, when it delivers the sixth X-37B Orbital Test Vehicle (OTV) mini-shuttle into low-Earth orbit for the USSF-7 mission on behalf of the U.S. Space Force. And if all goes well, SpaceX will send its frequently-flown B1049 Falcon 9 core on the fifth launch of its career in the small hours of Sunday morning—just 19.5 hours later—to boost another 60 Starlink low-orbiting internet communications satellites aloft. However, with weather conditions expected to be around 40-percent-favorable on Saturday, rising to 80-percent-favorable on Sunday, it remains to be seen if the ULA and SpaceX launch teams can “thread the needle” and fly both missions on schedule.
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Liftoff of the Atlas V—which is flying in its “501” configuration with a 17-foot-wide (5-meter) payload fairing, no strap-on boosters and a single-engine Centaur upper stage—is targeted from Space Launch Complex (SLC)-41 at Cape Canaveral Air Force Station, Fla., at 8:24 a.m. EDT Saturday. As outlined previously by AmericaSpace, it will be the third ULA flight of 2020 and honors all front-line workers in the continuing struggle against the COVID-19 coronavirus, under the banner “America Strong”. Emblazoned on the side of the Atlas V payload fairing is the dedication: “In memory of COVID-19 victims and tribute to all first responders and front-line workers”.
“Our invincible American spirit drives us to motivate, collaborate and innovate together to overcome adversity,” said Secretary of the Air Force Barbara Barrett in a recent USSF news release. “In dedicating this mission to the nation’s healthcare workers, first responders and essential personnel, the Department celebrates those who are keeping America Strong.” The America Strong campaign began on 23 April with joint and individual team flights of the Air Force Thunderbirds and Navy Blue Angels over cities across the nation and USSF-7 is the first space mission that it will feature.
“The U.S. Space Force and United Launch Alliance salute each American serving on the frontlines in our fight against COVID-19,” said Gen. John “Jay” Raymond, chief of USSF space operations and commander of U.S. Space Command. “We are proud to dedicate the upcoming launch of USSF-7 to showcase American resolve and national unity during these challenging times.”
“We are honored to collaborate with the U.S. Space Force and dedicate the USSF-7 mission to front-line responders and those affected by this global pandemic,” said Tory Bruno, president and CEO of ULA. “This launch provides us with a unique opportunity to honor those affected by COVID-19 and pay tribute to the hard-working first responders who are selflessly supporting the nation during this difficult time.”
Processing of the USSF-7 mission long predated last December’s official inauguration of the USSF, before which time its payload fell under the umbrella of Air Force Space Command. The 107-foot-tall (32-meter) Common Core Booster (CCB) of the Atlas V and its 41-foot-long (12.6-meter) Centaur upper stage arrived at Cape Canaveral from ULA’s facility in Decatur, Ala., last October, to begin pre-launch processing. In late April, the Launch Vehicle On Stand (LVOS) milestone got underway and culminated in the stacking of the CCB, Centaur, inter-stage adapter and the lower portion of the payload fairing in the Vertical Integration Facility (VIF) at the SLC-41 complex. The booster was declared fully stacked on 6 May, with the addition of the bullet-like Short Payload Fairing (SPF), containing the highly secretive X-37B mini-shuttle.
The Launch Readiness Review (LRR), chaired by ULA Launch Director Paul Aragon, was completed on Wednesday, and rollout from the VIF to the pad surface—a distance of about 1,700 feet (500 meters)—got underway under partly cloudly skies at 10 a.m. EDT Thursday. When the Atlas V reached the pad atop its Mobile Launch Platform (MLP) just 74 minutes later, umbilical connections were established and efforts to fill the CCB first stage with 25,000 gallons (113,650 liters) of highly refined rocket-grade kerosene (known as “RP-1”) got underway. “Bird is hard-down on the pad, checked out and ready to tank RP-1,” tweeted Mr. Bruno shortly after the booster’s arrival at SLC-41. Fueling of the CCB with liquid oxygen and the Centaur with its load of liquid oxygen and hydrogen is slated to get underway about 2.5 hours ahead of T-0 on Saturday morning.
Weather for Saturday initially seemed, at best, iffy, with initial predictions of only a 60-percent likelihood of acceptable conditions at T-0. However, by Wednesday Launch Weather Officer Jessica Williams had lowered the odds to just 40-percent-favorable, on account of uncertainty about the exact location and intensity of a developing subtropical boundary off the Florida coastline. A broad area of low pressure from this boundary was expected to increase the chance of scattered showers and isolated thunderstorms, noted the 45th Weather Squadron at Patrick Air Force Base in its Thursday morning briefing. “Scattered showers and an isolated thunderstorm cannot be ruled out,” it stated, “as there is still uncertainty in the exact location of where the low is going to develop and track. Winds are the main concern as a tight pressure gradient is forecast, regardless of the exact storm location.”
The low is expected to move slowly in a northeasterly direction by late Saturday, away from the coast, promising an 80-percent likelihood of good conditions for the backup launch date on Sunday. But Sunday is expected to see SpaceX launch its next batch of 60 Starlink low-orbiting internet communications satellites, at least some of which should benefit from new “VisorSat” technology to minimize their optical characteristics and impact on ground-based astronomy. The criticality of the USSF-7 launch carries priority and a scrub on Saturday would certainly push the SpaceX mission into next week at the soonest. And that leaves a very narrow period of just a week or so before SpaceX’s most significant flight of the year on 27 May to launch NASA astronauts Doug Hurley and Bob Behnken to the International Space Station (ISS) aboard a Crew Dragon. It will mark the first launch of U.S. citizens, aboard a U.S.-built spacecraft, atop a U.S.-built rocket, and from U.S. soil, since the end of the Space Shuttle era in July 2011.
However, should ULA and the USSF manage to “thread the needle” and get the Atlas V airborne on Saturday, and should SpaceX do likewise with its Starlink mission at 3:53 a.m. EDT Sunday, the Space Coast might reverberate to two rocket launches within just 19.5 hours. The booster core assigned to this flight—tailnumbered “B1049”—will become only the second Falcon 9 to log a fifth launch, having already boosted two previous 60-strong batches of Starlinks aloft last January and in May 2019. Before that, it also delivered a heavyweight geostationary payload in the form of the Telstar 18V communications satellite in September 2018 and the final group of Iridium NEXT low-orbiting satellites to orbit in January 2019.
Assuming B1049 accomplishes a smooth landing on the Autonomous Spaceport Drone Ship (ASDS), “Of Course I Still Love You”, it will become the first Falcon 9 core to return successfully from a fifth mission. Its predecessor B1048 completed its own successful fifth flight in March, but the core suffered a premature shutdown of one of its engines during the landing attempt and was lost.
With many commercial and government launches postponed in the wake of the COVID-19 march, Starlink missions have dominated SpaceX’s manifest for the first half of 2020. Five batches of 60 satellites per mission—300 in total—have already been launched between 6 January and 22 April.
SpaceX President Gwynne Shotwell has stressed her expectation that the missions will continue to fly, perhaps as often as every two weeks, although the extreme brightness of the Starlink “trains” in the night sky has caused some consternation among members of the public and the astronomical community. As such, it is expected that Sunday’s flight will include at least some Starlinks benefiting from “VisorSat” technology in the form of dark “sun visors” to limit their optical characteristics. SpaceX has also noted that Starlink missions from June will see all satellites benefiting from VisorSat technology.
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