If Dragon Endeavour crewmen Doug Hurley and Bob Behnken happened to look down towards Cape Canaveral earlier this evening, they may have experienced a peculiar pang of déjà vu, as the very same booster core which launched them into space seven weeks ago—tailnumbered “B1058”—rose again from Earth on another mission to orbit. Liftoff of the SpaceX Falcon 9 occurred at 5:30 p.m. EDT from storied Space Launch Complex (SLC)-40 at Cape Canaveral Air Force Station, Fla.
And in scenes which we dwellers of the second decade of the 21st century have now become comfortably accustomed, a few minutes after launch B1058 plummeted back through the atmosphere to alight with pinpoint grace on the deck of the Autonomous Spaceport Drone Ship (ASDS), even as the second stage headed towards geostationary transfer orbit.
Aboard today’s mission was South Korea’s first secure military communications satellite, variously known as ANASIS-II or K-MILSAT-1. Reportedly carrying a launch mass between 9,900 pounds (4,500 kg) and 13,200 pounds (6,000 kg), ANASIS-II is built upon Airbus’ EuroStar-3000 satellite “bus” architecture and is being flown on behalf of the Korean Agency for Defense Development (ADD). Delivered to Cape Canaveral last month from prime contractor Airbus in Toulouse, France, the EuroStar-3000 boasts high flexibility, enhanced payload accommodations, propulsion options ranging from chemical to all-electric and has been described as “a reference for challenging high-power missions”. Originally earmarked for development by Lockheed Martin, its construction was subcontracted out to Airbus in 2016, due to difficulties pertaining to cost.
When it enters operational service, ANASIS-II will join over 50 EuroStar-3000 satellites in geostationary orbit. These powerful satellites have previously flown aboard Russian Proton-M and Zenit boosters, Europe’s Ariane 5, the Japanese H-IIA and on three occasions aboard SpaceX Falcon 9 vehicles since March 2017. They carry dual solar arrays for electrical power provision, with a total wing span of up to 150 feet (45 meters), together with 50-90 Ku-band and C-band transponders.
As previously noted by AmericaSpace, this particular mission was originally earmarked for launch last week and B1058 was correspondingly rolled out from the Horizontal Integration Facility (HIF) to the SLC-40 pad surface on 12 July. Once there, the booster was put through a customary Static Fire Test of its nine Merlin 1D+ first-stage engines and launch was set for the 14th. Unfortunately, on the evening prior to launch, SpaceX called a halt to proceedings. “Standing down from tomorrow’s launch of ANASIS-II to take a closer look at the second stage, swap hardware if needed,” the Hawthorne, Calif.-based organization noted. “Will announce new target launch date once confirmed on the Range.”
In surprisingly short order, the 45th Weather Squadron at Patrick Air Force Base indicated through its briefings that a revised launch attempt might occur as soon as 19 July, but SpaceX later shifted this to no earlier than 20 July, which also happens to be the 51st anniversary of humanity’s first landing on the Moon. The “launch window” would be relatively spacious, lasting from 5 p.m. EDT until 8:55 p.m. EDT. And coupled with a generally favorable weather outlook, it seemed an ideal day to fly.
“Deep easterly flow will continue across the region through the week,” the 45th announced in its Sunday morning briefing. “The air mass across Central Florida remains slightly drier than normal for this time of year, which will limit precipitation coverage today into Monday.” This was expected to produce a 70-percent likelihood of acceptable weather, tempered by the risk of infringing the Cumulus Cloud Rule and Surface Electric Field Rule. A 24-hour slip into Tuesday, however, was predicted to see a marked downturn in the forecast, with only a 50-50 chance of suitable weather at T-0. “A disturbance currently over the eastern Bahamas will track northwest and approach Florida Monday night into Tuesday,” it continued, “bringing an uptick in moisture and greater coverage of showers and thunderstorms at that time.”
Preparations for today’s mission proceeded with the kind of clockwork precision for which SpaceX has become well-known. Fueling of the Falcon 9 with liquid oxygen and a highly refined form of rocket-grade kerosene (known as “RP-1”) got underway about 35 minutes before the scheduled T-0. Entering the Terminal Countdown phase at T-10 minutes, the nine Merlin 1D+ first-stage engines were chilled to prepare for ignition and with 60 seconds remaining on the clock the propellant tanks began pressing for flight and the vehicle transitioned to “Startup” as its computers assumed command of the countdown.
Liftoff occurred on time and B1058—which previously launched Dragon Endeavour on 30 May—powered smoothly uphill through Florida’s late-afternoon skies. Two and a half minutes into flight, its job done, the first stage was discarded and commenced a smooth descent, controlled by a symphony of engine burns and hypersonic grid-fins, to alight on the deck of the Autonomous Spaceport Drone Ship (ASDS), “Of Course I Still Love You”, situated offshore in the Atlantic Ocean. It marked the 37th successful drone ship landing on either the East or West Coasts of the United States since April 2016, out of a total of 46 attempts.
In the meantime, the Merlin 1D+ Vacuum engine of the second stage ignited for a 5.5-minute “burn” to deliver ANASIS-II towards its geostationary orbital slot. Deployment of the satellite was anticipated about 32.5 minutes after liftoff. “Per the customer’s request, live coverage will end shortly after first-stage landing,” SpaceX noted, in telling reference to the covert nature of ANASIS-II’s mission.
And while Falcon made another solid landing, both payload fairings were recovered as well, according to Elon Musk in a tweet following the launch.
This evening’s successful launch added a new record to the annals of the Space Coast. Launching only 51 days after its last mission, B1058 eclipses the now-retired Space Shuttle Atlantis for the shortest interval between two launches by a reusable, orbital-class vehicle. Atlantis launched her first flight, Mission 51J, on 3 October 1985, returning four days later from a classified Department of Defense assignment. And on the night of 26 November, she launched again for her second orbital voyage, Mission 61B, which set a launch-to-launch record of 54 days. That record remained unbroken for more than three decades. Until today.
With the ANASIS-II mission successfully completed, the end of July remains unclear at present. Argentina’s SAOCOM-1B Earth-imaging satellite is tentatively scheduled for the period from the 25th through the 30th and it would appear likely that this “customer” mission will leapfrog the still-waiting-in-the-wings Starlink/BlackSky flight, which has been repeatedly delayed since the last week of June.