It was a duty with a difference for SpaceX’s Falcon 9 this morning, as the previously-flown B1061 core took flight a few minutes after midnight to lift a powerful communications satellite on the inaugural leg of its trek up to Geostationary Earth Orbit (GEO). The B1061 first stage—whose two previous missions last November and April delivered humans to orbit—was this time tasked with boosting the heavyweight SXM-8 payload on behalf of New York-headquartered online and satellite radio broadcaster SiriusXM.
Liftoff from Space Launch Complex (SLC)-40 at Cape Canaveral Space Force Station, Fla., occurred at 12:26 a.m. EDT Sunday, at the opening of a 119-minute “window”, and marked the second SpaceX flight of June, following last Thursday’s spectacular launch of the CRS-22 Dragon cargo mission to the International Space Station (ISS).
Weather conditions for Sunday’s just-after-midnight launch were predicted to be around 60-percent favorable, trending upwards to 80 percent in the event of a 24-hour scrub. With a slow inland-moving East Coast sea-breeze expected to bring higher chances of rain and storms to the Spaceport over the weekend, a risk existed for late-night and early-morning onshore-moving showers.
Specifically, the 45th Weather Squadron at Patrick Space Force Base drew attention to the possibility of showers and storms before sunset on Saturday, “with lingering mid- and upper-level convective debris clouds around for the primary launch late-night window” and added that “a few Atlantic showers and cumulus in the vicinity cannot be ruled out”.
It has certainly proven an impressive year for B1061, which arrived in Florida last July to begin preparations for its maiden voyage to lift Dragon Resilience and Crew-1 astronauts Mike Hopkins, Victor Glover, Shannon Walker and Soichi Noguchi. Following a Static Fire Test of the nine Merlin 1D+ engines on Pad 39A at the Kennedy Space Center (KSC), B1061 successfully launched its human crew last 15 November, bound for a six-month stay on the ISS. It marked the first U.S. crewed night launch in more than a decade.
With NASA having authorized SpaceX to use once-flown Falcon 9 cores on future Commercial Crew missions, B1061 went directly into service on her second mission last 23 April to deliver Dragon Endeavour and Crew-2 astronauts Shane Kimbrough, Megan McArthur, Aki Hoshide and Thomas Pesquet to the space station. This made her the first launch vehicle since shuttle Atlantis to have lifted more than one crew of humans into orbit.
But with NASA having only granted approval for crews to ride “new” or once-flown boosters, it seems likely that B1061’s future will move to unmanned payloads. Six weeks after returning from her Crew-2 mission—and with two Autonomous Spaceport Drone Ship (ASDS) landings to her credit—she was trundled out to SLC-40 on Wednesday for a Static Fire Test and her third launch. Also on Wednesday, the ASDS, “Just Read the Instructions”, put to sea from Port Canaveral to recover the core stage.
Liftoff occurred on time at 12:26 a.m. EDT Sunday, right on the opening of a one-hour and 59-minute “window”, with B1061 powering smoothly uphill for the first 2.5 minutes prior to shutdown of her Merlin 1D+ suite and separation. Guided by hypersonic grid-fins and engine burns, she alighted smoothly on the deck of the ASDS, producing SpaceX’s 17th on-point drone-ship landing of the year and positions 2021 just behind last year’s record-setting accomplishment of 19 successful ASDS “slam-dunks”.
With B1061 gone, the single Merlin 1D+ Vacuum engine of the Falcon 9’s second stage picked up the baton to lift the 15,400-pound (7,000 kg) SXM-8 high-powered broadcasting satellite into orbit. Built by Maxar Technologies of Westminster, Colo., its design is based on the tried-and-true SSL-1300 satellite “bus” and SXM-8 will generate more than 20 kilowatts of electrical power. It features large unfurlable S-band antenna reflectors to broadcast directly to radios, thus bypassing the need for big, ground-based dishes.
Contracts to build two identical satellites—SXM-7 and SXM-8—were signed back in July 2016, with original expectations that both would be launched by 2020 at the latest. However, although SXM-7 was successfully launched atop a SpaceX Falcon 9 last December, it suffered a series of failures during its In-Orbit Testing (IOT) phase and was declared a total loss last February. It was due to replace the aging XM-3 satellite, which has been in orbit at 85 degrees West longitude since early 2005, with SXM-8 expected to replace the October 2006-launched XM-4 at 115 degrees West longitude.
SXM-8 was delivered to the Space Coast by Maxar in early May for pre-flight processing and integration into its payload fairing. It will now enter an approximately two-week period of orbit-raising maneuvers to attain geostationary altitude at 22,300 miles (35,900 km), after which its IOT phase, lasting about three weeks to a month, will begin. Assuming it does not fall foul to the IOT problems suffered by SXM-7, it is expected to then enter full operations as a Digital Audio Radio Service (DARS) provider.
With the SXM-8 mission behind it, SpaceX now turns attention to its fourth launch of a Block III Global Positioning System (GPS) satellite for the U.S. Space Force, currently targeted for no sooner than 17 June, again from SLC-40. The 8,500-pound (3,900 kg) payload, which is destined for emplacement into Medium Earth Orbit (MEO), at an altitude of about 12,200 miles (20,000 km), was delivered to the Cape from prime contractor Lockheed Martin in early April. GPS III-05 is the fifth member of the Block III fleet placed into orbit since December 2018 and follows on the heels of three satellites launched atop Falcon 9s and one via the final United Launch Alliance (ULA) Delta IV Medium.
But whereas each of SpaceX’s three previous GPS Block III launches in December 2018, June 2020 and last November rode brand-new Falcon 9s, the forthcoming GPS III-05 will employ a previously-flown booster. And that booster is none other than B1062, which delivered GPS III-04 to orbit last fall. It remains to be seen if B1062 is being held aside for dedicated GPS Block III launches, although its long wait between its first and second missions is certainly unusual. In any case, GPS III-05 will mark the first National Security Space Launch (NSSL) to fly a “used” rocket.