For the 25th time in a little under six years, the roar of a Falcon 9 rocket’s Merlin-class engines is expected to echo across Cape Canaveral Air Force Station, Fla., on Thursday, 26 May, delivering another payload towards space. Liftoff of the Upgraded variant of the SpaceX booster—equipped with improved Merlin 1D+ engines, structural enhancements to its airframe and benefiting from a “densified” cryogenic-loading protocol—is scheduled to occur from the Cape’s Space Launch Complex (SLC)-40 at 5:40 p.m. EDT Thursday. The relatively spacious, two-hour “launch window” is due to close around 7:40 p.m.
A customary Static Fire Test of the nine Merlin 1D+ engines of the Upgraded Falcon 9’s first stage was successfully conducted on Tuesday evening. “Static Fire complete in advance of Thursday’s launch,” tweeted SpaceX at 10:31 p.m. EDT Tuesday. In addition to transporting the heavyweight Thaicom 6 communications satellite to Geostationary Transfer Orbit (GTO), SpaceX will attempt another landing of the Falcon 9 first-stage hardware on the deck of the Autonomous Spaceport Drone Ship (ASDS) in the Atlantic Ocean.
Counting tomorrow’s launch, it has been an ambitious first 25 flights for SpaceX’s workhorse fleet. The first Falcon 9, flying in its “v1.0” configuration, with a “tic-tac-toe” layout of nine Merlin 1C engines at the base of its first stage, was launched on 4 June 2010 and delivered a qualification “boilerplate” of the Dragon cargo spacecraft into low-Earth orbit. This was followed by the first successful flight of a Dragon—executed as part of SpaceX’s Commercial Orbital Transportation Services (COTS) agreement with NASA—in December 2010, during which the spacecraft completed a smooth, parachute-assisted splashdown in the Pacific Ocean. Between May 2012 and April 2016, Falcon 9s have transported no fewer than nine Dragons toward the International Space Station (ISS), under the language of the Commercial Resupply Services (CRS) contract. Of these, all but one reached their destination, with last June’s CRS-7 Dragon lost in a high-altitude structural breakup, a little over two minutes after liftoff. These Dragon visitors enabled the delivery of science and supplies to and from the orbiting outpost, including large payloads, such as the Cloud Aerosol Transport System (CATS) and the Bigelow Expandable Activity Module (BEAM).
In tandem with its commitment the ISS, via Dragon, the Falcon 9 has also supported a range of other missions to low-Earth orbit, Geostationary Transfer Orbit (GTO) and beyond. In September 2013, the “v1.1” version of the rocket—equipped with uprated Merlin 1D engines—made its first flight, carrying Canada’s Cascade, SmallSat and IOnospheric Polar Explorer (CASSIOPE) satellite aloft. This was quickly followed, the following December, by SpaceX’s first foray into a 22,300-mile (35,900 km) GTO, carrying the SES-8 communications satellite. Eight more GTO-bound payloads followed, from Thaicom 6 in January 2014 to the flight of JCSat-14 on 6 May 2016. SpaceX has also lofted 17 Orbcomm Generation-2 (OG-2) satellites into low-Earth orbit, boosted the Jason-3 ocean altimetry mission for NASA and sent the Deep Space Climate Observatory (DSCOVR) to a Beyond Low-Earth Orbit (BLEO) destination at the L1 Lagrange Point.
During six years of operations, the Falcon 9 has undergone regular upgrades. Its v1.0 variant flew five times between June 2010 and its swansong in March 2013, after which the v1.1—powered by the Merlin 1D engine—picked up the baton for 15 missions between September 2013 and January 2016. During the v1.1’s career, the provision of landing legs and hypersonic grid fins allowed for the first efforts to land its first stages on the ASDS deck. Four “controlled oceanic touchdowns” in April, July and September 2014 were followed by four mixed-success attempts to physically land on the drone ship. Only on the maiden flight of the Upgraded Falcon 9 in December 2015 was a perfect controlled touchdown achieved, albeit not on the ASDS, but on solid ground: at Landing Zone (LZ)-1 at the Cape. Since then, with the exception of a landing failure in March 2016, two more Upgraded Falcon 9s have successfully returned their first stages back to the ASDS deck.
SpaceX currently boasts two operational drone ships in its inventory. The first, affectionately dubbed “Of Course I Still Love You”, is based on the East Coast, supporting launches out of the Cape, whilst the second, nicknamed “Just Read the Instructions”, is located on the West Coast for missions out of Vandenberg Air Force Base, Calif. And the East Coast ASDS certainly has had its sense of love tested in recent weeks. Including Thursday’s attempt, it will have welcomed three returning booster stages in less than two months. Maneuvered out to sea early last month, it supported the CRS-8 first stage landing on 8 April and was brought back to Port of Cape Canaveral and unloaded. It then returned into the Atlantic a second time to support the JCSat-14 landing on 6 May, returning to port with another scorched and blackened first stage at 10:22 p.m. EDT on 9 May.
A mere 12 days later, at 9:11 p.m. EDT last Saturday, the ASDS was towed back out to sea by the Elsbeth III tug. It was positioned about 420 miles (680 km) off the Cape for what is expected—like JCSat-14—to be a high-velocity and high-energy (and thus “hotter”) re-entry. Additionally, since GTO-bound missions carry greater energy requirements, there is less available propellant to support the re-entry and landing “burns”. This presses the envelope for a successful landing far closer to the wire than lower-energy missions to low-Earth orbit. The positioning of the ASDS is slightly further offshore than for the JCSat-14 mission, which Spaceflight101 noted might possibly allow for a longer re-entry burn to reduce the challenging conditions.
Thursday’s launch will be the third GTO mission of the year for SpaceX, tying with the company’s previous “personal best”, achieved in 2014. The primary payload, Thaicom 8, is reported to weigh 7,330 pounds (3,325 kg) and has been built by Orbital ATK at its Dulles, Va., manufacturing facility. Based on Orbital ATK’s GEOStar-2 three-axis-stabilized satellite “bus”, its pair of four-panel Ultra Triple Junction (UTJ) solar arrays and lithium-ion batteries can provide up to 5 kilowatts of electrical power to the payload. It is designed to remain operational at GTO for up to 15 years. Numerous GEOStar-heritage satellites have been launched via European Ariane 5 and Russian-built Soyuz-FG, Zenit and Proton-M rockets, as well as two payloads—SES-8 and Thaicom 6—by a Falcon 9.
As well as being the third GEOStar bus to be boosted by a SpaceX vehicle, Thursday’s mission is also the third satellite launched by a Falcon 9 on behalf of the Bangkok-headquartered Thaicom communications satellite services provider. A Falcon 9 v1.1 previously delivered Thaicom 6 to GTO in January 2014 and was followed in September 2014 by AsiaSat-6, half of whose 28 transponders were marketed as “Thaicom 7”. With Thursday afternoon’s launch, this brings to eight the total number of Thaicom satellites launched aboard Ariane 4/5 and Falcon 9 rockets since the inaugural Thaicom 1 arrived on-orbit, way back in December 1993. Among other achievements, the 2005-launched Thaicom 4 was the world’s first High Throughput Satellite (HTS) for broadband provision. All told, the Thaicom network provides more than 600 television channels, widespread broadband connectivity and has the demonstable capability to recover communications networks at times of natural disasters, such as in China, Japan and New Zealand.
In the late spring of 2014, as Thaicom 6 neared the completion of its In-Orbit Testing (IOT) and checkout phase and AsiaSat 6 was readied for launch, Thaicom announced that it would invest a ceiling of $178.5 million in the development of its next bird, which was due to fly in the first half of 2016. Stationed at 78.5 degrees East longitude—co-located with the 2006-launched Thaicom 5—the new satellite will “support the growth of [Thailand’s] broadcasting industry and strengthen its competitiveness in the international market”. Specifically, it will enable Thaicom to meet Thailand’s burgeoning ultra-high-definition-television (UHDTV) demands. Its 24 Ku-band transponders will cover Thailand, South Asia and Africa.
Late last month, Orbital ATK delivered Thaicom 8 from its manufacturing facility in Dulles, Va., to Florida. The satellite reached the Cape to begin pre-launch processing on 29 April. “We built and delivered this high-quality communications satellite for Thaicom PLC two months ahead of schedule, demonstrating our ability to manufacture reliable, affordable and innovative products that exceed expectations for our customer,” said Amer Khouri, Vice President of Orbital ATK’s Commercial Satellite Business. “As one of Asia’s leading satellite operators, we are grateful for Thaicom’s continued confidence and look forward to more successful partnerships in the future.”
Following Thaicom 8’s encapsulation inside the bulbous Payload Fairing (PLF), the Upgraded Falcon 9 stood 229 feet (70 meters) tall. As seen in previous Upgraded Falcon 9 countdowns, the utilization of “densified” liquid oxygen as part of its propellant load no longer requires an hours-long tanking regime. Instead, loading of the booster with cryogenics will begin around 35 minutes before T-0. Following liftoff, the nine Merlin 1D+ engines of the first stage will boost the stack for about 2.5 minutes, before separating and attempting a return to the ASDS. Meanwhile, the single Merlin 1D+ Vacuum engine of the second stage will conduct a pair of burns—the first burn lasting six minutes, followed by an 18.5-minute coasting phase and the second burn lasting about 70 seconds—to deliver Thaicom 8 into its targeted GTO location. It will begin a 30-day IOT and checkout phase, ahead of 15 years of orbital operations.
According to the 45th Weather Squadron at Patrick Air Force Base, meteorological conditions on Thursday afternoon are expected to be 90-percent favorable, with a slight chance of Liftoff Winds being the only violating factor. “Warm and dry conditions” are expected to persist across Central Florida, with a tropical disturbance east of the Bahamas expected to kept offshore and away from the spaceport. “On launch day, the tropical system will likely still be too far away to impact the spaceport’s weather,” it was noted, “leaving very little launch weather violation risk, other than liftoff winds. Maximum upper-level winds will be from the northwest at 25 knots at 40,000 feet.”
In the event of a scrub and a 24-hour turnaround, however, Friday’s forecast deteriorates to 70-percent-favorable. “On Friday, the tropical system will continue to slowly strengthen and move closer to the spaceport,” the 45th Weather Squadron explained in its Tuesday morning update. “Tropical moisture associated with the system will begin filtering in and help to destabilize the atmosphere.” This will generate an additional risk of violating the Cumulus Cloud Rule.
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