Six months after its 19th mission ended in catastrophe, SpaceX’s Falcon 9 booster is set for a long-awaited Return to Flight (RTF), no sooner than Tuesday, 15 December, carrying no fewer than 11 Orbcomm Generation-2 (OG-2) communications satellites into low-Earth orbit. According to sources within Orbcomm and the Air Force, a request for Eastern Range approval was granted, with a backup opportunity on the 16th.
As well as transporting the largest number of discrete satellites into orbit aboard a single SpaceX vehicle, the mission is expected to mark the maiden voyage of the “Full Thrust” (FT) variant of the Falcon 9 booster, also known informally as the “v1.2”. A successful flight in mid-December will open the floodgates for an ambitious 2016, which is expected to kick off with the Commercial Resupply Services (CRS)-8 Dragon cargo flight to the International Space Station (ISS) in the first week of January.
Although information remains scarce, comments from the Air Force today confirm that SpaceX is pressing ahead with its plans to land the Falcon-9 RTF Orbcomm first-stage booster on solid ground, rather than aboard the deck of the Autonomous Spaceport Drone Ship (ASDS) in the Atlantic Ocean. Earlier this year, Air Force Brig. Gen. Nina Armagno, commander of the 45th Space Wing at Patrick Air Force Base, signed a five-year lease with SpaceX to create a “Landing Pad” at Cape Canaveral Air Force Station’s historic Launch Complex (LC)-13. Utilized for Atlas Intercontinental Ballistic Missile (ICBM) tests and operational Atlas launches from August 1958 through April 1978, LC-13 was deactivated in 1980. More than three decades passed before SpaceX leased it in February 2015 and efforts to construct five landing pads for its returning Falcon 9 first-stage hardware got underway. The site is now designated “Landing Complex-1”.
“One thing that is true in recent news is that SpaceX is waiting on Federal Aviation Administration (FAA) approval for both return to flight and doing a land landing vs. drone ship,” explained Chrissy Cuttita, operations chief of 45th Space Wing Public Affairs, based at Patrick Air Force Base, in response to an inquiry from Zero-G News’ Managing Editor Matthew Travis, who shared the information with AmericaSpace this afternoon.
Media visiting pad 39A Dec. 1 were greeted by NASA Commercial Crew Program representatives, who hinted to the possibility in the first place. However, the USAF was not able to confirm anything until this afternoon, nor was a SpaceX spokesperson present to address journalists at their own launch pad.
UPDATE: On Dec. 3 a SpaceX spokesperson contacted AmericaSpace stating that they are hoping to have more info to provide in the coming days.
Contrary to earlier suggestions that the SES-9 communications satellite—destined for delivery into Geostationary Transfer Orbit (GTO) on behalf of the Luxembourg-based SES satellite services provider—would likely fly aboard the Falcon 9 Return to Flight (RTF) mission, it has become clear in recent weeks that 11 small Orbcomm Generation-2 (OG-2) communications satellites will instead form the primary payload. This will bring up to 18 the total number of OG-2 satellites launched, six of which were carried aloft by a Falcon 9 booster in July 2014 and one of which failed to achieve orbit, due to a second-stage thrust shortfall in October 2012. All satellites are operated by Orbcomm, Inc., a major Machine-to-Machine (M2M) messaging-services provider, headquartered in Rochelle Park, N.J.
Built by Sierra Nevada Corp. (SNC) of Sparks, Nev., each three-axis-stabilized OG-2 satellite weighs 380 pounds (172 kg) and, when fully deployed in orbit, measures 42.7 feet (13 meters) x 3.3 feet (1 meter) x 1.6 feet (0.5 meters) and generates about 400 watts of electrical power. Based upon the SN-100 spacecraft “bus”, they are designed for minimum five-year operational lifetimes and utilize a modular payload deck which can be rapidly integrated and tested.
They are the current generation of a series which has seen 53 Orbcomms launched since July 1991, aboard a variety of rockets, including Europe’s Ariane 4, the air-launched Pegasus booster, Orbital Sciences’ Taurus, China’s Long March 4B, India’s Polar Satellite Launch Vehicle (PSLV) and Russia’s Cosmos-3M. Initial “Concept Demonstration Satellites” led to the OG-1 network and a replenishment series of “Quick Launch” missions, with OG-2 intended to supplement and ultimately replace the first generation. “Due to their high efficiency and modular design, these satellites have substantially more capacity to service a larger number of subscribers, thus making the network more efficient with few satellites than the OG-1 satellites that are currently in orbit,” explained Pat Remias, SNC’s Space Systems senior director of programs, speaking before the July 2014 mission. “SNC has established a satellite production line in our Louisville facility to integrate and test each vehicle rapidly, with up to six satellites processing simultaneously.”
In May 2008, Orbcomm signed a $117 million contract with SNC to build 18 OG-2 satellites, with an option to purchase up to 30 more, in order to augment its existing on-orbit infrastructure. “Orbcomm anticipates selecting the launch vehicle within 12 months,” it was noted, “and plans to launch the 18 OG-2 satellites in three separate missions of six satellites each between 2010 and 2011.” Added flexibility was provided by SNC’s unique mechanical configuration, which enabled multiple satellites to be packaged efficiently into several different types of launch vehicle. At length, in September 2009, Orbcomm selected SpaceX’s Falcon 1e launch vehicle to deliver the 18 satellites into low-Earth orbit, from “as early as the fourth quarter of 2010 through 2014”.
However, schedule slippages pushed this plan increasingly to the right and the Falcon 1e was eventually withdrawn from the market, before it had even flown a single mission, due to limited demand for its services. Payloads originally earmarked for the Falcon 1e were remanifested to exploit excess capacity aboard the more powerful Falcon 9 v1.0 and the first “prototype” OG-2 satellite was launched from Space Launch Complex (SLC)-40 at Cape Canaveral Air Force Station, Fla., in October 2012, riding “piggyback” alongside SpaceX’s first dedicated Dragon cargo mission to the International Space Station (ISS). Unfortunately, an upper stage thrust shortfall in one of the Falcon 9’s cluster of Merlin 1C engines caused the OG-2 to be inserted into a low orbit of just 125 x 200 miles (200 x 320 km), instead of the intended 220 x 470 miles (350 x 750 km). Although the small satellite was successfully deployed from the second stage of the Falcon 9 v1.0, it quickly became apparent that the orbit was “unworkable” and it re-entered the atmosphere to destruction a couple of days later.
The next batch of six OG-2 satellites were delivered to the Cape in April 2014 and, after multiple launch delays, were successfully boosted into orbit atop an uprated Falcon 9 v1.1 on 14 July. Planning called for the remaining satellites to be lofted in the fall of the following year, but the loss of a Falcon 9 v1.1 during first-stage flight on 28 June 2015 imposed a hiatus as SpaceX sought to discover what had caused the accident. At length, on 16 October, Orbcomm announced that all 11 satellites would fly aboard the upgraded variant of the Falcon 9—variously identified as the “Falcon 9 v1.2” or “Falcon 9 Full Thrust (FT)”, as detailed in a previous AmericaSpace article—on the Return to Flight (RTF) mission.
Targeted to take place approximately “in the next six to eight weeks”, the Eastern Range has since conferred approval on SpaceX for an opening launch attempt from SLC-40 at Cape Canaveral Air Force Station on 15 December, with a backup opportunity on the 16th. “We are excited to launch our 11 OG-2 satellites aboard SpaceX’s newly upgraded Falcon 9 rocket and have full confidence in SpaceX and their dedication to this launch,” said Orbcomm CEO Marc Eisenberg. “We look forward to completing the deployment of our next-generation constellation and delivering a higher level of performance, coverage and reliability through our modernized and upgraded OG-2 network to our customers around the world.” More recently, SNC confirmed that all 11 satellites completed their Pre-Ship Review in mid-October and were subsequently delivered to the Cape for final checkout and integration aboard the Falcon 9 v1.2/FT.
Flying for the first time with its 11 OG-2 passengers, the upgraded booster will see its first-stage Merlin 1D+ and second-stage Merlin 1D+ Vacuum engines running at their full, 100-percent power level. This is in contrast to the 80 percent of rated performance seen on previous Falcon 9 v1.1 missions. A further 13 percent of additional performance will be accrued through a range of structural enhancements to the vehicle’s airframe and a process of “densifying” and thereby increasing the liquid oxygen propelland load. All told, this is expected to yield a performance “gain” of 33 percent over the v1.1.
It is understood that the v1.1 utilized the Merlin 1D engines at 80 percent of rated capacity, with 20 percent held in reserve, in order to afford maximum flexibility to the payload to achieve its correct orbital position. In contrast, the v1.2/FT architecture centers around the enhanced “Merlin 1D+” engine, which is reportedly capable of 1.53 million pounds (694,000 kg) of thrust at T-0, effectively operating at “full” (100 percent) capability. This will increase to about 1.7 million pounds (771,100 kg) as the vehicle travels higher into the rarefied upper atmosphere. Similarly, the Merlin 1D Vacuum engine of the second stage will see a corresponding increase in propulsive yield from 180,000 pounds (81,600 kg) in the v1.1 to 210,000 pounds (95,250 kg) in the v1.2/FT. According to a source close to SpaceX, “FT” is the internal code name for calculating the Merlin 1D’s output at 100 percent, adding that “this improves the Falcon 9’s performance by 20 percent, although this “improvement” was not really new: it was always there, but never utilized.” At the time of last summer’s failure, it is understood that SpaceX intended to stage its first v1.2/FT launch in July 2015, delivering SES-9 to GTO.
However, the 20-percent performance hike achieved by throttling the engines from their 80-percent to 100-percent power levels has been expanded yet further to reach an overall 33-percent “performance gain” over the v1.1. This gain has been met in part through structural enhancements to the vehicle’s airframe, including a 10-percent increase in propellant tank volumes, a lengthened second stage with extended Merlin 1D+ Vacuum engine, upgraded landing legs and grid fins, an improved “Octaweb” support structure for the first-stage engine suite, a strengthened “interstage” between the two stages and a central “pusher” to ensure a smooth stage-separation process. All told, this increases the height of the v1.2/FT vehicle to 229.6 feet (70 meters), about 5.6 feet (1.6 meters) taller than the v1.1.
Additionally, the 33-percent performance gain has been met through “super-cooling” the liquid oxygen load—in what Musk described as “deep cryo oxygen”—below its normal saturation condition, in order to increase its density and permit the carriage of a larger load of propellants in the Falcon 9’s tanks. “Propellant densification,” noted engineers Ke Nguyen and Timothy Knowles in an American Institute for Aeronautics and Astronautics (AIAA) paper, “is one of the key technologies needed to meet the challenges of future reusable launch vehicles.” The densification process, AmericaSpace understands, has required the installation of specialized cooling stations at SpaceX’s dedicated Falcon 9 pads of Space Launch Complex (SLC)-40 at the Cape and Space Launch Complex (SLC)-4E at Vandenberg Air Force Base, Calif.
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