Having completed a successful Static Fire Test of the nine Merlin 1D first-stage engines on its Falcon 9 v1.1 booster on Wednesday, 25 February, SpaceX stands ready to deliver its first dual-satellite mission toward Geostationary Transfer Orbit (GTO), no sooner than Sunday, 1 March. Originally scheduled to fly Friday night, liftoff was realigned by 48 hours and is presently expected to occur within a 45-minute “window,” which extends from 10:49-11:34 p.m. EST. In the event of a scrub on Sunday night, SpaceX has Eastern Range approval for a backup opportunity Monday, with the window opening at the slightly earlier time of 10:45 p.m. and extending until 11:30 p.m. Flying from Space Launch Complex (SLC)-40 at Cape Canaveral Air Force Station, Fla., the mission will be SpaceX’s third flight of 2015 and its payload—the Eutelsat 115 West B and Asia Broadcasting Satellite (ABS)-3A communications satellites—marks the company’s fifth cargo bound for geostationary orbit.
This follows on the heels of a highly successful 2014, which saw SpaceX launch a personal-best-beating six missions, and an ambitious start to 2015, which has so far seen the delivery of the latest Commercial Resupply Services (CRS) Dragon cargo craft to the International Space Station (ISS) in January and this month’s flight of the Deep Space Climate Observatory (DSCOVR) on a 110-day journey to the L1 Lagrange Point for extended studies of Earth and the Sun. Nor are the records expected to end there, for the Hawthorne, Calif.-based launch operator anticipates the maiden voyage of its Falcon Heavy booster later in 2015, which, when operational, will surpass the Delta IV Heavy as the largest and most powerful vehicle in active service, anywhere in the world. Moreover, Sunday’s launch of the Eutelsat and ABS birds marks the first occasion on which SpaceX has delivered two geostationary payloads on the same mission. During its previous four GTO-bound missions—SES-8 in December 2013, followed by Thaicom-6 in January 2014 and the AsiaSat-8 and AsiaSat-6 payloads in August and September of last year—the Falcon 9 v1.1 completed a standard first-stage ascent, followed by the execution of two “burns” by the Merlin 1D Vacuum engine of its second stage to deliver its payloads.
With the standard Static Fire Test of the nine Merlin 1D engines on the Falcon’s first stage having been successfully conducted at SLC-40 on Wednesday, 25 February, the current prediction from the 45th Space Wing at Patrick Air Force Base calls for partly or mostly cloudy conditions on Sunday afternoon and into Monday morning, with a 30 percent likelihood of rain and a 10 percent probability of lightning. An Airspace Closure Area has been secured from 10:44 p.m. EST Sunday through 12:06 a.m. Monday, with a Security and Safety Zone active from 8:49 p.m. through T-0.
According to the 45th Space Wing at Patrick Air Force Base, there exists a 70-percent likelihood of acceptable conditions for Sunday’s opening launch attempt. With brisk winds and clouds in attendance, an earlier cold front is expected “to migrate back northward, keeping the winds gusty, but turning them more on-shore,” it was highlighted. The primary risk for a launch on Sunday night are lingering thick clouds and cumulus clouds associated with the rain showers. This picture is expected to improve to 80-percent favourable, in the event that the launch attempt moves 24 hours to the right, with cumulus cloud cover posing the sole hazard. “On Monday, winds remain light and turn more southeasterly, keeping a slight risk for a coastal shower,” it was explained, “but less upper-level clouds and ridging moves in aloft.”
Following the Static Fire Test, the booster was removed from SLC-40 for the installation of its twin satellite cargoes, before heading toward its Launch Readiness Review (LRR), ahead of a return to the pad on Saturday. The Falcon 9 v1.1 will be fueled with liquid oxygen and a highly refined form of rocket-grade kerosene, known as “RP-1.” The cryogenic nature of the oxygen—whose liquid state exists within a temperature range from -221.54 degrees Celsius (-368.77 degrees Fahrenheit) to -182.96 degrees Celsius (-297.33 degrees Fahrenheit)—requires the fuel lines of the engines to be chilled, in order to avoid thermally shocking or fracturing them. All propellants should be fully loaded within one hour, and at 10:36 p.m. Sunday, assuming no technical constraints, the countdown will pass its final “Go/No-Go” polling point of all stations at T-13 minutes.
The Terminal Countdown will get underway at T-10 minutes, during which time the Merlin 1D engines will be chilled, ahead of their ignition sequence. All external power utilities from the Ground Support Equipment (GSE) will be disconnected, and at 10:44 p.m. the roughly 90-second process of retracting the “strongback” from the vehicle will occur. The Flight Termination System (FTS)—which is tasked with destroying the Falcon 9 v1.1 in the event of a major accident during ascent—will be placed onto internal power and armed. By T-2 minutes and 15 seconds, the first stage propellant tanks will attain flight pressure, after which the engines will be purged with gaseous nitrogen, and at T-60 seconds the SLC-40 complex’s “Niagara” deluge system of 53 nozzles will come to life, flooding the pad surface and flame trench with 30,000 gallons (113,500 liters) of water, per minute, to suppress acoustic energy radiating from the engine exhausts.
At T-3 seconds, the Merlins will roar to life, ramping up to a combined thrust of 1.3 million pounds (590,000 kg). Following computer-commanded health checks, the stack will be released from SLC-40 to begin SpaceX’s third flight in less than two months. Although not a personal-best-beater—for the AsiaSat-8, AsiaSat-6, and CRS-4 Dragon missions all flew within a seven-week period in August-September 2014—this is an impressive indicator of the rapid maturity of Falcon 9 v1.1 systems and operations. Immediately after clearing the tower, the booster will execute a combined pitch, roll, and yaw program maneuver to establish itself onto the proper flight azimuth to deliver the Eutelsat/ABS payload stack into space.
Eighty seconds into the climb uphill, the vehicle will exceed the speed of sound and experience a period of maximum aerodynamic duress—colloquially dubbed “Max Q”—on its airframe. At about this time, the Merlin 1D Vacuum engine of the second stage will undergo a chill-down protocol, ahead of its own ignition later in the ascent. At 10:51 p.m., 130 seconds after liftoff, two of the first-stage engines will throttle back, in order to reduce the rate of acceleration at the point of Main Engine Cutoff (MECO). Finally at T+2 minutes and 58 seconds, the seven remaining engines will shut down, and, a few seconds later, the first stage will separate from the rapidly ascending vehicle.
Unlike last month’s attempt to soft-land the Falcon 9 v1.1’s first stage on the Autonomous Spaceport Drone Ship (ASDS) in the Atlantic Ocean—which resulted in the hardware reaching the deck, but impacting at a 45-degree angle and exploding—the Eutelsat/ABS mission will not perform such a feat. The delivery of payloads to a geostationary altitude of approximately 22,300 miles (35,900 km) requires the maximum performance of the booster, and both the Elsbeth III and Go Quest support vessels for ASDS operations will remain in the Port of Jacksonville for this mission.
With the first stage gone, the turn will then come for the Falcon 9 v1.1’s restartable second stage, whose Merlin 1D Vacuum engine—with a maximum thrust of 180,000 pounds (81,600 kg)—will come to life to support two discrete “burns,” then set the Eutelsat/ABS stack free about a half-hour after leaving the Cape. The first burn will get underway at about T+3 minutes and 10 seconds, firing for up to six minutes to establish the payloads into a “parking orbit.” During this time, the 43-foot-long (13.1-meter) Payload Fairing (PLF) will be pneumatically jettisoned, exposing the satellites to the space environment for the first time, and the Merlin 1D Vacuum will shut down about nine minutes after launch.
The combo will then “coast” for a further 16 minutes, ahead of the second burn at T+25 minutes, which is timed to run for about 60 seconds, to position the payloads for separation. ABS-3A will be the first to depart the second stage at T+30 minutes, after which the second stage will perform a “Reorientation Between Separation Events,” prior to the departure of Eutelsat 115 West B at T+35 minutes.
Scheduled to operate for up to 15 years at an orbital position of 114.9 degrees West longitude, Eutelsat 115 West B was previously designated “SatMex-7,” until the takeover of Satelites Mexicanos by Eutelsat in March 2014. In keeping with its new satellite-naming system, Eutelsat—the European Telecommunications Satellite Organisation, headquartered in Paris, France—identified the satellite with a number to describe its orbital position and a letter to indicate its order of arrival at that position. When operational, Eutelsat 115 West B will provide a C-band “Pan-American Beam” for coverage of Alaska, western Canada, the contiguous United States, Mexico, Latin America, and the north-western regions of South America, as well as multiple Ku-band beams for Mexico and its environs, the majority of South America not covered by its C-band counterpart and the entire United States—with the exception of Florida—and Canada. These beams will offer direct-to-home television, broadband, cellular backhaul, and social connectivity. Built by Boeing Defense & Space, the satellite is expected to provide the Americas with a new capacity to attend strategic markets serving high-growth applications in video, data, mobility, and government, as well as generally strengthening Eutelsat’s “footprint” in the area with optimized regional beams.
Founded in 1977, Eutelsat was originally an Inter-Governmental Organization (IGO) to develop a satellite communications infrastructure for western Europe. Its first satellite, Eutelsat 1-F1—also designated the European Communications Satellite (ECS)-1—was launched atop an Ariane 1 booster from Kourou, French Guiana, in June 1983, and the organization subsequently expanded to cover not only western Europe, but also central and eastern Europe in the years surrounding the collapse of the Soviet Union, as well as the Middle East, Africa, and large parts of Asia and the Americas. From the mid-1990s, Eutelsat was broadcasting direct-to-home television services for the first time to Europe, thanks to its Hot Bird satellite network, and became a private company in July 2001.
Based upon Boeing’s new BSS-702SP (“Small Platform”) spacecraft “bus,” both Eutelsat 115 West B and ABS-3A rely upon an all-electric propulsion system, thereby freeing up volume for payloads and reducing overall mass by eliminating the need for a chemical propulsion apparatus. The development of the bus—which provides a payload power range from 3-8 kilowatts—was inaugurated in 2012, and after completing its Critical Design Review (CDR) the following year, production got underway and presently four satellites are scheduled to utilize the 702SP, with Eutelsat 115 West B and ABS-3A expected to mark its first customers to actually reach orbit. Both spacecraft buses were built at Boeing’s Satellite Development Center in El Segundo, Calif.
Measuring 15 feet (4.6 meters) tall and 7 feet (2.1 meters) in diameter and weighing about 3,970 pounds (1,800 kg) at launch, the cylindrical 702SP will be powered by twin solar arrays and lithium-ion batteries and stabilized by means of a state-of-the-art attitude-determination and control system with star trackers, Earth sensors, and reaction wheels. Their relatively low mass enables two of them to fly atop one booster, thus resulting in a 20 percent cost reduction over existing alternatives. After the departure of the satellites from the second stage of the Falcon 9 v1.1, they will employ their electric propulsion systems to deliver themselves from the initial transfer orbit to their operational geostationary positions. The electric propulsion system consists of four 9.8-inch (25-cm) thrusters, with a listed specific impulse of 3,400-3,500 seconds and 79-165 mN of thrust.
“We are the first aerospace company to develop this highly efficient and flexible all-electric satellite and we completed the first two 702SPs less than three years after contract award,” said Mark Spiwak, president of Boeing Satellite Systems International, speaking in January 2015, after the completion of testing of Eutelsat 115 West B and ABS-3A. “With more than 210,000 hours of on-orbit experience with electric propulsion, we recognized that this highly efficient, lighter weight propulsion system would translate into cost savings for our customers.”
Also benefiting from the 702SP bus is Asia Broadcasting Satellite’s ABS-3A, which will be located at 3 degrees West longitude to cover the Americas, Europe, Africa, and the Middle East, and is equipped with 24 C-band and 24 Ku-band transponders. The former will deliver three C-band beams for the Eastern Hemisphere (Africa, Madasgascar, Europe, the Middle East, and western Asia), the Western Hemisphere (South America, the Caribbean, Cuba, Florida, the United States’ Eastern Seaboard, and eastern Canada), and a “Global Beam” to cover the satellite’s entire “footprint” from the west of South America to central India. Meanwhile, the four Ku-band beams will principally cover the Americas, Europe, the Middle East, and North Africa (MENA) and South Africa (SAF).
The MENA beam came about following a strategic commercial agreement, signed last summer, between ABS and Arab Satellite Communication Organisation (ARABSAT) for a multi-transponder lifetime Ku-band payload aboard ABS-3A. “The MENA beam of ABS-3A is the first time ABS has been able to provide a complete coverage of all of Middle East and North Africa,” said ABS Chief Executive Officer Tom Choi. “We are proud to announce ARABSAT as our strategic partner on this capacity which will serve the growing needs of their MENA customer base.” In addition to providing television, Internet Trunking, and cellular backhaul capabilities, ABS-3A also offers maritime services, since it will cover most of the Atlantic Ocean and large portions of the Indian Ocean.
Last November, Eutelsat 115 West B and ABS-3A were stacked, in readiness for launch, marking the first time that Boeing had “conjoined” two satellites in this fashion. The company developed a patented system to stack the satellites, without the need for a central adapter. Moreover, there was no need for the lowermost satellite in the stack—Eutelsat 115 West B in this case—to receive any structural modifications to support the loads of its uppermost counterpart. It was also intended that both satellites would not be separated from the launch vehicle until after orbital injection, thereby allowing them to be considered as a single payload, which reduces complexity for the launch provider.
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