SpaceX has triumphantly accomplished “Three for Three,” delivering a third mission to space in as many months, as the Hawthorne, Calif.-based launch operator successfully boosted the Eutelsat 115 West B and Asia Broadcasting Satellite (ABS)-3A communications satellites to Geostationary Transfer Orbit (GTO). Liftoff took place on time at 10:50 p.m. EST on Sunday, 1 March. Thus continues a spectacular 2015 for SpaceX, which has already despatched the latest Commercial Resupply Services (CRS) Dragon cargo ship into low-Earth orbit, bound for the International Space Station (ISS) and the Deep Space Climate Observatory (DSCOVR) on a journey to the L1 Lagrange Point, more than 930,000 miles (1.5 million km) beyond Earth. Although the company has delivered three missions within three months previously—launching the AsiaSat-8, CRS-4 Dragon, and AsiaSat-6 payloads in a seven-week period, last summer—this is the first time it has boosted three back-to-back payloads into quite different orbits and onto quite different trajectories. It also marks SpaceX’s third launch in just 50 days.
Following a successful Static Fire Test of its nine Merlin 1D first-stage engines on Wednesday, 25 February, out at Space Launch Complex (SLC)-40 at Cape Canaveral Air Force Station, Fla., the two-stage Falcon 9 v1.1 booster was returned to a horizontal configuration for the installation of its primary payloads. It was returned to the pad on Saturday for final processing. Although this was SpaceX’s first mission to carry two satellites to GTO—as noted in AmericaSpace’s preview article—the rocket used a standard 43-foot-long (13.1-meter) Payload Fairing (PLF), because Eutelsat 115 West B and ABS-3A both utilize Boeing’s new 702SP (“Small Platform”) satellite bus. This allows them to be “conjoined,” one atop the other, with no need for a connecting mechanism, and considered as a singular payload, thereby simplifying the task of the launch provider.
With the Florida weather posing a 70 percent likelihood of acceptable conditions at T-0 on Sunday, SpaceX teams pressed ahead with their opening launch attempt, threatened by partly or mostly cloudy skies, a 30 percent chance of rain, and a 10 percent probability of lightning. According to the 45th Space Wing at Patrick Air Force Base, the presence of brisk winds and attendant cloud cover and the effects of an earlier cold front were expected to create a primary risk from lingering thick clouds and cumulus clouds associated with rain showers. However, it was noted that conditions were expected to improve to 80 percent favorable in the event of a scrub and 24-hour turnaround. “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 as ridging moves in aloft.”
Earlier today (Sunday), the Falcon 9 v1.1 was 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 booster’s fuel lines of the engines to be chilled, in order to avoid thermally shocking or fracturing them. By this time, SpaceX had slightly adjusted the T-0 time to 10:50 p.m. EST, with Sunday’s “launch window” running for 45 minutes and closing at 11:35 p.m.
All propellants were fully loaded within one hour, and at 10:37 p.m., the countdown passed its final “Go/No-Go” polling point of all stations at T-13 minutes. Weather conditions had improved to 90-percent “Go,” with all stations reporting their status as “Green.” The Terminal Countdown got underway at T-10 minutes, during which time the Merlin 1D engines were chilled, ahead of their ignition sequence. All external power utilities from the Ground Support Equipment (GSE) were disconnected, and at 10:45 p.m. the roughly 90-second process of retracting the “strongback” from the vehicle occurred. The Flight Termination System (FTS)—tasked with destroying the Falcon 9 v1.1 in the event of a major accident during ascent—was placed onto internal power and armed. By T-2 minutes and 15 seconds, the first stage propellant tanks attained flight pressure, after which the engines were purged with gaseous nitrogen, and at T-60 seconds the SLC-40 complex’s “Niagara” deluge system of 53 nozzles came 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 nine Merlin 1D engines roared to life, ramping up to a combined thrust of 1.3 million pounds (590,000 kg). Following computer-commanded health checks, the stack was released from SLC-40 to begin SpaceX’s third flight within the first three months of 2015, and its third overall mission in just 50 days. Although not a personal-best-beater—for the AsiaSat-8, CRS-4 Dragon, and AsiaSat-6 payloads all flew within a 47-day period in August-September 2014—this is an impressive indicator of the rapidly maturing nature of Falcon 9 v1.1 operations.
Immediately after clearing the tower, the booster executed 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 exceeded the speed of sound and experienced 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 underwent a chill-down protocol, ahead of its own ignition later in the ascent. At 10:52 p.m., 130 seconds after liftoff, two of the first-stage engines throttled 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 shut down, and, a few seconds later, the first stage separated from the rapidly ascending vehicle.
Unlike January’s attempt to soft-land the Falcon 9 v1.1 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 was not intended to 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 remained in the Port of Jacksonville for this mission.
With the first stage gone, the turn then came 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)—came 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 kicked off at about T+3 minutes and 10 seconds, firing for close to six minutes to establish the payloads in a “parking orbit.” During this time, the 43-foot-long (13.1-meter) Payload Fairing (PLF) was pneumatically jettisoned, exposing the satellites to the space environment for the first time, and the Merlin 1D Vacuum was shut down about nine minutes after launch.
The combo then “coasted” for a further 16 minutes, ahead of the second burn at T+25 minutes, which ran for about 60 seconds, to position the payloads for separation. ABS-3A was first to depart the second stage at about T+30 minutes, at 11:20:10 p.m. EST, after which the second stage performed a “Reorientation Between Separation Events,” prior to the departure of Eutelsat 115 West B at T+35 minutes, at 11:25:10 p.m. EST.
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 currently 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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