Making their fourth orbital launch of the year, the SpaceX team have conducted another Falcon 9 mission on Tuesday, deploying China’s AsiaSat-8 satellite into geosynchronous transfer orbit. The launch took place from Cape Canaveral, with a T-0 of 08:00 UTC – following a hold during the initial attempt at the opening of the window.
Falcon 9 v1.1/ASIASAT-8:
The AsiaSat-8 spacecraft was constructed by Space Systems/Loral, and carries 24 transponders operating in the Ku band of the electromagnetic spectrum with a bandwidth of 54 megahertz, along with a single Ka-band transponder. It is based on the LS-1300 bus.
Powered by twin solar arrays, each with four panels, the satellite’s communications systems can produce an output of 8.5 kilowatts.
AsiaSat-8 is the ninth satellite to be operated by China’s Asia Satellite Telecommunications Company, which was formed in 1988 and is based in Hong Kong.
AsiaSat-8 is intended to augment the older AsiaSat-7 spacecraft, and will be located in geostationary orbit at a longitude of 105.5 degrees East.
The satellite is designed for a fifteen year mission and will provide communications services to China, the Middle East, India and Southern Asia.
AsiaSat’s first satellite, AsiaSat-1, had originally been built for the Western Union Telegraph Company as Westar-6 and was launched by Space Shuttle Challenger during 1984’s STS-41B mission.
However, a failure of the Payload Assist Module which was to have boosted the satellite into geosynchronous transfer orbit resulted in the spacecraft becoming stranded in low Earth orbit.
The spacecraft was recovered and returned to Earth by Shuttle Discovery nine months later and following refurbishment it was sold to AsiaSat. The satellite was returned to orbit by a Chang Zheng 3 rocket in April 1990, in what was China’s first ever commercial launch, and operated successfully for thirteen years.
AsiaSat-2 was launched in 1995 by a Chang Zheng 2E rocket, and left frontline service in 2009 when AsiaSat-5 entered service. After being leased to Israel’s SpaceCom to cover the Amos 5 satellite’s slot until its launch in 2011, the spacecraft was decommissioned in 2012.
AsiaSat-3 had been intended to increase the company’s available capacity, however the upper stage of the Proton rocket carrying it malfunctioned, placing it into an unusable orbit. A replacement, AsiaSat-3S was ordered, with Intersputnik’s AP-2 satellite, formerly part of Russia’s Gorizont constellation, being leased as AsiaSat-G until the new spacecraft entered service.
The AsiaSat-3 satellite itself was returned to its manufacturer, Hughes, who were eventually able to manoeuvre it into geosynchronous orbit after making two flybys of the Moon to gain gravitational assists. The satellite was later operated by PanAmSat, but had been retired by July 2002.
AsiaSat-3S was successfully orbited in March 1999 and remains in service, as does AsiaSat-4 which was launched in April 2003 atop an Atlas IIIB. AsiaSat-5 was deployed by a Proton in 2009 and AsiaSat-7, which had originally been ordered as a spare, was deployed two years later by another Proton.
In addition to AsiaSat-8, the company plans to introduce two more satellites in the coming years; AsiaSat-6 is scheduled for launch later this month and will be positioned in a Thai slot at 120 degrees East, under an agreement which will see half of its transponder capacity leased to Thaicom.
AsiaSat-9 will launch on a Proton in 2016 to replace AsiaSat-4. Like AsiaSat-8, both of these spacecraft are based on Loral’s LS-1300 platform.
Friday’s launch marked the eleventh flight of SpaceX’s Falcon 9 rocket, and the sixteenth launch for the company overall. Formed in 2002 by PayPal founder Elon Musk, SpaceX’s goal has been to reduce the cost of access to space.
Initial plans called for a family of rockets, from the small, low-capacity Falcon 1, through a medium-capacity Falcon 5, up to a larger Falcon 9 and beyond.
These plans have evolved over time, with the Falcon 5 being eliminated and the Falcon 1 retired in favour of flying smaller satellites as secondary payloads in Falcon 9 missions.
The Falcon Heavy configuration, based on the Falcon 9 but adding two boosters, based on the first stage, to provide additional thrust during the early stages of flight, will be able to lift much heavier payloads when it enters service next year.
SpaceX’s first launch occurred in 2006, with a Falcon 1 lifting off from Omelek Island on Kwajalein Atoll in the Marshall Islands with the FalconSat-2 spacecraft for the US Air Force.
It was not until the fourth launch that the rocket successfully reached orbit; the maiden flight suffered a first stage engine failure, the second – a demonstration flight – failed after a series of events led to the premature cutoff of the second stage engine.
On the third flight control of the rocket was lost after recontact between the first and second stages occurred during separation. The Department of Defense’s Trailblazer satellite was lost in the failure, along with NASA’s PRESat and NanoSail-D CubeSats and a Celestis space burial payload.
The fourth Falcon launch took place on 28 September 2008, successfully placing a demonstration payload nicknamed RatSat into orbit. This paved the way for the launch of Malaysia’s RazakSAT in July 2009, which was also successful.
Although at the time that was not intended to be the last Falcon 1 mission, SpaceX announced plans to introduce a redesigned version, the Falcon 1e, to increase its payload capacity. This was later quietly abandoned, with all smaller payloads being remanifested for the Falcon 9, either as secondary payloads or as part of cluster launches.
The Falcon 9 first flew in June 2010, making a demonstration mission with the Dragon Spacecraft Qualification Unit, an inert mockup of the Dragon spacecraft which SpaceX was at the time developing for the Commercial Orbital Transportation Services program.
Following the successful launch the Dragon made its maiden flight atop the next launch that December along with a cluster of CubeSats. Three more launches in 2012 and 2013 deployed Dragon missions which berthed at and resupplied the International Space Station; the October 2012 launch having also been tasked with deploying a prototype satellite for Orbcomm.
Although all three Dragons were orbited successfully, the Orbcomm satellite was lost as a malfunction of the Falcon’s first stage forced the second stage to expend more fuel than planned making up the shortfall – leaving it unable to reach the Orbcomm deployment orbit.
The first five launches used a configuration which has retrospectively become known as the Falcon 9 v1.0. The sixth launch, in September 2013, introduced the v1.1 configuration.
With elongated first and second stages, uprated engines and a revised engine arrangement on the first stage, this change has increased the amount of payload which the Falcon is able to place into orbit.
The September 2013 launch, which also marked the first time SpaceX had launched a rocket from the West coast of the United States – at Vandenberg Air Force Base – deployed Canada’s CASSIOPE satellite and a group of secondary payloads.
The AsiaSat-8 mission was the third Falcon 9 mission to a geosynchronous transfer orbit. The previous missions carried the SES-8 and Thaicom-6 satellites in December 2013 and January 2014 respectively. Since then two more Falcons have launched successfully; deploying the CRS-3 Dragon mission in April and six Orbcomm satellites last month.
SpaceX intends to continue development of the Falcon 9, with a view of eventually making it reusable.
To this end, recent launches have conducted demonstrations aimed at proving that the first stage can be recovered.
Following engine restart tests on the CASSIOPE launch, April’s Dragon mission flew with deployable landing gear attached to the first stage.
Following separation the stage was successfully guided to a controlled landing in the Atlantic Ocean, downrange of the launch site.
This feat was repeated on the Orbcomm mission in July – (left is a screenshot from video showing the Stage returning). However, in both cases the stages sank before they could be recovered – though this was not a primary objective of either demonstration.
Tuesday’s mission was a strictly one-way trip for the Falcon; the heavier AsiaSat spacecraft and high deployment orbit will require all of the rocket’s available performance, leaving no fuel available for a recovery demonstration.
Falcon 9 launches from the East coast of the United States are made from Space Launch Complex 40 of the Cape Canaveral Air Force Station, a facility which was originally constructed in the 1960s for the Titan III.
Part of the Integrate-Transfer-Launch Complex, along with the nearby Launch Complex 41 – now used by United Launch Alliance’s Atlas V – the first launch from Complex 40 occurred in June 1965 when the Titan IIIC made its maiden flight.
In November 1966 the complex hosted the launch of a mockup of the planned Manned Orbiting Laboratory, a military space station which would have been manned by US Air Force crews launched in Gemini spacecraft.
The refurbished Gemini II spacecraft was also flown atop the rocket, separating before the rest of the payload entered orbit for a successful recovery downrange.
Following the mockup launch, LC-40 entered a period of renovation in order to allow it to support manned MOL missions, although no such missions ever occurred. The pad returned to use with the deployment of a pair of Vela satellites in April 1970. In all twenty six Titan IIIC vehicles flew from LC-40 before the type was replaced by the Titan III(34)D, or Titan 34D, which used the pad eight times.
In the early 1990s LC-40 hosted Martin Marietta’s short-lived Commercial Titan III which flew three times in 1990 with communications satellites, and once in 1992 with NASA’s ill-fated Mars Observer mission.
The final Titan rockets to use LC-40 were the Titan IVA and IVB, which made a total of seventeen flights from the pad. These launches included the deployment of NASA’s Cassini mission to explore Saturn, which was orbited by a Titan IV(401)B with a Centaur upper stage in October 1997.
After SLC-41 closed in 1999 to begin its transition to an Atlas V launch pad, SLC-40 became the last Titan launch pad at Cape Canaveral.
In April 2005 the last Titan mission from the Cape carried an Onyx radar imaging satellite into orbit for the National Reconnaissance Office.
In preparation for Tuesday’s liftoff, the Falcon 9 successfully completed a static fire test last Thursday.
The first stage had previously been tested in June at SpaceX’s test stand in McGregor, Texas. The AsiaSat-8 satellite arrived at Cape Canaveral on 11 June.
Tuesday’s countdown began with the rocket being powered up around ten hours in advance of the planned launch.
Fuelling began around four hours before liftoff with RP-1 loading; oxidiser tanking will begin about forty minutes later and aside from topping off the oxidiser tanks.
Fuelling was completed by the three hour, fifteen minute mark in the countdown. Oxidiser topping continued through the countdown until the tanks are pressurized around forty seconds before liftoff.
The terminal phase of the countdown was initiated at the ten minute mark, with the rocket’s onboard automated sequence being initiated around six and a half minutes before launch. At around the six minute mark the rocket went to internal power and tank pressurization began.
Work to remove the Strongback structure, used to transport the rocket to the launch pad and erect it there, began with clamps releasing around five minutes and ten seconds before liftoff.
The Strongback itself began backing away from the rocket around half a minute later, however stayed close to vertical in order to provide connections for the rocket’s umbilicals.
The Flight Termination System, which will be used to destroy the rocket if it goes off course, was transferred to internal power around three minutes before launch. The Launch Director then confirmed the rocket was go for launch with 150 seconds to go, and the Range confirm that it was go for launch at the 120-second point in the countdown.
The rocket entered its startup configuration, under internal control, a minute before launch. Also around this time, the “Niagara” pad deluge system was to be be turned on to protect the launch pad from the rocket’s exhaust. However, an abort was called just seconds prior to launch.
The SpaceX team successfully resolved the issue with the first stage (hydraulic parameters) and recycled, resulting in the nine Merlin-1D engines powering the first stage igniting at the T-3 second mark in the countdown, with liftoff taking place the count reached zero.
The Falcon climbed away from Cape Canaveral, manoeuvring onto an easterly trajectory over the Atlantic Ocean which allowed it to establish a near-equatorial orbit.
Arranged in an octagonal pattern, the nine first stage engines are intended to allow redundancy in the event that one fails, giving the Falcon a limited engine-out capability.
Since the AsiaSat-8 payload is close to the rocket’s maximum capacity, it is unclear whether this option was available to Tuesday’s mission in the event of an engine failure. All nine engines appeared to work as advertised during the launch.
Maximum dynamic pressure, or max-q, occurred at around the 80-second point in the flight shortly after the rocket’s velocity had exceeded the speed of sound. The first stage burn lasted for around two minutes and 56 seconds, separating four seconds later.
Ignition of the second stage’s engine – another Merlin which is optimised for performance in the vacuum conditions of space – occurred eight seconds after staging to make the first of two burns.
The second stage’s first burn lasted five minutes and thirty-three seconds, with separation of the payload fairing occurring around a minute into the burn. At the end of the burn a 17-18 minute coast phase took place, before the second stage ignited for its second burn.
With a duration of about a minute, the second burn raised the orbit’s apogee to near-geosynchronous altitude. Five minutes after its conclusion the spacecraft separated into its deployment orbit.
The target orbital parameters for Tuseday’s mission are a perigee of 185 kilometres (115 statute miles or 99.9 nautical miles), an apogee of 35,786 kilometres (22,236 mi, 19,323 nmi) and 24.3 degrees inclination. From this orbit, AsiaSat-8 will raise itself into its final geostationary orbit using an onboard apogee motor to begin its operational life.
Tuesday’s launch was the fourth of the year for SpaceX, the most the company has conducted in a calendar year so far. Despite this the company shows no sign of stopping, with five more launches planned before the end of December.
The next Falcon launch is scheduled for the end of August, carrying another AsiaSat spacecraft; AsiaSat-6 will be positioned at a longitude of 120 degrees East, with plans in place to lease fourteen of its transponders to Thaicom.
With both AsiaSat launches complete, SpaceX will turn its attentions back to the International Space Station in September, despatching a Dragon spacecraft on a Commercial Resupply Services mission to deliver supplies and equipment to the outpost.
By the end of November missions to deploy eleven Orbcomm communications satellites into low Earth orbit and a larger communications satellite for Turkmenistan into a geosynchronous orbit are also scheduled to be executed. Another Dragon mission is planned for early December to complete the year.
(Images: via SpaceX, SSL, ASIASAT and L2).
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