SpaceX has conducted its second mission for China’s Asia Satellite Telecommunications Company Sunday, with a Falcon 9 launching the AsiaSat-6 satellite into a geosynchronous transfer orbit. Liftoff occurred at 01:00 local time (05:00 UTC) from the Cape Canaveral Air Force Station, ten minutes into a 104 minute window.
Sunday’s launch came a month after the previous Falcon 9 mission successfully lofted AsiaSat-8.
This spacecraft has now reached geostationary orbit and is currently undergoing checkout and on-orbit testing high over the crossing of the Equator and the Greenwich Meridian. Once testing is complete the satellite will be moved to its operational station at 105.5 degrees East.
AsiaSat-6, which will be the tenth satellite to be operated by AsiaSat, is based around the same LS-1300 bus as AsiaSat-8, however at around 3,700 kilograms (8,200 pounds) its mass is around 800 kilograms (1,800 lb) less.
Designed for at least fifteen years’ service, the satellite carries 28 C-band transponders. Fourteen of these will be leased to Thailand’s Thaicom, who will operate them as Thaicom 7.
In return Thaicom paid 170 million Hong Kong Dollars (700 million Thai Baht, 22 million USD) and provided the use of a geosynchronous slot at 120 degrees East, where the satellite will be stationed.
The 120 East slot had previously been occupied by AsiaSat’s aging AsiaSat-2 satellite. Launched in 1995 the spacecraft was positioned at the slot in 2011 to reserve it for future use, however it had to be retired the following year after its fuel reserves reached the minimum level at which it could be safely decommissioned and moved out of geosynchronous orbit.
Founded in Hong Kong in 1988, the Asia Satellite Telecommunications Company, or AsiaSat, saw its first satellite – a relaunch of the failed Westar 6 satellite – deployed by a Chang Zheng 3 rocket in 1990 as AsiaSat-1.
AsiaSat-1 has since been retired from service, and at present the company’s operational fleet consists of AsiaSat-3S, 4, 5 and 7, with AsiaSat-8 undergoing commissioning.
AsiaSat-3S was a replacement for the original AsiaSat-3, which was lost in a launch failure. As a result of this failure, a former Gorizont satellite was briefly leased from Russia’s Intersputnik as AsiaSat-G.
Thaicom, which was formed as the Shinawatra Satellite Company in 1991, is a Thai company which operates that country’s fleet of communications satellites. Its first satellite – Thaicom 1 – was launched in 1993 and has been followed by five more satellites – the most recent being Thaicom 6 in January.
Thaicom’s fleet currently consists of three satellites; Thaicom-4, 5 and 6. Another satellite, Thaicom 8, was ordered this April with launch expected in 2016. AsiaSat-6 is not the first time AsiaSat and Thaicom have collaborated on a mission; AsiaSat previously leased its on-orbit spare satellite, AsiaSat-7, to Thaicom in order to cover its slot for the Thaicom 6 satellite.
The static firing for Sunday’s mission, which gives SpaceX an opportunity to conduct a full test of the rocket’s systems, including its first stage engines, took place on 22 August when the launch was still scheduled for the following week.
SpaceX opted to delay the mission hours before its planned liftoff in order to conduct further tests of the Falcon’s systems following the loss of its Falcon 9R Dev-1 test article.
The Dev-1 vehicle was used for a series of atmospheric flights from SpaceX’s test facility near McGregor, Texas, to test approach and landing for the development of a reusable Falcon 9.
A few hours before the AsiaSat mission’s static firing, the Dev-1 test vehicle was destroyed by its onboard flight termination system when a guidance malfunction was detected.
When the failure occurred the AsiaSat mission was delayed 24 hours to allow precautionary checks to be made, however a late call hours before the rescheduled launch time resulted in the delay to September.
The loss of the Dev-1 test article marks the first loss-of-vehicle event for SpaceX since the third Falcon 1 mission in August 2008, which failed to achieve orbit after losing control because of recontact between its first and second stages at separation.
In terms of orbital launches, the only mishap SpaceX have encountered since the first three Falcon 1 missions was a first stage engine failure on the fourth Falcon 9 launch in 2012.
That mission continued to orbit and was able to deploy the SpaceX CRS-1 Dragon spacecraft for a successful mission, however the other payload aboard the rocket, a prototype Orbcomm satellite, was a total loss as the Falcon lacked sufficient fuel to restart and reach its planned separation orbit.
Flying in the v1.1 configuration, the Falcon 9 is a two-stage vehicle, consisting of a nine-engined first stage with a single-engine upper stage.
All ten engines are Merlin-1Ds, produced in-house by SpaceX, which burn RP-1 propellant oxidised by liquid oxygen.
The second stage engine has been optimised for operation in vacuum conditions, while the first stage engines are arranged in an octagonal, or ‘octaweb’ layout.
The v1.1 is the second version of the Falcon 9 which replaced the previous version, which has become known retrospectively as the v1.0, after the first five launches.
The original Falcon 9 had shorter first and second stages with the first stage engines arranged in a square pattern. The newer configuration increases the rocket’s performance, allowing it to deliver a heavier payload into orbit.
Rollout for Sunday’s mission took place Saturday morning local time, with the vehicle being transported to and erected upon Cape Canaveral’s Space Launch Complex 40.
Now used for Falcon launches the complex was originally developed for the US Air Force’s Titan III rocket.
The pad was converted in 2008 for the Falcon 9, having been used by Titan rockets for forty years.
Part of the Integrate-Transfer-Launch complex, along with nearby Launch Complex 41, Complex 40 was used by fifty five Titan rockets between June 1965 and April 2005; including the Titan III, Titan 34D, Commercial Titan III and Titan IV.
The final launch, which was the penultimate launch of the Titan IV, carried an Onyx radar imaging satellite into orbit.
Following the Titan’s retirement SLC-40 was abandoned until SpaceX opted to construct a launch pad at Cape Canaveral having previously planned to fly the Falcon 9 from their existing launch site at Kwajalein Atoll. Sunday was the eleventh time SLC-40 has hosted a Falcon 9 launch.
Countdown events began ten hours in advance of liftoff, with the rocket being powered up. As the countdown proceeds the Falcon was loaded with the fuel and oxidiser it requires for its journey; beginning with RP-1 propellant loading at the four hour mark in the count.
Forty minutes later liquid oxygen tanking started, with filling completed by the three hour, fifteen minute mark, except for topping up the oxidiser tanks which continued until the final seconds before launch as the oxygen boils off.
The terminal countdown, the automated series of events that comprise the last stage of the count, commenced ten minutes before liftoff and the Falcon’s onboard automated sequence will begin four minutes later.
At around the five minute point the strongback structure used to erect and supply the rocket while at the pad began to detach from the vehicle, rotating away from the rocket about minute later.
Arming of the Flight Termination System (FTS) occurred three minutes prior to liftoff. The FTS is the system used to destroy the rocket in the event that it should malfunction and potentially pose a hazard to populated areas.
At around the same time oxidiser topping ended. Final approval for launch came in the form of calls from the Launch Director and Range Control Officer just ahead of 120 seconds out from liftoff.
At the one minute mark the Falcon began its startup sequence and transferred to internal control, while startup of the pad water system also began.
In the last minute of the countdown a series of steering checks were performed upon the first stage engines and the rocket’s tanks were raised to flight pressure.
Three seconds before the countdown reaches zero, the nine first stage engines lit up, building to full thrust in time for liftoff at T-0. Beginning its ascent east over the Atlantic Ocean, the vehicle ascended towards a near-equatorial orbit.
The rocket passed through the area of maximum dynamic pressure, or max-q, around a minute and twenty seconds after launch, passing through the sound barrier at around the same time.
First stage powered flight lasted two minutes and 56 seconds, with staging taking place four seconds later and second stage ignition another eight seconds after that.
During Sunday’s mission the second stage was called upon to make two burns, the first to establish a parking orbit and the second to inject the payload into its planned transfer orbit. The first event during the second stage’s initial burn was the separation of the payload fairing, around fifty seconds after ignition.
The fairing, which encapsulates the payload to protect it from atmospheric turbulence and friction during the early stages of flight, was no longer required once the vehicle reaches space and is discarded to save weight.
The first burn lasted for five and a half to six minutes, after which the rocket coasted for seventeen minutes. Once the coast phase of the mission ended, the second stage restarted for a short burn, approximately a minute in duration, to inject AsiaSat-6 into its transfer orbit.
Spacecraft separation occurred thirty two minutes into the mission, around five minutes after the end of powered flight. From its transfer orbit, AsiaSat-6 will use an onboard apogee motor to raise itself into its final geostationary orbit.
Sunday’s launch was the seventeenth for SpaceX and the twelfth for its Falcon 9 rocket, which first flew in June 2010. The fifth Falcon 9 launch of 2014 it demonstrates an increase in the rocket’s flight rate as SpaceX endeavours to capture a large share of the commercial launch industry.
The effect of this has already been noticed as Sea Launch have been forced to suspend operations and International Launch Services have laid off staff, as their more expensive Zenit and Proton rockets cannot compete.
New Proton launch contracts have also been affected by the vehicle’s poor reliability; the rocket having suffered six launch failures in the last four years.
Proton is still to return to flight after May’s failed launch of Ekspress-AM4R – itself a replacement for a satellite lost in another Proton failure three years ago.
It is the fifty third orbital launch of 2014, and the seventeenth of the year to be conducted by the United States.
The year’s launches to date include two unsuccessful attempts – both made by Russian rockets; the Proton-M launch of Ekspress-AM4R which failed to achieve orbit in May, and the recent Soyuz launch from French Guiana carrying a pair of Galileo navigation satellites.
It remains unclear whether the Galileo launch is an outright or partial failure, as it has not yet been established whether the satellites will be usable for anything beyond tests.
SpaceX’s next launch is expected to take place at the end of the month, when another Falcon 9 will orbit a Dragon spacecraft on the SpaceX CRS-4 mission.
Bound for the International Space Station, this mission will carry cargo to the astronauts at the outpost as well as miniaturised satellites for deployment.
Before that, the next American launch will be of an Atlas V on 16 September with the CLIO satellite for an undisclosed US government agency.
Likely a follow-up to 2009’s PAN mission, CLIO is expected to be a communications satellite of some type, heading for geosynchronous orbit.
(Images: via SpaceX, SSL, ASIASAT and L2).
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