SpaceX launched an international ocean research mission Sunday via its Falcon 9 rocket, the final F9 to fly in the v1.1 configuration. Flying from Vandenberg Air Force Base, the rocket lifted off with the Jason-3 spacecraft from Space Launch Complex 4E at 10:42 local time (18:42 UTC). The attempt to land the first stage on the ASDS in the Pacific Ocean was unsuccessful.
Sunday’s launch, SpaceX’s first of 2016, carried the Jason-3 satellite into orbit.
The third Jason satellite, Jason-3 joins a series of spacecraft launched under partnership between the US National Oceanic and Atmospheric Administration (NOAA), NASA, pan-European weather research organisation EUMETSAT and French space agency CNES.
Jason-3 is a 510-kilogram (1,120 lb) spacecraft which was constructed by Thales Alenia Space around the Proteus satellite bus – which also formed the basis of the earlier Jason-1 and Jason-2 satellites. Its primary purpose – like its predecessors – is to monitor sea surface topography worldwide, producing a global map of sea surface levels.
The Jason series was conceived to replace the earlier TOPEX spacecraft that had been launched by a European Ariane 4 rocket in August 1992.
With the value of the scientific data returned by the TOPEX mission apparent, NASA and CNES began development of another spacecraft, Jason, to replace it. Jason launched atop a Delta II in 2001, by which time TOPEX was long past the end of its design life but continuing to operate successfully – it remained in operation until early 2006.
A further satellite, Jason-2, was launched aboard a Delta II in June 2008 with its operation also named the Ocean Surface Topology Mission (OSTM). Entering the same orbit as the first Jason, the two spacecraft operated together until Jason-1’s retirement in 2013. Jason-2 remains in service.
The primary suite of instruments aboard Jason-3 is similar to that aboard the Jason-2 satellite; with the Poseidon-3B altimeter replacing the Poseidon-3 unit carried aboard the earlier satellite – the first Poseidon having been part of the TOPEX satellite.
Poseidon-3B is a 70-kilogram (154 lb) radar altimeter, which uses the round trip time for radio signals from the satellite to be reflected back to the spacecraft from the Earth’s surface in order to determine the distance between the satellite and the surface.
By combining this with precise measurements of the spacecraft’s orbit, the difference between the measurement and the satellite’s calculated altitude above mean sea level at that point in its orbit can be used to map differences in the height of the Earth’s surface.
Collecting these measurements over water allows the satellite to map changes in the topology of the ocean surface. Poseidon simultaneously uses two different radio frequencies; 5.3 and 13.6 gigahertz (located in the C and Ku bands of the IEEE-defined electromagnetic spectrum respectively), allowing data to be corrected for interference from free electrons in the atmosphere, which is proportional to the frequency used. The measurement capabilities of Poseidon-3B are identical to Poseidon-2 and 3.
The Advanced Microwave Radiometer 2 (AMR-2) is a passive instrument, using a radiometer to measure the emission in three critical wavelengths from the Earth’s surface and atmosphere. By observing emissions at a frequency of 23.8 gigahertz, the satellite can detect water vapour in the atmosphere; with observations at 34 gigahertz accounting for clouds and 18.7 gigahertz providing a correction for activity due to winds close to the sea surface.
AMR-2 will support Poseidon by providing measurements that can be used to correct observational data; the round trip time of radio signals can be affected by atmospheric water content.
The Doppler Orbitography and Radio Positioning Integrated by Satellite (DORIS) DGXX-S instrument consists of a receiver which will pick up radio transmissions from a network for sixty ground-based beacons. By comparing Doppler shift from the satellite’s movement in two signals broadcast simultaneously, the spacecraft’s orbit can be determined to within a few centimetres.
A Global Positioning System Payload (GPSP) is also aboard the satellite for position determination – using the US Air Force’s network of Global Positioning System satellites to triangulate the host craft’s location. A Laser Retroreflector Array (LRA) is installed upon the nadir side of the vehicle providing nine corner cube reflectors for ground-based laser ranging experiments.
In addition to its primary instrument suite, Jason-3 plays host to a Joint Radiation Experiment (JRE), consisting of CNES’ Characterisation and Modelling of Environment 3 (CARMEN-3) charged particle detector and the Light Particle Telescope (LPT), provided by the Japan Aerospace Exploration Agency (JAXA), which will count incident particles.
JRE, which builds upon radiation payloads carried by the previous Jason missions, will allow scientists to study the radiation environment surrounding the satellite.
Jason-3 is designed to operate for three years. However, its sister satellite Jason-2 has been operational for seven and a half, with Jason-1 achieving eleven and a half years of service despite having only a three-year life expectancy. The Sentinel-6A satellite, scheduled for launch in 2020 and also known as Jason-CS1, is expected to serve as its replacement.
Jason-3 was launched by SpaceX, atop a Falcon 9 carrier rocket. Sunday’s launch marked the final flight of the Falcon 9’s v1.1 configuration, which is being withdrawn in favour of the “Full Thrust” (FT) configuration that was first used in December’s successful Orbcomm launch.
The Falcon 9 v1.1 was introduced in 2013 as a stretched and re-engined version of the original Falcon 9; replacing the square arrangement of nine Merlin-1C first engines on early flights with an octagonal, or “OctaWeb”, arrangement of nine Merlin-1Ds.
The Falcon 9 FT stretches the second stage further and introduces other upgrades including uprated engines and supercold propellant.
These modifications allow SpaceX to make attempts to return the first stage to its launch site without compromising on payload capacity. Alternatively, without the return to launch site, the FT configuration could potentially be used to offer an increased maximum payload capacity.
During the previous Falcon 9 launch, the Full Thrust model was successfully demonstrated; the second stage dispensing eleven Orbcomm communications satellites into low Earth orbit while the first stage flew back to Cape Canaveral, performing a successful landing at SpaceX’s Landing Zone 1 (LZ-1) facility – the former Launch Complex 13.
This marked the first powered recovery of part of a rocket used in an orbital launch; however unpowered recoveries of booster rockets descending under parachute were successfully achieved throughout NASA’s Space Shuttle program, while the European Space Agency occasionally recovers Ariane 5 boosters by parachute for quality control and research purposes.
After landing, the first stage was transported to SpaceX’s newly completed integration facility at the Kennedy Space Center’s Launch Complex 39.
Following checkout, it was transported back to its launch pad at Cape Canaveral, Space Launch Complex 40, where it completed a static firing on Friday to demonstrate that it was still operable after its mission.
The successful first stage recovery on land followed two attempts to recover the stages at sea by landing them on a floating barge – the Autonomous Spaceport Drone Ship (ASDS).
Both of these attempts were unsuccessful; during the first – last January – the stage came in hard after depleting its hydraulic fluid and exploded upon contact with the landing platform. The second recovery attempt, in April, saw the rocket topple over and explode as it touched down.
Despite the successful land recovery during December’s Orbcomm mission, Sunday’s launch targetted a barge recovery which would have marked the first attempt to recover the first stage on a launch from the West Coast.
For the barge used, an ASDS based on the Marmac 303 barge and bearing the name “Just Read the Instructions”, was involved with the first recovery attempt. The name Just Read the Instructions, an homage to the literary works of Iain M. Banks, was previously borne by the first ASDS, based on the Marmac 300 barge.
This has since been converted back to a standard barge and as such is no longer used for recovery operations.
Sadly, despite the first stage nailing the landing, one of the landing legs failed to lock, resulting in the stage toppling over on the deck.
“Definitely harder to land on a ship. Similar to an aircraft carrier vs land: much smaller target area, that’s also translating and rotating,” wrote Elon Musk.
“However, that was not what prevented it being good. Touchdown speed was OK, but a leg lockout didn’t latch, so it tipped over after landing.
“At least the pieces were bigger this time! Won’t be last RUD (Rapid Unscheduled Disassembly), but am optimistic about upcoming ship landing.”
It is believed the large amount of fog at the launch site may have added condensation to the structure, which turned to ice, potentially impacting on the landing leg locking joint.
Sunday’s launch was only the second flight of a Falcon 9 from Vandenberg; the v1.1 book-ending its career with West Coast launches – the previous Vandenberg launch was the configuration’s maiden flight in September 2013.
That launch carried Canada’s CASSIOPE spacecraft into orbit along with five small satellites. Falcon 9 launches from Vandenberg use Space Launch Complex 4E; a former Titan facility which was the site of the final Titan launch in 2005.
Rebuilt for SpaceX, the pad is part of a two-pad complex, with the nearby Space Launch Complex 4W undergoing conversion to serve as a landing site for future Falcon missions.
The previous launch of the Falcon 9’s v1.1 configuration occurred last June, ending in failure after the second stage suffered a structural failure. December’s Falcon 9 FT launch served as SpaceX’s return to flight after the anomaly.
Sunday’s launch operations commenced with the rocket being powered up ten hours in advance of launch. Loading of the rocket’s RP-1 propellant began three and three-quarter hours before liftoff, with the oxidiser – liquid oxygen – beginning to be loaded at the three-hour mark in the count.
The Jason-3 launch, as the final v1.1 launch, was the last to use this fuelling arrangement as the supercold liquid oxygen used by the Full Thrust configuration is loaded later in the count.
Following a poll around the thirteen-minute mark, the terminal countdown began ten minutes before liftoff with an automated sequence controlling launch operations. The vehicle was transferred to internal power six minutes before launch.
Ignition of the nine first stage Merlin engines took place two seconds before liftoff, allowing a short window for the onboard computer to abort the launch had anything off-nominal been detected. The rocket began its ascent when the countdown reached zero.
Climbing towards orbit, the Falcon reached the speed of sound seventy seconds after launch, passing through the area of maximum dynamic eight seconds later.
The first stage burn lasted for two minutes and thirty-four seconds before shutting down in preparation for stage separation.
Three seconds after cutoff, the first and second stages separated. Ignition of the second stage’s single Merlin Vacuum engine occurred eight seconds after staging, with the second stage continuing to orbit while the first stage returned to Earth to attempt what was an ill-fated landing aboard the ASDS.
The Falcon 9’s payload fairing separated from around Jason-3 twenty-seven seconds into the second stage burn. The first burn of the second stage lasted approximately seven and a quarter minutes.
This was followed by a coast phase of around 46 minutes before the stage restarted for a twelve-second circularisation burn. A few seconds after the second burn ends, Jason-3 separated from the Falcon 9 to begin its mission.
Jason-3 is targeting the same orbit that its predecessors, TOPEX, Jason and Jason-2 were placed into. This is a circular orbit at an altitude of 1,336 kilometres (850 miles, 721 nautical miles) and an inclination of 66 degrees to the equator, giving the satellite optimal coverage of the Earth’s oceans.
While the second stage was making its first burn, the first stage performed manoeuvres of its own to facilitate its landing attempt. This was considered a purely experimental objective, with no bearing on the overall outcome of the launch.
To facilitate recovery, the first stage restarted three times after separating from the rocket.
The first of these was a boostback manoeuvre to change the stage’s trajectory and put it on course for the ASDS. This began about 100 seconds after stage separation; four minutes and 25 seconds after liftoff.
The stage then made a burn at around the seven minute mark in the flight, to slow itself as it reenters the atmosphere, before finally restarting shortly before landing in order to slow its speed. The landing attempt was approximately eight and a half minutes after launch, although video from the ASDS was lost prior to confirmation it was unsuccessful.
Sunday’s mission was the first of 2016 for SpaceX and for the United States. In 2015 SpaceX launched seven Falcon 9s – the most it has achieved in a single year to date – despite the rocket being grounded for half the year after June’s failure.
If SpaceX is able to avoid further incidents causing the rocket to be grounded, they look likely to launch more in 2016 although the exact number of launches to be attempted this year is not yet clear.
After Sunday, the Falcon’s next flight will be in early February, with a Falcon 9 FT flying a geostationary mission from Cape Canaveral with the SES-9 satellite.
Worldwide, the Jason-3 launch was the second orbital launch of 2016 after China began the year with a successful Chang Zheng 3B launch from Xichang on Friday.
(Images: SpaceX, NASA and L2 – via Philip Sloss at Vandenberg for NSF and rendering from L2 artist Nathan Koga – The full gallery of Nathan’s (SpaceX Dragon to MCT, SLS, Commercial Crew and more) L2 images can be *found here*)
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