Falcon 9 launches with CRS-11 Dragon on 100th 39A launch

by William Graham

SpaceX launched its first re-used Dragon spacecraft aboard a Falcon 9 on Saturday, beginning the CRS-11 resupply mission to the International Space Station. The first attempt was scrubbed during the initial attempt due to poor weather, meaning Falcon 9 lifted off from the Kennedy Space Center – making the hundredth flight from the historic Launch Complex 39A – at the weekend.

Falcon 9 Dragon Launch:

CRS-11 is the thirteenth flight of SpaceX’s Dragon spacecraft and the eleventh in support of NASA’s Commercial Resupply Services (CRS) program, which sees Dragon transport cargo to and from the International Space Station (ISS).

Dragon is one of two US spacecraft contracted to provide logistics to the Space Station, along with Orbital ATK’s Cygnus. Both spacecraft were developed and demonstrated under NASA’s Commercial Orbital Transportation Services (COTS) program, with contracts for operational launches issued under CRS. The US spacecraft, along with Russia’s Progress and Japan’s Kounotori, or HTV, spacecraft, provide regular deliveries of supplies, equipment and experiments to the outpost. Dragon is the only one of these spacecraft designed to survive reentry, allowing it also to return cargo to Earth at the end of its mission.

Dragon consists of a capsule, which carries pressurized cargo to and from the station, and an unpressurised Trunk which houses the spacecraft’s solar arrays and provides capacity to transport unpressurised cargo into orbit. Unlike the capsule, the Trunk cannot be recovered. Instead, it is jettisoned at the end of the mission and burns up in the atmosphere.

The first Dragon spacecraft was launched in December 2010, completing two orbits of the Earth before a successful recovery in the Pacific Ocean. May 2012’s Dragon C2+ mission saw the second Dragon complete its remaining demonstration objectives under the COTS program, and make its first visit to the ISS.

The CRS-11 mission is flying aboard Dragon spacecraft C106, which previously conducted 2014’s CRS-4 mission. Launched aboard a Falcon 9 v1.1 from Cape Canaveral Air Force Station, CRS-4 lifted off on 21 September and arrived at the Space Station two days later.

After a month berthed to the nadir port of the station’s Harmony module, CRS-4 returned to Earth on 25 October. The capsule descended under three parachutes and was recovered from the Pacific Ocean.

C106 is the first Dragon spacecraft to be used for a second mission. The spacecraft was inspected and refurbished following its return to Earth and has had its heat shield replaced. However, the spacecraft’s hull and most of its systems are flight-proven.

The first re-use of a Dragon comes two months after SpaceX successfully demonstrated re-use of a Falcon 9 first stage for the first time, with March’s launch of the SES-10 satellite. The launch will use a new booster, core 1035. However, this will be targeting a return to Earth for future re-use. Following stage separation, the booster will fly back to the Cape Canaveral Air Force Station and attempt a landing at Landing Zone 1 – the former Launch Complex 13.

Falcon 9 is unique among active orbital launch systems in that it was designed with reuse in mind. Early flights – using a configuration now known retrospectively as the Falcon 9 v1.0 – could be equipped with parachutes, although this proved impractical as the stage did not survive reentry.

An upgraded v1.1 configuration was introduced in 2009, stretching both stages of the rocket, upgrading the vehicle’s engines from the Merlin-1C to Merlin-1D and switching from a square grid engine arrangement to an octagonal, or OctaWeb, arrangement, on the first stage. With the subsequent additions of legs and grid fins, the Falcon 9 v1.1 was equipped to make a series of engine burns for a powered landing.

Further upgrades were introduced in December 2015, resulting in a configuration which has become known as the Falcon 9 v1.2, or Falcon 9 Full Thrust. This further stretched the rocket’s second stage, uprated the Merlin-1D engines and cooled the vehicle’s oxidiser – liquid oxygen – to supercold temperatures allowing it to be stored at a higher density in the rocket’s tanks so that a greater amount can be carried. On its maiden flight the Falcon 9 v1.2 completed its first successful first stage recovery, with the booster landing at the Cape Canaveral Air Force Station.

When conducting low Earth orbit missions, such as Dragon launches, SpaceX will typically attempt to return the first stage to Cape Canaveral. For higher energy missions, such as geosynchronous launches, the boosters can also be recovered at sea via the Autonomous Spaceport Drone Ship (ASDS), a converted barge which can be positioned downrange to catch the stage as it descends. Where additional performance is required – for example the Inmarsat-5 F4 mission conducted last month – Falcon 9 can also fly in a fully expendable configuration.

First launched in June 2010, Falcon 9 is a two-stage liquid-fuelled rocket. Both stages use RP-1 propellant oxidized by liquid oxygen. The launch is the thirty-fifth launch of the Falcon 9 and the fifteenth of the Falcon 9 v1.2. The rocket’s only launch failure to date came during June 2015’s flight of a Falcon 9 v1.1 with the CRS-7 Dragon spacecraft, when a second stage cryogenic overwrap pressure vessel (COPV) broke loose during ascent, causing the stage’s oxidiser tank to overpressurize and rupture.

A second Falcon 9 – a v1.2 – was lost along with its payload, Israel’s Amos 6 communications satellite, during a pre-launch accident last September when the rocket exploded during fuelling for a static fire test. That failure was also traced to a second stage COPV, which had burst due to bubbles of oxygen building up and solidifying between its inner lining and outer casing.

The explosion damaged SpaceX’s launch pad at Cape Canaveral Air Force Station, Space Launch Complex 40 (SLC-40), so East Coast launches have instead been using the Kennedy Space Center while SLC-40 is repaired. The pad is expected to return to service later in the year.

In the meantime, the historic Launch Complex 39A at NASA’s Kennedy Space Center has been playing host to Falcon 9. LC-39A, the same pad from which Apollo 11 launched in 1969, was leased to SpaceX in 2014 to provide additional capabilities for Falcon 9 launches carrying manned Dragon spacecraft and US Government payloads, and to give the larger Falcon Heavy rocket an East Coast launch site. The launch marks the hundredth launch from Pad 39A.

Launch Complex 39 was built as a two-pad launch facility for the Saturn V rocket in the 1960s. The iconic Vehicle Assembly Building (VAB) was built as part of the complex, with rockets integrated vertically atop a Mobile Launcher – which also housed a Launch Umbilical Tower.

This platform would then be carried atop a Crawler Transporter to one of the two pads via the Crawlerway. During the Apollo program, twelve Saturn V rockets launched from LC-39. Eleven of these used pad A, including the rocket’s maiden flight – Apollo 4 – the first manned mission to orbit the Moon – Apollo 8 – and all manned lunar landing missions. Due to short turnarounds between Apollos 9, 10 and 11, Apollo 10 was the only Saturn V launch to use the backup pad, LC-39B.

In 1973, following the end of the Apollo lunar program, a thirteenth and final Saturn V launch – using a two-stage configuration – carried America’s first space station, Skylab, into orbit. This launch was the last Saturn mission from Pad 39A, with the launch complex entering conversion ahead of the Space Shuttle program. Three manned missions to Skylab launched from Pad B, using Saturn IB rockets fired from a Saturn V Mobile Launcher adapted by means of a platform dubbed the Milkstool. A fourth Saturn IB launch from LC-39B was made for the Apollo-Soyuz Test Project, the final flight of an Apollo spacecraft.

Launch Complex 39A returned to action in April 1981 when Space Shuttle Columbia made her maiden flight, STS-1, from the complex.

The first twenty-four missions of the Space Shuttle program flew from LC-39A, while pad B was undergoing conversion. The first Shuttle mission to launch from LC-39B was STS-51-L, which ended with the loss of Challenger and her crew 73 seconds after launch. When the Shuttle returned to flight in 1988, launches were shared between the two pads.

Discovery’s STS-116 mission in 2006 was the last of fifty-three Space Shuttle missions to use Launch Complex 39B before the pad underwent modifications to support the then-planned Constellation program. The Ares I-X demonstrator mission launched from LC-39B in October 2009, bringing Pad 39B to a total of 59 launches. The pad is expected to be used by NASA’s Space Launch System, whose maiden flight is currently scheduled No Earlier Than (NET) 2019.

The final launches of the Space Shuttle were made from LC-39A, with the orbiter Atlantis flying STS-135, the final mission, in July 2011. Eighty-two Space Shuttle missions used pad 39A. The launch is the sixth time a Falcon 9 has lifted off from the pad – all of which have come in the last three-and-a-half months. Falcon’s first launch from the Kennedy Space Center was made on 19 February, carrying the previous Dragon mission, CRS-10.

Unlike the Saturn V and Space Shuttle, Falcon does not make use of the Vehicle Assembly Building or the Mobile Launcher Platforms – as the Mobile Launchers were redesignated following their conversion for the Shuttle. Instead, SpaceX has constructed a hangar at the base of the pad’s launch ramp. Rockets are integrated horizontally and transported the short distance to the launch pad mounted on top of a strongback structure. This is used to erect the rocket on the pad and provide umbilical connections between the rocket and the ground.

The launch was the 160th from the Kennedy Space Center overall; in addition to the one-hundred from LC-39A and 59 from LC-39B, a single air-launched Pegasus rocket was dropped from a B-52 flying from the Shuttle Landing Facility.

Fuelling of the Falcon 9 began with a poll 78 minutes before the rocket was due to lift off. Eight minutes later RP-1 propellant began to be loaded into the Falcon’s tanks. Oxidiser loading began 45 minutes before launch. The launch could be one of the last to load oxidiser at T-45 minutes, as SpaceX aims to move to a faster fuelling process beginning ten minutes later – as used in last month’s Inmarsat launch – going forwards.

The core built for CRS-11 was not built to support this process, so the old fuelling procedure is being used instead. The old procedure will also be used for the BulgariaSat-1 launch later this month, as this is reusing core 1029, which previously flew January’s Iridium-NeXT mission.

Seven minutes before launch, Falcon 9 initiated an engine chilldown and Dragon transfered to internal power. During the final minutes of the countdown the strongback was prepared for retraction, with clamps opening and the structure rotating slightly away from the vehicle. Full retraction occurred as the rocket lifted off.

Following approval from the US Air Force’s Range Control Officer (RCO) and SpaceX’s Launch Director, the countdown proceeded into the final minute where the onboard computers took over conducting final checks before liftoff. The vehicle’s fuel tanks were pressurized and the launch pad water deluge system activated.

Ignition of the nine first stage Merlin-1D engines occurred three seconds before the countdown’s zero mark. At zero Falcon lifted off to begin her journey towards orbit. The rocket passed through the area of maximum dynamic pressure, or Max-Q, seventy-eight seconds into flight.

The first stage boosted the rocket for the first two minutes and 22 seconds of the flight. Its engines then shut down, an event designated main engine cutoff, or MECO. Because the Dragon launch does not require the rocket’s maximum performance, the first stage saves sufficient propellant for its landing attempt. The stage separated three seconds after MECO, with second stage ignition seven seconds later.

Falcon 9’s second stage is powered by a single Merlin-1D engine, optimized for vacuum performance. This burned for six minutes and 38 seconds, placing Dragon into low Earth orbit. Spacecraft separation took place a minute after the end of second stage powered flight – ten minutes and 20 seconds after liftoff.

While the second stage is placing Dragon into orbit, the first stage made three burns as it fly back to the Cape. The first of these, a boostback burn, began thirteen seconds after separation to reverse the rocket’s course and fly back uprange towards the landing zone. An entry burn, beginning six minutes and ten seconds into the flight, slowed the rocket as it re-entered Earth’s atmosphere to protect it from heating. The final burn began seconds before touchdown, which occurred at seven minutes, 27 seconds mission elapsed time. Landing was again successful.

Following separation from the Falcon 9, Dragon deployed its solar arrays and will make a series of burns as it chases down the International Space Station. Rendezvous is scheduled for 4 June. Dragon will be captured by astronauts aboard the station, using the CanadArm2 robotic arm, and berthed at the nadir, or Earth-facing, port of the Harmony module. Dragon is expected to stay at the station for around a month – with departure currently slated for 2 July.

When it leaves the station, the spacecraft will be unberthed and released using CanadArm2 before performing a deorbit burn, jettisoning its trunk section and splashing down in the Pacific.

Dragon is carrying 2,708 kilograms (5,970 lb) of cargo to the station. The pressurized cargo includes 242 kilograms (534 lb) of supplies for the crew, 199 kg (439 lb) of station hardware, 27 kg (59 lb) of computer equipment, 56 kg (123 lb) of equipment to support spacewalks and 1,069 kilograms (2,357 lb) of scientific equipment and experiments. Dragon’s Trunk contains the Roll-Out Solar Array (ROSA), Neutron Star Interior Composition Explorer (NICER) and Multiple User System for Earth Sensing (MUSES).

ROSA is a prototype for a new compact solar array, which will be deployed at the space station to test its deployment mechanism and demonstrate it in orbit, although this will not form a permanent part of the station’s power generation system.

NICER is an externally-mounted astronomy package, including a timer and a spectrometer, to monitor pulsars – collecting data and demonstrating, as part of the Station Explorer for X-ray Timing and Navigation Technology (SEXTANT) experiment, whether they can be used for spacecraft navigation. MUSES carries optical and hyperspectral imaging payloads for Earth remote sensing.

Dragon is carrying five single-unit CubeSats to the space station for deployment from the station. These include the first satellites for Bangladesh, Ghana and Mongolia. These make up the Birds constellation, a multi-national research program led by Japan’s Kyushu Institute of Technology (KIT).

Each satellite carries Earth imaging, amateur radio and microcontroller technology demonstration experiments. The spacecraft were built by KIT, in conjunction with students from the other participating institutions. The engineering of the satellites draws on KIT’s experience with its Horyu series of small satellites.

Bangladesh’s satellite, BRAC Onnesha, or Bird B, will be operated by BRAC University. Ghana’s ANUSAT-1, or Bird G, is being flown for the All Nations University College of Koforidua. Bird J will be operated by KIT itself. Mazaalai, also known as NUMSAT-1 and Bird M, will be operated by the National University of Mongolia.

EduSat-1, or Bird N, will be operated by Nigeria’s Federal University of Technology. Taiwan’s National Cheng Kung University and King Mongkut’s University of Technology North Bangkok of Thailand are also participating in the program, although without their own satellites.

SpaceX’s launch was to be the second of three planned for worldwide – following Japan’s successful launch of the Michibiki No.2 satellite at 00:17 UTC (20:17 on Wednesday at Falcon 9’s launch site). However, the move to Saturday made it the third.

This is because Arianespace suffered from no weather issues as it conducted an Ariane 5 launch from Kourou in French Guiana, which at 23:45 UTC on Thursday – an hour and fifty minutes after what would have been Falcon 9’s departure. The Ariane launch carried two commercial communications satellites – ViaSat-2 and Eutelsat 172B.

Falcon 9’s next launch is currently slated for NET 15 June, carrying the BulgariaSat-1 communications satellite. Ten days later a launch from Vandenberg Air Force Base will deploy ten Iridium-NeXT satellites, in SpaceX’s second mission for Iridium. SpaceX is targeting a pace of two or three launches per month for the rest of 2017, as it aims to cut down its backlog of commercial missions. Dragon’s next flight, CRS-12, is currently slated for 1 August.

(Images via Mike Deep, SpaceX, NASA and L2). To Join L2 and support NSF’s running costs, please click here: //www.nasaspaceflight.com/l2/)

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