SpaceX’s Dragon spacecraft began its fifteenth mission to the International Space Station Monday with a launch aboard a Falcon 9 rocket. Liftoff, from Space Launch Complex 40 of the Cape Canaveral Air Force Station, occurred at 16:30 Eastern Time (20:30 UTC).
Monday’s launch carried CRS-14, the fourteenth flight of Dragon under NASA’s Commercial Resupply Services (CRS) contract that sees commercial cargo vehicles make deliveries to the International Space Station (ISS).
SpaceX’s Dragon is one of two vehicles currently in service making CRS flights – with Orbital ATK’s Cygnus also used for cargo runs to the outpost. The CRS vehicles form part of an international fleet of ships supporting the space station, which also includes Russia’s manned Soyuz and unmanned Progress spacecraft and Japan’s Kounotori – or H-II Transfer Vehicle.
Dragon first flew in December 2010, with a short test mission that ended with the spacecraft being recovered successfully in the Pacific Ocean. The spacecraft’s first two flights were made under NASA’s Commercial Orbital Transportation Services program, which funded development of Dragon and Cygnus ahead of the operational CRS resupply contracts being awarded. Dragon’s second flight, in May 2012, culminated in a successful rendezvous with and berthing at the space station, paving the way for it to begin operational missions.
Dragon began its first operational mission, CRS-1, in October 2012 and has made twelve further flights to date. All of these have seen Dragon arrive at the space station and return to Earth successfully, except for June 2015’s CRS-7 mission which failed to achieve orbit after a malfunction of the Falcon 9 rocket that was carrying it. CRS-14 is the fifteenth Dragon mission to launch to the station, however as CRS-7 did not reach orbit, if successful it will be the fourteenth to reach the outpost.
Dragon consists of a pressurized capsule and an unpressurized Trunk section. The Trunk houses cargo to be mounted to the space station’s exterior and also provides Dragon with power through its solar arrays. Aside from Soyuz, Dragon is the only spacecraft currently flying to the space station that also has the ability to return cargo to Earth.
Following a month at the station Dragon will be released to begin its return journey, ending with the capsule descending under parachutes into the Pacific Ocean. The Trunk is not designed to be recovered and will separate from the capsule after it has been deorbited, burning up in the atmosphere.
After recovery, Dragon capsules can be refurbished to fly again on future missions. The Dragon that will fly CRS-14 previously conducted the CRS-8 mission in 2016, delivering a cargo that included the Bigelow Expandable Activity Module (BEAM) to the space station.
CRS-8 lifted off aboard a Falcon 9 on 8 April 2016 and arrived at the International Space Station a little under two days later. After spending just over a month at the station, Dragon returned to Earth on 11 May.
The CRS-14 mission is carrying 2,647 kilograms (5,836 pounds) of cargo. Within the capsule, this includes 1,070 kilograms (2,359 lb) of scientific hardware and experiments, 344 kilograms (758 lb) of provisions for the crew, 148 kilograms (326 lb) of equipment to support the US segment of the space station and 11 kilograms (24 lb) of hardware for the Russian side of the Station .
The cargo also includes 99 kilograms (218 lb) of equipment to support the crew in conducting extra-vehicular activities – or spacewalks – and 49 kilograms (108 lb) of computer equipment.
The cargo includes a new heater controller for the station’s carbon dioxide scrubbers, high-definition camera assemblies to be mounted outside of the ISS and a spare Common Communication for Visiting Vehicles (C2V2) assembly that will be installed to improve reliability ahead of the arrival of a Cygnus mission next month. A new HP Envy printer will also be delivered for the crew’s use.
Science aboard the Dragon’s capsule includes a study of the effects of microgravity on bone marrow – to confirm whether long-duration spaceflight affects marrow and blood cell production in the same way that it would affect a patient in long-term bed rest on Earth.
Another experiment, Sample Cartridge Assembly – Gravitational Effects on Distortion in Sintering (SCA-GEDS), will study how microgravity affects the process of liquid phase sintering – which is used in the fabrication of composite materials and could in the future play an important role in constructing and repairing spacecraft in situ. The Veggie PONDS experiment will demonstrate a passive orbital nutrient delivery system (PONDS) to provide water and nutrients to a crop of lettuce and mizuna that will be grown aboard the space station for crew consumption.
Two small satellite missions are also being flown aboard the capsule for deployment from the International Space Station. These are the commercial Overview-1A satellite for US company SpaceVR, and the British RemoveDEBRIS mission which is being conducted by the University of Surrey.
Overview-1A is a three-unit CubeSat which was built by Pumpkin Incorporated. The five-kilogram (11 lb) satellite carries a virtual reality imaging payload that SpaceVR aim to use to provide subscribers with the experience of being in space and seeing the Earth from orbit. A second satellite – Overview-1B – is also under construction, while SpaceVR aim also to place satellites in orbits of other planets.
The University of Surrey’s RemoveDEBRIS is a larger satellite that was built by Surrey Satellite Technology Ltd (SSTL), based around the SSTL-42 satellite bus. The mission, which has received funding from the European Union, will see the satellite demonstrate techniques for capturing and deorbiting debris from low Earth orbit.
Following deployment from the space station via the Japanese Experiment Module’s robotic arm, RemoveDEBRIS will itself deploy the first of a pair of two-unit CubeSat subsatellites – DebrisSAT-1 (DS-1). DS-1 will deploy an inflatable balloon to increase its size and drag, before RemoveDEBRIS attempts to capture it with a net. Once caught in the net, DebrisSAT-1 will be left to decay from orbit – with the increased drag from its balloon hastening this process.
RemoveDEBRIS will deploy its second subsatellite, DebrisSAT-2 (DS-2), which will serve as a target for its second experiment, Vision-Based Navigation (VBN). During this phase of this mission, the RemoveDEBRIS satellite will use a camera and a light detection and ranging (LIDAR) system to track the DS-2 CubeSat. This will allow algorithms for debris tracking to be refined and developed for future missions.
The third phase of the mission will see RemoveDEBRIS attempt to harpoon a third target, which will be extended out from the main satellite. The final phase of the mission will test the deployment of an inflatable sail, which will increase the satellite’s drag aiding its removal from orbit.
The remaining 926 kilograms (2,041 lb) of cargo is located in the unpressurized Trunk. This includes the Materials ISS Experiment Flight Facility (MISSE-FF), an externally-mounted materials research platform that will allow up to fourteen interchangeable sample modules to be exposed to the space environment at one time.
The facility will be attached to one of the ExPrESS Logistics Carriers (ELCs) attached to the space station’s truss. A refurbished Pump and Flow Control Subassembly for the station’s solar array cooling system – one of the outpost’s orbital replacement units (ORUs) – will also be delivered via the Trunk.
The third payload in Dragon’s Trunk is the European Space Agency’s Atmosphere-Space Interactions Monitor (ASIM). ASIM will be mounted to one of the external payload racks of the station’s Columbus module. The 314-kilogram (692 lb) instrument will be used to study high-altitude electrical activity within Earth’s atmosphere. The aim of the experiment is to provide a better understanding of transient luminous events (TLEs) or ionospheric lightning, little-understood electrical phenomena known as sprites, jets and ELVES.
Monday’s launch marked the fifty-second launch of SpaceX’s Falcon 9 rocket – which first flew in June 2010 with a mockup Dragon spacecraft aboard. Falcon 9 has boosted all of Dragon’s missions – across three different configurations of the rocket. Early Dragon missions used the original version of the rocket – retrospectively known as the Falcon 9 v1.0 – with launches moving to the more capable Falcon 9 v1.1 following its introduction in 2013 and then to the Falcon 9 v1.2 in 2016.
The Falcon 9 was designed to be at least partially reusable, with SpaceX still hopeful of eventually making the complete vehicle reusable. Currently, the rocket’s first stage, or Core, is the only component that can fly more than once – although SpaceX is making progress with attempts to recover the rocket’s payload fairing as well. The company’s last two west-coast launches have included attempts to catch half of the fairing – as it falls under a parachute – with a specially modified ship. On both flights, the fairing has missed the ship but landed intact in the water nearby.
The Dragon spacecraft is aerodynamic and does not require a fairing to protect it as Falcon 9 climbs through the atmosphere. CRS-14 was boosted by a previously-flown – or “flight-proven” – first stage, Core B1039.2, which first flew last August in support of the CRS-12 mission. B1039 was the first Falcon 9 core built to Block 4 specifications to fly and, after sending CRS-12 on its way to the space station, flew back to the Cape Canaveral Air Force Station for a successful landing at SpaceX’s Landing Zone 1.
SpaceX only flies Block 3 and 4 Falcon 9s twice, and as B1039 was making its second launch SpaceX did not attempt to recover the stage again. Instead, the stage was used to demonstrate a landing close to the rocket’s limits, collecting data for future missions. SpaceX is expected to introduce the Block 5 version of Falcon 9, which will be capable of multiple re-flights, later this month.
Monday’s launch took place from Space Launch Complex 40 (SLC-40) at the Cape Canaveral Air Force Station. One of two Falcon 9 pads on Florida’s Space Coast – along with the Kennedy Space Center’s Launch Complex 39A (LC-39A) – SLC-40 is a former Titan III and Titan IV launch pad whose lease was taken over by SpaceX in 2007.
The pad was the site of Falcon 9’s maiden flight and supported all East Coast Falcon missions until it was damaged in a test accident in September 2016.
A Falcon 9 exploded during fuelling for a static fire test ahead of the planned launch of the Amos 6 satellite, which put the pad out of use for over a year. At the time of the accident, LC-39A was being developed as a second East Coast pad, so this was rushed into service to support upcoming missions, with SLC-40 returning to operations last December.
Falcon’s nine Merlin-1D first-stage engines began their ignition sequence three seconds before the rocket’s planned liftoff. The rocket left the launch pad and began its ascent towards orbit once the countdown reached zero. Sixty-eight seconds into the mission, Falcon passed through Max-Q – the area of maximum dynamic pressure.
The first stage – B1039.2 – powered Falcon 9 for the first two minutes and 41 seconds of the flight. At this point in the mission it shut down its engines – a flight event designated main engine cutoff, or MECO.
The first and second stages separated four seconds after MECO, with the second stage firing its Merlin Vacuum (MVac) engine – a version of the Merlin-1D optimized to operate in the vacuum of space – seven seconds after separation. The second stage will make a single burn to deploy Dragon, which will last six minutes and 11 seconds.
At ten minutes and three seconds mission elapsed time – about a minute after the second stage completes its burn – Dragon separated from the Falcon 9. The spacecraft deployed its solar panels 57 seconds after separation, before opening its guidance, navigation and control (GNC) bay doors two hours and twenty minutes into the mission. Dragon will make a series of thruster burns to achieve rendezvous with the International Space Station, where its arrival is expected on Wednesday.
When Dragon arrives at the space station, it will maneuver into range of the station’s CanadArm2 arm.
Japanese astronaut Norishige Kanai, assisted by NASA’s Scott Tingle, will use CanadArm2 to grapple Dragon and berth the spacecraft to the nadir – or Earth-facing – port of the Harmony module. At the end of Dragon’s stay – currently expected on 2 May – CanadArm2 will again be used to unberth the spacecraft and release it for the return to Earth.
Monday’s launch was the seventh of 2018 for SpaceX – following five Falcon 9 missions and the successful debut launch of Falcon Heavy in the first quarter of the year. SpaceX’s next launch is scheduled for 16 April, with a Falcon 9 due to deploy NASA’s Transiting Exoplanet Survey Satellite (TESS).
The next ISS resupply mission will be undertaken by Orbital ATK: the OA-9 mission, using a Cygnus spacecraft, is due to lift off atop an Antares rocket on 9 May. Dragon’s next flight is expected no earlier than 9 June.