CRS-19 Dragon completes journey to the ISS

by William Graham

Following her launch on SpaceX’s Falcon 9 rocket, the company’s CRS-19 Dragon spacecraft completed journey to the ISS. The resupply flight launch from Cape Canaveral’s SLC-40 on Thursday before being captured by the Station’s robotic arm on Sunday morning.

The launch began the month-long CRS-19 mission which will see Dragon deliver new research and supplies to the space station before returning to Earth with surplus hardware and the results of scientific investigations conducted aboard the outpost.

CRS-19 is the twenty-first flight of the first-generation version of Dragon and marks its twentieth mission to the International Space Station – a number that includes both its successful second demonstration flight under the Commercial Orbital Transportation Services (COTS) program and the CRS-7 flight which failed to reach orbit.

The launch began what is expected to be the penultimate flight for this incarnation of Dragon, with the cargo version of the upgraded Dragon 2 spacecraft expected to take over next year under the second phase of NASA’s Commercial Resupply Services (CRS) contract.

Dragon 2 approaches the ISS – envisioned by Nathan Koga for NSF/L2

Under CRS, both SpaceX and Northrop Grumman (the latter since its 2018 takeover of Orbital ATK) carry out regular uncrewed flights to the ISS, delivering a multitude of cargoes including provisions for the crew, space station hardware and scientific investigations. SpaceX was awarded an initial contract for twelve CRS missions in December 2008, with subsequent extensions increasing this to twenty flights.

A new contract under the second phase of the program was announced in 2016, with Dragon and Northrop Grumman’s Cygnus continuing while Sierra Nevada Corporation’s Dream Chaser was also added to the program.

The CRS vehicles form part of an international fleet of spacecraft supporting the space station, which also includes Russia’s Progress and Japan’s Kounotori. A Progress mission is currently due to lift off on Friday, arriving at the station on Monday, two days after Dragon if both missions stick to their schedules.

Building on the success of CRS, NASA has contracted with SpaceX and Boeing to outsource crewed missions to the ISS under its Commercial Crew program, with the first astronauts expected to fly aboard these missions next year. SpaceX will use Dragon v2, an enhanced version of the Dragon spacecraft which was first demonstrated with the uncrewed DM-1 mission earlier this year. Boeing’s Starliner is due to fly its demonstration mission later this month.

Before carrying out its CRS contracts, SpaceX flew two demonstration missions with Dragon under NASA’s Commercial Orbital Transportation Services (COTS) program. The first of these was a short-duration free-flying test of Dragon in low Earth orbit, which launched on 8 December 2010 and splashed down three hours and nineteen minutes later. In late May 2012 the second mission, C2+, culminated in Dragon’s first berthing and delivery of cargo to the International Space Station. Four months later, in early October, Dragon flew its first operational CRS mission.

Dragon is equipped to carry both pressurized and unpressurized cargo – the former within its recoverable capsule and the latter in the aft trunk section which also houses the vehicle’s solar arrays. The recoverable capsule provides a unique capability to return large amounts of cargo to Earth, whereas all of the other uncrewed spacecraft currently servicing the space station are not designed to survive reentry. Only the capsule is recovered – Dragon’s trunk will burn up when it reenters Earth’s atmosphere at the end of the mission.

The Dragon capsule can be reused for multiple missions. CRS-19 is the third flight for spacecraft C106, which first flew in September 2014 for the CRS-4 mission.

The first flight of this Dragon on CRS-4 – via NASA

After spending a month berthed at the space station Dragon returned to Earth, splashing down in the Pacific Ocean. After extensive inspections and refurbishment C106 became the first Dragon to make a second trip into space with June 2017’s CRS-11 flight. It is the second capsule to make a third flight, following C108 which flew the CRS-18 mission earlier this year. With the end of CRS Phase 1 and the Dragon v2 spacecraft due to come online next year, CRS-19 will be Dragon C106’s last visit to the International Space Station.

Dragon’s cargo for the CRS-19 mission includes thirty-eight experiments to be performed aboard the space station, as well as station equipment and supplies for the outpost’s crew. In total, the spacecraft is carrying 2,617 kilograms (5,769 lb) of cargo, 1,693 kilograms (3,732 lb) of which is contained within the pressurized capsule. This includes 306 kilograms (675 lb) of equipment for the station, 65 kilograms (141 lb) of hardware to support future spacewalks, 15 kilograms (33 lb) of computer equipment and 256 kilograms (564 lb) of provisions for the crew.

Scientific payloads account for 977 kilograms (2,154 lb) of the pressurized cargo aboard Dragon. Highlights include Confined Combustion, which will investigate how flames behave and spread within differently-shaped containers to help improve understanding of how fires evolve – both in space and on Earth. New hardware for the Cold Atom Lab will aid gravitational research aboard the station. A food physiology experiment will study the effects of the astronauts’ diets on their bodies.

The Germination of ABI Voyager Barley Seeds in Microgravity experiment will study the growth of barley grains in microgravity, investigating whether growth in the space environment alters the crop physically or genetically. The experiment – which is being conducted in partnership between NASA and brewery Anheuser-Busch – also incorporates a sample of dried seeds that will be grown upon their return to Earth to compare results.

Dragon will also deliver the Rodent Research 19 experiment, which will study the proteins myostatin and activin in rodents to see if they can help mitigate muscle and bone loss from long-duration spaceflight. Researchers hope that this will not only help astronauts on future space missions but also have applications for treating patients on earth with conditions such as osteoporosis and heart disease.

Dragon’s unpressurized Trunk contains the Hyperspectral Imager Suite (HISUI), an Earth remote sensing payload that is being carried for the Japan Aerospace Exploration Agency (JAXA). HISUI will be mounted on the exposed facility of the Kibo module, where it will image a 20-kilometer (12-mile, 11-nautical-mile) swath of the Earth’s surface at resolutions of up to 20 meters (66 feet). HISUI incorporates a visible and near-infrared spectrometer and shortwave infrared spectrometer, allowing it to cover 185 spectral bands at wavelengths between 0.4 and 2.5 micrometers.

HISUI follows on from the Sasuke, or ASNARO-1, satellite launched in 2014, and the Fuyo (JERS-1) satellite before it. Data collected by HISUI will help differentiate between different coverings on the Earth’s surface, such as soil, vegetation or ice, which will help to identify resources and manage the environment.

NASA’s Robotic Tool Stowage (RiTS) is also aboard Dragon’s Trunk. RiTS provides a storage area to house robotic devices operating outside the space station, such as the Robotic External Leak Locators (RELLs) that are currently stored inside the station when not in use. Storing these devices outside the station will save space and simplify their deployment when they are required.

As well as carrying research to be performed aboard the International Space Station, CRS-19 is transporting a group of small free-flying satellites that will be deployed from the outpost at a later date. These have been built to the CubeSat standard, a series of common form factors based around units with sides of 10 centimeters (3.9 inches). The CubeSats are being carried as part of NASA’s Educational Launch of Nanosatellites (ELaNa) initiative: AzTechSat-1, SORTIE and CryoCube make up the ELaNa-25B mission, while CIRiS and EdgeCube comprise ELaNa-28.

NASA’s CryoCube is a three-unit CubeSat which will conduct fluid dynamics experiments in orbit using liquid oxygen. Once in space, the satellite will deploy a sun shield, incorporating solar cells for power generation, and a second shield to block infrared radiation from the Earth. Doors on the spacecraft’s exterior allow its oxygen tank to be exposed to space when the Earth is between it and the sun. The satellite will investigate the properties of slosh within the oxygen tank, transfer of cryogenic fluids and will experiment with sensing the position of fluids within the tank. Research will be aided by a solid-to-gas converter aboard the satellite, and cameras inside the cryogenic tank.

Scintillation Observations and Response of The Ionosphere to Electrodynamics (SORTIE) is another six-unit CubeSat. It was constructed by the University of New Mexico, on behalf of a consortium led by Astra LLC, who will use it to study plasma structures and bubbles forming in the Earth’s ionosphere. The satellite carries two instruments: a miniature ion velocity meter and a micro planar Langmuir probe.

Mexico’s AztechSat-1 was developed by the Universidad Popular Autónoma del Estado de Puebla. A single-unit CubeSat, it will carry out communications experiments via the Globalstar network as a pathfinder for future missions.

Utah State University’s Compact Infrared Radiometer in Space (CIRiS) – a six-unit CubeSat – will test the Ball Experimental Sea Surface Temperature (BESST) radiometer in orbit. This is a long-wave infrared imaging payload developed by Ball Aerospace, which is geared towards research into Earth’s water cycle and aquatic resources. The satellite’s primary objective is to demonstrate the instrument and evaluate its performance for applications on future environmental research or remote sensing missions.

EdgeCube, developed by a consortium of universities led by California’s Sonoma State University, is a single-unit CubeSat which will be used for environmental research. The satellite carries imaging sensors which will help it study a phenomenon known as red edge, caused by changes in vegetation that cause leaves to reflect more light in the near-infrared. By monitoring red edge, natural and man-made changes in Earth’s ecosystems can be detected, observed and studied.

Dragon’s ride to orbit was a two-stage Falcon 9 Block 5 rocket with a brand new first stage. The core, B1059.1, is the first newly-built Falcon 9 booster to fly since June’s Falcon Heavy launch and the first to be used on a single-core Falcon 9 mission since the CRS-17 launch the previous month. The success that SpaceX has achieved with recovery and re-use of Falcon’s core stage has allowed the company to slow down its production of new stages. After completing its role in the launch, B1059 landed on the Autonomous Spaceport Drone Ship (ASDS), Of Course I Still Love You, stationed 343 kilometers (213 miles, 185 nautical miles) off the Floridian coast.

The use of Of Course I Still Love You for this mission, rather than performing a return-to-launch-site profile with a landing at Cape Canaveral’s Landing Zone 1, was driven by SpaceX’s desire to perform additional tests with Falcon 9’s second stage after spacecraft separation.

Once Dragon was deployed, the stage will remain on orbit for six hours to investigate thermal characteristics for future satellite launches that might require long coasts between upper stage burns. To leave enough propellant in the second stage for these tests, Falcon’s first stage needed to burn for longer than on a typical CRS mission, meaning that it didn’t have enough propellant remaining to make it back to shore. The ASDS was positioned to meet it following a partial boostback burn after separation.

The launch was the seventy-sixth flight of a single-core Falcon 9, while the three-core Falcon Heavy has now made three flights. Building on knowledge SpaceX gained working with the smaller Falcon 1 rocket, Falcon 9 first flew in June 2010. The current Block 5 version is the ultimate product of incremental upgrades across the rocket’s first eight years of service, making its debut in May 2018. Block 5 froze the Falcon 9 design, incorporating changes required to human-rate the vehicle for NASA’s Commercial Crew program and to help SpaceX achieve its goal of rapid reuse over multiple flights.

Of the seventy-five Falcon 9 launches and three Falcon Heavy launches to date, all but two have been completely successful. The rocket’s fourth launch, in 2012, suffered an engine failure during first stage flight but was still able to deploy its primary payload as planned – although a second satellite aboard the rocket was lost. Falcon 9’s only launch failure was in June 2015 when a cryogenic overwrap pressure vessel (COPV) in the second stage broke loose, causing the oxidizer tank to rupture and destroying the vehicle and its payload – a Dragon spacecraft on the CRS-7 mission.

Another Falcon 9 was lost on the ground in 2016 during preparations for a prelaunch static fire test, with a buildup of solid oxygen between one of the COPV tanks and its casing caused the tank to buckle which led to an explosion. The launch pad explosion, which occurred several days before the planned liftoff, claimed the Amos 6 satellite which had already been mated to its carrier rocket.

This launch was the sixtieth consecutive success for Falcon 9 and Falcon Heavy since the CRS-7 failure. Falcon has already achieved fifty consecutive successes since returning to flight after the Amos 6 test anomaly, with the CRS-19 launch aiming to extend this to fifty-one.

Falcon 9 was raised to vertical at Cape Canaveral Air Force Station’s Space Launch Complex 40 (SLC-40) following late cargo loading at the launch pad Tuesday, after which final preparations for launch began. SLC-40 is a former Titan launch pad, originally built in the 1960s, which SpaceX leased from the US Air Force in 2007.

SLC-40 with Falcon 9 ahead of CRS-19 – via Brady Kenniston for NSF

During its Titan era, SLC-40 was part of the Integrate-Transfer-Launch (ITL) complex, which included nearby Space Launch Complex 41 and shared assembly and vertical integration buildings.

Titan IIIC, III(34)D, Commercial Titan III and Titan IV rockets launched from the pad between 1965 and 2005, with significant launches including the first Titan IIIC flight in June 1965, a mockup of the US Air Force’s MOL space station and an unmanned Gemini spacecraft in November 1966, NASA’s ill-fated Mars Observer probe in September 1992 and the successful Cassini-Huygens mission to Saturn in 1997.

SpaceX’s conversion of SLC-40 for the Falcon 9 included demolition of the Titan IV fixed and mobile service towers and construction of a hangar to facilitate horizontal integration of Falcon rockets.

The rocket is placed on top of a Transporter-Erector structure known as the Strongback, which is then used to convey Falcon to her launch pad, raise her into the vertical position and provide umbilical connections during the final stages of the countdown.

SLC-40 is one of two launch complexes SpaceX operate on Florida’s Space Coast, alongside Launch Complex 39A at the nearby Kennedy Space Center. Falcon 9 can fly from either launch pad, although only 39A is equipped for crewed missions and Falcon Heavy launches. SpaceX also operates Space Launch Complex 4E at Vandenberg Air Force Base in California for Falcon 9 launches to polar orbits.

Both the first and second stages of Falcon 9 use RP-1 kerosene propellant oxidized by supercooled liquid oxygen. Because of the oxygen’s low temperature, the rocket is not fuelled until the last thirty-five minutes of the countdown. After the flight director verifies that all systems are go to begin the process, loading of RP-1 into both stages and liquid oxygen into the rocket’s first stage begins at the T-35 minute mark in the count.

Second stage oxidizer loading began slightly later, at the T-16 minute mark. The liquid oxygen continued to be topped off until the last minutes of the countdown, replacing oxidizer that boils off and is vented from the rocket.

Falcon 9 and Dragon transitioned to internal power in the last ten minutes before liftoff. With about four and a half minutes to go the arms on the Strongback open in preparation for the structure to be retracted. The strongback initially rotates about 1.5 degrees away from the rocket, remaining in this position until the rocket lifts off.

In the final minute of the countdown, Falcon 9 will enter startup mode, with onboard computers taking over control of the vehicle. The rocket’s tanks were brought up to flight pressure and the computers performed final checks on all systems. At the forty-five-second mark, the Launch Director gave a final “go” for launch.

Falcon 9’s first stage is powered by nine Merlin-1D engines. These ignite three seconds before liftoff, with the rocket held down for a short time to ensure they are operating as expected before liftoff occurs at T-0.

Falcon climbed away from her launch pad, pitching downrange on a north-easterly azimuth as she takes aim on the International Space Station. Seventy-eight seconds into flight the rocket passed through the area of maximum dynamic pressure – Max-Q – where the rocket experiences the greatest level of mechanical stress due to aerodynamic conditions. Around this time the rocket reached Mach 1 and went supersonic.

The first stage burned for the first two minutes and 31 seconds of flight. The end of its burn is designated Main Engine Cutoff, or MECO. At this point, the nine Merlin-1D engines shut down and three seconds later the rocket’s first and second stages separated from each other. The first stage reoriented itself to begin its boostback burn, while the second stage ignited eight seconds after separation to continue Dragon’s journey into orbit.

After separation, Core 1059 performed three burns. The first of these, the boostback burn, arrested its movement downrange and put it on a course towards the drone ship. This began thirteen seconds after staging. With the boostback complete, the core deployed its grid fins, used to provide additional stability as the core descends back into Earth’s atmosphere.

At about six minutes and eleven seconds mission elapsed time, the core fired again for its entry burn, reducing its velocity to limit heating as it passes into the denser regions of the atmosphere. The final landing burn began about a minute later, with landing seven minutes and 48 seconds after liftoff.

While the first stage landed aboard Of Course I Still Love You, Falcon’s second stage got on with the primary mission: delivering Dragon to orbit. The second stage burn lasted five minutes and 53 seconds, placing itself and the payload into an initial low Earth parking orbit.

One minute after second stage engine cutoff, or SECO, the Dragon spacecraft separated to begin its mission. Dragon’s solar arrays deployed shortly afterward – just over 12 minutes into the flight – while the door of its guidance, navigation and control (GNC) bay was opened two hours and 19 minutes after launch.

Dragon performed a series of maneuvers over the following days to set up a rendezvous with the space station on Sunday. Upon arrival, Dragon was grappled by astronauts using the station’s CanadArm2 robotic arm, to be berthed at the nadir – or Earth-facing – port of the Harmony module.

The CRS-18 Dragon approaching the ISS – via NASA

ESA astronaut Luca Parmitano performed this operation, aided by NASA’s Andrew Morgan. Dragon is expected to remain at the station until early January. While berthed at the outpost Dragon’s cargo will be unloaded and the capsule will be loaded with equipment to be returned to Earth – including 54 completed scientific investigations. The total mass of cargo to be returned to Earth is expected to be around 1,633 kilograms (3,600 lb).

Upon departure, the spacecraft will be unberthed using CanadArm2 and released away from the station. Dragon will then deorbit itself and separate its Trunk section before the capsule reenters and splashes down in the Pacific Ocean under parachute. The Trunk and any equipment loaded into it will be destroyed upon reentry.

The launch was the twelfth of the year for SpaceX, a number which includes ten Falcon 9 and two Falcon Heavy missions. The company’s next launch is slated for the middle of December, with a Falcon 9 deploying the Kacific-1 communications satellite.

Another Falcon 9 launch is also expected towards the end of the month, with another batch of Starlink satellites, while SpaceX is also expected to carry out an in-flight abort test of the Dragon v2 spacecraft, using a Falcon 9 first stage to boost the capsule to altitude before simulating an emergency and activating the spacecraft’s launch abort system.

Dragon’s next CRS mission, CRS-20, is currently scheduled for early March next year, with Northrop Grumman flying a Cygnus mission ahead of it in early February. CRS-20 will be the last mission to use the current-generation Dragon before flights switch to Dragon 2 Cargo under the Phase 2 CRS contract.

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