Flight proven Falcon 9 launches previously flown Dragon to ISS

by William Graham

SpaceX launched a flight-proven Falcon 9 rocket Friday, deploying a Dragon spacecraft on the CRS-13 resupply mission to the International Space Station. The launch was conducted at the returning Space Launch Complex 40 (SLC-40) at the Cape Canaveral Air Force Station, lifting off at 10:36 Eastern time (15:36 UTC).

SpaceX CRS-13 Launch:

The launch was the first for SpaceX since their successful deployment of Koreasat-5A on 30 October. Northrup Grumman’s Zuma mission, which had been scheduled for launch in November, has been delayed until early January (NET – No Earlier Than – January 4) following concerns over the rocket’s payload fairing.

At nearly 46 days, the gap between the Koreasat launch and this latest mission was the longest time between two SpaceX launches this year. It was the seventeenth Falcon launch of 2017, with one further mission planned later this month for Iridium, at Vandenberg Air Force Base.

SpaceX’s Dragon spacecraft does not require a payload fairing, although SpaceX officials noted the fairing issue has now been cleared.

CRS-13 is Dragon’s fifteenth flight overall and its fourteenth mission to deliver cargo to the International Space Station. For this launch, both the Dragon spacecraft and the first stage of the Falcon 9 rocket are re-used from previous missions. This marks the second time a Dragon spacecraft has been re-flown and the fourth flight of a re-used – or “flight-proven” – first stage, although it is the first time Dragon had flown atop a re-used booster.

The first stage for the launch is Core 1035. A Block III booster, Core 1035 was previously part of the Falcon 9 rocket that launched another Dragon mission, CRS-11, in June.

CRS-13 is the first NASA mission to fly aboard a flight-proven Falcon 9 and the first NASA mission to launch on a re-used rocket since the Space Shuttle was retired in 2011.

NASA’s approval for the use of a flight-proven booster for the launch came following a thorough internal review and was conditional on the rocket having only been used for one previous low Earth orbit (LEO) mission.

To date, all of the boosters that SpaceX has reflown were first flown on LEO launches and have only made a single reflight.

The Dragon spacecraft itself, C108, was previously flown in 2015 for the CRS-6 mission.

Launched on 14 April 2015 atop a Falcon 9 v1.1 rocket, Dragon spent almost 37 days in orbit – 34 of those berthed at the space station – before returning to Earth on 21 May for a successful water recovery off the coast of California.

C108 is the second Dragon to be reflown – capsule C106 was used for 2014’s CRS-4 mission before returning to space as CRS-11 earlier this year, atop the same first stage that will be used to launch CRS-13.

Developed under NASA’s Commercial Orbital Transportation Systems (COTS) project, Dragon first flew in December 2010. It is one of two US unmanned cargo vehicles used for resupply and logistics missions to the outpost under NASA’s Commercial Resupply Services (CRS) program, alongside Orbital ATK’s Cygnus.

These are to be joined by Sierra Nevada Corporation’s Dream Chaser Cargo System (DCCS) in 2020 under the second phase of the program. SpaceX is also developing a manned version of Dragon to fly commercial crew missions to the space station; this is expected to fly next year.

Dragon consists of a pressurized capsule and an unpressurized trunk section. The trunk houses vehicle systems, such as solar panels to power Dragon, and provides a space for externally-mounted cargo to be carried.

The capsule contains pressurized cargo for the space station and houses in its nose the Common Berthing Mechanism (CBM) that will be used to attach it to the station.

The capsule is designed to be recovered, while the trunk is discarded at the end of its mission and burns up in the atmosphere.

CRS-13 is the same capsule that flew on CRS-6, with a new trunk. The spacecraft’s heat shield has also been replaced.

Dragon is carrying 2,205 kilograms (4,861 lb) of cargo to the space station. This includes 490 kilograms (1,080 lb) of supplies and provisions for the crew, 711 kilograms (1,568 lb) of scientific equipment and experiments, 189 kilograms (417 lb) of space station hardware, five kilograms (11 lb) of computer equipment and 165 kilograms (364 lb) of hardware to support extra-vehicular activities (EVAs), or spacewalks, from the station.

Two unpressurized payloads, with a combined mass of 645 kilograms (1,422 lb) are contained within Dragon’s Trunk.

The Space Debris Sensor (SDS) will be mounted to the outside of the Columbus laboratory. With a surface area of one square meter (11 square feet), it will detect impacts from small pieces of orbital debris measuring as small as 50 microns across.

The sensor – a prototype for a follow-up mission to be placed into a higher orbit – will operate at the station for at least two years, recording the velocity and size of objects that impact it.

The Total and Spectral Solar Irradiance Sensor (TSIS) will be mounted on the station’s ExPRESS Logistics Carrier 3 (ELC-3) platform, which is attached to the station’s P3 port truss segment.

TSIS will make measurements of the amount of energy received from the Sun: the total solar irradiance (TSI) is the total amount of energy received from the sun, while the spectral solar irradiance (SSI) measures energy received at specific wavelengths.

Understanding the amount of energy Earth receives from the sun helps scientists to monitor Earth’s radiation budget, while measuring specific wavelengths helps to characterize how the sun affects Earth’s atmosphere and climate.

TSIS provides a replacement for solar irradiance sensors aboard NASA’s aging Solar Radiation and Climate Experiment (SORCE) satellite, which launched in January 2003 aboard a Pegasus-XL rocket.

SORCE was originally designed to operate for five years but its mission has been extended to allow irradiance measurements to continue until a replacement is established in orbit. NASA intended for the Glory satellite to take over these measurements, however it was lost in a March 2011 launch failure, when the payload fairing of its Taurus-XL rocket failed to separate.

Another sensor, Total Solar Irradiance Calibration Transfer Experiment (TCTE) was launched aboard the US Air Force’s STPSat-3 spacecraft in 2013 to ensure continuity of measurements until TSIS is in service.

The TSIS instrument was commissioned for the National Oceanic and Atmospheric Administration’s (NOAA’s) NPOESS-C1 satellite. After the NPOESS program was canceled in 2010, TSIS became part of the JPSS Free Flyer satellite, complementing the Joint Polar Satellite System (JPSS) developed in place of NPOESS. The JPSS Free Flyer was also canceled.

The launch took place from Space Launch Complex 40 (SLC-40) at the Cape Canaveral Air Force Station (CCAFS).

It was the first launch from this complex since a Falcon 9 exploded during a static fire test on 1 September last year, two days ahead of the planned launch of Spacecom’s Amos-6 satellite. Both the Falcon 9 and Amos 6 were destroyed in the accident, which was traced to the structural failure of a composite overwrapped pressure vessel (COPV) in the second stage oxidizer tank.

The last launch from SLC-40 occurred two and a half weeks earlier, successfully deploying JCSAT-16.

While repairs have been underway at Complex 40, Falcon 9 has been launching from Launch Complex 39A (LC-39A) at the nearby Kennedy Space Center. With SLC-40 now returned to service, SpaceX can complete work at LC-39A to enable the maiden flight of its Falcon Heavy rocket, currently scheduled for January.

In preparation for the launch, the Falcon 9 conducted a successful static fire last Wednesday. With the test complete, Falcon was returned to its hangar and mated with the Dragon spacecraft. The launch was delayed when SpaceX engineers noticed debris/contamination inside the second stage, which had to be cleaned out.

During the launch campaign, fuelling began with the loading of RP-1 propellant seventy minutes before liftoff. Liquid oxygen was loaded into the vehicle from the T-35-minute mark in the countdown. This combination of fuel and oxidizer is used on both of the Falcon 9’s two stages, with the liquid oxygen supercooled to increase the density at which it can be stored in the rocket’s tanks.

The rocket flew in the Falcon 9 v1.2 configuration, with a Block III first stage. In addition to using supercold oxidizer, this version of the rocket is stretched compared to the original Falcon 9 and uses an octagonal arrangement – or OctaWeb – of first stage engines as opposed to the square layout used on early flights.

Fuelling continued until about a minute before Falcon 9 was scheduled to lift off, at which point its tanks were pressurized. The nine Merlin-1D first stage engines fired three seconds before launch, with liftoff occurring at the zero mark in the countdown.

The engines that powered Core 1035’s launch are the same nine that were used during its first flight in June.

Seventy-eight seconds into the flight, Falcon passed through the area of maximum dynamic pressure, or Max-Q. The first stage powered the rocket for the first two minutes and 21 seconds of its flight before main engine cutoff, or MECO. Four seconds after MECO the stage separated. The second stage’s single Merlin-1D Vacuum engine ignited eight seconds after stage separation, beginning a six-minute, 27-second burn.

While the second stage powered Dragon towards orbit, Core 1035 began its descent back towards Earth for its second landing at Cape Canaveral’s Landing Zone 1 (LZ-1).

Built on the site of a former Atlas launch pad at Launch Complex 13, Landing Zone 1 is used for land-based recovery of Falcon 9 first stages. It is used for low Earth orbit launches from the East coast, while geosynchronous launches – where possible – target landings aboard an Autonomous Spaceport Drone Ship (ASDS) downrange.

Core 1035 was the first flight-proven booster to attempt a landing at LZ-1 – all previous reflown cores have made a geosynchronous launch as their second mission with their second landings using the ASDS.

To reach LZ-1, Core 1035 made a series of three burns. The first of these, the boostback burn, began about thirteen seconds after it separated. This burn neutralizes the stage’s downrange motion and changes its course back towards Florida.

The stage then coasted to the apogee – or highest point – of its trajectory before falling back towards Earth. An entry burn began about six minutes and seven seconds into the flight, slowing the stage to protect it from heating as it reenters Earth’s atmosphere.

The final landing burn, using a single engine, began as the booster approached the landing site. Touchdown came around seven minutes, 46 seconds mission elapsed time.

Second stage engine cutoff, or SECO, occurred nine minutes after liftoff. This marked the end of the second stage’s powered flight. Sixty seconds later Dragon separated to begin its mission, deploying its solar arrays a further minute after separation. Two hours and twenty minutes into the mission, the spacecraft will open its guidance, navigation and control (GNC) bay door.

Dragon will arrive at the International Space Station on Sunday. Astronauts Mark Vande Hei and Joe Acaba will use the station’s CanadArm2 arm to capture the spacecraft and maneuver it to the nadir – Earth-side – port of the Harmony module where it will be berthed until January.

When it is time for Dragon to depart the space station, CanadArm2 will be used to unberth and release it. Dragon will be deorbited, with the capsule expected to parachute into the Pacific Ocean for recovery while the trunk section will burn up in the atmosphere.

The launch marked the forty-fifth flight of the Falcon 9 rocket and the fiftieth orbital launch overall for SpaceX.

It was the seventeenth and penultimate Falcon 9 mission planned for 2017, with the rocket’s last mission of the year expected to fly out of California’s Vandenberg Air Force Base in the evening of 22 December local time (23 December UTC) with ten Iridium communications satellites.

Falcon’s next East coast launch will take place in early January with the enigmatic Zuma payload. Dragon’s next mission, CRS-14, is slated for March.

CRS-13 was the first of two spacecraft launching to the International Space Station this week. On Sunday Russia will launch Soyuz MS-07 from the Baikonur Cosmodrome with three members of the outpost’s Expedition 54 and 55 crews.

The Falcon 9 launch was to be one of three planned worldwide for Tuesday. However, the plans soon changed.

First, Falcon 9 was stood down to allow for work to correct a contamination issue in her second stage, which pushed the launch back to the final opportunity in this current window. Also, Rocket Lab is still waiting to conduct the second test flight of their Electron rocket, named Still Testing, from New Zealand.

However, Arianespace did launch an Ariane 5ES rocket carrying four Galileo navigation satellites from Kourou, French Guiana.

(Images: NASA, SpaceX, L2 imagery: Brady Kennison and Chris Gebhardt for NASASpaceFlight.com). (Click here to join L2)

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