SpaceX’s CRS-5 Dragon spacecraft departed the International Space Station (ISS) ahead of a return to Earth on Tuesday. The EOM (End Of Mission) events climaxed with a parachute-assisted splashdown in the Pacific Ocean at around 7:44 pm Eastern, concluding another successful mission for the commercial resupply spacecraft.
CRS-5 Dragon – EOM:
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Launched atop of SpaceX’s Falcon 9 v1.1 launch vehicle on January 10, Dragon has enjoyed yet another successful mission at the orbital outpost – her sixth ISS stay in total.
Grappled by Canada’s Space Station Remote Manipulator System (SSRMS) two days after launch, Dragon was carefully translated towards her new home on the Earth facing port of the Harmony module.
(Animation created by Artyom Zharov, via L2’s huge collection of Dragon arrival hi res images)
Riding uphill with the Dragon was a cargo complement of almost 5,000 pounds of supplies and experiments to the International Space Station during a month-long stay.
A number of specific payloads rode uphill, including the Microbial Observatory-1, the Flatworm Regeneration payload, the “Wearable Monitoring” ASI payload, the Free-Space PADLES (Passive Dosimeter for Life-Science Experiment in Space) payload for JAXA and the Fruit Fly Lab-01.
Dragon’s array of cargo will support more than 250 experiments that will be conducted by the Station’s Expeditions 42 and 43 crews.
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The ISS crew removed and stored the cargo, before refilling Dragon with downmass. Dragon is the only American vehicle capable of returning downmass since the retirement of the Space Shuttle fleet.
She also provided the Station with a payload that was launched in her Trunk section, namely the CATS (Cloud-Aerosol Transport System).
CATS uses a Lidar instrument, consisting of a laser which is directed at the Earth’s surface allowing backscattered light to be analysed.
The primary objectives of the mission are to measure the altitude distribution of aerosols in the Earth’s atmosphere and to collect data to help improve climate models. It follows on from the CALIPSO satellite, launched in April 2006, which forms part of the A-train constellation.
The operation was the responsibility of Canada’s space robot, Dextre (SPDM), along with the assistance of the JAXA robotic arm – marking the first time both robotic assets had worked together on such a task.
With the primary mission complete, and Dragon packed with downmass, the EOM (End Of Mission) objectives are next up for the spacecraft.
To kick off the homecoming, the long sequence of events – that will ultimately lead to Dragon safely bobbing up and down in the Pacific Ocean – saw the ISS crew initiate the unberthing of Dragon from the Node 2 Nadir CBM, via the release of 16 bolts around the CBM berthing collar on the ISS side, performed in four sets of four bolts to ensure even unloading on the CBM interface.
Dragon’s removal was commanded by Canadian Space Agency (CSA) ground controllers, working with the ISS Flight Control Room at the Johnson Space Center.
With the SSRMS holding on to the Dragon – and the bolts released through the opposite process that saw first and second stage capture – the “big arm” pulled Dragon away from the port.
Dragon was maneuvered to a release position approximately 30 feet below the ISS.
Once in the release position, the time came for Dragon and the ISS to part ways.
This procedure was initiated by the release of the snares holding the SSRMS Latching End Effector (LEE) to the Dragon Flight Releasable Grapple Fixture (FRGF) – effectively “letting go” of the Dragon.
MCC-H controllers first checked the lighting conditions were acceptable ahead of the 2:09 pm Eastern release.
With the SSRMS retracted safely clear of the spacecraft, Dragon conducted three departure burns to depart to vicinity of the ISS, edging away from the orbital outpost, with small thruster firings to push down the R-Bar.
This departure towards the edge of the ISS’ neighborhood was monitored by the COTS UHF Communication Unit (CUCU) Crew Command Panel (CCP), which was successfully checked out ahead of the departure events.
The third burn was the larger of the firings, which sent Dragon outside of the approach ellipsoid, at which point SpaceX controllers inside MCC-X at SpaceX’s Californian facility took full control of the mission.
Dragon enjoyed a free-flying phase on-orbit, during which time she completed a critical action – closure of the GNC bay door, to which the FRGF is mounted – before conducting the de-orbit burn, which was completed at around 7 pm Eastern.
The 10 minute deorbit burn was conducted by the spacecraft’s Draco thrusters.
The umbilical between Dragon and her Trunk then disengaged, prior to the Trunk separating from the Dragon capsule.
As the spacecraft moved into Entry Interface (EI), she was protected by the PICA-X heat shield – a Thermal Protection System (TPS) based on a proprietary variant of NASA’s phenolic impregnated carbon ablator (PICA) material, designed to protect the capsule during Earth atmospheric re-entry, and is even robust to protect Dragon from the high return velocities from Lunar and Martian destinations.
Once at the required velocity and altitude, Dragon’s drogue parachutes deployed, followed by Dragon’s main parachutes, easing the vehicle to a splashdown in the Pacific Ocean off the coast of California at around 7:44 pm Eastern.
Three main recovery boats soon arrived on station, with fast boats racing to meet the Dragon shortly after she hit the water, allowing for the recovery procedures to begin.
The vehicle was powered down and then hooked up to the recover assets.
Dragon is now being transported to the port of Los Angeles, prior to a trip to Texas for cargo removal.
Providing SpaceX had remained on track for the realigned Tuesday launch of its Falcon 9 v1.1 with the DSCOVR spacecraft, a fascinating scenario would have been on the cards.
DSCOVR was due to launch at 6:05 pm Eastern from Cape Canaveral’s SLC-40, with the core stage set to make a return to the Autonomous Spaceport Drone Ship (ASDS) off the Florida coast.
This return was to occur less than an hour before Dragon is making her re-entry plunge back towards a splashdown off the coast of California, marking the first time SpaceX has conducted three major operations – countdown/launch, core stage return and Dragon return – on the same day.
However, the launch was scrubbed due to red upper level winds. It was also noted earlier in the count that it was unlikely SpaceX would have proceeded with the ASDS landing, even if they had launched the mission, due to unacceptable conditions over the landing site in the Atlantic.
(Images: via L2’s SpaceX Special Section, which includes over 1,000 unreleased hi res images from Dragon’s flights to the ISS. Other images via NASA and SpaceX)
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