Two days after departing Space Launch Complex (SLC)-40 at Cape Canaveral Air Force Station, in a blazing light show, SpaceX has successfully delivered its fifth dedicated Dragon cargo mission (CRS-5) to the International Space Station (ISS). Capture of the spacecraft by Expedition 42 Commander Barry “Butch” Wilmore and Flight Engineer Samantha Cristoforetti took place at 5:54 a.m. EST Monday, 12 January, as Dragon and the station flew high above the Mediterranean, just to the southeast of Barcelona. The progress of this latest visitor to the ISS had gone so smoothly that the capture occurred a full 18 minutes ahead of schedule, prompting Capcom Randy Bresnik in the Mission Control Center (MCC) at the Johnson Space Center (JSC) in Houston, Texas, to jokingly advise Wilmore: “Not bad … for a Navy guy!” Exactly three hours after the initial grapple of the spacecraft, a perfect berthing at the Earth-facing (or “nadir”) port of the Harmony node was completed and Dragon is now a part of the ISS until 10 February.
Yesterday (Sunday), the Expedition 42 crew practiced extensively for the CRS-5 capture operation. “You can’t have too many #Dragons!” tweeted astronaut Catherine “Cady” Coleman. At about the same time, astronaut Doug Wheelock shared a list of key rendezvous milestones, detailing each of Dragon’s intricate final steps and ending with a targeted capture by the 57.7-foot-long (17.6-meter) Canadarm2 robotic arm at 6:12 a.m. EST Monday, just 26 minutes before local orbital sunset.
For the six-strong Expedition 42 crew—which consists of Commander Barry “Butch” Wilmore of NASA and Flight Engineers Aleksandr Samokutyayev, Yelena Serova, and Anton Shkaplerov of Russia, U.S. astronaut Terry Virts, and Italy’s first woman in space, Samantha Cristoforetti—Monday marked a busy start to a busy week aboard the ISS. The crew arose early, ate a quick breakfast, and began setting up their laptops and other equipment in the station’s multi-windowed cupola, which would afford them a panoramic view of the final stages of the rendezvous as it unfolded. Overseeing today’s capture and berthing were Wilmore and Cristoforetti, with Samokutyayev joining them in the cupola to provide photographic coverage of the rendezvous. “A #Dragon is coming!” tweeted Cristoforetti with excitement, adding an image of herself and Wilmore in appropriately labeled T-shirts. “#DontPanic and be ready to capture it! #ISSCargo.”
Overnight Sunday, the Dragon conducted a series of burns of its Draco thrusters to bring itself closer to the ISS, along the so-called “R-Bar” (or “Earth Radius Vector”), an imaginary line running from the center of Earth to the station. By thus approaching its quarry from “below,” Dragon took advantage of natural gravitational forces to brake its final approach and limit the need for additional burns. Similar R-Bar rendezvous profiles have been adopted since the shuttle-Mir era in the 1990s. A carefully orchestrated symphony of maneuvers brought the cargo ship to a “Hold Point” about 1.5 miles (2.4 km) from the ISS, whereupon it was required to pass a “Go/No-Go” poll of flight controllers before advancing closer.
Further polls and hold points were made at distances of 3,700 feet (1,130 meters) and 820 feet (250 meters). Moving at a steady, slowpoke pace of less than 3 inches (7.6 cm) per second, Dragon entered the Keep-Out Sphere (KOS)—a collision avoidance exclusion zone, extending 650 feet (200 meters) around the ISS—and slowed its rate of approach to just under 2 inches (5 cm) per second. At 4:20 a.m. EST, Terry Virts tweeted that Dragon was just 0.6 miles (1 km) from the station.
Shortly afterwards, at 4:40 a.m., Capcom Randy Bresnik in the Mission Control Center (MCC) at the Johnson Space Center (JSC) in Houston, Texas, advised Cristoforetti that Dragon had arrived at its milestone positions a few minutes ahead of schedule, allowing the crew to grapple the cargo ship about one minute after local orbital sunrise, and as much as 20 minutes before the originally planned 6:12 a.m. capture time. NASA commentator Rob Navias explained that the 6:12 a.m. time was by no means set in stone and was modified in real time, coming on the heels of a near-perfect two-day rendezvous regime. Indeed, by 4:57 a.m., the snub-nosed cargo ship—which consists of a pressurized segment and an unpressurized “Trunk”—had reached its next-to-last Hold Point at 90 feet (30 meters). By this stage, both Dragon and the ISS were flying high above the Tasman Sea.
In the meantime, NASA and SpaceX controllers were polled for their readiness to support a resumption of movement toward the 30 feet (10 meter) “capture point,” which would place the visiting vehicle within range of Canadarm2’s Latching End Effector (LEE). The mechanical arm is part of Canada’s contribution to the ISS and builds upon the heritage of the original “Canadarm,” the shuttle’s Remote Manipulator System (RMS), which supported dozens of missions and a wide range of construction, retrieval, deployment, and repair tasks from November 1981 until July 2011.
Today’s grapple of CRS-5 marked the 13th overall capture of a cargo ship by Canadarm2, which was installed aboard the ISS by the STS-100 shuttle crew, way back in April 2001. Since September 2009, the “Big Arm” has supported the capture and berthing of four H-II Transfer Vehicles (HTVs) on behalf of the Japan Aerospace Exploration Agency (JAXA), six Dragons—including the Commercial Orbital Transportation Services (COTS) Demo in May 2012 and the five dedicated CRS missions—and three Cygnus resupply ships for Orbital Sciences Corp. Adding its own blend of humor to today’s proceedings, the Canadian Space Agency (CSA) tweeted a correction to an earlier mis-tweet: “Did we say 30 mins? We meant less than 30 meters!”, before adding “That’s what happens when you tweet before your #maplecreamcookies!”
Inward motion toward the ISS resumed at 5:13 a.m., as Dragon pulsed its Draco thrusters to continue the final approach. In the minutes thereafter, Rob Navias noted that the anticipated grapple time had been revised to no sooner than 5:39 a.m. This was a full 33 minutes ahead of the original timeline, thereby also producing an earlier-than-intended berthing of the cargo ship at the Earth-facing (or “nadir”) port of the Harmony node. Cristoforetti reported that Dragon’s strobe lights had been commanded “Off,” thereby avoiding a distraction of Wilmore during the final capture phase. At 5:31 a.m., the extended Canadarm2 was within the 30 feet (10 meter) range of Dragon and the cargo ship was commanded into “Free Drift,” deactivating its Draco thrusters, ahead of capture. By this stage, the cargo ship and the ISS were flying high above Ann Arbor, Mich., heading in the direction of Detroit and onward toward southern Canada.
Orbital sunrise occurred at 5:40 a.m. and, at length, Randy Bresnik radioed the “Go for Capture.” He also advised the crew that they could expect “some ratty comm” between 5:44 and 5:49 a.m., then wished Wilmore good luck and closed with “We’re all counting on you!” As well as being fellow astronauts, Wilmore and Bresnik are former shuttle crewmates, having flown together aboard Atlantis on STS-129 in November 2009—the former as pilot, the latter as a mission specialist. The official time at which Canadarm2’s LEE seized Dragon was at 5:54 a.m., just a little over 49 hours since Saturday morning’s 4:47 a.m. liftoff from Cape Canaveral Air Force Station, Fla.
“Not bad for a Navy guy!” quipped Bresnik, honoring Wilmore’s military service. He apologized to the Expedition 42 crew for the belated arrival of their Christmas presents—which were originally meant to arrive in mid-December—and joked that they were aligned more closely with the Eastern Orthodox traditional date of Christ’s birth.
Over the following 2.5 hours, flight controllers—notably Robotics Officer John Bellingham—and the Expedition 42 crew worked to maneuver Dragon to its eventual berthing point at the Earth-facing (or “nadir”) port of the Harmony node. At 6:50 a.m., a little over 60 minutes after the grapple, Canadarm2 was repositioned to begin the movement. The tongue-in-cheek Canadian humor could not be kept at bay for too long, as its Big Arm performed its sterling work. “Inching closer,” CSA tweeted at 7:40 a.m., then added: “Oh right, we’re Canadian, we do metric. Centimetering closer, then.”
The Ready-to-Latch (RTL) process to attach Dragon to the ISS formally got underway shortly after 8:30 a.m., with an exchange between Wilmore and Capcom Josh Matthew. The physical berthing of the cargo ship occurred in two parts, with the astronauts overseeing “First Stage Capture” at 8:45 a.m., in which hooks from Harmony’s nadir Common Berthing Mechanism (CBM) extended and grabbed Dragon to pull their respective CBMs into contact. This was followed by “Second-Stage Capture,” in which a series of 16 bolts—four gangs of four bolts apiece—were driven to rigidize the two spacecraft in a tight, mechanized embrace. This was confirmed by NASA as having been successfully completed at 8:54 a.m., exactly three hours after the initial grapple by Canadarm2. Wilmore’s crew have now been given a “Go” to pressurize the vestibule leading from the Harmony nadir hatch into Dragon, which is bringing about 3,700 pounds (1,680 kg) of experiments, technology demonstrations, and supplies to the ISS. At present, the ingress into Dragon is planned for early Tuesday, but it seems likely that the crew will elect to enter the cargo ship later today.
So begins a four-week period of berthed operations, with the primary payload—NASA’s Cloud Aerosol Transport System (CATS)—expected to be removed from Dragon’s unpressurized Trunk, via Canadarm2, early Friday morning, and attached to the Exposed Facility (EF) of Japan’s Kibo laboratory. This instrument will spend between six months and three years measuring the location, composition, and distribution of pollution, dust, smokes, aerosols, and other particulates in the atmosphere, using Light Detection and Ranging (LIDAR). Operating at three wavelength bands, at 1,064, 532 and 355 nanometers, the data from CATS will be utilized to explore the properties of cloud and aerosol layers, as well as helping to develop and refine climate models and provide insights for future observations of Mars, Jupiter, and other planetary bodies.
Current plans call for Dragon to depart the ISS at 1:53 p.m. EST on 10 February for its return to Earth. Cristoforetti will assume primary control of Canadarm2 for next month’s unberthing operation, backed up by Terry Virts. Dragon is presently the only visiting vehicle capable of returning large quantities of payloads safely back to Earth; all other cargo craft—Russia’s Progress, Japan’s HTV, Europe’s Automated Transfer Vehicle (ATV), and Orbital Sciences’ Cygnus—are not designed to be recovered and are intentionally destroyed during re-entry. Dragon, on the other hand, returns to a parachute-assisted splashdown in the Pacific Ocean, off the coast of Baja California. The departure of CRS-5 will come just a few days before a salvo of three EVAs by Wilmore and Virts, which are scheduled to occur between 16 and 25 February to install Common Communications for Visiting Vehicles (C2V2) hardware and route cables and umbilicals for the arrival of the two International Docking Adapters (IDAs) later this year.
It has been a remarkable and eventful weekend. Launched at 4:47 a.m. EST Saturday, and captured in a stunning folio of imagery by the AmericaSpace team, the CRS-5 mission was the fifth dedicated flight under SpaceX’s $1.6 billion Commercial Resupply Services contract with NASA, signed back in December 2008. Under its language, the Hawthorne, Calif.-based launch services organization—headed by entrepreneur Elon Musk—must fly 12 dedicated mission by 2016 and deliver a total of 44,000 pounds (20,000 kg) of payloads, equipment, and supplies to the ISS. To date, SpaceX has lofted an average of two Dragons per year since 2012, including the inaugural Commercial Orbital Transportation Services (COTS) Demo Mission, but anticipates as many as four flights in 2015 to deliver a smorgasbord of payloads, including two International Docking Adapters (IDAs), the Cosmic Ray Energetics and Mass (CREAM) experiment, and the Bigelow Expandable Activity Module (BEAM).
Although the delivery of Dragon formed the primary objective of Saturday’s blazing launch, another key goal was to perform the first landing attempt of Falcon 9 v1.1 hardware on an ocean-going barge. As described in a recent AmericaSpace article, it was hoped that after its portion of the ascent had been completed, the vehicle’s first stage would execute a trio of engine firings to bring itself back through the “sensible” atmosphere and—assisted by a combination of landing legs and extendible hypersonic “grid fins”—to perform a soft touchdown on the deck of the 288 x 100-foot (87.8 x 30.5-meter) Autonomous Spaceport Drone Ship (ASDS) in the Atlantic Ocean.
This audacious test was given only a 50-50 chance of success by SpaceX officials, although some of its core capabilities drew extensively on a heritage of Grasshopper and Falcon 9 Reusable Development Vehicle (F9R Dev) test flights between 2012 and 2014. Moreover, for the first test on Saturday morning, the landing would be conducted entirely in the hours of darkness, with local sunrise not expected until 7:16 a.m. Although the ASDS was brightly lit, the dark and foggy conditions prevented the acquisition of good landing/impact video and added another element of complexity to an already difficult endeavor. As circumstances transpired, the first stage apparently performed its trio of engine burns without incident—an initial “boost-back” burn to adjust its targeted impact point, then a “supersonic retro-propulsion” burn to slow it to about 560 mph (900 km/h) and a final “landing” burn to bring this velocity down to just 4.5 mph (7.2 km/h)—and subsequently deployed its four lattice-like hypersonic grid fins. Laid out in an “X-wing” configuration, the fins served to control the stage’s lift vector and, together with engine gimbals, were designed to enable a precise touchdown on the ASDS.
Early indications suggested that the landing attempt was not entirely successful, though far from a “failure,” as discussed by AmericaSpace’s Ken Kremer in a recent BBC Radio 5 Live interview. Tweeted remarks from Elon Musk noted that the first stage “made it to the drone spaceport ship, but landed hard,” adding that the test “bodes well for the future,” but that there was “no cigar this time.” He stressed that the grid fins “worked extremely well from hypersonic velocity to subsonic, but ran out of hydraulic fluid right before landing,” with a 50 percent greater quantity of fluid to be carried for future attempts. However, Mr. Musk explained that the ASDS survived the impact, a fact reinforced by other SpaceX sources. It was pictured, looking rather scorched and blackened, with some damage to equipment on deck, returning to the Port of Jacksonville on Sunday, 11 January. This damage was presumably caused by the explosion of the first stage during impact.
Towing the barge back to land was the 82-feet-long (25-meter) Elsbeth III tug, which was recorded as having arrived in Port of Jacksonville at 12:10 p.m. EST Sunday. The next reported destination for the Elsbeth III is Oakland, Calif., although AmericaSpace understands that the ASDS itself will remain stationed in Port of Jacksonville for the foreseeable future. The Elsbeth III’s arrival came a few hours after the 6:26 a.m. return of the 164-feet-long (50-meter) Go Quest communications and tracking vessel. Large elements of tarpaulin covered what appeared to be fragments of Falcon 9 v1.1 hardware on the ASDS deck, and AmericaSpace has been told that it is likely that this particular first stage will not be reusable, even with repair. Having said this, SpaceX teams are reportedly confident that they can effect repairs to the ASDS and return it to normal operations within the next three weeks. Certainly, it was reported in July 2014 that both CRS-5 (Falcon Flight 14) and the launch of NASA’s Deep Space Climate Observatory (DSCOVR)—currently scheduled to fly on 29 January as the 15th Falcon 9 mission—will make ASDS landing attempts.
This article will be updated immediately after berthing.
Missions » ISS » COTS » CRS-5 » Missions » ISS »