First Reusable Dragon Cargo Mission Launches Science and Supplies to Space Station

The CRS-11 Falcon 9 first stage returns to Earth, making a successful landing back at Cape Canaveral AFS after launching Dragon to the ISS minutes earlier from KSC pad 39A. Photo Credit: NASA TV

If candles celebrate an anniversary, then the roar of Merlin 1D+ rocket engines honored the 100th launch from Pad 39A at the Kennedy Space Center (KSC) in Florida, earlier today (Saturday, 3 June). SpaceX’s Upgraded Falcon 9 booster roared aloft from the historic complex at 5:07 p.m. EDT, precisely on the cusp of an “instantaneous” launch window. The launch occurred on the second attempt, following a scrub less than a half-hour before Thursday’s planned attempt, due to lightning in the KSC area.

Less than eight minutes after leaving the pad—which has supported 82 Space Shuttle launches, including the first and last missions in the 30-year program, as well as the first flight to assemble the International Space Station—three more historic events transpired: the injection of the ISS-bound CRS-11 Dragon cargo ship into low-Earth orbit, the first reflight of a “used” Dragon and the pinpoint touchdown of the Upgraded Falcon 9’s first stage on Landing Zone (LZ)-1, approximately nine miles (15 km) away from Pad 39A.

Falcon 9 coming in to land. Photo Credit: John Studwell / AmericaSpace

Pad 39A has seen use over the last five decades for many of the grandest adventures ever undertaken by humans in space. First utilized for the maiden launch of the Saturn V in November 1967, it went on to serve as the staging-point for the first manned voyage to lunar orbit in December 1968 and the triumphant planting of U.S. boots on the Moon in July 1969. All told, the pad hosted 12 Apollo-era missions, bookended by the launch of America’s Skylab space station in May 1973, after which it was extensively modified for the Space Shuttle program. Between April 1981 and July 2011, it supported the maiden launches of shuttles Columbia, Challenger, Discovery and Atlantis.

Following the retirement of the shuttle fleet, NASA handed Pad 39A over to SpaceX on a 20-year lease in April 2014 for Falcon 9 operations. Between February 2017 and tonight’s mission, the Hawthorne, Calif.-headquartered launch services organization—headed by entrepreneur Elon Musk—has staged six flights from the historic complex. These have delivered two Commercial Resupply Services (CRS) Dragon missions to the ISS, together with three powerful communications satellites to Geostationary Transfer Orbit (GTO) and the top-secret NROL-76 payload for the National Reconnaissance Office.

Having already pioneered the reusability of its Upgraded Falcon 9—one of whose recovered first stages was successfully launched a second time on 30 March 2017—tonight’s mission marked the first-ever reflight of a Dragon. The CRS-11 pressurized cargo module had previously launched on the ISS-bound CRS-4 flight, back in September 2014, splashing down in the Pacific Ocean five weeks later and receiving extensive modification in support of another voyage. Under the terms of the original $1.9 billion Commercial Orbital Transportation Services (COTS) agreement with NASA, signed in December 2008, SpaceX was required to launch a “new” Dragon on each of its 12 contracted cargo supply missions to the space station. Kicking off with a Demonstration flight in May 2012, the first dedicated mission occurred the following October and SpaceX has since flown an average of two Dragons per annum to successive ISS crews.

In January 2016, NASA selected its current CRS partners SpaceX and Orbital ATK, together with Sierra Nevada Corp., to fulfil a follow-on CRS-2 series of resupply missions from 2019 through the anticipated end of ISS operations in December 2024. Last fall, Space News highlighted that reusing previously flown hardware would allow SpaceX to close down its first-generation Cargo Dragon production line and bring the next-generation Dragon-2 (or Crew Dragon) spacecraft to operational readiness.

All told, 5,970 pounds (2,708 kg) of payloads and supplies are riding to orbit aboard Dragon for CRS-11. Almost half of this amount comprises scientific experiment hardware for Expedition 52, together with smaller quantities of crew supplies, vehicle hardware, spacewalking gear and computer resources. Major research payloads include the Roll-Out Solar Array (ROSA), the Neutron Star Interior Composition Explorer (NICER) and the Multiple User System for Earth Sensing (MUSES).

Last Sunday, as is customary before each mission, the 230-foot-tall (70-meter) Upgraded Falcon 9 underwent a Static Fire Test of the nine Merlin 1D+ first-stage engines, which raised a thunderous roar, a cloud of smoke and a yield of 1.5 million pounds (680,000 kg) of thrust. The booster was then returned to a horizontal configuration and returned to the nearby integration facility, where the CRS-11 Dragon cargo ship was installed, preparatory to an opening launch attempt on Thursday, 1 June.

The weather outlook was predicted to be marginal, with a 70-percent likelihood of acceptable conditions at T-0. “Moisture has begun to build in aloft today, signaling the start of Central Florida’s convective season,” noted the 45th Weather Squadron at Patrick Air Force Base in its L-2 briefing on Tuesday morning. “The storms will be guided by the orientation of the Bermuda Ridge axis, which is forecast to gradually shift north of the Spaceport over the next few days.” It was expected that the Bermuda Ridge axis would steer most inland storms away from KSC by Thursday, although upper-level winds were predicted to bring anvil clouds eastwards, creating a potential violation of the Cumulus Cloud Rule and Anvil Cloud Rule.

Falcon 9 soars with Dragon CRS-11 for the ISS. The booster landed a few miles south of KSC pad 39A just a few minutes later. Photo Credit: John Studwell / AmericaSpace

It was reported that a scrub on Thursday would lead to a 48-hour turnaround and a second launch attempt on Saturday evening, where the risk level increased to a 60-percent likelihood of acceptable conditions, with concerns centering on the presence of anvil and cumulus clouds, together with a chance of violating the Flight Through Precipitation Rule. This was expected to deteriorate to just 50-percent favorable in the event of a delay to Sunday, 4 June.

Marching towards its opening CRS-11 launch attempt on Thursday evening, the loading of propellants aboard the Upgraded Falcon 9 got underway about an hour before T-0, with a highly refined form of rocket-grade kerosene (known as “RP-1”). “Vapor plumes can be seen streaming from the rocket as it stands on the launch pad,” noted AmericaSpace’s Launch Tracker at 4:52 p.m. EDT. “This is confirmation that the fueling processes are underway and that the RP-1 propellant is being pumped into the on-board tanks.” Since last September’s on-the-pad explosion of the Amos-6 mission, the booster has been put through a slightly longer fueling regime. Forty-five minutes before the opening of the launch window, at 5:10 p.m., liquid oxygen began flowing aboard the rocket.

Dragon CRS-11 awaits launch atop 39A. Photo Credit: SpaceX

At this stage, however, overcast skies and rumbling thunder in the area meant the weather outlook remained “Red” (“No-Go”) for launch. At 5:27 p.m., SpaceX tweeted that it was tracking a pair of weather fronts in the vicinity of the Spaceport. However, Thursday would not be SpaceX’s day and by 5:30 p.m. the presence of lightning led to a decision to scrub the launch. “The rules for a lightning strike within ten miles of the launch pad require a 30-minute period with no lightning before a launch can take place,” noted AmericaSpace’s Launch Tracker. “With just 25 minutes left in the window, an automatic scrub was called.”

Efforts were immediately set in motion for a 48-hour turnaround. Heading into Saturday, the weather exhibited a marked deterioration, hovering at only 60-percent favorable under a backdrop of iron-gray skies at KSC. By 3:55 p.m. EDT, loading of RP-1 was underway, quickly followed by the onset of liquid oxygen fueling at 4:22 p.m. EDT. As the countdown entered into its final half-hour before T-0, the Eastern Range declared its readiness to support both the launch and the touchdown of the Upgraded Falcon 9’s first stage on LZ-1. In tandem, weather conditions had steadily improved to 90-percent favorable.

Passing T-10 minutes, the terminal countdown autosequencer was initiated and the nine Merlin 1D+ engines of the first stage, configured in a circle of eight, with a ninth at the center, were chilled-down, ahead of the ignition sequence. At T-2 minutes, the Air Force Range Safety Officer declared all ground assets as “Go for Launch” and the Upgraded Falcon 9 transitioned to Internal Power and assumed primary command of all critical functions, going into “Startup” at T-1 minute. At this stage, the Niagara deluge system began flooding the pad surface with 30,000 gallons (113,500 liters) of water, per minute, to suppress the acoustic energy. The Eastern Range declared its readiness as “Green”.

Three seconds before liftoff, the Merlins roared to life, pumping out a combined thrust of 1.5 million pounds (680,000 kg) of thrust. Liftoff occurred on-time at 5:07 p.m. EDT, a little over two hours shy of sunset. It was SpaceX’s 12th cargo delivery run to the ISS, counting the COTS Demonstration mission in May 2012 and eleven “dedicated” CRS flights between October 2012 and April 2017. However, CRS-11 was actually the 11th ISS-bound Dragon to actually achieve low-Earth orbit, following the high-altitude breakup of a Falcon 9 v1.1 booster and the loss of the CRS-9 payload in June 2015.

Immediately after clearing the tower, the Upgraded Falcon 9 executed a combined pitch, roll and yaw program maneuver to establish itself onto the proper flight azimuth to inject the CRS-11 Dragon into orbit at an inclination of 51.66 degrees to the equator. Passing the point of maximum aerodynamic turbulence (colloquially dubbed “Max Q”) at 70 seconds into the flight, the booster later throttled back two of the Merlins to reduce the rate of acceleration at Main Engine Cutoff (MECO). Two and a half minutes after launch, the seven remaining Merlins fell silent and the first stage separated from the stack.

Photo Credit: Ben Cooper / SpaceX

It was now the turn of the second stage, equipped with a single, restartable Merlin 1D+ Vacuum engine, capable of 210,000 pounds (92,250 kg). This now picked up the baton to deliver its payload into low-Earth orbit. During its burn, the protective nose fairing—covering Dragon’s berthing mechanism—was jettisoned and the spacecraft separated from the second stage a little under ten minutes after launch. Shortly thereafter, its pair of power-generating solar arrays were deployed. By 2.5 hours into the flight, Dragon’s Guidance and Navigation Control (GNC) Bay Door was opened to expose critical rendezvous sensors, ahead of the three-day journey to the ISS.

As with its predecessors, CRS-11 will approach the space station along the “R-Bar” (or “Earth Radius Vector”), which provides an imaginary line from Earth’s center, effectively approaching from “below”. In so doing, Dragon will take advantage of natural gravitational forces to brake its final approach and reduce the need to perform excessive numbers of thruster firings. By Tuesday morning, it will reach a “Hold Point” about 1.5 miles (2.4 km) from the station, whereupon it must pass a “Go/No-Go” poll of flight controllers in order to draw nearer.

The CRS-11 Falcon 9 on final, about a second from achieving another successful landing at Cape Canaveral AFS. Photo Credit: John Studwell / AmericaSpace

Further polls and holds will be made at distances of 3,700 feet (1,130 meters) and 820 feet (250 meters), after which Dragon will creep toward its target at less than 3 inches (7.6 cm) per second. Critically, at 650 feet (200 meters), it will enter the “Keep-Out Sphere” (KOS), which provides a collision avoidance exclusion zone, and its rate of closure will be slowed yet further to just under 2 inches (5 cm) per second. After clearance has been granted for the robotic visitor to advance to the 30-foot (10-meter) “Capture Point”, the final stage of the rendezvous will get underway, bringing Dragon within range of the station’s 57.7-foot-long (17.6-meter) Canadarm2 and capture by Expedition 52 Flight Engineer Jack Fischer, backed-up by Commander Peggy Whitson. Both crew members will be based in the multi-windowed cupola for the operation. This is Whitson’s second Dragon capture, following her role in the CRS-10 rendezvous and berthing in April 2017.

The Robotics Officer (ROBO) in the Mission Control Center (MCC) at the Johnson Space Center (JSC) in Houston, Texas, will then command the physical berthing of the cargo ship to the Earth-facing (or “nadir”) Common Berthing Mechanism (CBM) of the Harmony node. Berthing will occur in two stages, with the crew overseeing “First Stage Capture”, in which hooks from the node’s nadir CBM will extend to snare the cargo ship and pull their respective CBMs into a tight mechanized embrace. “Second Stage Capture” will then rigidize the two connected vehicles, by driving 16 bolts, effectively establishing Dragon as part of the ISS for the next month. Shortly afterwards, the Expedition 52 crew will be given a “Go” to pressurize the vestibule leading from the Harmony nadir hatch into the cargo ship.

Although the primary focus of today’s launch was to deliver the CRS-11 Dragon into orbit, the discarded first stage was assigned the secondary objective of returning to a soft landing on the LZ-1 pad at Cape Canaveral Air Force Station. SpaceX’s record of bringing its Falcon hardware back through the “sensible” atmosphere has evolved considerably over the last three years. The provision of landing legs and hypersonic grid fins on the Falcon 9 v1.1 allowed for four “controlled oceanic touchdowns” of first stages in April, July and September 2014, followed by four mixed-success attempts to physically land on the deck of the Autonomous Spaceport Drone Ship (ASDS) in the Atlantic Ocean.

Only on the maiden flight of the Upgraded Falcon 9 in December 2015 was a perfect controlled touchdown achieved; a success sweetened yet further by the fact that it did so on solid ground, at LZ-1. Since then, with the exception of three ASDS landing failures in January, March and June 2016, six returning Falcon first stages have touched down perfectly on the drone ship—the most recent instance being 30 March’s SES-10 mission—and another three have alighted on LZ-1.

Less than three minutes after leaving Pad 39A, the Upgraded Falcon 9’s first stage executed the first “burn” of its Merlin 1D+ engines—the so-called “Boost-Back”—which adjusted the impact point, pushing it upward and directly it towards LZ-1. Assisted by on-board nitrogen-fed thrusters, the first stage “flipped” over and performed Entry and Landing burns to incrementally slow it down, initially to about 560 mph (900 km/h) and eventually a touchdown velocity of 4.5 mph (7.2 km/h). Controlling the first stage’s lift vector were four lattice-like hypersonic grid fins, configured in an “X-wing” layout, and the Falcon touched down perfectly on LZ-1, less than eight minutes after departing Pad 39A.

In the meantime, heading up to the ISS are three key external research payloads for Expedition 52. These will be installed onto the station by 57.7-foot-long (17.6-meter) Canadarm2 mechanical arm—ground-commanded by ROBO—over the course of the next three weeks. Assuming an on-time rendezvous and berthing on Tuesday, checkout of the 672-pound (305 kg) Multiple User System for Earth Sensing (MUSES) will get underway almost immediately, with the Mobile Transporter (MT) translating to Worksite-6 on the Integrated Truss Structure (ITS) to perform an initial survey of Dragon’s trunk. On Thursday, MUSES will be extracted from the trunk and “temp-stowed” on the Enhanced Orbital Replacement Unit (ORU) Temporary Platform (EOTP) on Canadarm2’s Dextre robotic “hand”. It will then be relocated on Wednesday to its permanent location on ExPRESS Logistics Carrier (ELC)-4 on the Earth-facing (or “nadir”) side of the S-3 truss segment. MUSES will monitor stratospheric aerosols and lightning and conduct high-resolution Earth imaging.

Kicking off Saturday, 10 June, will be the installation of the 820-pound (372 kg) Neutron Star Interior Composition Explorer (NICER), which will conduct X-ray spectrometry of emissions from distant neutron stars. It will be extracted from Dragon’s trunk on Friday, temp-stowed on Dextre’s EOTP and finally installed on the space-facing (or “zenith”) side of the S-3 truss for deployment and range-of-motion testing next weekend.

Finally, the 716-pound (325 kg) Roll-Out Solar Array (ROSA) is intended as a technology demonstration of more compact power-producing solar arrays than the current rigid-panel designs. Unlike MUSES and NICER, this experiment is not intended for permanent installation onto the space station, but will remain grappled by Dextre. It is expected to be robotically extracted from Dragon’s trunk on 16 June, and will be deployed for a week of tests. It will then be re-inserted back into the trunk on on 24 June, with the CRS-11 spacecraft currently scheduled to unberth and depart the ISS on 4 July. The trunk and ROSA will be destroyed during re-entry, whilst the pressurized cargo module will perform a parachute-assisted splashdown in the Pacific Ocean.



    Be sure to “LIKE” AmericaSpace on Facebook and follow us on Instagram Twitter!


Missions » ISS » COTS » CRS-11 »


  1. I’m old enough to remember when “experts” on here and elsewhere were complaining about hover-slam and landing legs. Amazing progress in just a few short years. And to top it off another SpaceX first, how many more can they fit in one year? Great time to follow space.

  2. I certainly didn’t see the hover-slam working without any margins. I was also skeptical about the barge landings. It has reached the point here I am concerned about too many people waiting on SpaceX to solve problems like they used to wait on NASA to solve them. It’s about time for the competition to start stepping up. The talent and resources are there, maybe it’s just been waiting on the stimulus of a real game changer.

    I’m still Missouri on the F9H, but then with no skin in the game I can afford to be.

    • Well it is SpaceX and Blue in that horse race. Almost everyone else is by gimped design, which is sad. Masten has the talent and vision but not the resources. Blue is a nice gut check for SpaceX. FH center and side core already static fired, one more side core to go but the real hang up is getting LC40 back online to free up the downtime on 39A to do the FH work. The fall SpaceX announcement will put things in perspective visa vi Blue. Expecting a large (not ITS large) fully RLV Raptor system to provide both commercial lift and Mars pathfinder. This is according to the rumors flying around.

  3. John and Chris,
    Is Musk really a genius …Or is everybody else just really really corrupt? There is other technology out there that hasn’t been used. Why have we NOT heard anything about the X-33 SSTO to orbit? Oh wait here it is…

    “In December 2016, a $3.4 million contract from a private company was signed for the Haas 2CA launcher. The team decided to incorporate new technologies, like the pressure-fed, multi-chamber, linear aerospike engine, and the use of the hydrogen peroxide and kerosene combination into the Haas 2CA SSTO.”

    I am thinking that Arcaspace bought the areospike engine from none other than Lockheed Martin that came out of the X-33 development. This was the demo craft for the Shuttle replacement Venture Star…20 tons to orbit for $20M with 2 week turnaround.

    • X-33 SSTO numbers never closed. It continued on for a while, like a lot of government programs, despite no chance of ever working. Not sure why you are in so much love with X-33/VentureStar when there are plenty of two stage RLV systems that make sense. You are stuck in the 90s…although that is better than NASA, they are stuck in the 70s.

      • Chris,
        The Haas 2CA is completely reusable as a SSTO. Does this NOT prove the concept. Complete the carbon fiber manufacturing, put landing legs on it, scale its size and then… don’t we have a version 2 SSTO?

        • There is a massive difference between claims and reality, especially from a company with no successful track record. I have seen dozens or possibly hundreds of claims by organizations that they are going to do such and so, only to see them fold before flying a single article. I would give odds that the Haas 2CA never flies, and higher odds that it never reaches SSTO even without a payload.

          It is also easily possible to powerpoint an aerospike engine without buying the rights from anybody. BTW, an aerospike is just a nozzle arrangement that is not particularly difficult to draw. It remains to be seen if they can solve the known problems of weight and thermal management on a test stand.

          • But John hasn’t SpaceX proven the return and the reuse of the booster…making it easier for everybody else? And I thought Lockheed perfected the Areospike engine in 1990 ..and then put it on the shelf not sharing it with anyone until such a day that some SOB would build a reusable booster system … That being now!

            • SpaceX has returned a first stage from a fraction of orbital velocity.
              Lockheed demonstrated a test stand aerospike, which is a far different thing from an operational engine, and even farther from perfecting the technology

              • John,
                Ok then is the real return test then what they do with the 2nd stage? which I think musk said he would try during the F9H demo?

                    • Less flippant. A 100 ton hydrogen RLV has 2 tons of engine, 300 cubic meters of tankage, over a ton of TPS, and shrouds or equivalent before there is any payload at all. Without payload, a rocket is just a really expensive toy.

                    • John and Chris,
                      You are crushing my dreams…Of the return of the VentureStar!

                    • Your dreams may still is still alive. Start a colony on the Moon or Mars, then your SSTO dreams are a lot more viable.

  4. Now if we could just get Musk to work on internal security …I think he would have a way to stop attacks on everyday citizens…Maybe his AI company could handle this?

  5. It’s not about proving the concept or not. It’s a dumb idea because the physics is working against you. A carbon fiber 2 stage RLV will have much much higher payload mass fraction. So an arbitrary structures improvement just makes the 2 stage system better too. Before SSTO makes any sense there needs to be a much bigger jump in either structures and/or propulsion where the payload fraction simply doesn’t matter anymore. That is a wish but not reality.

    • Chris,
      If with a fully reusable SSTO like the Haas 2CA and by getting the weight down I am thinking 1000 lbs. to LEO for $100,000 price point or less. That’s $100 lb.! Wouldn’t there be demand for this all day? With advances from coming, we could see massive structures being built soon.

      • Why not $50,000 for $50 a pound while we are making things up? Their own marketing is 10x that price for 100kg . Even if they make those numbers (which is tricky) that is to LEO for small payloads which is a market but niche albeit growing. I’m not against people banging their heads on the wall to see if something shakes loose, but this system won’t scale. And I don’t see anything about reuse here.

  6. Chris,
    Go to the Arcaspace website the Hass 2CA will use a parachute. Yes I see the current price but …competition in this market niche will drive costs down dramatically.. As the Electron Rocket is at this level also and several others

  7. SpaceX tried recovery via parachute early on. It didn’t work out, even for the first stage. For an SSTO, it’s going to be even harder due to the increased speed of reentry. Good luck to them, but I don’t put too much faith in their recovery efforts.

‘Just Do It…Again’: 10 Years Since STS-117 Changed the Face of the Space Station (Part 1)

‘Knight in Shining Armor’: 10 Years Since STS-117 Changed the Face of the Space Station (Part 2)