Success in Orbit as Dragon Cargo Ship Arrives at ISS

Similar to this view from the CRS-1 capture in October 2012, today's grapple and berthing of a Dragon cargo craft will kick off a three-week period of unpacking equipment and supplies. Photo Credit: NASA
Similar to this view from the CRS-1 capture in October 2012, today’s grapple and berthing of a Dragon cargo craft will kick off a three-week period of unpacking equipment and supplies. Photo Credit: NASA

Less than two days since its impressive launch, and only 24 hours later than planned, SpaceX’s remarkable Dragon cargo ship has been successfully captured and berthed to the International Space Station. The snub-nosed craft was seized by the station’s Canadarm2 robotic arm—deftly manipulated by Expedition 34 Commander Kevin Ford—at 5:31 a.m. EST, about half an hour earlier than the time published by NASA yesterday afternoon. The final approach of Dragon ran smoothly and with perfection, and at the time that this article was being prepared the ISS crew had been given a “Go” to pressurize the vestibule between the craft and the Harmony node, ahead of opening the hatches tomorrow.

This mission—the third Dragon to visit the multi-national outpost and the second under SpaceX’s $1.6 billion Commercial Resupply Services (CRS) contract with NASA—had much to prove when it roared into space atop a Falcon 9 booster at 10:10:13 a.m. EST, Friday. The CRS-1 mission, last October, experienced an engine-out anomaly which doomed a small Orbcomm piggyback satellite, but Friday’s CRS-2 launch suffered no such problems … at least, that is, until Dragon separated in orbit. At that point, only one of the ship’s four Draco maneuvering thruster pods was fully operational, a situation which could have potentially ruined the mission, for at least three are required to be in working order for the ISS Program to approve a rendezvous and docking with the space station.

Stunning view of the CRS-2 Dragon launch from Cape Canaveral Air Force Station, Fla., on Friday 1 March. Photo Credit: John Studwell
Stunning view of the CRS-2 Dragon launch from Cape Canaveral Air Force Station, Fla., on Friday, 1 March. Photo Credit: John Studwell

The cause was traced to a blockage in a propellant pressurization line, which threw out-of-sync a number of other pre-programmed tasks, including the deployment of Dragon’s electricity-generating solar arrays. As noted by the website, Dragon’s initial problems were triggered when the fuel tanks pressurized correctly, but only one oxidiser tank showed its nominal pressure response. The solar arrays were unfurled, nevertheless, and engineers eventually “jack-hammered” the helium isolation system valves by commanding them to cycle on and off several times in succession. At length, this succeeded in clearing the blockage. Dragon’s scheduled arrival at the ISS on 2 March was called off as troubleshooting efforts got underway, but within a matter of hours the other three Draco pods were restored, a critical orbit-adjustment maneuver was satisfactorily performed, and SpaceX CEO Elon Musk tweeted Friday night that Dragon was “back on track.” Yesterday, the two space vehicles drew ever closer, and Expedition 34 crewman Chris Hadfield remarked at one stage that the cargo ship was about 1,770 miles “ahead” of them.

Also on Saturday, NASA announced that the berthing time had been updated to 6:01 a.m. EST. To accomplish the capture and berthing of the cargo ship at the nadir-facing Harmony node, the three U.S. Operating Segment (USOS) crewmen—Ford, Hadfield, and NASA astronaut Tom Marshburn—ate breakfast and set up their laptops and other equipment in the multi-windowed cupola, which would afford them an expansive, panoramic view of the events to follow. Shortly after 2 a.m. Sunday, Ford reported his first visual sighting of Dragon as a star-like blob against the black sky—a star which grew steadily brighter and more pronounced as the time passed.

By 3:40 a.m., the ship had arrived at a position known as the “R-Bar,” or “Earth Radius Vector,” whereby it completed the final stages of its rendezvous with the ISS. Effectively rising to meet its target from “below,” Dragon took advantage of natural gravitational forces to brake its approach and limit the need for thruster firings. Similar R-Bar profiles have been adopted since the Shuttle-Mir era in the mid-1990s. A carefully orchestrated symphony of maneuvers brought the cargo craft to a “Hold Point” about 1.5 miles from the space station, where it passed a “Go/No Go” poll to proceed. Further polls and holds were made at distances of 3,700 feet and 820 feet, with the latter “Hold Point” being reached at 3:55 a.m., as both vehicles flew high above the Black Sea. Ten minutes later, Dragon continued its approach, keeping to the R-Bar path and creeping toward the ISS at a steady, slowpoke pace of less than three inches per second. By 4:20 a.m., it had entered the so-called “Keep Out Sphere”—a collision-avoidance exclusion zone, extending to 650 feet around the ISS—and by the time it reached a distance of 300 feet its rate of closure had slowed to a little under two inches per second.

Today's effort to capture and berth the CRS-2 Dragon craft was conducted from within the multi-windowed cupola. Here, Chris Hadfield gazes wistfully outside during work with Canadarm2. Photo Credit: NASA
Today’s effort to capture and berth the CRS-2 Dragon craft was conducted from within the multi-windowed cupola. Here, Chris Hadfield gazes wistfully outside during work with Canadarm2. Photo Credit: NASA

The minutes passed. At 5 a.m., watched by the ISS crew and an anxious Mission Control Center in Houston, Texas, the cargo ship had reached its next-to-last “Hold Point” at 100 feet, where SpaceX controllers verified good navigational data and the polling of relevant personnel began. Five minutes later, Dragon was cleared to approach to the 30-foot “Capture Point,” within range of the Canadarm2, and proceeded to hold its position. At 5:25 a.m., Capcom Kate Rubins radioed Commander Kevin Ford with a “Go for Capture.” The official time at which the Canadarm2’s Latching End Effector grappled the craft was 5:31 a.m EST., a little over 43 hours after launch. In an intricate operation which lasted several hours and was punctuated by lunch and the need to exercise, Ford and Marshburn maneuvered Dragon toward its berth on the Harmony node, with Hadfield in charge of driving the capture latches into position. Official “berthing” of the cargo ship occurred at 8:56 a.m. EST, and the crew was given a “Go” to pressurize the vestibule an hour later. With this remarkable revival of fortunes, it is confidently expected that the CRS-2 mission will remain docked for three weeks, pending a scheduled departure and return to Earth on 25 March.

Ahead for the crew is the physical unpacking of Dragon, which should begin tomorrow. For Kevin Ford, Oleg Novitsky, and Yevgeni Tarelkin—the first half of the Expedition 34 team, launched last October—today’s berthing makes them the first crew to welcome two Dragons to the station during their residency. They were also aboard at the time of the CRS-1 mission. A little more than half of CRS-2’s load is devoted to ongoing scientific research aboard the space station and includes a pair of GLACIER experiment refrigerators, a spare electronics unit for a MELFI freezer, a carbon dioxide removal assembly, and general crew provisions. Mounted on the unpressurized Trunk are two Heat Rejection Subsystem Grapple Fixtures (HRSGFs), which will be installed on the station’s truss during an EVA by astronauts Chris Cassidy and Luca Parmitano in July.


  1. Does anyone think that this was the result of sabatoge….The Malfunctions that is…

  2. Tracy, why do you suspect sabotage? In complex machinery a malfunction may occur at any time for any number of reasons.

    At least Dragon can be examined for any form of sabotage on return to Earth.

  3. SpaceX business model has been stated by MUSK to be be based on its successful implementation of a completely reuseable space craft that if realized will drastically push the cost of space launch and travel down making it more difficult for competitors to keep up…So Any delay in keeping that from happening translates into future income from existing launch providers…

    • You’re right. Worse, SpaceX has yet to recover a Falcon 9 first stage. The reason is that SpaceX has the wrong parachute.

      The story goes that when SpaceX was designing the Falcon 9 first stage and went parachute shopping, it picked the same chute as one of the three mains being used on Orion. The problem is that the velocity profiles at the point of chute deployment of the two craft are very different. When the Falcon 9 first-stage chute is deployed, it doesn’t survive for the most part. That is the same fate suffered by the Falcon 9 first-stage.

      While it’s just a guess, I think the reason SpaceX wants the Falcon 9 first-stage to have a powered landing is that the company may be thinking that the mass penalty is less than it would be for a series of chutes that would allow a recoverable, and reusable, first-stage. But Tracy, you have brought-up an interesting issue and one we here should investigate.

  4. Jim,
    Wouldn’t powered decent be more controllable than a parachute? And wouldn’t it be quicker as well? As I understand it ….SpaceX MUST create a fully reusable rocket or they do NOT survive…As musk has said all along he is going to MARS and he MUST have a reusable system to do that…if not he can just sell the company…On another note I also think that once this contract is over with the ISS he will not renew….To much BS at NASA to deal with…

    • Tracy,

      You’re correct, a powered is much more controllable than using parachutes. But it is also a very technically challenging option. Returning to KSC (a populated area) from over 20 miles altitude and a who knows (I can’t find the data) how many miles downrange has never been done by anyone. A vertical landing means that the first-stage needs its own redundant GNC, extra fuel with margins, landing structure, likely strengthened first-stage structure, and who knows what else. The mass-penalty on payload–one additional pound on the first-stage means a loss of 5 pounds of payload in orbit–will not be insignificant for a rocket that only launches 10.45 mt to 28 degrees LEO. Just 1 mt (2,204 lbs) of additional mass on the first-stage means that the Falcon 9’s payload drops to 5.45 mt.

      Parachutes may not allow for the precision of a powered-landing, but they are simple. No GNC, no new structural mods to the already parachute returning Falcon 9 first-stage, no reserve fuel.

      The CRS contract may involve working with NASA BS, but it also means $1.5B, money that SpaceX needs to survive. And ISS won’t be around significantly beyond 2020, so I’m unsure what SpaceX will do after that for a paying customer.

  5. Agreed the life cycle of SpaceX I believe will end if the have not perfected a totally reuseable craft by 2020. I just think that up to this point he is BUYING market share with his current program and does not make a profit per launch or a sustainable one. Furthermore at the end of the day ….I don’t see NASA ever agreeing to put astronauts on this reusable system… Unless it just happens that every launch SpaceX does for NASA they are using a brand new vehicle and will use the reuse for cargo…As for the calcualtions… Musk has already stated that he will lose 40% lift capability on the reusable system to account for retained fuel and increased weight of the propulsed landing system because he can lower price by a factor of 2 assuming he gets 1000 launches per hardware….A $60,000,000.00 mission would then cost $600,000 Even if he only lowered the cost by a factor of 1 that is 6,000,000 at 60% of the weight of the expendable system…As for the risk to the populated areas….I see him moving the launches …out of the US juridication….To much Gov BS…time will tell

  6. The Dragon problem encountered recently by SpaceX will strangely increase their kudos with Nasa and other customers. They did not panic, they “worked out” the problem.
    Interestingly as this drama was resolved I’m sure purely by coincidence Russia announced their “Soyuz” flight will from launch to ISS docking will last a whole six hours.
    Rather like a game of poker I really wouldn’t be surprised if SpaceX in reply release another “good news” Grasshopper progress report soon. With regards to Merlin engine efficiency Tracy I doubt the Merlin D will be the last “improved” model.

    I do agree with you that Nasa might be hesitant to have astronauts fly on a reusable craft. The deciding factor would be the level of refurbishment.

    A remote launch site shouldn’t be to difficult to find, ESA did it. Unfortunately it’s Dollars flying out the door again.

    • Stuart,
      Agreed. SpaceX handled several issues during CRS-1 & now on CRS-2. The company has shown a “can do” attitude, worked and then resolved the issue. Also agree with your Merlin comments. SpaceX continues to refine their skills & hone their capabilities. I’ve said it before, they had no harsher critic than me – until they put their money where their mouth was & did what they said they would do.
      Sincerely, Jason Rhian – Editor, AmericaSpace

      • Stuart and Jason,
        Curious do the the SpaceX issues continue to a point of failure of the mission which then dooms the company or are reduced to the point that the issues become “Not significant to be Reportable” ?….. Is everyone convinced that failure will occur to the point of loss of life irregardless of a safety protocal simply because with space flight one can never account for all of the variables due to unknown “Unkowns”??

        • Tracy,
          From what I’ve seen SpaceX, like all aerospace firms, is encountering issues during their first flights. However, they appear to be resolving these issues (take a look at how they worked through the recent Dragon drama for an example). When the Falcon had an “engine-out” anomaly? They worked that too (despite the loss of Orbcomm’s payload). Protocol is…different…than if this was a NASA mission. As I’ve said, NewSpace will not be treated kindly when they lose a crew – I think SpaceX is hyper-aware of this & will take the necessary precautions. So, in short, Elon’s company has no harsher critic than myself – but having said that – you can’t argue with success. They’ve encountered problems, worked through them & appear to be doing really well in the space flight arena.
          Sincerely, Jason Rhian – Editor, AmericaSpace

          • Jason,
            What is the logic then that allowed the loss of two shuttle missions after what was considered enough time to work out the bugs? Maybe the comparison does not really work… But for all the money that was spent on the shuttle, wouldn’t a crew escape system have saved both crews? Is it a given that NewSpace will lose a crew sooner or later?

            • Tracy,
              A commercial company already lost people, on the ground in a test. I think it’s a fairly safe bet that one of these companies will lose a crew.

              As to “what is the logic” – there wasn’t any. It was pride & over confidence that cost those two crews their lives. It was also less about the tech – & more about management. Some of the folks that were involved with the Columbia disaster – still hold positions of authority within the agency.

              What it seems you’re suggesting is that we put blind faith in commercial companies. Many compare them to commercial airlines. Given that example – how many commercial planes are lost every year? How many horror stories do we hear out of them? Moreover, working around these folks I can state that I’ve seen more than a little smug arrogance off of these folks. Given how much more complex spaceflight is compared to air travel? That scares the hell out of me.

              Sincerely, Jason Rhian – Editor, AmericaSpace

  7. Stuart
    The real surprise has been the lack of Change from Lockheed and Boeing…
    I really expect to here something on reuseability from them soon.. Then again they are stuctured for the big Gov contracts…..Russia’s days are numbered as well and they are limited to the Soyez. I don’t think they can build a new craft to compete with SpaceX unless a new private venture forms in Russia but I do not see that happening until big political change occurs…And China won’t let a private company do space launch….Then again there is Jeff Bezos Blue Origin

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