Status of the third recovered Falcon 9 first stage

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The recovered first stage from SpaceX’s last Falcon 9 launch experienced significant wear and tear during its high speed descent and landing.

They do not think they will be able to use the stage again, but will instead test it to determine the engineering tolerances that need to be met to make recovery and reuse in these situations more likely. The data will also help them increae the likelihood of reusability on launches that are less stressful.

Posted from Belize.


  • alex

    Landing the first stage, is only the first step in a complex scenario of reuse process installation. There might be a very, very long way to real reusability, which exhibits significant cost reduction of about 90% or so. It seems that even moderate 20% reduction should be considered as a great success today.

  • Phillip

    They wrote an entire article based on a tweet containing almost no information. Just click bait if you ask me. The tweet said that the rocket took max damage. That might just mean that it was the maximum possible damage on a re-entry, not a quantification of the damage to the rocket. The tweet said that they wouldn’t re-fly the rocket, but it didn’t say that it was damaged beyond repair. It could just mean that it has more value as engineering data than as a launch vehicle.

  • ken anthony

    Other companies and NASA will want their data. SpaceX, by taking the initiative, is moving everyone forward. SpaceX will learn the most.

  • Alex

    Phillip, you wrote: “It could just mean that it has more value as engineering data than as a launch vehicle.” That is exactly my interpretation of article’s content.

  • Tom Billings

    “but will instead test it to determine the engineering tolerances that need to be met to make recovery and reuse in these situations more likely. ”

    These are the key words, IMHO. They exhibit, once again, the intent to make rapid changes that allow an evolving launch vehicle family to get to its goals, …in this case, reliable reusability, rather than bleed money from Congress.

  • Alex

    Tom Billings: The second private company (BO?) that follows SpaceX regarding reusability may have some advantages compared to SpaceX because it may benefit from SpaceX investments, design solution and “errors” without investing same amount of money and time.

  • wodun

    Blue Origin is already re-flying their vehicle though.

    I have no idea how closely the two companies follow each other’s engineering but it seems that neither company really needs to. They are working independently to solve the problem of reusability.

    ULA has a working relationship with BO though, so the question is, why are they going with some sort of crazy parachute scheme to recover only their engines?

  • Edward

    Blue Origin only flies to 50 km, with no residual velocity. They do not yet have to get an upper stage to an altitude and velocity to get an upper stage to orbit, so their reentry is not as stressful as SpaceX’s. I am sure that Blue Origin is paying close attention to white papers and rumors coming out of SpaceX, NASA, and their partners, and vice versa.

    As we can see with the latest Falcon, a little more speed and altitude than taking a payload to Low Earth Orbit in order to take it to Geostationary Transfer Orbit (GTO) is the difference between reusability and “max damage.” This suggests to me that Falcon was designed on the edge of reusability. It also seems that a GTO launch is also on the edge of recoverability, since the successful recovery was only a hoped-for bonus to the launch.

    Previous rocket scientists and engineers had concluded that it was not practical to make a booster rocket reusable, and the reference to “max damage” also suggests to me that they were probably right, for their time. SpaceX has probably used lighter and hardier materials than were available back then. The ability to make Falcon lighter means that it undergoes lower stresses, and the hardier materials allows for better survivablility under the stresses, heat, and other conditions that Falcon sees during reentry.

    I expect that SpaceX used computer modelling to find where they could lighten the rocket and where they had to beef it up. The latest recovered rocket will certainly be compared to the model for improvements to both. This way they can make Falcon reusable after launching payloads to GTO, which is a popular launch option.

    For the future: making sure Falcon is reusable after launching a payload to escape velocity, which may be a popular launch option in a decade or two.

    (Yes, I am still hoping for Single Stage To Orbit, such as Skylon.)

  • Alex

    Hello Wodun: I am fully aware of BO’s flights and landings, but it does not compare in many aspects to F9 first stage landings (thermal and aerodynamic loads, robustness or propellant mass fraction of propulsive stage). F9’s first stage is extremely light weight (more extreme if you eliminate all landing assisting systems), a requirement which is not necessary for New Shepard, due to smaller delta-v needs.
    However, I am sure, that BO works on its own solution for reusable orbital vehicle using its BE-4 engine. BO can now learn from SpaceX results and may even go a step further. Edward: You are correct with many of your statements, but BO went to about 110 km (not 50 km).

  • pzatchok

    The Falcon9 could have just had a hard landing and bent the superstructure around the lading gear.

    Everything else could be just fine on the craft and thus reusable.

    I seriously doubt any extra damage came from its flight.

    They left it up to the on board computers to calculate and ignite the engines for landing. Due to low fuel they might have fired very late and thus didn’t scrub off all the speed they needed to.

  • Alex

    Pzatchok: You forgot the intensive thermal load to the tank structure, which is made from low-melting Al-Li-alloy. It so intensive that paint is charred and partly burned away.

  • Edward

    Thanks for the correction. I seem to have regressed to the 1960s, when the US considered 50 miles to be outer space, then absent mindedly changed the units. Aren’t you glad I don’t build the airplanes that *you* fly on?

    Of course, the Karman line, internationally recognized as the edge of space, is 100 km, not 50.

    Blue Origin has stated that they intend to use their BE-4 engine for their own orbital rocket (and sell it to other orbital launch companies, too), but how far they are on the design or construction of this rocket is not yet clear.

    We will have to wait to find out what Musk meant by “max damage.” Perhaps he only meant that it received more damage than any of the other recovered boosters. Maybe even without a dent. I have not yet found a clarification, after all the reports from the other day.

  • Wayne

    Q: Any sort of heat “shielding,” engineered into the first stage?

  • pzatchok

    If the craft heated enough to be annealed and loose its temper or rigidity then you would be able to visually see wrinkles form on the outer surface when it landed.

    I am sure that they use the outer body of the craft as a major part of its structural system and if it softened that whole thing would crumple on even a soft landing.

    I bet they use the highest temp alloys in the outer skin to make sure that they have the best chance of a working vehicle when it is recovered.
    It would cost them nothing extra in weight.

  • Alex

    Pzatchok: Major part of the outer skin of the vehicle is identical to the LOX and RP-1-tanks itself. This is true for every space launcher ever launched. The tanks of F9 are made of lithium-aluminium-alloy, which melts at about 550°C, but loss its strength at much lower temperature.

  • Edward

    The SpaceX animations that I have seen suggest that the Falcon 9 reenters tail first, putting much of the heating and shockwave forces onto the Merlin 1D engine bells. These are already engineered for high temperatures and high forces, although engineering to handle a shock wave may have required some unusual designing.

    The only reason that I can think that the engines survive reentry without a heat shield is that the rocket’s speed in only around 1 mile per second, rather than the 5 miles per second that reentry from orbit would have. It is clear to me that the Merlin 1D engines are performing well in the absence of a heat shield.

    The SpaceX animations that I have seen suggest that they are thinking of reentering future upper stages nose-first, and that they will have some amount of heat shielding.

    In the 1990s, two of the three proposed single stage to orbit rockets, Delta Clipper and Roton’s Rotary Rocket, would reenter from orbit tail-first. They would have heat shields, but their launch engines would also be at the aft end, exposed to the forces and heats of reentry.

    The now-defunct Kistler Aerospace intended to have a similar system, but one that had a “fully reusable launch assist platform.” Again, reentry would have exposed a rocket engine to heat and stress. (2 minutes)

  • Wayne

    Thanks for the info!
    Wasn’t thinking an actual “heat shield” per se, rather the whole design acting as its own giant heat dissipater, as much as possible.

    Can the first Stage just “melt” itself, in the atmosphere, if for some reason the engines didn’t slow re-entry? Or is it not high enough to “melt?”

    Where does the 2nd Stage end up? For example, the last launch, 2nd Stage was up pretty high. Does it make a few orbits and then fall back down?

    Is it correct to say: “The shock-wave you experience on re-entry, is the same as the “max-Q” shock wave you encounter on the way up?”

  • Edward

    Aluminum melts at a temperature much lower than fire, so most of a rocket would burn up during orbital reentry, but first stages remain intact enough to splash into the ocean (or crash onto land).

    If you have an aluminum pan, you can melt it on your stove, aluminum’s melting temperature is around 700 F, but various alloys can have different melting temperaures. I know this from first-hand experience; one evening I was boiling water, left the kitchen, and distracted myself until the fire alarm sounded. I can now claim that my cooking skills are so bad that I burn water.

    In an attempt to prevent space debris, many upper stages are placed into orbits in which they eventually reenter the atmosphere and burn up. This could be the next orbit, but the generally accepted standard is that objects in space should be placed into orbits in which they reenter within 25 years. This, of course, is impossible for high orbits such as geostationary orbit.

    The shock-wave on reentry is due to a blunt part of the vehicle being the front. On launch, the rocket is pointy in order to minimize the shock wave compression.

    On reentry, the blunt end causes a lot of compression in front of the vehicle. As you recall, when you compress a gas, it heats up, and that is where a majority of the heat of reentry comes from. Friction with the vehicle is a lesser contributor to the heating.

    Thus, this is not the same as max-Q, (Q is used as a symbol for dynamic pressure). Max-Q is an effect on the shroud, and it also contributes a force that the engines have to overcome to accelerate the rocket into orbit. This is a period of time in which the shroud is most stressed, and the engines are not accelerating as much per pound of propellant as when the dynamic pressure is lower.

  • Wayne

    Cool. Appreciate the effort, on the rocket info.
    –One time I boiled a pressure-cooker dry. It was glowing red by the time I turned off the gas.

    “To understand how something works, figure out how to break it.”
    Nassim Taleb
    (“Fooled by Randomness”)

  • Alex

    Edward: It seems to me that the upper part of F9 first stage (which is connected to the second stage in launch configuration) is also subject of internsive heat flow, because the paint is burnt as the lower end more worse. The geometry of the stage is very different to common blunt capsule shapes. Its lenght-to-diameter ration is very high, that the flow/shoke may reattached at this upper region of the stage and imposes higher heat flow to the structure. BTW. melting point of common aluminium is about 650 C (Li-Al-alloy as applied to F9 are about 100 C lower). See page 6 of linked paper:

  • wodun

    BO can now learn from SpaceX results and may even go a step further.

    Sure, but even an knowledgeable outsider such as yourself can only learn so much without being privy to SpaceX’s internal data. I doubt the two companies are exchanging information on this level while they are doing their best through OSINT.

  • Alex

    Cost of range safety shall not forgotten in context with overall launch cost analysis and reduction efforts. Who is paying now for these costs in case of SpaceX? The tax-payer, because it is contributed for free by Air Force? The video gives – even if more modern supervision can be applied – an overview of required effort:

  • Edward

    Dry pressure-cooker is scary. Eeek!

    Yes. The lower portion is not the only part that sees heating. The Space Shuttle had some heat protection on its upper regions for this reason, and you can see some effects of heat on the upper portions of Apollo, Gemini, and Mercury capsules.

    Melting aluminum is not the real problem, but I use the low melting temperature to help describe the susceptibility to heating effects of the rocket structure.

    I do not know what alloys SpaceX uses, but I often used 6061-T6 aluminum when designing space instruments. The “6061” was the alloy and the “T6” was the temper applied to the alloy, strengthening it. It could lose its temper — strength — by being overheated. I am sure SpaceX has this same concern about the portions of the rocket in which the paint has burned off. If it has been weakened by overheating, then it may no longer be strong enough to successfully launch payloads to orbit.

    Alex, You seem to be under the impression that US commercial space companies get to use US Government launch facilities and infrastructure for free. That is not the case.

    There are plenty of other costs associated with using US Government launch infrastructure, other than range safety and facility use. The bureaucratic process is burdensome. Scheduling can be problematic. Security restrictions hampers ease of use of several government facilities. Pad/base rules are also burdensome, as many rules need not apply to commercial launches but are still necessary for military launches, thus they apply to all launches at that pad/base. SpaceX is building its own launch facility in order to minimize these costs of compliance.

    Ultimately, the payload owner — the customer — pays the cost through the price charged by the launch company. The launch company pays the government for the use of the various infrastructure assets used.

    However, I do not know whether the initial cost to produce the infrastructure is amortized into the price the government charges the launch company.

    There are some modern contracts, such as SpaceX’s contract to lease KSC’s pad 39A. Orbital ATK has a contract to launch from a pad at Wallops.

    As with airlines, there are certain aspects of space travel that *are* free to the commercial space industry. As far as I know, the Space Fence, the system that tracks satellites and debris and warns of potential collisions, is not charged to satellite operators or to launch companies that have rocket sections still in orbit.

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