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Hot answers tagged

62

The O-rings and the temperature were only the last in the long chain of blunders, and that had little to nothing in common with reusability. The construction of the SRBs wouldn't be much different with no reusability in mind. Indeed, SRBs of very similar design are to be used in SLS, and they are not intended to be reusable. About the most important factor ...


59

There are many key points to this, probably none on their own sufficient to ditch the parachutes approach (except economics, those are good enough on their own), but together they make for a compelling case against it; Descent control: As already mentioned, there's a significant guidance uncertainty with the use of a parachute system. Some of it comes from ...


58

The fairings are not boats. While they appear to float (at least for some time), there will also be water on the inside of the fairing. That results in some issues. Inside the fairing, there are electronics and other corrodable materials. Now the fairing is designed to be as light as possible. Therefore, SpaceX probably doesn't want to make the entire ...


56

SpaceX's demonstrated booster-landing ability isn't the result of a breakthrough but rather a bunch of small incremental improvements. The major limitation has been funding and the will to make it happen. In 1966, unmanned spacecraft landed on the Moon under rocket power in the Surveyor program. It used (IIRC) three fixed-position thrusters, pulsed, to ...


50

They're already made, have plenty of usable life left, were stored in a way that facilitates reuse, and apparently cost less than building and certifying brand new ones. https://www.nasa.gov/feature/proposed-station-water-system-looks-to-retired-shuttles In order to reduce the cost and complexity of the proposed system, NASA engineers looked at reusing ...


44

It was charred by the center core after separation: (Source: SpaceX FH launch webcast) Looking at it I would expect one side to be charred too but it may not be - the nose cone is afaik composite (same as the interstage) and not metal.


39

Neither has much financial purpose without the other. A BFR cannot perform any useful function without an upper stage, and that is the BFS. Since the whole platform is a major investment in a new architecture, they are starting with the smaller piece - the BFS. Since it uses some of the same engines as the BFR, it can act as a testbed for both BFR and BFS ...


39

It would only make sense to keep the fairing attached if the stage it was attached to was going to be recovered. The SpaceX falcon and falcon heavy are multi-stage rockets, only the first stage is reusable. The fairing is jettisoned once the aerodynamic pressure is low enough it isn't needed anymore, which is before orbital velocity is reached. Because it's ...


38

In addition to the water damage is the impact damage: the fairings wouldn't "touch" the water they'd hit the water, even with parachute retardation. A net slows deceleration down and spreads it more evenly across the structure, which is a lot friendlier to the materials and the supporting electronics.


34

Earlier on Musk indicated it may be possible to fly a block 3/4 booster more than twice but it would depend on the missions flown, with LEO missions like this Commercial Cargo mission being easier than GTO missions. I suspect this booster and the previous one that did two cargo missions could be reused if SpaceX wanted to but they are choosing to move ...


33

There are many contributing factors to this problem. The Shuttle was designed in the 1970's and technology has matured since then. Additionally, the issues the Shuttle ran into (While in truth may have been predictable at the time) are now more obvious and a new design can try to avoid them. Consider the simple case of the heat shield on the Shuttle. It ...


33

At the moment no one knows, since no one has done quite this task before. SpaceX is learning alot with each recovered core. In this image of three of the recovered cores in the LC-39A HIF building you can see different levels of wear on each stage. You can see that some of the engines have been removed for likely testing on the initial Orbcomm mission ...


30

That is my estimation of CoG of nearly empty Falcon 9 booster. On the left is GoG with legs opened, on the right with legs retracted. The landed vehicle is pretty stable. It could withstand the winds of 50 m/sec (97 knots!), if sliding is prevented. There are relatively narrow limits on horizontal component of landing speed as well as on rotational velocity ...


30

Nobody knows, but it seems pretty safe to assume, for a while, things will continue as normal. SpaceX will continue launching rockets and attempting to land them. They will take the one they have (and any more they acquire) and analyse them extensively to determine if they are, in fact, flightworthy again and what effects being used has had on their ...


29

A Space Elevator would still be amazingly useful The two factors that come to mind are forms of power and scale: Power With a space elevator connected to the ground, you could use the energy in your power grid to lift everything up. By doing this, we can use green and renewable energies. With rockets, baring any massive advancements, we are restricted to ...


29

Elon Musk stated in a news conference after the Falcon Heavy launch that the BFS will be the focus because they think they understand designing booster rockets pretty well, and thus they decided to focus on the more difficult piece first. He answers this in response to a question that starts at 20 minutes 52 seconds here, and speaks specifically to starting ...


27

Yes, definitely. For example: Taurus, now Minotaur-C first stage (US, Orbital Sciences Corporation), based on Peacekeeper ICBM first stage. 9 launches since 1994, out of which 3 failures. Minotaur I (US, Orbital Sciences Corporation), repurposed Minuteman missile with M55A1 first stage and SR19 second stage. 11 launches since 2000, all successful. Minotaur ...


27

Dumping it into orbit, even retrograde, will still leave objects in orbit, slowly falling down until they burn up. But for that entire period of time, they become possible hazards to anything in that orbit or lower. A launcher with some minor amount of velocity would speed up the deorbiting, but it would still be there. You would probably want it somehow ...


26

I bet that's every rookie US Navy pilot's thought too on their first carrier landing approach. Thing is though, that unlike aircraft, Falcon 9 first stage can't really maintain altitude before landing. Even single of its nine Merlin engines throttled all the way down is too powerful for hovering on nearly empty tanks and landing is really going to be more of ...


25

I am referring to rockets capable of taking supplies and humans to other planets. For an interplanetary single-stage rocket with tens to hundreds of tons of payload capability, no existing propulsion system can do the job in a practical way. Chemical rockets lack the fuel efficiency; electric rockets don't have the thrust required to leave Earth's surface. ...


25

The fairings are detached to prevent carrying their un-necessary mass to orbit. This typically happens during the second stage burn. See this question for information about the timing of fairing jettion: How strong and "hot" is the wind on the payload after the fairing is deployed at ~110km? An image showing the fairing separation during the ...


24

To avoid the hazard of going off-topic, I will start by re-framing the question into 2 different parts. This is done so that all the evidence directly builds to an answer to the question. In this case, the question is: Why did the Shuttle's effort at economic reusability fail? Why do many experts believe that the current SpaceX attempt will not fail in the ...


24

Not reusability per se, but design and politics. The competitor to build the SRBs for the Shuttle program was Aerojet, and their design was monolithic. In other words, no segments. Aerojet was actually selected as the winning contractor but the NASA administrator Fletcher overrode this and gave it to Morton Thiokol. Aerojet had already built an awe-...


24

I think that's the fairing (the shell around the satellites on top of the second stage). The fairing separates into 2 halves, those are the only objects large enough to be visible in this photo. At T+3:18 of that video, you can hear one of the technicians say "Fairing separation confirmed". Right after that, the first bright object separates from the ...


22

While the ISP on Ion thrusters is awesome, the overall thrust is pretty low. Thus the transit time from LEO to GEO would be quite long and slow. In some cases this matters. If it takes an extra year to get in service, that is a year of lost service while in transit. In fact a critique of the Falcon 9's ability to do dual launches is that only the smaller ...


22

                     Key phases in the launch-and-landing plan for SpaceX Falcon 9 rocket. Image credit: Jon Ross, NBC News.com After the first stage main engine cutoff, cold gas N2 thrusters are used to rotate the booster into the direction of flight, they ...


22

The TL;DR answer is: it depends. What's rapidly transforming the industry is that some rockets are now partially, (even mostly) reusable. Below, the two boosters from the Falcon Heavy land. Both are reused from previous flights. SpaceX and Blue Origin have both launched and successfully landed boosters, and both companies have re-flown those boosters. It's ...


22

If you check the Reddit Wiki listing all the SpaceX Falcon 9 first stage cores, you will see that they are flying the Block 3 and Block 4 boosters only twice. What is interesting has been that they still often fly them on the second flight with legs. They have been using these flights to test the edges of the flight envelope. In some ways, the Block 3/4 ...


21

No, the previously used External Tanks (ETs) disintegrated in the atmosphere before they fell into the sea. Notably, Buzz Aldrin and others proposed different ideas for reuse of the tank in orbit, and allegedly NASA said that they would be willing to take external tanks to orbit if a private company would use them. No private effort ever stepped up to the ...


21

Edit Jan. 25, 2015: Geoffcc recently provided a link to words straight from the Horse's mouth, Elon Musk. Musk says the payload hit for RTLS (Return To Launch Site) is 30% vs a 15% payload hit for landing on a downrange ocean platform. Musk also said said safety is a reason for having an ocean landing platform -- "As far as the safety aspect of the return to ...


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