64
votes
Accepted
Did the Challenger SRBs fail due to design for reuse?
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 ...
- 54.4k
61
votes
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What technological breakthroughs were required to land booster stages?
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 ...
- 166k
61
votes
Isn't Starship way too big?
The purpose of Starship is not merely to put satellites into orbit for cheap. If that were its purpose then you'd be correct; it's way overbuilt for that.
Starship wasn't created to put satellites ...
- 904
59
votes
Accepted
Why can't Falcon 9 fairings touch the water?
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 ...
- 1,334
51
votes
Accepted
Why use water tanks from a retired Space Shuttle?
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/...
- 1,270
50
votes
Why not land SpaceX's Starship like a plane?
There is not enough air on Mars. You would need absolutely humongous wings. There is no air at all on the Moon.
Surely SpaceX can find a quick and easy way to get Starship vertical and in position ...
- 17.8k
46
votes
Accepted
Why not land SpaceX's Starship like a plane?
You're basically describing the Space Shuttle.
The Space Shuttle wasn't even a good solution when it was designed. It had precisely one goal - to look like a plane for the image of the Air Force. As ...
- 1,930
46
votes
Why keep expending SpaceX boosters?
Falcon 9 Replaces Falcon Heavy for Many Missions
When Falcon 9 was first developed, it had a max payload to Low Erth Orbit (LEO) of 9t, and 4.8t to Geostationary Orbit (GEO). Falcon Heavy was built ...
- 2,193
45
votes
Accepted
Why the soot pattern on the nosecone of Falcon Heavy side booster?
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 (...
- 5,118
43
votes
Accepted
Why are only 2 out of the 3 boosters on Falcon Heavy reused?
The Falcon Heavy is a flexible system. Depending on how much you are willing to pay, in order to get the proper payload and orbit.
To date (3 launches + one today in theory as I write this) they have ...
- 79.1k
42
votes
Accepted
Why is SpaceX building the Big Falcon Ship before the Big Falcon Rocket?
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 ...
- 6,427
40
votes
Why can't Falcon 9 fairings touch the water?
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 ...
- 19.9k
40
votes
Reusable spacecraft: why still have fairings detach, instead of open/close?
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 ...
- 19.9k
37
votes
Accepted
Do Falcon 9s get a thorough wash or a fresh coat of paint (they look clean pre-reflight)?
It's easy to see by just looking at photos and videos of launches of re-used boosters that they don't. There are only a very few very small white lines, probably where engineers inspected some weld ...
- 17.8k
34
votes
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What work needs to be done before reusing Falcon 9?
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 ...
- 79.1k
34
votes
Why won't they recover the Falcon 9 from CRS-14?
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 ...
- 1,196
32
votes
Why is SpaceX building the Big Falcon Ship before the Big Falcon Rocket?
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 ...
- 121k
30
votes
Now that they can land a Falcon 9, what will they do with it?
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 (...
- 1,234
29
votes
Would reusable rockets render the idea of space elevators useless?
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 ...
- 391
28
votes
Accepted
Are SpaceX Falcon rocket boosters significantly cheaper to operate than traditional expendable boosters?
We don't know.
One thing we do know is that SpaceX launches are fairly cheap compared to their competitors. Whether that is because of reuse, because their rockets are generally cheaper independent of ...
- 17.8k
28
votes
Accepted
Isn't Starship way too big?
The size is mostly based around missions to Mars as opposed to satellite launch. Where satellite launch is almost a side mission.
Refueling missions for Mars missions will require 7 launches (1 ...
- 79.1k
28
votes
Why do $\text{CH}_4$ (Raptor) engines produce less soot than RP-1 (Merlin) engines?
As GandalfDDI notes, you always run your engine fuel-rich so it doesn't start running engine-rich. This results in incomplete combustion of the fuel.
Methane is a single carbon atom bonded to four ...
- 14.1k
27
votes
Reusable spacecraft: why still have fairings detach, instead of open/close?
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 ...
- 177k
27
votes
Accepted
Is Falcon 9 repainted before reuse?
No. According to this article it is not even cleaned: https://www.arstechnica.com/science/2018/12/singed-and-sooty-spacexs-falcon-9-rocket-still-looked-brilliant-monday/
- 1,788
26
votes
Did the Challenger SRBs fail due to design for reuse?
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 ...
- 177k
26
votes
Accepted
Why is there a need for getting rid of ISS trash using the empty ATV and similar vehicles
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 ...
- 79.1k
25
votes
Accepted
What happens to payload fairings of GEO launches?
A payload fairing is separated as soon as possible when the air is so thin that the payload needs no protection anymore. This reduces the weight of the remaining rocket.
The fairing is usally ...
- 48.7k
25
votes
Why do $\text{CH}_4$ (Raptor) engines produce less soot than RP-1 (Merlin) engines?
As explained to me (carefully and fully) by a Rocketdyne engineer you ALWAYS run rocket engines fuel rich. If you run lean the oxidizer looks at the metal parts of the engine (remember the engines are ...
- 908
24
votes
Accepted
What are the two bright objects separating from the Falcon 9?
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 ...
- 124k
24
votes
Why are only 2 out of the 3 boosters on Falcon Heavy reused?
It's perhaps worth noting that Falcon Heavy is difficult to operate in a fully-reusable configuration. Consider that it basically offers two use cases relative to the Falcon 9...
Payloads which are ...
- 351
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