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Questions tagged [falcon-9]

Questions regarding the Falcon launch vehicle developed by SpaceX for medium payloads (15,000 lbs) to LEO and GEO (via GTO, second stage cannot inject into GEO direct)

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8answers
30k views

Why would SpaceX not use parachutes for the final descent of the first stage?

According to what I've read, SpaceX tried to use parachutes to recover the first stage of the Falcon 9, but it did not survive reentry. Now they plan to use 2 separate rocket burns to land: Reentry ...
52
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2answers
17k views

How does the Falcon 9 first stage avoid burning up on re-entry?

Now that a Falcon 9 first stage has successfully landed after a launch mission, I want to know how the first stage can avoid burning up when coming back down to earth. There doesn't appear to be any ...
51
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3answers
43k views

What happens to the Falcon 9 second stage after payload separation?

In a Falcon 9 launch, the second stage looks like it achieves orbit along with the payload. But is that impression accurate? Does SpaceX need to do anything to deorbit the stage? I can see a few ...
51
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3answers
16k views

Why would NOAA restrict the ability of SpaceX to live stream the second stage?

I was watching the live stream of the Iridium-5 launch and they mentioned that NOAA had restricted their ability to live stream the second stage and that SpaceX was working to remove this restriction. ...
48
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2answers
9k views

How does the SpaceX Falcon 9 first-stage straighten for landing?

I just saw this video of supposed "SpaceX Rocket Camera Landing Footage Fakery" with over a million views. The narrator repeatedly says it's complete garbage because he doesn't understand and would ...
44
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3answers
9k views

Is a SpaceX launch completely automated?

Once the engines are ignited and liftoff occurs, are any operators/controllers on the ground making any manual changes to the flight? Or are they simply monitoring the entire event until the boosters ...
40
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4answers
9k views

Why can't Falcon 9 fairings touch the water?

SpaceX is spending considerable effort to catch Falcon 9 fairings into a giant net on a ship. I am aware that salt water ruins almost everything in the long run, but the fairings are a composite ...
37
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3answers
4k views

Why was AMOS-6 mounted on the rocket for a test fire?

I understand that the static test is a general test of pre-launch procedures, but risking a multi-million dollar payload for a test seems remarkable. Couldn't they use a mass simulator or something? ...
32
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3answers
7k views

What is the primary reason for SpaceX motion to have astronauts board Dragon before fueling up the rocket?

News piece: NASA supports SpaceX plan to fuel rockets with astronauts on board. The move is criticized by many as unnecessarily dangerous. From what I understand though, it shouldn't be necessary - ...
32
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6answers
18k views

Why did SpaceX attempt to land the booster on a barge instead of somewhere on land?

I understand the benefits of reusability for the rocket booster. But I don't understand why they're landing it on a barge. I've read tons of articles about this but not one has even hinted at an ...
31
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2answers
4k views

What holds SpaceX’s rocket in place in this launch?

On a recent launch video, the gantry is at an angle and only loose tethers are attached as the rocket is prepared for launch. What is keeping it upright and in place at this point? The engines haven'...
31
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1answer
9k views

Why does the Falcon 9 consume hydraulic fluid?

According to many news articles, the crash of the Falcon 9 during landing on 1/10/2015 was due to running out of hydraulic fluid for the steerable hypersonic grid fins. This was seemingly confirmed ...
30
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3answers
12k views

Why does the SpaceX Falcon 9 rocket do a 180 flip for reentry?

I am very new to the rockets and this can be a very dumb question, just that I am not sure if my understanding here is right? All of the rockets engines are at bottom which help it take off and ...
30
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3answers
7k views

Why won't they recover the Falcon 9 from CRS-14?

According to the upcoming livestream of SpaceX CRS-14 (resupply of ISS): SpaceX will not attempt to recover Falcon 9’s first stage after launch. Why not? Wasn't that the whole point of (among ...
29
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1answer
2k views

What work needs to be done before reusing Falcon 9?

In this article Elon Musk said that first stage of Falcon 9 which landed on the barge in April will be reused in June. Launching and landing wears material down, what parts need to be replaced and ...
28
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4answers
7k views

Why does the Falcon 9 have 9 engines?

What are the reasons for using 9 engines in the first stage of the Falcon 9? Why not 8 or 10? Looking at the Raptor engine, they seem to be looking at 9 engines again. Is there some specific advantage ...
28
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4answers
2k views

What started the explosion on the crashed Jason-3 stage landing on the barge?

If you watch the truly awesome video of the Jason-3 first stage landing on the ASDS Barge Just Read The Instructions, it is pretty clear that for one thing, they landed it. Then the leg gave out, ...
28
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2answers
6k views

What is the “emergency crush core”?

In his tweet Elon Musk said: "Rocket is extra toasty and hit the deck hard (used almost all of the emergency crush core)" What is he talking about?
27
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5answers
4k views

Falcon 9: engines stabilize spin

On CRS-16, the landing Falcon 9 booster entered a spin rotation due to a stalling grid fin hydraulic pump. According to Musk, the engines stabilized the spin. How is this possible? The main engines ...
27
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4answers
3k views

Now that they can land a Falcon 9, what will they do with it?

As most of you, I am super stoked by the amazing success of SpaceX with their Falcon 9 first stage landing back on land! We also know that they have a huge backlog (over 50 flights) and are building ...
27
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2answers
31k views

What computer and software is used by the Falcon 9?

I don't know if this would be public, but what CPU / Microcontrollers are used and what software do they run on the Falcon 9? Do they use an OS or is it just bare metal programming? I found some ...
27
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1answer
3k views

Was Amos 6 insured for pre-launch operations?

The Falcon 9 rocket, complete with the Amos 6 payload, just blew up (Or RUDed) on the launch pad. I believe the standard language for most launch insurances is that it is only covered after "...
26
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7answers
5k views

How can a 9-engine Falcon rocket be cheaper than single engine rockets?

From what I understand, the engine is usually the most expensive part of each rocket, excluding payload. I'm struggling to understand how SpaceX can have one of the cheapest launchers on the market ...
26
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3answers
10k views

What makes 21st century fairings so valuable that they'd potentially be recovered and re-used?

I've read in @geoff's answer that SpaceX is doing some experimentation that may lead to fairing recovery capability. In fact I remember hearing Elon Musk mentioning a few years ago that it was being ...
26
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2answers
5k views

Why did SpaceX retire Falcon 1?

Why did SpaceX retire Falcon 1? Wouldn't it have been more cost effective then Falcon 9 for lighter missions?
25
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3answers
5k views

How can the reusable Falcon 9 succeed when the reusable Space Shuttle failed?

Space Shuttle was designed to be partially reusable but was later shut down because it turned out to be very expensive to run compared to disposable spacecraft. Now Falcon 9 is suddenly reusable to a ...
25
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1answer
5k views

Falcon 9 design: Why is the cargo fairing so much wider than the lower parts?

Why does the cargo fairing have a much larger diameter than the lower part of the rocket? Of course a larger diameter lets thicker payloads fit. But then the first, inter, and second stage could have ...
25
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1answer
17k views

What are the droplets/particles falling off rockets at launch?

In this picture from the AsiaSat 6 launch by Falcon 9 on 8th September 2014, the part of the rocket between the fairing and the engine appears to be surrounded by dust, water droplets or debris: ...
24
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2answers
11k views

How are the SpaceX Falcon 9 Mod 3 and Mod 4 grid fins different?

Elon Musk tweeted "Flying with larger & significantly upgraded hypersonic grid fins. Single piece cast & cut titanium. Can take reentry heat with no shielding." These have been commonly known ...
24
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3answers
3k views

When SpaceX claims to build 4 engines/week, which engines do they mean?

In this Tweet (dated 11 Sept 2013) Peter de Selding reported that Gwynne Shotwell of SpaceX said: SpaceX's Shotwell: We're building 7 Falcon 9 fairings/yr now, 15 in 2014, & 4 engines/week ...
23
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2answers
21k views

What is the cost breakdown for a Falcon 9 launch?

I don't know if this was already asked, but I'm very curious about the cost breakdown of a Falcon 9 launch.
22
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4answers
2k views

How does the Falcon 9 know where the landing barge/pad is?

The descending Falcon 9 has got to hit (preferably gently) the tiny target of the Autonomous Spaceport Drone Ship (ASDS) in the middle of the ocean. How does the Falcon 9 know where the ASDS is? ...
21
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4answers
4k views

Why does the Falcon 9 use RP-1/LOx and not LH2/LOx?

Why does SpaceX use RP-1 in the first and second stages of their rockets? In my view at least the second stage could use hydrogen as it currently is not being reused. I am aware that you have higher ...
21
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8answers
5k views

Why isn’t the “JRTI” barge larger?

The barge that SpaceX's Falcon 9 was trying to land on is creatively called "Just Read The Instructions"(hereafter known as JRTI). I've been told that SpaceX is using the barge to avoid a land based ...
21
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2answers
2k views

What are the two bright objects separating from the Falcon 9?

On the recent Iridium 1 launch the separation of the first and second stages can be seen at T+3:50. In the following screenshot we see the second stage burning at the lower left of the frame and the ...
21
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1answer
5k views

How does SpaceX ignite their engines?

Based on the aborted launch on Thanksgiving 2013 of the first Falcon 9 v1.1 from Florida, we know that an issue occurred where oxygen got into the ground based TEA-TEB sources. I understand that TEA-...
21
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1answer
3k views

What makes the Merlin vacuum engine so deeply throttleable?

According to the October 2015 revision of the Falcon 9 User's Guide, the Falcon 9's first stage Merlin 1D engines have a 70%-100% throttle range, while the second stage Merlin 1D Vac engine has a 38.5%...
20
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7answers
14k views

How stable would a Falcon 9 first stage be after it has landed on a drone ship?

Presumably, the booster would be a very light, very tall tube (Most of the fuel spent) standing on 4 fairly small legs on a ship in the middle of the ocean. It would also still contain some LOX and ...
20
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2answers
6k views

Why won't SpaceX launch a rocket for a month?

The last launch of a Falcon 9 (Intelsat 35e) took place on July 5, but the next launch of a falcon 9 (CRS-12) won't take place until August 10. Elon said that SpaceX still had 12 launches to go this ...
20
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1answer
6k views

What made the Earth appear to be flat during the recent SpaceX launch?

During the recent SpaceX CRS-12 launch which was broadcast live on YouTube, it appeared at one point as if the horizon of the earth was completely flat. What caused this to happen?
20
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3answers
3k views

How does SpaceX plan to achieve reusability of the Falcon 9 *second* stage?

Update 08 April 2017: Elon Musk tweeted an indication that they're revisiting the possibility of second stage recovery, so this question is again relevant, and the details of the new solution may be ...
20
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1answer
495 views

Does the proximity of engines in engine clusters cause interference?

One way to create a heavy launch vehicle is by clustering large numbers of small engines together in a stage. An example of this approach is the SpaceX Falcon 9: Now I've heard people arguing against ...
19
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4answers
4k views

Is SpaceX the only launch service provider who can attempt another launch the next day after a scrub?

Is SpaceX really the only launch service provider, who can attempt another launch the very next day after a scrub? While other providers may need weeks of preparations before another try. If that is ...
19
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2answers
3k views

Will SpaceX delay launches, if the landing site weather is unacceptable?

With the initial landing attempts, it was not a big deal, twas all an experiment and they only reused Block 1-4 boosters once at best. So holding a launch because of weather at the landing site ...
19
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1answer
3k views

Why are Falcon 9 main engines throttled down and up shortly after launch?

On the official webcast of SpaceX's Iridium-4 mission a "throttle down and throttle back up of the Falcon 9 first stage engines" is mentioned. Why would one throttle down at a crucial time during ...
19
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2answers
4k views

Falcon 9 fairings cost and reusability

I read that SpaceX is starting to work on fairings reusability. I couldn't find any information, so I would like to know more about them. In particular, I remember a quote from Musk saying that ...
19
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2answers
6k views

How did the Falcon 9's 1st stage return back to Cape Canaveral?

SpaceX's original plan was landing the 1st stage to a landing ship, that waits far away from the launch site, and it was like this: But tonight, the rocket's first stage landed at Cape Canaveral. ...
18
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1answer
5k views

Why is Falcon 9's fairing so big?

The Falcon 9 fairing costs millions of dollars. It is 5.2 meters wide while the rocket itself is only 3.7 meters wide. There is no aerodynamic reason that the fairing has to be so big, since Dragon ...
18
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2answers
4k views

More efficient SpaceX landings?

Although the exact trajectory of a rocket is not known before launch, could SpaceX position its landing barge even further down range of the launch pad and eliminate the need for a boostback burn ...
18
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2answers
10k views

Where is the other half (stage two) of the SpaceX Falcon 9 rocket?

The big news yesterday and today is that SpaceX had a successful launch, payload delivery, and landing of the Falcon 9 stage 1 rocket. My question is, where is the second stage of Falcon 9 now, and ...