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32

NASA tends not to insure its missions, nor do any government missions. These missions are one-of-a-kind, and so expensive that the satellite insurance market would have a hard time making it work. They simply triple-check everything they can, and expect to lose a few missions, so called "Self-insurance". They have considered insuring things like the ISS ...


19

The JWST is made to fold up, to fit inside the standard fairing. You can sort of see this in your image, 3 mirror segments are visible (the hexagons in the middle), other segments are viewed side-on and aren't visible. Folding animation Time lapse showing the folding during assembly


19

Altitude drops like that are common when the orbital stage has a high-efficiency, low-thrust engine. It takes a few minutes for the upper stage to bring the craft up to orbital speed. During that period, the craft is indeed starting to fall back towards Earth. The rocket's travel over the curvature of the Earth contributes an effective altitude gain that ...


17

Not a complete answer (update in the footer!) because I wasn't able to find any official explanation, but I did find enough that I thought you might be interested in my findings so far. It also gets more and more intriguing, check this out:                  Ariane 44L launching ...


17

It's an Helium tank; nicknamed LHESS This website capcomespace.net have a very good article on the subject (in french) Extract (roughly translated): The tanks pressurisation system preserve the tanks structural integrity, and a continuous propellant flow. The LOX tank is pressurised by 141kg of liquid helium stored at 7°K and 19 bar, warmed up by ...


16

Meet the Ariane EAP (Étage d'Accélération à Poudre, "Solid Booster Stage"): what are the (presumably eight) circular spots on the external nozzle-like protrusions at the bottom of each of the (presumably solid rocket) boosters on either side of the main engine? They are the business ends of the fusées d'éloignement, or separation motors, which push the ...


15

Insurance is done when losing a mission would mean an unacceptable financial loss, e.g. when a launch failure would bankrupt your company. The government is large enough to absorb such losses, so no insurance is necessary.


14

I think you already know the answer, it is not really a technical issue, it is (mainly) political. The Germans have experience with liquid engines (they make major parts for the liquid main engine of Ariane 5) and the Italians have experience with solid fuel (they make part of the solid boosters for Ariane 5 and the majority of the solid fueled Vega-rocket). ...


13

This is a pretty interesting question in retrospect now. When it was asked in 2013, booster re-usablity was just a gleam in SpaceX's eye. The first Falcon 9 attempt to land a booster wasn't until 2015. But clearly SpaceX's pricing was already a problem for ESA, the Falcon 9 is roughly equivalent to the Ariane 5 in launch capacity, but have always been ...


10

Ariane 5 does not shed ice at liftoff. The first stage is covered in foam insulation that prevents ice buildup. In this image, the insulation is the brown stuff. Later Ariane 5 versions switched to light-blue insulation tiles. The Shuttle had insulation on its External Tank for the same purpose. For the Shuttle, it was critical not to have chunks of ice ...


10

That ULA video was great. I googled for "fairing vibrational modes after jettison" and came up with a lot of interesting links. The prize is probably this paper "Simulation of the behavior of a payload fairing during separation" which includes this graphic showing motion just like what's in the video. and this description The vertical jettison ...


10

The shuttle SRBs weren't really cost-effective to reuse. The nozzles and nozzle boots were replaced completely, as were many other components; the segment casings were deformed by the force of splashdown, and had to be reshaped. Designing the booster for reuse, and inspecting each rebuilt booster thoroughly to be assured that it was safe to use — ...


9

Okay, here's the general break down in Solids vs Liquids debate, with a bit of help from Wikipedia, ESA, and NASA: Solids- Solid fueled rockets must be manufactured in a controlled environment. If not constructed properly, they can have impurities resulting in uncontrolled expansions (Explosions). They are safer generally speaking than Liquids, and don't ...


8

The loss of the commercial market is clearly caused by a series of bad decisions starting in the 1980's and 1990's. With the advent of the Space Shuttle, it was US policy for a while to launch everything on the Shuttle. This made some kind of sense at the time, since they still lived under the illusion that they would be able to meet a high flight rate on ...


8

We know that the tough part of getting to space isn't getting there, it's going fast enough to stay there. One of the key reasons is that the rocket is concentrating more on gaining horizontal speed than vertical height. So the rocket will eventually start being pulled down vertically. The atmosphere is such at that altitude that the rocket won't be ...


6

Is there a lock down mechanism somewhere? There doesn't seem to be. Detail of the aft skirt: Note the lack of attachment hardware. The page on the launch table says: A la nuance près que si Ariane 4 est attachée par quatre crochets, Ariane 5 ne l’est pas. With the nuance that although Ariane 4 is attached by four brackets, Ariane 5 is not. ...


6

Ariane 6 had one goal: to reduce cost compared to Ariane 5. To achieve this, they took several steps: replace vertical integration with horizontal integration. All components of Ariane 5 are integrated vertically. Ariane 6's first and second stages, on the other hand are integrated horizontally. This makes the integration building cheaper. Cost reductions ...


6

That is a cover plate at the top of the Etage d'Acceleration à Poudre (EAP) – solid rocket booster at the nose cone that at the time of launch comes off exposing the separation rockets. Video of Covers coming off This slow motion video of the Ariane V launch shows the plates coming off a few seconds after ignition. In the video, they fall away at 41 second ...


5

The loads (acceleration, vibration) that occur during launch are specified in the Ariane 5 user manual. The payload is attached to the top of the PAF via the ring at the top.


5

http://www.spaceflightnow.com/falcon9/007/131124commercial/#.UpPAyeLCf2M This is one of the better answers Basically, the Atlas V and the Delta IV are significantly more expensive than an Ariane V or Proton. Also the former were designed mainly for the USAF and their payloads and they have structured their business that way.


5

The Ariane 5 user manual has the following data: Using a storable propellant upper stage, through a delayed ignition of this upper stage, Ariane 5, in the A5G version, has demonstrated its ability to carry a satellite weighing 3065 kg, leading to a total required performance of 3190 kg, towards the following earth escape orbit: - infinite velocity V∞ =...


4

They do. Ariane 5 uses Liquid Oxygen/Liquid Hydrogen for its main stage engine, so ice accumulation on the body also occurs. See this video for a very clear example of it falling away, but on most launches it's still visible. Here's ice falling from a SpaceX vehicle: This question gives more examples with images of US-based launches demonstrating the same ...


4

Adding liquid rocket engines to a stage that is otherwise unchanged (i.e. without increasing fuel tankage) could increase the rocket's acceleration, but, because of the added engine mass, actually reduces the total velocity that can be imparted by the stage. The higher acceleration reduces the total time to orbit and thus slightly reduces the amount of ...


4

I suspect you're referring to articles like this one: With Ariane 6 Launch Site Selected, CNES Aims To Freeze Design of the New Rocket in July ... Taking advantage of work done years ago on what was then a quarry, CNES officials have selected a site to the north of the Ariane 5’s launch site for Ariane 6, an area called Roche Nicole. Quarry ...


3

There are lots of tradeoffs at work here: cryogenic stages are more difficult to design than storable liquid stages, so space agencies tend to start building storable liquid stages, then move on to cryogenics when they have some experience. cryogenic stages offer higher performance (Isp) than storable liquid or solid stages. solid stages can be simple, ...


3

Liftoff at T-0 is common, but not universal. For Ariane 5, T-0 is the moment of ignition of the Vulcain engine. In a nominal countdown, checkout takes 6 seconds, and the solids are ignited when checkout finishes, leading to liftoff at T+7. I suspect there is some flexibility built into this: if the checkout takes longer, this is easily accommodated and ...


3

Yes, at least once, for the Rosetta launch. The damage was discovered before the launch: A fallen chunk of foam insulation from the rocket’s fuel tank scuppered the latest launch attempt. During a final inspection of the Ariane-5 launch rocket at 0100 GMT on Friday, a 10 by 15 centimetre chunk of foam was found on the movable launch “table” that supports ...


3

Let's start with the text in the middle of the plot: "r.m.s acceleration 7.3 g" That means that, typically and without paying attention to frequency, you'll be seeing a vibrational acceleration around 7.3 g. You need to design for that. Now, what if your device responds differently at different frequencies? I.e. it has a beam inside it that resonates ...


2

If I were the engineer responsible the RL-10-C engine development, and I had this kind of good-looking test in that stage of engine development, at sea level pressure, I'd be a very happy engineer. Addressing @EverydayAstronaut's request for clarification: three factors that contribute to me saying "looks good": continuous combustion (I don't have the ...


2

The choice of units is more a historical/maths thing than the physical meaning being very clear. In power spectral densities, the 'power' is defined as the square of the signal. This is useful to engineers because it make the maths work, but it make sense to think of this as sort of like a power, as in typical SHM conditions this is strongly related to ...


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