41
votes
Will the James Webb Space Telescope be insured against launch failure?
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. ...
- 121k
28
votes
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What does the Ariane 5 rocket use to turn?
Like most large modern launchers, Ariane uses gimbaled engines for attitude control during ascent.
Both the Vulcain liquid-hydrogen engine and the nozzles of the solid rocket boosters on the Ariane ...
- 167k
24
votes
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What is the reason for the Ariane 5 launcher with Intelsat 29e losing altitude?
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 ...
- 167k
21
votes
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How can the 6.5 m primary mirror of the JWST fit inside the 5.4 m fairing of Ariane 5?
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 ...
- 126k
19
votes
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What's the shiny silver turnip on the bottom of this Ariane 5 launcher?
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 ...
- 12.6k
19
votes
Accepted
What are these circular spots on these Ariane V SRB nozzles?
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 ...
- 167k
18
votes
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Why does the core stage of the Ariane 5 produce more thrust in vacuum?
It's because the ambient atmospheric pressure affects the thrust generated by the engine.
(Image source)
An engine nozzle has a "design altitude" at which the pressure of the exhaust at the exit ...
- 178k
18
votes
Why are Europe’s Air & Space Academy and DLR urging ESA and CNES to reconsider the use of solid fuels for the proposed Ariane 6?
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 ...
- 1,234
16
votes
Will the James Webb Space Telescope be insured against launch failure?
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 ...
- 126k
12
votes
Accepted
Are all payload fairings this floppy?
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 ...
- 178k
11
votes
Accepted
Why do Ariane rockets not have ice break off on liftoff?
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 ...
- 126k
11
votes
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Why aren't the Ariane 5's SRBs reused?
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 ...
- 167k
10
votes
What is the reason for the Ariane 5 launcher with Intelsat 29e losing altitude?
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 ...
- 121k
10
votes
What does the Ariane 5 rocket use to turn?
The first stage of Ariane V has in fact RCS thrusters, but only for roll control. While the solid boosters are burning, roll control of the whole stack is exercised by differential gimbaling of the ...
9
votes
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Ariane 6 upper stage schematic showing integration of APU
I found a doctoral dissertation that discusses the possibility of increasing the thrust of the two nozzles (TAPUs) of the APU on Ariane 6's upper stage. The drawings in the dissertation when combined ...
- 2,301
8
votes
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Is the Ariane 5 rolled out or is the hangar moved away?
The Ariane 5 is moved from the BAF (FR: Bâtiment d’Assemblage Final, EN: Final Assembly Building) to the launch pad:
There is no encapsulation facility at the launch pad, which is "approximately ...
- 9,685
7
votes
Accepted
Does Arianespace have a modified Soyuz launch vehicle?
Soyuz launch vehicles have been launched from Arianespace's launch facility in French Guiana since 2011.
OneWeb has already used the French Guiana Soyuz in 2019 (Flight VS21)
"ownership" is ...
6
votes
Accepted
Why is ESA developing the Vinci engine rather than buying RL10Bs?
The RL10 is a terribly expensive engine to produce (I've seen estimates of US$25 million per unit), mainly due to its welded-tube nozzle construction. I expect Vinci will be substantially cheaper to ...
- 167k
6
votes
What are these circular spots on these Ariane V SRB nozzles?
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 ...
- 126k
6
votes
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Is vertical assembly worth the cost (Ariane 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 ...
- 126k
6
votes
Accepted
What is this flying debris during Ariane 5 liftoff
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 ...
- 1,064
6
votes
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Ariane 5 performance data for escape missions
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 ...
- 126k
6
votes
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How long does it take for Ariane 5 to roll to the launch pad?
For the upcoming JWST launch - which is presumably representative - the rollout will take a couple of hours:
Ground crews at the jungle spaceport in French Guiana planned to transfer the European ...
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5
votes
How to identify loads for a Payload Adapter System during Rocket Launch?
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.
- 126k
5
votes
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Why doesn't Ariane-5 lift off at T=0 seconds?
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 ...
- 126k
5
votes
Accepted
Will Ariane 5 ECA have LES for the launch of JWST?
There is no* safe condition used by Ariane 5.
It is not common to use Launch Escape Systems for UNmanned flights. Actually the hardware of a spacecraft is not as costly as you may think, the ...
- 3,308
5
votes
Why is Ariane-5's upper stage appear to vent exhaust post engine cut off?
ESA's space debris mitigation guidelines are aimed towards reducing the generation of space debris by following two approach
The most effective shortterm means of reducing the space debris growth ...
- 4,469
4
votes
Could we easily build a "super-heavy" Ariane 6?
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 ...
- 167k
4
votes
Why do Ariane rockets not have ice break off on liftoff?
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 ...
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4
votes
How much fuel did JWST save due to an accurate launch, and how much will remain after L2 orbit?
The three MCC course correction burns, which are listed In this NASA blog and and this NASA blog have totaled 24.4$\frac{m}{s}$ fuel used so far, in burns totaling 79.5 minutes.
Dec 25th, 20$\frac{m}{...
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