2. Not most dangerous; less dangerous than launch for certain. And the rocket sitting fueled on the launchpad is not quite safe either.
3. The aluminium shell can evacuate the area in time. Astronaut climbing to it from that concrete room can't.
4. If you modify things deviating from the regular procedure for this specific type of rocket, the most dangerous part (launch) becomes much more dangerous.
Take a rocket that is loaded with so much payload and fuel it has TWR of exactly 1 on launchpad. It must burn some fuel to actually start climbing. Now keep adding more fuel instead. It won't take off until all that extra fuel is burnt and its TWR climbs above 1. And it will still burn lots and lots of fuel before it gets up to any reasonable speed.
Adding 10% fuel, and 10% thrust, plus 10% infrastructural overhead, will give you 10% more payload. Adding just fuel, not changing thrust nor infrastructure, from a certain point on, has rapidly diminishing returns. And all launches operate well on the "diminishing returns" side of the curve, following the adage 'fuel is cheap, engines are expensive'.
For your truck analogy, adding 10% of payload to climb a hill requires extra fuel. But that extra fuel needs to be carried uphill as it's spent as well, adding to total mass - and requiring even more fuel. And add to that that the truck's wheels are constantly slipping.
That one is the infamous Amos-6. I believe GP referred to some prior unspecified event. Amos was not an instant explosion; it was a rapid fire, and indeed LES would save the day.
Most of Dragon cargo launches don't reach full payload capacity, being limited by volume more than mass. With manned launch there will be much more empty space added. That means they absolutely don't need the extra delta-V.
The primary benefit to SpaceX fueling immediately before launch is that they do it before every cargo launch nowadays, and they have at least two launches per month. They have all the systems and engines calibrated for supercooled propellants, and everything is running smoothly. The last thing they want is change the process when they are launching humans to orbit.
It's safer. Is it entirely safe? And in case something *does* go wrong, while the astronauts are on the launchpad, preparing for boarding, or on the lift, are they safer than inside the capsule?
The difference is "higher chance of accident with a low chance of death" vs "low chance of absolutely deadly accident."
The 2016 explosion didn't rip the fairing apart. There's the entire service module (trunk) as a buffer between the launcher and the capsule. The engines are on the sloped sides, not beneath the capsule. And in the end, after analyzing the incident, Musk announced "Dragon would have been fine"
> it lessens the vehicle's weight because it can be built smaller and lighter....which would be an issue in pretty much any other case, except SpaceX launchers are reusable, so the extra cost is insignificant.
As for payload to orbit, once again, we're talking manned launches. The launcher in current form, fueled before boarding, is perfectly capable of fulfilling the payload requirements for that type of missions. There's simply no need for that extra payload capacity. It would be worthwhile for cargo launches, but with these the entire boarding issue doesn't exist.
The volume of propellant is reduced when supercooled, yes, but even if the capsule is boarded after fueling the rocket up, the propellant doesn't heat up to boiling point, or anywhere close. You're losing maybe 2% of volume, not the entire 10%.
Due to tyranny of rocket equation, increasing fuel capacity by 10% does not increase payload capacity by 10%.
As for added risk: once again, while the risk of an emergency situation occurring with astronauts in danger radius is increased, the risk of astronaut death in case such occurs is actually reduced, as at no point are they in position where they wouldn't be able to escape. Since the moment fueling starts, nobody has to approach the rocket anymore, and the astronauts can activate LES at any time. This is not the case if they need to board a fully fueled rocket.
After fueling, the rocket is supposed to be again inert. Leaks, short circuits, construction bending under strain, oxygen corroding stuff, static charge accumulating, ice buildup, these things can cause problems even on an "inert" rocket.
Of course LES is not meant as replacement for safe procedures, but having the secondary safety feature accessible and ready to use throughout all operations is preferable to just relying on nothing going wrong during boarding. I'd call it a very valid part of safety procedures.
And they really, really don't need to squeeze these extra few kilograms of oxidizer at the last second for manned launches. What are they gonna load up into the saved space? Several extra cans of food? An extra astronaut? Extra fuel to reboost ISS into an even higher orbit? Launches to ISS are as routine as they get. They follow a fixed schedule, if there's need for extra payload, it can be squeezed into a cargo mission, there's very little benefit from increasing the payload capacity of a manned launch above nominal, and liquid oxygen is cheap enough it would be outright stupid to try to save off on the hour or so of boil-off.
Since Apollo, all manned vehicles use atmosphere-like mix at 1bar. Apollo used pure oxygen at about 0.3 bar, which was sufficient for breathing but made everything extremely flammable. (although EVA suits are still pressurized to 0.3 bar with pure oxygen - thankfully the chance for a fire inside a spacesuit is rather low.)
Is it safer to do a whole lot of manipulation (as required with the boarding procedure, climbing the launch tower, sealing the hatch etc) around a rocket that is already filled with potentially explosive material, and might blow up at any point consuming in a ball of fire anything within the area that can't get away fast enough?
Or would it be safer to enter the capsule while the rocket is just an inert tube, buckle up, and wait till the rocket is filled up, sitting comfortably in a hermetic capsule equipped with a launch escape system - capable of getting away from the explosion fast enough to be safe?
Paradoxically, before the launch, the crew compartment is the safest of all places near the rocket.
As soon as they invent cameras that can display stuff on the surface of their lenses and speakers that have displays on the membrane, the cutouts will be gone.
never mind, they managed to purge the summary of any relevant data, filling it with sensationalist 'mind-boggling', 'extreme' and '16 years of preparation'.
Slashdot Mirror
The idea of microcode is neat, but lawyers and marketing drones can shit up any neat idea by tacking a shitty license on top of it.
1. Not during. Before.
2. Not most dangerous; less dangerous than launch for certain. And the rocket sitting fueled on the launchpad is not quite safe either.
3. The aluminium shell can evacuate the area in time. Astronaut climbing to it from that concrete room can't.
4. If you modify things deviating from the regular procedure for this specific type of rocket, the most dangerous part (launch) becomes much more dangerous.
I don't talk your ghetto slang, and I differentiate between combustion, deflagration and detonation.
I wonder what sort of shrapnel can penetrate the heatshield...
On the flip side...
Take a rocket that is loaded with so much payload and fuel it has TWR of exactly 1 on launchpad. It must burn some fuel to actually start climbing. Now keep adding more fuel instead. It won't take off until all that extra fuel is burnt and its TWR climbs above 1. And it will still burn lots and lots of fuel before it gets up to any reasonable speed.
Adding 10% fuel, and 10% thrust, plus 10% infrastructural overhead, will give you 10% more payload. Adding just fuel, not changing thrust nor infrastructure, from a certain point on, has rapidly diminishing returns. And all launches operate well on the "diminishing returns" side of the curve, following the adage 'fuel is cheap, engines are expensive'.
For your truck analogy, adding 10% of payload to climb a hill requires extra fuel. But that extra fuel needs to be carried uphill as it's spent as well, adding to total mass - and requiring even more fuel. And add to that that the truck's wheels are constantly slipping.
That one is the infamous Amos-6. I believe GP referred to some prior unspecified event. Amos was not an instant explosion; it was a rapid fire, and indeed LES would save the day.
Can you link to that "previous falcon fueling" accident you refer to?
Most of Dragon cargo launches don't reach full payload capacity, being limited by volume more than mass. With manned launch there will be much more empty space added. That means they absolutely don't need the extra delta-V.
The primary benefit to SpaceX fueling immediately before launch is that they do it before every cargo launch nowadays, and they have at least two launches per month. They have all the systems and engines calibrated for supercooled propellants, and everything is running smoothly. The last thing they want is change the process when they are launching humans to orbit.
It's safer. Is it entirely safe? And in case something *does* go wrong, while the astronauts are on the launchpad, preparing for boarding, or on the lift, are they safer than inside the capsule?
The difference is "higher chance of accident with a low chance of death" vs "low chance of absolutely deadly accident."
The 2016 explosion didn't rip the fairing apart. There's the entire service module (trunk) as a buffer between the launcher and the capsule. The engines are on the sloped sides, not beneath the capsule. And in the end, after analyzing the incident, Musk announced "Dragon would have been fine"
> it lessens the vehicle's weight because it can be built smaller and lighter. ...which would be an issue in pretty much any other case, except SpaceX launchers are reusable, so the extra cost is insignificant.
As for payload to orbit, once again, we're talking manned launches. The launcher in current form, fueled before boarding, is perfectly capable of fulfilling the payload requirements for that type of missions. There's simply no need for that extra payload capacity. It would be worthwhile for cargo launches, but with these the entire boarding issue doesn't exist.
The volume of propellant is reduced when supercooled, yes, but even if the capsule is boarded after fueling the rocket up, the propellant doesn't heat up to boiling point, or anywhere close. You're losing maybe 2% of volume, not the entire 10%.
Due to tyranny of rocket equation, increasing fuel capacity by 10% does not increase payload capacity by 10%.
As for added risk: once again, while the risk of an emergency situation occurring with astronauts in danger radius is increased, the risk of astronaut death in case such occurs is actually reduced, as at no point are they in position where they wouldn't be able to escape. Since the moment fueling starts, nobody has to approach the rocket anymore, and the astronauts can activate LES at any time. This is not the case if they need to board a fully fueled rocket.
Why wouldn't it be? Critical failure of rocket on launchpad, endangering the astronaut lives. This is the primary job of the LES.
> After fueling, the rocket is once again inert.
After fueling, the rocket is supposed to be again inert. Leaks, short circuits, construction bending under strain, oxygen corroding stuff, static charge accumulating, ice buildup, these things can cause problems even on an "inert" rocket.
Of course LES is not meant as replacement for safe procedures, but having the secondary safety feature accessible and ready to use throughout all operations is preferable to just relying on nothing going wrong during boarding. I'd call it a very valid part of safety procedures.
And they really, really don't need to squeeze these extra few kilograms of oxidizer at the last second for manned launches. What are they gonna load up into the saved space? Several extra cans of food? An extra astronaut? Extra fuel to reboost ISS into an even higher orbit? Launches to ISS are as routine as they get. They follow a fixed schedule, if there's need for extra payload, it can be squeezed into a cargo mission, there's very little benefit from increasing the payload capacity of a manned launch above nominal, and liquid oxygen is cheap enough it would be outright stupid to try to save off on the hour or so of boil-off.
Thing is putting astronauts in a capsule equipped with a Launch Escape System while the rocket beneath can't explode yet, makes it actually *safer*.
Since Apollo, all manned vehicles use atmosphere-like mix at 1bar. Apollo used pure oxygen at about 0.3 bar, which was sufficient for breathing but made everything extremely flammable. (although EVA suits are still pressurized to 0.3 bar with pure oxygen - thankfully the chance for a fire inside a spacesuit is rather low.)
Here's a video of Soyuz using its LES. It definitely saved the crew.
Is it safer to do a whole lot of manipulation (as required with the boarding procedure, climbing the launch tower, sealing the hatch etc) around a rocket that is already filled with potentially explosive material, and might blow up at any point consuming in a ball of fire anything within the area that can't get away fast enough?
Or would it be safer to enter the capsule while the rocket is just an inert tube, buckle up, and wait till the rocket is filled up, sitting comfortably in a hermetic capsule equipped with a launch escape system - capable of getting away from the explosion fast enough to be safe?
Paradoxically, before the launch, the crew compartment is the safest of all places near the rocket.
As soon as they invent cameras that can display stuff on the surface of their lenses and speakers that have displays on the membrane, the cutouts will be gone.
You mean, the Confederates(Democrats) were conservatives, and Lincoln (Republican) was not?
" Ironically I don't see any Democrats doing that shit. "
Then start looking unironically. You are doing that shit right in your post without even realizing it.
Like that "Grab 'em by the pussy," Look up the origin of that "quote." Find the actual quote, actual context.
ops. replied to wrong post.
Beter recheck your history books. Or just Wikipedia. Democrats were the core of Confederation, opposed by Lincoln, a Republican.
never mind, they managed to purge the summary of any relevant data, filling it with sensationalist 'mind-boggling', 'extreme' and '16 years of preparation'.
hologram camera maintenance break.
There are - ask the Chinese!
Chang'e 3 is fully operational (except for the rover.)