'The Ares I test is supposed to take place this year'
No it's not. The first test of Ares 1 is due in 2011.
NASA has announced a successful test related to its new Ares I astronaut-carrying rocket, the planned successor to the space shuttle. A key part of the structure, critical to safe parachute recovery of the discarded first stage, successfully blew itself up last week during a trial on the ground in Utah. The Ares I/Orion stack …
"once lit there is no off, there is no throttle either
Solid fuel is either on - full burn, or off"
I could be mistaken, but I thought they were supposed to change it so [somehow] the solid booster can be shut off in some way. Still no way to throttle it, though.
And what is different about this skirt design vs the one used on the Apollo rockets? Haven't they already messed with pyrotechnically separating different sections? Or is it the vibration of the solid boosters that requires a stronger design...
The first Ares test IS scheduled for this year. Ares 1 X is a test of the first stage solid rocket. The rest of the stack (ie second stage and crew exploration vehicle) will just be dummy mass though. See PDF from NASA:
It goes on to say :
"The Ares I-X test is part of a larger flight test program that will include five tests of the Orion launch abort system between 2008 and 2011, a follow-on Ares I-Y test in 2012, and an integrated test of both the launch vehicle and spacecraft, called Orion 1, in early 2013. "
There are advantages to solid fuel, such as it being more stable, less complex, more thrust for the same size, etc. The first stage doesn't need variable thrust - it just needs to get the rocket as high as possible. The second stage is liquid, and allows for varied thrust. The space shuttle has been using a combination of solid fuel and liquid fuel since its inception - it has two solid boosters on either side of a liquid tank. There have been 124 space shuttle missions, with two shuttles destroyed - one by a fault in a solid rocket booster, and one because of a piece of foam insulation used to keep the liquid fuel cold. So two accidents, one due to each fuel type.
The Ares I X test is planned for July 2009, although some delay looks likely. A four segment SRB with a dummy fifth segment.
A test of the first-stage flight control systems, parachute recovery system and the system that separates its first and second stages. Parts are mock-ups, but an aerodynamically exact mock-up of the real Ares 1.
@ Solid fuel????
Yes. Very similar to the two used for every Shuttle flight.
Huh, I thought it really WAS going to be a rocket blowing up on the pad, with some NASA goon (the bureaucrats rather than the scientists) saying "Guh, it was supposed to do that." What do you know it appears it was a REAL test.
RE: solid fuel?
It's a major problem if the rocket goes off course. Otherwise, it's safe and reliable. There's no "off", but there's ALSO not all this complicated plumbing with liquid oxygen and propellant, no valves, no O-Rings (Challenger's downfall), no problems with the mixture, and so on. They already know how much fuel is needed to get launched so it has that much. From what I've read, the tanks alone for a liquid fuel setup add significantly to the weight, which is a big issue for a launch into space.
If there's an off-course condition, the launch vehicle has basically an ejection system*, then the rocket can be remotely blown up. (*Is the ejection system survivable? It's supposed to be, but is definitely better than being rocketed back into the ground.)
When they go bang, they do so without *any* warning whatsoever, unlike liquids which usually let you know in time to exit stage left.
We already lost one Shuttle crew to solids, why are we doing this? Because NASA admin are idiots, and again not listening to their engineers.
My tax dollars "at work" as usual. We're hoping Obama tosses Griffin on his ear, and we can scrap this POS, but so far, he hasn't.
"Upper skirt extension"?
First there's that screw-up with the nappy-wearing loony astronaut, and NOW the US taxpayers are funding some sort of high-tech exploding transvetism.
Well *I'm* not impressed by the direction government-funded projects have taken under the new administration. So much for the increased oversight and responsible spending President Obama promised.
Disgusted of Tunbridge Wells.
By Fred Posted Monday 2nd February 2009 18:35 GMT
The primary stage is to be solid fuel?!
once lit there is no off, there is no throttle either
Solid fuel is either on - full burn, or off
Seems like an accident waiting to happen" "
Its not like the Astronauts need to slow down a spacecraft on the way up to space thats why the boosters always are solid fuel and this is nothing new. Spacecraft Manoevering Thrusters on the other hand are alway liquid fuel because they are only fired when needed for short durations.
Actually, Ares uses Mediated Solid Fuel (or MSF) which uses engineered "smart particles" distributed throughout the oxidising substrate to accelerate or decelerate solid fuel burn.
By applying targeted high energy radio waves at the fuel source various characteristics of the smart particles can be tuned in real time - including volume, and reactivity. These can be changed gradually to change flight characteristics (speed adjustment), or rapidly to - almost instantaneously - render the solid fuel source effectively inert and "shut down" the solid fuel engine.
More information can be found at: http://en.wikipedia.org/wiki/AFakeWikiPage
Yup. Before the Shuttle NASA considered solid fuel rockets to be too dangerous to be used for human flights. It was only after Congress told them that they could only have 1/2 of what they were asking for to design what became the Shuttle that money won out and they decided to use them (and due to more political finagling we ended up with the Challenger disaster).
Actually the SRB on Challenger never exploded, the o-ring failed (due to extreme cold on the launch pad) on one of the section joints allowing exhaust gas to escape which cut through the supports which held the SRB to the external tank. They had had this o-ring fail on previous flights but the hole was blocked by debris, which did happen on Challenger but was dislodged due to large amounts of steering caused by wind shear. In all likelihood if the oring had failed on the other side of the SRB then there wouldn't have been an accident. I suspect that if something similar happened with Ares I then it would not cause a major failure.
Yep - It was actually the liquid fuel that exploded after the leak from the booster melted through the liquid fuel tank. It wasn't debris and wind shear that caused it though. The low temperature (18°F) prevented the o-rings from being able to flex as needed, which allowed hot gasses to escape. In previous flights, the secondary o-ring was able to prevent leaks when the primary failed.
do they need to blow it apart? surely a fails under tension loading type coupling would be best here? ie just stack it on top when stationary gravity ensures compression attachment during launch the thrust ensures compression, after the solid fuel is burnt the connection goes into tension and fails...
Solid motors (the Shuttle SRBs at least) do have some capability to be switched off in flight. The burn rate of these propellants is strongly dependent on internal pressure. Opening a large vent port (once only, with explosives) at the top of the booster drops the pressure and reduces burn rate to a crawl. This is already done on the Shuttle when the SRBs are jettisioned.
It makes little difference to Ares (I've no idea if such a system is even fitted), but it's a workable bit of rocket motor technology.
"But there's only one of them - so it's twice as safe as the Shuttle!"
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Or more accurately, half as dangerous. 1% chance of failure with 2, 0.5% chance with 1 (I'm making these up as an example), so safety increase from 99.0% to 99.5% - not really doubling.
And that's ignoring the combinational statistics involved (that 1% is made up of 1 failing, the other failing, or both failing)
Though as Jimmy Carr mentioned on QI, the odds are always 50/50. It either blows up, or it doesn't
Thank god someone here noticed that tiny little detail.
The major design flaw that caused the loss of both space shuttles was the side-by-side design. If NASA had used their previous stacked-on-top design (which they have reverted to here) the blow-out on the booster would not have hit anything, and the foam loss would not occurred either. The first incident then becomes potentially survivable, and the latter a non-incident.
With regard to the skirt, I don't believe that the Apollo first stages worried about recovery, and therefore did not need to care about parachute deployment.
A Nonymous said:
"thats why the boosters always are solid fuel and this is nothing new."
Hah, it's only been used on the shuttle with disasterous consequences in 1986. It had happened before, and can be seen in various launch videos, but in 1986, the burn through was pointed at the big tank, and that blew up at 73 seconds, killing all aboard as they fell back to earth.
Solid booster technology is a cheap way to go, but a dangerous way to go, and no one outside NASA management is happy to see it again in this Ares I stack. It would save a ton more money if they just used a Delta rocket to launch the crew, and an Atlas V to launch their lunar lander. I have no idea why Griffin though we needed another damned launch option, when we have so many already. Lockheed can build the capsule in the next few years, and with a launcher off the shelf, we would not have the multi-year gap they project now.
All you "solid fuel=teh sux" proponents seriously need to review the design requirements of a liquid fuel booster before you weigh in, especially the bit about how to move the fuel and oxidiser quickly enough to suit the application. I thought everyone in our business understood the basic idea that high speed moving parts in the critical path are a bad thing, to be moved away from if any viable alternative presents itself.
As for the chance of explosion doing away with the crew - rockets are inherently super dangerous. Only a fool would think that so much energy piled into a pipe could be called "safe" after we set fire to the contents. The thing is *designed* to explode for Azathoth's sake, just very slowly in a "controlled" manner.
Perhaps it is possible to get the crew away from the fireball of an out-of-design-spec excursion event in time. I seriously doubt it, and from the suggestions I've seen coming later than Gemini (Apollo used older "Mercury-era" tech) the whole astronaut safety thing is a smoke and mirrors affair designed to allow politicians to speak in public about things they manifestly know nothing about while spending public money venally to benefit themselves, their constituents and not at all the people sitting in the cabin at t=0.
If only the general public could be educated that Real Life <> Star Trek and that travelling to the ISS isn't like nipping down to the shops for twenty Rothmans (unless you smoke 'em), perhaps the money to properly investigate the useful applications of space tech would become available (hint, cheap power is still do-able with tech we already have to hand) and we could have the nifty new frontier (which is the bit I want) as a side product.
For the love of Arthur. It's nearly 2010 and still no Space Wheel.
I agree with Craig Matthews who say; Instead of trying to rush forward and get this new vehicle human-rated, what is wrong with resurrecting the Apollo/Saturn technology? Aside from space and size limitations, what was wrong with Apollo?
The J2-X engine proposed for Ares' upper stage is a direct descendant of the J2s used in the Saturn V, but with the sort of gains in efficiency and manufacturing that might be expected after 55 years. A stack design in which all the potentially explosive stuff is as far away from the crew as possible is, again, identical to Saturn V, and the Orion module is largely based on Apollo (it even looks identical at a glance), albeit with the experience of that 55 years built in, not to mention a good deal more computing power.
Repurposing the Shuttle SRBs makes good sense: the plants are up and running already and the SRBs are known to work. They can do the job, so why reinvent the wheel? Getting Saturn V manufacturing up and running again would be no mean feat, and doubtless take longer and cost more.
The more pertinent question is, and has been for a long time, just how NASA got into a position where it had no credible plan in place to replace the Shuttle.
"But there's only one of them - so it's twice as safe as the Shuttle!"
In defence of Martin, your apparently reasonable skills at arithmetic and pedantry aren't matched by the level of irony-detection and humour-appreciation required for reading these comments.
Do we really all need to use the joke icon as a defence against the irony deficient?
<quote>So much for the increased oversight and responsible spending President Obama promised.</qoute>
Wow - I knew some people thought that Obama is an all seeing god but even god will take some time to go through the entire US budget. What has he been in Office - 16 days????
Oops! Sorry I did not mean to tell everyone that Obama is god.... what if that is widely known??? Time to leave before the natives get upset
The story that I heard was that the engineers wanted to build single piece solid rockets on site in Florida - but because of the pork issues the rockets "needed" to be built in Utah. That required that they be made in two parts so that they could send them to Florida on the train... Sounds like the way Chrysler products are designed and built.