NASA Shakes, Bakes, and Rattles Lunar Spaceship 44
coondoggie writes to tell us that NASA has apparently successfully concluded putting the new Lunar Reconnaissance Orbiter through its paces. Using vibration and rotation tests NASA scientists were able to determine the center of gravity and were also able to observe the structural integrity during the vibration tests used to simulate launch aboard an Atlas rocket. "It is expected that the LRO will by the end of the year make its way to NASA's Kennedy Space Center in Florida for final launch preparations. The orbiter and the Lunar Crater Observation and Sensing Satellite, a mission to smack into the moon in search of water ice, are scheduled to launch atop an Atlas V rocket from Cape Canaveral Air Force Station in Florida sometime between Feb. 27, 2009 and the end of March 2009."
FRYING damnit, what about FRYING?!?! (Score:5, Funny)
Seriously. We need to test the hell out of this thing:
* Test monster-proofness of hatches and bulkheads.
* Ensure that air filters can handle sapient moon-dust clouds.
Oh . . . this is just a damn unmanned orbiter?
OK. Please forget this post. I'll use it again when they test the Orion lunar craft.
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* Test monster-proofness of hatches and bulkheads.
Yeah, but what if a piece of foam breaks off the Godzilla suit? Can it withstand that?
Young Zaphod Plays it Safe (Score:5, Insightful)
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It's just the first step in NASA's plan to make sure the Moon is "perfectly safe."
Yes, but (Score:5, Funny)
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Will they use Judas Priest to test it? (Score:4, Funny)
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I hope not! (Score:5, Insightful)
. Using vibration and rotation tests NASA scientists were able to determine the center of gravity...
That should be:
If they couldn't determine the center of gravity before they built the thing, they have some serious issues. Vibration characteristics are a bit more difficult, but I suspect the folks at NASA are smart enough determine those before they built the thing too.
Re:I hope not! (Score:4, Informative)
. Using vibration and rotation tests NASA scientists were able to determine the center of gravity...
If they couldn't determine the center of gravity before they built the thing, they have some serious issues. /p>
THAT should be: If they couldn't engineer the thing with the center of gravity exactly where they want it... Center of Gravity and Center of Lift are usually two things aircraft are designed around. Hopefully a rocket based craft would be designed with the center of lift centered in the engine cluster, with the vector pointing generally up the middle and through the center of Gravity of the whole ship. Vectored or differential thrust shifting this lift vector around that CG point to change where its going. If you dont put the CG where you want it, it doesnt fly where you want it to. Granted, the CG of the capsule is high enough on the rocket and of low enough mass that its CG point can probably be off a good bit and still be compensated for, but the CG should still be an easy engineering calculation given the computer models, etc. They should even have the CG pinpointed for every load scenario of passengers and other cargo items, so they can load the craft without displacing the CG too greatly.
Tm
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Re:I hope not! (Score:4, Interesting)
That should be:
If they couldn't determine the center of gravity before they built the thing, they have some serious issues
It is the difference between theory and reality.
Due to non-homogenous material like composite honeycomb panels and things notoriously difficult to model like wiring bundles, you have to do a mass properties test to know (and adjust) the mass distribution within some tolerance permitted by the launch vehicle.
Otherwise, spin stablized orbital injection burns might not give enough forward thrust due to product of inertia wobble.
The center of gravity is important. (Score:2, Funny)
Hmm... Center of gravity... For space... These days I'm more and more convinced that these scientists are just pulling our leg.
"Hey Mort, let's ask them for billions so we can build something to send to space!"
"Haha, space? Where do you come up with this stuff?"
"Yeah, it'll be great!"
"I have another idea, let's tell them we need to determine the center of gravity!"
"The center of *gravity* for *spacecraft*? Right after we told them we found water on Mars? Isn't it a bit obvious?"
"No man, it
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Hmm... Center of gravity... For space... These days I'm more and more convinced that these scientists are just pulling our leg.
They probably did spend way too much money doing it, but testing for the center of gravity is important if you actually want it to get into space and in the right direction. And in the extreme case, it keeps the rocket from arching back down to earth.
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Center of *gravity* on an ungravity scenario?
I must point out that despite the center of mass being the more correct way to describe it under all scenarios, in this case I'm correct. During lift-off, gravity still acts on the object uniformally. If it is not placed in correct alignment based in its center of mass/gravity, the shuttle will be off balance, if even by a little bit, and would need a course-correction. In practice it wouldn't make much of a difference, but still...
I'll keep my card, thank you very much.
Re:The center of gravity is important. (Score:5, Informative)
I happen to be an aerospace engineer (formerly at JPL), and the center of gravity is actually extremely important after launch as well. NASA is not pulling your leg.
You may replace the "center of gravity" with "mass distribution" or "center of mass" if it makes you feel better. The term is a hold-over from the early days, and is a term of art than any engineer would recognize and understand. You just need the contextual information that an engineering education provides.
The actual product of the test is both a location of the center of mass of the spacecraft and a mass distribution matrix, commonly called an inertia matrix or inertia tensor.
The attitude control system (my specialty) requires very accurate knowledge of where the center of gravity and the geometric centers are. These are used to compute both control and disturbance torques on the spacecraft. Without a C.G test it is almost impossible to get the pointing performance (sub-arc-second) many of the payloads require on modern spacecraft. The CAD/Solidworks models are rarely good enough for this, and although some things can be done to estimate the C.G. in-orbit, you still have to get through launch and initial checkout with whatever data you launched with. C.Gs are estimated in space to handle things like fuel loss.
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I know, I'm an engineer myself, it's just funnier to think that all this is just an elaborate prank :P
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This is routine testing (Score:5, Informative)
That's normal stuff. I used to work for a company that built satellites. One of their test fixtures was a shake table connected to a water-cooled voice-coil actuator with a megawatt amplifier driving it. They had accelerometer data from actual launches, and they'd use that to drive the shake table.
What about the smell test? (Score:2)
5 ton shake table (Score:4, Interesting)
I remember visiting a facility in Brooklyn shake testing a 5 ton piece of gear for a Navy ship. When we got out of the car we noticed the parking meter was vibrating due to vibrations being transferred to the earth. I'm sure the folks living nearby must have enjoyed it when stuff fell over in their apartments. Later the gear was shock tested by attaching it to a barge and setting off explosive charges in the water. This was done in an old flooded slate quarry.
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That is nothing. The place I was working at in Covina was doing a full scale dead load creep tests when the Whittier Narrows earthquake occured. The three story tall deal load machine failed the test . . .
What happened to the Indian & Japanese spacesh (Score:2)
NASA gets a lot of microscopic attention for a spaceship which won't even launch until the next president, if the moon program still exists by then. Meanwhile there are still developments with an Indian spaceship which is supposed to launch this year & the Japanese spaceship put out another movie from the actual moon yesterday, just in a format no-one can play.
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Info on the Indian spacecraft can be found at http://www.chandrayaan-i.com/ [chandrayaan-i.com]
As for the attention LRO is getting... well good! The various instruments on this orbiter will provide massive amounts of data, useful in several fields of science. It's also an important step for the planned presence on the moon.
So, does that mean the Easy Bake oven goes to (Score:1)
"QUEASY Bake"?
Robot scouts ftw! (Score:3, Interesting)
Open-Source the Darn thing (Score:1)
This - http://hardware.slashdot.org/article.pl?sid=08/08/01/1344232 [slashdot.org] (3D Printing for Everyone) is a great opportunity for the community to develop lunar spaceships. If they can make a Lego-kit with a working scale engine, remote control and propellant - I open-source develop the heck out of this thing!
Anyone else?