May 19, 2006 4:00 AM PDT

NASA searches for a better heat shield

A correction was made to this story. Read below for details.
MOUNTAIN VIEW, Calif.--Scientists here at the NASA Ames Research Center are testing high-tech materials they hope will hold up to temperatures three times hotter than the surface of the sun.

The research could lead to the improvement of the so-called heat shields that are critical to space flight. The space shuttle Columbia, for example, exploded during re-entry into the atmosphere in February 2003 when a hole in its outer surface caused the craft to break apart under extreme temperatures.

Right now, NASA is designing a heat shield for the Crew Exploration Vehicle, a planned spacecraft the Bush administration hopes will transport six astronauts to the moon and back by 2012. On Thursday, NASA Ames opened the lab, called the arc jet facility, to the press and demonstrated a test that was akin to seeing a lightning bolt up close.

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Designing a heat shield for the CEV will be a challenge because it will travel beyond what scientists call low-Earth orbit. A craft traveling to the moon can reach speeds of 25,000 miles per hour upon re-entry--8,000 miles per hour faster than a spaceship returning from low-Earth orbit. The difference in speed can make temperatures the ship has to withstand increase more than tenfold, said James Reuther, product manager of heat-shield testing for the CEV.

"It's a real challenge," Reuther said.

The arc jet where NASA tests materials is a 20-foot-long hollow tube with air running through it. When it's turned on, two charges are emitted, which create a bolt of lightning. That lighting, or plasma torch, gets directed on shield materials the size of hockey pucks, which are at the end of the tube. The lightning inside the tunnel travels at supersonic speed, or 17,000 miles per hour, and heats up to two or three times the temperature of the sun.

With the conditions of atmospheric re-entry simulated, NASA scientists can measure the effect on various materials and whether they can take the heat. They also use computer simulations to predict the materials' sturdiness. When the heat shield is eventually built, it will be 16.5 feet in diameter and shaped like an upside-down frisbee attached to the base of the CEV's crew capsule.

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Video: Nothing's too hot for NASA
Designing heat shields for the Crew Exploration Vehicle.

Better heat resistance won't be the only difference in the planned spacecraft's heat shield. Researchers are also looking at ways to build the heat shield out of a series of "blades" that would melt away as the ship re-enters the atmosphere. Current heat shield designs, like those on the bottom of the space shuttle fleet, rely on tiles that can be reused.

So far, NASA is studying five test materials for these blades. They include a honeycomb structure with blades made of resin and quartz and another made of something called Pica, which is a thermo-protection material designed at Ames that combines various ceramics and composites. The others are handmade, and their details haven't been revealed yet.

NASA Ames has been involved in testing heat-resistant materials for 45 years. Its facility is the largest in the United States; the arc jet can generate up to 60 million watts of energy.

 

Correction: This story incorrectly identified the month of the space shuttle Columbia disaster. The accident occurred in February 2003.

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22 comments

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heat shields
Is the solution in finding better materials or in a new system of protecting the craft?
What system does nature use to protect us from the sun's heat?. Why not duplicate the system artificially from the exterior of the spacecraft to the interior?
Just thinking.

wahmadu
Posted by wahmadu (4 comments )
Reply Link Flag
Well...
First, good idea, second, bad concept. First, designing a better method is crucial. We have lost waay too many Astronauts to NASA's famous yestertech methodoloy, and there ARE better ways ou there already. Just need to buy them. Cheap. Such methods as the heat dissipative cement foam designed by an Arizona Sculptor, that they can spread in a fairly thin layer on a house and it's heat/fire PROOF. Not resistant, proof. Another way would be to utilize Burt Rutan's re-entry methods, the "falling leaf" method. He's done it. Twice. It works perfectly. He won the X Prize doing it. No heat generated, no shielding needed. And the garbage about the return being so fast they need new ways to guard against higher heats. There are reaction mass-free ways to slow down.
As to how nature protects us from the heat of the Sun being used, well, "nature" "uses" something like the inverse square law to "protect" us. It's our distance from the sun that does it. I may be wrong on the exact equations involved, but the concept is correct. Distance is the key. So, if we take NASA at it's word,which would be foolish, then to use nature's methods, we'd have to place the capsule 3-4 times farther from re-entry heat than we are from the Sun. This may not be an exactly workable method. Nice thought, but really, unworkable.
Posted by Souldreamer (13 comments )
Link Flag
heat shields
Is the solution in finding better materials or in a new system of protecting the craft?
What system does nature use to protect us from the sun's heat?. Why not duplicate the system artificially from the exterior of the spacecraft to the interior?
Just thinking.

wahmadu
Posted by wahmadu (4 comments )
Reply Link Flag
Well...
First, good idea, second, bad concept. First, designing a better method is crucial. We have lost waay too many Astronauts to NASA's famous yestertech methodoloy, and there ARE better ways ou there already. Just need to buy them. Cheap. Such methods as the heat dissipative cement foam designed by an Arizona Sculptor, that they can spread in a fairly thin layer on a house and it's heat/fire PROOF. Not resistant, proof. Another way would be to utilize Burt Rutan's re-entry methods, the "falling leaf" method. He's done it. Twice. It works perfectly. He won the X Prize doing it. No heat generated, no shielding needed. And the garbage about the return being so fast they need new ways to guard against higher heats. There are reaction mass-free ways to slow down.
As to how nature protects us from the heat of the Sun being used, well, "nature" "uses" something like the inverse square law to "protect" us. It's our distance from the sun that does it. I may be wrong on the exact equations involved, but the concept is correct. Distance is the key. So, if we take NASA at it's word,which would be foolish, then to use nature's methods, we'd have to place the capsule 3-4 times farther from re-entry heat than we are from the Sun. This may not be an exactly workable method. Nice thought, but really, unworkable.
Posted by Souldreamer (13 comments )
Link Flag
Magnetic Field Protection?
Sorry for my lack of advanced physics knowledge, but shouldn't you be able to contain heat away from the ship by using a strong magnetic field. I know they use magnetic fields to contain super hot plasma reactions, so couldn't you have one facing away from the ship, or is too much energy involved? I would think they could have some type of sterling engine or series of engines that could capitalise off the intense re-entry heat and power the field itself. I must be missing something, or I would think someone would have thought of this already.
Posted by MrHandle (71 comments )
Reply Link Flag
not quite right
heat is not something you can move away, the heat is caused by friction of the shuttle hitting the air at great speeds, this causes the heat. this idea would work if a magnetic field could keep the air off the surface of the shuttle but it can't. the heat is not electromagnetic in nature so magnetic field would have no effect on it.
Posted by R K K9684 (13 comments )
Link Flag
Magnetic Field Protection?
Sorry for my lack of advanced physics knowledge, but shouldn't you be able to contain heat away from the ship by using a strong magnetic field. I know they use magnetic fields to contain super hot plasma reactions, so couldn't you have one facing away from the ship, or is too much energy involved? I would think they could have some type of sterling engine or series of engines that could capitalise off the intense re-entry heat and power the field itself. I must be missing something, or I would think someone would have thought of this already.
Posted by MrHandle (71 comments )
Reply Link Flag
not quite right
heat is not something you can move away, the heat is caused by friction of the shuttle hitting the air at great speeds, this causes the heat. this idea would work if a magnetic field could keep the air off the surface of the shuttle but it can't. the heat is not electromagnetic in nature so magnetic field would have no effect on it.
Posted by R K K9684 (13 comments )
Link Flag
I had the same idea some time ago :) Apparently they have already thought about that (see a random paper here http://www.jstage.jst.go.jp/article/jjsass/54/628/54_181/_article or just look for "electromagnetic heat shield"). Sure: normally you can not contain "heat" using a magnetic field. On the other hand you can deflect charged particles in a hot plasma and - hopefully - reduce their heat transfer to the ship body. With all the speed and high pressure involved I guess it is a hell of a problem... but, why not!
Posted by Swhel (2 comments )
Link Flag
Plasma aerodynamcis

even better, look at this: http://www.spacedaily.com/reports/AFRL_Proves_Feasibility_Of_Plasma_Actuators.html
There seems to be quite a bit of research around plasma physics and hypersonic flight in recent years. If you can fabricate electromagnetic flaps then you can possibly also deflect ionized particles produced at re-entry away from the ship surface.
Posted by Swhel (2 comments )
Link Flag
"so called"
"so called" heat shields? Why the skepticism? They're called heat
shields, no big deal.
Posted by CE10 (11 comments )
Reply Link Flag
"so called"
"so called" heat shields? Why the skepticism? They're called heat
shields, no big deal.
Posted by CE10 (11 comments )
Reply Link Flag
NASA
I sure hope they can find what they need! ! !
Posted by kussart1 (2 comments )
Reply Link Flag
NASA
I sure hope they can find what they need! ! !
Posted by kussart1 (2 comments )
Reply Link Flag
 

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