A carbon fiber-reinforced ceramic composite material is on its way to Jupiter on the Juno spacecraft. The composite forms an optical bench on the outside of the spacecraft at the end of one of the solar array wings.
The materials manufacturer, SGL Group, exhibited an example of the optical bench at the recent Hannover Fair in Germany. The optical bench is mounted on a stable magnetometer boom, and holds the magnetometer that will measure Jupiter's magnetic field.
Juno, which was launched last August, is scheduled to arrive at Jupiter in 2016. It will orbit Jupiter's poles for about a year, taking the first pictures of the planet's polar regions, making maps of its gravitation and magnetic fields, and measuring the amount of water and ammonia in Jupiter's atmosphere.
A carbon fiber-reinforced ceramic composite material forms an optical bench on the Juno spacecraft, scheduled to arrive at Jupiter in 2016. (Source: NASA)
On Earth, optical tables are usually made of a sandwich structure consisting of outer sheets of steel or aluminum, or sometimes carbon fiber, enclosing a honeycomb structure. Optical benches, or rails, are a smaller version, and consist of a long, narrow piece of metal, usually steel or aluminum, shaped like a shallow rain gutter, which components can be bolted onto.
On a spacecraft, the material for this application had to be nonmagnetic, as well as light in weight and extremely strong. At the same time, it had to withstand the high thermal and mechanical stresses that occur during both the launch of the spacecraft and the flight to Jupiter.
SGL said its Sigrasic material, a carbon fiber-reinforced silicon carbide, was chosen as the material for the optical bench because of its balance of properties. Combing carbon fibers with a ceramic matrix gives the material lightweight and high resistance to wear and fracture, as well as enough stability to withstand temperature extremes.
The material is manufactured by infiltrating carbon fiber-reinforced carbon with silicon. Because of the way that the carbon fibers are reinforced, when the hard silicon carbide material is stressed it becomes pseudo-ductile, so it bends instead of breaking. The material is used in structural components for aerospace and industrial applications, as well as components for high-temperature applications, chemical process equipment, and oxidation-resistant and thermal shock-resistant components for glass processing.
A well-known application for the carbon-ceramic material is the brake disk, which debuted in 1999 and appeared as a standard component on the Porsche GT2. It has since been used in other luxury and sports cars.
The optical bench was by collaboration among SGL subsidiary: HITCO Carbon Composites, Electro-Tech Machining, and TQ Abrasives. SGL is exploring other applications for some of the properties of Sigrasic that were utilized in the optical bench, such as its ability to be shaped into complex geometric designs and minimal thermal expansion.
Hard to believe we can get a spacecraft to Jupiter. So if the craft gets to its destination in 2016, when is it slated to come back to earth? That's an incredible journey and one that will likely give engineers some real feedback on the durability and structural integrity of composites going forward.
@Ann: Thanks for another interesting article, and for another reminder that even though the shuttle program may be over, interplanetary exploration is still going strong. Besides the Juno mission to Jupiter, the Curiosity rover will be landing on Mars later this summer. There are a lot of exciting things going on.
Liquid infiltration of carbon-carbon composites is an interesting topic. You can find a good review here. To me, one of the most interesting things is that you can make a very strong ceramic composite material by pyrolizing wood which has been treated with sodium silicate. This way you can take advantage of the natural structure of wood, along with the strength of a silicon carbide ceramic.
When it comes to space applications of composites, I've been very interested in the application of shape-memory composites as actuators for the deployment of solar arrays, reflectors, and other space hardware. These materials offer a significant weight savings compared to traditional mechanical actuation systems.
Dave, thanks for that info on other materials, especially the shape memory composites. And the info about pyrolizing wood to make a ceramic is also fascinating.
Beth, according to this info from Juno's original launch http://www.nasaspaceflight.com/2011/08/ula-atlasv-nasa-juno-jupiter/ it will come back in 2013 for a flyby which will give it a gravitational assist, or slingshot, to send it all the way out to Jupiter. But there's no word about a final return, so perhaps, as Glenn says, it won't come back at all. It does carry comms equipment and will be transmitting data while it's out there.
That makes sense, I suppose. After reading the post last week about "space trash," I suppose these abandoned satelittes will just add to the problem. And I agree with Naperlou, that while reentry might be problematic, the ability to reexamine the physical vehicle would certainty shed some light on how composite structures fare under long-term atmospheric pressures.
Beth, I had the same thought also because of last week's post and discussion about space junk. And I think it would be excellent to be able to check out the materials' performance under such harsh conditions. But recovery and/or return cost a lot and isn't simple to do.
I agree, Ann, that returning a craft to Earth would be tricky. In addition to the technology needed to power the craft, gather and transmit data, the craft would also have to include materials to keep the craft from burning up as it re-enters Earth's atmosphere.
On return missions to earth, I wonder if there is danger of introducing new materials or elements or even viruses that could interact negatively with our environment. I wonder if there is a testing/incubation procedure to examine materials before they are openly exposed to earth and humans.
Ann, always enjoy information on the materials science side of things. If I could magically turn back the clock to my 20's I probably would have focused on that area for my degree. It would be interesting to see more articles about materials designed specifically for harsh or difficult environments. I'll bet those solar panels mentioned in the article are only distant cousins to the PV cells found in the consumer market for example.
Scott, I'd bet you are right about the solar panels on Juno being massively ruggedized compared to their commercial cousins. OTOH, as I discovered during the reporting for my upcoming June feature article on Materials for Miniaturization, the materials for making solar junction box and connector materials are going through a sea-change of increased strength as they get smaller and must increase their flame retardance and electrical and impact resistance properties. Meanwhile, DN has published several articles on structural materials and fasteners for harsh environments, including fasteners http://www.designnews.com/document.asp?doc_id=241288 coatings http://www.designnews.com/document.asp?doc_id=237966 smart paint http://www.designnews.com/document.asp?doc_id=238756 and adhesives http://www.designnews.com/document.asp?doc_id=237011
Hard to believe we can get a spacecraft to Jupiter. So if the craft gets to its destination in 2016, when is it slated to come back to earth? That's an incredible journey and one that will likely give engineers some real feedback on the durability and structural integrity of composites going forward.
This is probably a one way trip - I don't recall mention of a sample return function. The last Jupiter mission that I remember was Galileo, which was eventually deliberately sent into the Jovian atmosphere and destroyed. The reasoning that I heard was to prevent possible contamination of Europa, which may have a liquid ocean and possibly extra-terrestial life.
Glenn, that may have been one of the the reasons to fly Gailieo into Jupiter, but it also was able to send back some interesting information while it was plunging to its death.
Beth, I am unaware of ANY interplanetart flights that have retruned to earth. The original Vouager has now passed out of the solar system, I believe. The craft either fall into a planet or just keep on going. Becuase a lot of them use nuclear power sources (solar is not viable far from the sun), they can last for an incredible period of time. These satelites send back information and that is what they are used for. It would be interesting to recover one to observe the effects of being in space for a long time, but recovering one would be problematic.
naperlou; Search "Satrdust". Sample return mission from comet Wild 2. Also a Mars moon sample return is in discussion. I'm not sure if it would be Phobos or Deimos. And I think Galileo did an Earth flyby on its gravity-assist flight to Jupiter. Technically not a 'return', just a visit.
Ann, I looked it up. You are correct. I think it is one of the first interplanetary flights. Of course it is only going as far as Jupiter. The solar panels are somewhat large becuase of the distance from the sun. As mentioned on the NASA web site, you are five times the distance from the earth to the sun, so since solar radiation follows a power law, you need 25 times the area you would need in earth orbit.
naperlou, I was amazed that Juno is powered by solar panels. Aside from their size, solar power technology has obviously gotten a lot more powerful and power-dense if we can power a satellite with it for all that time.
Ann—very very interesting article.Composites, I feel, represent the future of material science.Of course, we will never "outgrow" conventional materials; i.e. steel, aluminum, etc but composites can provide strength to weight ratios remarkably beneficial to design engineers for exotic uses such as the JUNO unmanned program.I also thought about material science but decided on mechanical engineering due to the great number of directions you can go relative to professional life.
bobjengr, thanks for the feedback. I agree that composites will not be the only material used for structural applications, but they certainly have a lot to offer that metals don't. I'm still amazed that they've gotten tough enough to go to Jupiter.
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