Archive of Joyce Dever's chat on May 19, 1998

[ JoyceDever - 1 - 07:49:56 ]
Good Morning!

[ Tish/NASAChatHost - 4 - 08:00:08 ]
Welcome to our web chat with Joyce Dever. If you have not read her profile, please do so at: http://quest.arc.nasa.gov/women/bios/jd.html You may begin submitting questions as soon as we see Joyce on and ready.

[ JoyceDever - 5 - 08:00:55 ]
Welcome students! I'm looking forward to chatting with you about your career interests or whatever. Just to let you know what I'm doing this morning, I am preparing a presentation on work I did on synchrotron (x-ray and vacuum ultraviolet) radiation effects on Teflon. This is for a conference next week.

[ JoyceDever - 10 - 08:13:26 ]
RE: [BurtonValley] Hi - We would like to know what types of space materials you test on. Do you mean space craft?
Good morning, Burton Valley! Our group tests materials to be used on various spacecraft surfaces: solar cell arrays, spacecraft insulation blankets, temperature control surfaces (referred to as thermal control coatings which can radiate waste heat away from the spacecraft) and other miscellaneous exterior spacecraft surfaces.

[ JoyceDever - 12 - 08:17:17 ]
RE: [BurtonValley] Can radiation hurt space craft while there are missions or is your work involving satelites and materials that stay up for long periods of time? How long can material stay in space?
Radiation is a great concern for spacecraft. If spacecraft are not properly shielded, radiation can damage electrical components leading to many problems with spacecraft operations. We are concerned mostly with long-term missions such as Hubble Space Telescope and Space Station, but we also design flight experiments for the Shuttle which have 1 week or so exposure times.

[ JoyceDever - 13 - 08:20:35 ]
RE: [BurtonValley] What happens to materials in space after you have finished using them? Where do they go?
Materials that have been tested in space are often retrieved - many of our experiments have been on Shuttle missions that return with the Shuttle, and Hubble servicing missions have brought back samples. Some materials (especially polymers) do not survive in space and become eroded and volatilize (become gaseous). This can happen on longer term materials experiments.

[ JoyceDever - 14 - 08:24:56 ]
RE: [Sarah/Greenmeadow] Have you ever been discriminated against as a women?
Hi Sarah, I have been fortunate to be in a working environment that does not tolerate discrimination, and I feel that I am treated as part of the team without regard to gender. However, several years ago, there was a male technician who I relied on to build parts for my experiments, and he would look at my drawings and say "That's pretty good for a girl" and other demeaning comments about how women should be home having babies, etc. Working with him was very upsetting to me, as I often felt inadequate and completely foolish. Good thing he did not work with our group for very long! These days he would be fired readily for such remarks.

[ JoyceDever - 15 - 08:27:34 ]
RE: [Tish/NASAChatHost] Via email from Chris - Why do you use teflon for space materials?
Chris, Teflon has wonderful properties in that it is highly transparent to much of the sun's radiation and it can also efficiently radiate away waste heat. When Teflon is metalized on the backside (i.e. a second-surface mirror) it has a high thermal emittance and low solar absorptance which are ideal properties for temperature control on spacecraft insulation.

[ JoyceDever - 19 - 08:30:02 ]
RE: [JoyceDever] Chris, Teflon has wonderful properties in that it is highly transparent to much of the sun's radiation and it can also efficiently radiate away waste heat. When Teflon is metalized on the backside (i.e. a second-surface mirror) it has a high thermal emittance and low solar absorptance which are ideal properties for temperature control on spacecraft insulation.
Chris, One disadvantage of Teflon is that it is damaged by radiation in space. It becomes brittle. When Teflon is bonded to a metal surface or a reinforcement fabric, it doesn't matter so much that it becomes brittle, because it can't detach from the surface. However, on an insulation blanket where it is free to "flop around" a bit, embrittlement can lead to cracking as has occurred on the Hubble Space Telescope. We have been studying this problem extensively for the last few years.

[ JoyceDever - 20 - 08:32:55 ]
RE: [St.Josephs] How do you stay current on your work?
Hi St.Josephs, I stay "current" by a number of methods: 1. searching the literature for the latest developments (internet searching and various other NASA-specific searching modes) 2. Attending conferences which describe the latest aerospace materials developments. 3. Interaction with colleagues from other NASA centers and organizations involved in the same research areas.

[ JoyceDever - 25 - 08:38:38 ]
RE: [St.Josephs] Has there ever been any accidents or problems because space materials where hurt by radiation?
The Hubble Space Telescope would experience temperature control problems due to the radiation-induced cracking of Teflon, except that it is serviced every few years by astronauts. In this way, repairs will be made which will prevent Hubble from temperature-related problems (sometimes 2 pieces of equipment cannot run at the same time if they generate too much heat and the temperature control coatings cannot get rid of the heat efficiently enough.) In one incident, spacecraft charging from solar storms interruped the communication of telephone systems in Canada that relied on a particular satellite system.

[ JoyceDever - 27 - 08:43:27 ]
RE: [BurtonValley] Can you tell us about space garbage? Is this something that you work on?
Burton Valley, Can you be specific about the space garbage you are referring to? I assume you mean old spacecraft and satellite parts abandoned which will decay in their orbit and burn up as they eventually re-enter the earth's atmosphere. Parts of the old SkyLab were known to have descended on parts of Australia years ago. I do not know the policy on space garbage, but I do know that a lot of it is generated. For example, in 1993 both the solar arrays from the Hubble Space Telescope were supposed to be retrieved and brought back to earth by astronauts. One of them was bent and couldn't be folded up to bring back so it was "shoved" out into space. It seems that we ought to be finding ways to keep space a little cleaner. Don't you think?

[ JoyceDever - 28 - 08:46:17 ]
RE: [Patti/DiscoveryCharterSchool] What does an engineer actually do?
Patti, An engineer can do any of a variety of things, but one thing that all engineers have in common is applying scientific knowledge to solving problems. My experiences as a materials engineer are a good example: Studying the space environment effects on materials, then conducting tests to determine how long materials may last, and finally making recommendations on appropriate materials.

[ Vincent/WashingtonElementary - 29 - 08:48:03 ]
Good Morning, what an interesting conversation...

[ Tish/NASAChatHost - 30 - 08:48:03 ]
Glad you could join us Vincent. We only have about 10 minutes left with Joyce so if you have questions please feel free to submit them now.

[ JoyceDever - 33 - 08:50:04 ]
RE: [St.Josephs] Do you purposely make space materials out of things that will erode and volatize? Is there a concern about things left in space? How long is "longer term" materials experiments?
Sometimes the best materials for a certain application happen to erode in space (i.e. most polymers). We certainly don't want a material to fall apart when used on a spacecraft component, so we use protective coatings (usually transparent metal oxides, but there are others) which will minimize this effect. Longer term space experiments may last from 1 year (as in a recent experiment where a tray of materials was put on the Russian MIR spacecraft) to 6 years (in the case of the Long Duration Exposure Facility which was essentially a materials experiment satellite) and on up wherever possible. Many "long term" experiments are planned to be located on the International Space Station

[ JoyceDever - 35 - 08:51:17 ]
RE: [BurtonValley] What ever happened to the Pathfinder and Sojourner? Are they still in space?
Pathfinder and Sojourner were not retrieved, so they are still on Mars.

[ JoyceDever - 39 - 08:52:27 ]
RE: [Patti/DiscoveryCharterSchool] How long do satelites last in space?
Patti, Satellites can be designed for short or long missions. There is a broad scope from less than a year up to many years. The price and complexity of satellites will increase with the length of the mission, of course.

[ JoyceDever - 40 - 08:54:36 ]
RE: [Vincent/WashingtonElementary] Do you create and design stuff on the computer before you test it in space?
Vincent, Although many engineers do computer models as part of spacecraft design; my work is more experimental. We take proposed materials and put them in chambers which simulate the vacuum environment, oxygen atoms that reside in some parts of space (low Earth orbit), ultraviolet and other types of radiation, temperature extremes, etc. and test them for durability.

[ Sarah/Greenmeadow - 37 - 08:51:46 ]
Joyce, why did you choose a career in science?

[ Patti/DiscoveryCharterSchool - 38 - 08:51:46 ]
What made you want to do this job?

[ JoyceDever - 41 - 08:55:44 ]
Sarah and Patti, I got involved in a career in science/engineering because I love science and had an aptitude in math as well. So far it has not disappointed me. It's very exciting to be involved with the cool projects NASA does.

[ JoyceDever - 43 - 08:58:36 ]
RE: [Patti/DiscoveryCharterSchool] How was it when you first started working in the NASA team?
Patti, When I first started at NASA, I had a lot to learn that school did not prepare me for. Learning how to make a presentation, run a meeting, etc. were things you didn't learn in school as much as the science/engineering part. But I loved my job from the start. On-the-job training (especially in my early years) is where I probably learned the most skills that help me every day.

[ Tish/NASAChatHost - 44 - 08:58:48 ]
We are just about out of time with Joyce. This has been a fascinating hour and we appreciate your well thought out questions. It is evident that you researched Joyce's work before coming to the chat and we like to see that! This chat will be archived and linked from Joyce's profile later today. Please check the SpaceDay chat schedule at http://quest.arc.nasa.gov/common/spaceday.html and join us for our other chats all day today and tomorrow.

[ JoyceDever - 45 - 09:00:08 ]
Thanks everyone and have a great summer!!