November 21, 2000
QuestChat with Peter Gage
NASA Ames Research Center, Moffett Field, CA
[ Susan/NASAChatHost - 4 - 09:34:20
Welcome to the Chat with Peter Gage! This chat will begin Tuesday, November
21, 2000 at 9 AM Pacific. After the chat we would really appreciate it if
you would take the time to complete the feedback form at http://quest.nasa.gov/activities/chats/feedback.html
[ PeterGage/Ames - 7 - 09:00:17 ]
It looks like 9 o'clock by my clock in California. Good morning all from
[ Susan/NASAChatHost - 8 - 09:01:26
Good morning Peter is here to take your questions!
[ Blake/USSpaceCamp - 9 - 09:01:43 ]
I will miss the first 20 minutes of the chat but have some questions.
What is the difference between the heat shield of the orbiter and the
reusable X vehicles?
[ Susan/NASAChatHost - 11 - 09:02:44
Hi Blake I hope you will rejoin the chat!
[ PeterGage/Ames - 14 - 09:07:09 ]
The Space Shuttle orbiter mainly uses ceramic tiles on the windward side,
where it gets extremely hot. The X-33 uses a "standoff metallic" heat
shield. As the name suggests, the heat shield is mainly metal, and it
is supported on posts some distance from the main structure. Any thermal
protection system is designed to be as light as possible, while providing
adequate protection from the heat. One of the big jobs for designers is
deciding what material to use where. The Space Shuttle orbiter uses about
10 different materials in different regions, and there have been several
improvements made in the last 20 years. The heatshield used today is a
bit different from the first one that flew.
[ nicolas - 10 - 09:01:54 ]
Hello Peter, I am a French student attending an Aerospace Engineering
school with a major in Aircraft design. I read your biography with much
interest and I have a few questions to ask you. 1) I am very interested
in having a first job experience (training session or first job) in the
US or Canada. I heard that most canadian aerospace companies were facing
a lack of graduates because of many reasons (concurrency with IT ...).
How is the aerospace situation in the USA and how do you feel about it?
2) What are the scheduled programs regarding Mars Exploration and the
philosophy of Nasa specialists and engineers about them for the twenty
next years ? Thanks a lot in advance.
[ Susan/NASAChatHost - 12 - 09:03:34
Bonjour Nicholas! Your English is very good!
[ PeterGage/Ames - 18 - 09:12:12 ]
Hi Nicolas. Prospects for people starting out in aerospace are quite good
here. Aerospace people don't earn as much as IT specialists but there
is plenty of interesting work. It can be a little tricky for foreigners
to get a start here, but if you find an employer who wants you, they can
figure out the paperwork to get you legal work status. As for Mars exploration,
it looks like there will be missions roughly every 2 years (the interval
between suitable alignments of Earth and Mars is a little more than 2
years) for the foreseeable future. Two landers will go in 2003, and a
large orbiter is planned for 2005. NASA officials have plans well beyond
that, but I don't know the details.
[ PeterGage/Ames - 21 - 09:19:38 ]
RE: [Blake/USSpaceCamp] Compared
to Apollo days, how has technology brought the temps down during re-entry?
Hi Blake, this is a response to your question about re-entry temperatures
now as compared with Apollo days. Sometimes surface temperatures on the
vehicles today are higher than they were in Apollo days. Different materials
have different temperatures that they can endure, and they are chosen
according to requirements of a particular mission. The Apollo vehicles
were returning from the moon, so their initial velocity was very high.
That meant lots of kinetic energy to convert to heat. No material could
withstand the expected temperatures without being modified. Apollo used
an ablating heatshield, which means that some of the material charred
(went like charcoal) and some material burned off into the atmosphere.
The Space Shuttle orbiter reuses its heatshield, so it can't have it burning
off on each entry. This vehicle has a lower initial velocity than Apollo,
and uses lift so that it takes longer to slow down. The heating environment
is less severe than Apollo. For Mars entry vehicles, which don't need
to be reused, ablating heat shields are used.
[ PeterGage/Ames - 22 - 09:23:13 ]
RE: [Blake/USSpaceCamp] What would
be the temp. of a vehicle during entry at Mars? The materials are used
for something like this?
I can't give exact figures for peak temperatures for Mars vehicles, but
something around 2000 degrees is possible. They use carbon phenolic sometimes.
Lightweight ceramic ablators are also being developed my materials researchers
here at NASA Ames.
[ PeterGage/Ames - 23 - 09:25:58 ]
RE: [Hugo] Good morning, my name
is Hugo, I study electronics and I´m from Mexico. Have new upgrades to
the space shuttle´s thermal protection system been recently made?
Hi Hugo. Improvements to the Space Shuttle thermal protection system are
still being made. They have saved weight and reduced maintenance effort
in recent years by putting felt blankets on the lee side (the top of the
orbiter which doesn't get quite so hot). These are pretty advanced blankets,
and they endure tough conditions very well.
[ PeterGage/Ames - 26 - 09:29:08 ]
RE: [Susan/NASAChatHost] Peter, I received this question
in email, I'm not sure if you have any answers about this or not. If you
know anything about the OGS (Oxygen generating subsystem) project, I would
like to ask you some questions about it. 1. How many of those OGSs do
we need to provide oxygen for Mars?
I know very little about Oxygen Generating Systems, but I know that people
are working very hard on this problem. Preparing for manned exploration
of another planet is astonishingly difficult. It is essential to avoid
carrying all your supplies with you, because that is too heavy. We need
to figure out how much we can use that is already available at the destination.
[ PeterGage/Ames - 28 - 09:33:30 ]
RE: [Hugo] Thank you, I´m pleased
to be online with you. I would like Mr. Gage to answer a few questions:
How do you gather information on the processes of entry or reentry? Mainly
based on experiments on earth or in space?
We gather information about entry and reentry however we can get it. Ground
experiments are conducted in arc jets (very hot wind tunnels) and ballistic
ranges. It's too complicated to give details here, but my journal has
information on the ballistic range, and George Raiche and maybe others
have information on arcjets. We cannot exactly simulate the correct conditions
in ground experiments, so we collect flight data whenever we can. There
is lots of data from the Space Shuttle, and also some from planetary probes.
These days, we use computational fluid dynamics (CFD) calculations a great
deal, to supplement ground and flight data and to help make predictions
about what would work better.
[ PeterGage/Ames - 30 - 09:34:52 ]
RE: [Justin] How long have you worked
Good morning, Justin. I have worked at Ames for a little more than 3 years.
When I was a graduate student, I did research with NASA people, too.
[ Susan/NASAChatHost - 25 - 09:28:02
Hi Justin, I am so glad you can join us today!
[ PeterGage/Ames - 36 - 09:38:47 ]
RE: [Kaylan] What is your favorite
part of your job?
Hello, Kaylan. My new favorite part of my job is online chats! Actually
I like most of my job, but it is most exciting when something works pretty
much the way you predicted it would. So when a new model flies down the
range just right, or you can hold something in your hand that you had
modeled on the computer, and all the pieces fit together as they should,
it's pretty satisfying. Attending meetings can sometimes be boring. Writing
papers is something I find very difficult, but it is very satisfying when
they are done.
[ Susan/NASAChatHost - 29 - 09:33:57
Hi Kaylan! Good question!
[ PeterGage/Ames - 38 - 09:40:33 ]
RE: [Hugo] Are you involved in such
programs as Mars Direct Plan or Nasa´s Reference Mission?
I am not working on a particular mission right now. We are developing
software that will help designers for lots of future missions.
[ PeterGage/Ames - 42 - 09:43:44 ]
RE: [Tyara] What or who encouraged
you the most?
Tyara, this is a difficult question! Definitely my family has helped the
most, but different members at different times. These days, I am lucky
that my wife is happy for me to do work that I love, and both of my children
like NASA. The rest of our family would like us to live in Australia still,
but they understand that NASA is a good place to be working.
[ PeterGage/Ames - 46 - 09:47:51 ]
RE: [Andre] Do you have to wear any
special clothing for your job?
Good morning, Andre. My clothing for work is pretty ordinary. If we go
in an area with machinery, we might wear heavy boots and safety glasses.
Arc jet testing requires safety glasses. Most of my time is spent in an
office or a computer room so I wear casual clothes. For big meetings,
we sometimes put on a jacket and tie.
[ Susan/NASAChatHost - 35 - 09:36:55
Hi Andre, do you wear uniforms at your school?
[ PeterGage/Ames - 54 - 09:51:55 ]
RE: [Hugo] In the case of Mars, with
the big lag of communications between planets (40 minutes), and assuming
its an unmanned ship how do you manage to control entry of the spacecraft
and make sure the thermal protection will work?
Hugo, you are right that the communication lag prevents control of Mars
entry from Earth. A day or two before entry the mission controllers do
a final course correction to line up the vehicle exactly right. Then it
is left to itself. Recent missions have been passive: the vehicle is stable
and requires no control. It is difficult to land at an exact spot this
way, so precision guidance is planned for future missions. This means
you need sensors to figure out where you are, and actuators (little thrusters)
to shift the vehicle to the correct location. Conceptually, it's a lot
like landing an aircraft with autopilot.
[ PeterGage/Ames - 56 - 09:56:35 ]
RE: [Blake/USSpaceCamp] I am back.
Thanks for those great answers. Where is the testing going on for these
NASA centers and industry particpants are doing ground testing of X vehicles
all around the country. Heat shields are tested here, structural components
are tested at NASA Langley in Virginia, and Marshall Space Flight Center
in Alabama. Flight tests are conducted in the California desert, especially
at NASA Dryden. That's only a few examples, because all the components
get tested somewhere.
[ Susan/NASAChatHost - 58 - 09:57:14
Peter says he can stay to answer all those questions you have already
asked. This has been a great chat. I so please you could join us today!
[ Susan/NASAChatHost - 59 - 09:58:40
After the chat we would really appreciate it if you would take the time
to complete the feedback form at http://quest.nasa.gov/activities/chats/feedback.html
[ Hugo - 60 - 09:59:26 ]
Thanks a lot, greetings from Mexico City.
[ Susan/NASAChatHost - 61 - 09:59:44
[ PeterGage/Ames - 62 - 10:00:37 ]
RE: [Selina] Has your wife ever helped
you with an idea to develop?
Hello, Selina. My wife helps me all the time. Sometimes when you are struggling
to figure something out it can really help to talk about it. My wife asks
great questions: she always seems to know when I am skipping over a tough
bit. Long before we were married, she read a paper I had written about
aerospace in Australia. She commented that I had written what I expected
people would like to read, instead of what I believed. We argued, but
she was right. I had to re-do the whole thing, but it was much better
in the end!
[ Susan/NASAChatHost - 41 - 09:42:57
Great question Selina :o)
[ PeterGage/Ames - 63 - 10:04:02 ]
RE: [Tommy] What kind of materials
do you use for the thermal protection tiles? Is it like the shuttle?
Hi Tommy. I hope you have been able to wait for me to respond. I'm not
great at typing. My 2nd grade daughter always tells me I use the wrong
fingers! Thermal protection tiles are mainly ceramic. The original tiles
on the Shuttle were very fragile, and there has been lots of development
to make them tougher. The Shuttle is the only operational vehicle using
tiles, I think, but we don't know yet what materials will be used for
[ PeterGage/Ames - 64 - 10:07:08 ]
RE: [TJNelson] Do you have a budget
for equipment or do you have a lab and supplies? We are 4th graders in
Ms.Thompson's class. Thank you!
Hello to Ms Thompson's 4th grade class. I am not responsible for budget,
but we do need to buy computers and software and experimental equipment.
We also need to pay for travel to meet other engineers working on the
[ Susan/NASAChatHost - 45 - 09:47:43
Tommy,Tj and Ms. Thompson and class! Thanks for such interesting questions!
[ PeterGage/Ames - 65 - 10:11:41 ]
RE: [Lamont] Do you have special
tools besides computers to help you design? Do you have specialized software
to help you?
Hi Lamont. We do experiments and build models to help with design. Often
people talking about alternatives generate the most interesting ideas.
When we come to analyze the proposed design, we use the computer. There
is lots of specialized software. CAD, CFD, structural analysis, trajectory
analysis each require software that costs thousands of dollars. And because
our problems are so unusual, we often have to write some software ourselves.
[ Susan/NASAChatHost - 50 - 09:49:36
hey Lamont and Kelsey! I bet you have success with computers!
[ PeterGage/Ames - 66 - 10:13:15 ]
RE: [Blake/USSpaceCamp] Do Space
Campers in Mt. View visit that area you work in ever?
Hi Blake. Space campers don't visit my building, but they do get to see
lots of interesting stuff at NASA. My children can't wait to be old enough
for Space Camp!
[ PeterGage/Ames - 67 - 10:16:09 ]
RE: [Kelsey] How many successful
projects have you developed?
Hi Kelsey. I have not worked on any flight projects that flew yet. I have
only been here 3 years, and they need to be fully designed at least a
couple of years before they go. I have worked on some things that got
cancelled, too. The ballistic range experiments that I have done were
all successful: we tested several unusual shapes and got good data for
all of them.
[ PeterGage/Ames - 68 - 10:18:03 ]
RE: [Alex] Have you ever worked on
the space shuttle reentry?
Good morning Alex. I have not worked on Space Shuttle Entry. NASA is preparing
for a Shuttle replacement in the next 10 years or so. I am involved in
preparing design software for that project.
[ Susan/NASAChatHost - 53 - 09:51:41
Hello Alex, would you like to see the shuttle lands someday? I would.
[ PeterGage/Ames - 69 - 10:21:35 ]
RE: [Emily] Do you have a favorite
part to design on a plane?
Good morning Emily. All parts of an airplane or entry vehicle are interesting.
I work mainly with people who design heatshields, and I am fortunate to
have a dynamic and engaging office-mate who loves heatshield design, but
I am most interested in how all the pieces fit together. All the different
subsystems have different requirements and figuring out how they can work
together is a real challenge.
[ PeterGage/Ames - 70 - 10:24:19 ]
RE: [Blake/USSpaceCamp] Honestly,
does NASA have a target date to have human on Mars? How long would the
rounf trip take?
Blake, I really can't speak for NASA's plan for humans going to Mars.
You might check the Johnson Space Center website to see if they provide
detailed plans. I do know it is very difficult thing to do, and lots more
preparation is required. I think the fastest return mission would take
about 2 years (about 10 months in each direction and a little time at
Mars) but planners would really like a more extended stay at Mars.
[ Susan/NASAChatHost - 71 - 10:29:17
Thanks so much Peter this has been a terrific chat! We've all learned
from your expertise! I hope you will chat with us again soon!
[ PeterGage/Ames - 72 - 10:29:29 ]
Well, I think I responded to everything. This was a lot of fun for me.
Thanks for all the great questions. I hope everyone has a nice Thanksgiving!