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Mars Team Online WebChat

Date: March 11, 1998

Featuring: Rich Hogen
Operations, Mars Global Surveyor
Lockheed Martin Astronautics, Denver, Colorado


[ Sandy/NASAChatHost - 30 - 10:22:53 ]
Welcome to today's chat with Rich Hogen! Rich will be here in approximately 40 minutes. In the meantime, if you haven't had a chance to read his very interesting bio, please do so at: http://quest.arc.nasa.gov/mars/team/hogen.html Have your questions ready :-)

[ Sandy/NASAChatHost - 32 - 10:53:38 ]
RE: [Kye-Carl/homeschooled] Hi Sandy! I'm really glad to see the internet behaving better today!!!
Hi Kye and Carl! I'm glad to see you made it to chat room. And I agree with you about the Internet's behavior-- let's hope it's on its best behavior today! Rich should be here shortly... Where are you two from and what grade are you in?

[ MrsTsurunagasClass-Nancy/WoodlandHillsElementaryLAUSD - 34 - 10:58:15 ]
We are a 5th grade class in Woodland Hills, CA.

[ Sandy/NASAChatHost - 35 - 10:58:35 ]
RE: [MrsTsurunagasClas-Nancy/WoodlandHillsElementaryLAUSD] Our whole class is here. We're looking forward to chatting with Rich.
Wow, that's great! Welcome to all of you :-) Where is Woodland Hills Elementary located? And how many are in your class? Rich will be here in 5 minutes...

[ Sandy/NASAChatHost - 39 - 11:02:56 ]
RE: [Kye-Carl/homeschooled] Carl is my son, who is in the 11th grade. We are in our 9th year of home schooling.I am also especially interested in the Mars chats because I have an educational web page (as a hobby), using astronomy and space exploration to help kids have fun learning about math and science. I especially look for space events that are in the news (like water ice found on the Moon and ?Mars? because I also give them things to do with direct observations from their yard, being an avid amateur astronomer.
Sounds like you do some pretty interesting and innovative stuff for your son and other kids as well! You might want to consider joining our project's discuss mail list to chat with other teachers and parents to share ideas.

[ MrsTsurunagasClass-Nancy/WoodlandHillsElementaryLAUSD - 40 - 11:03:09 ]
There are 40 of us here today for the chat. Woodland Hills is in the West San Fernando Valley near Los Angeles.

[ Sandy/NASAChatHost - 41 - 11:03:43 ]
RE: [Rich/LMA/Denver] Hello, everyone. I'm here! How can I help you?
Welcome Rich. thanks so much for taking the time to chat with all of us today :-) Ok everyone, let your questions fly!

[ Rich/LMA/Denver - 46 - 11:05:31 ]
RE: [MrsTsurunagasClass-Nancy/WoodlandHillsElementaryLAUSD] Hi Rich! How long does it take for one rotation of the MGS around Mars?
Right now the period of MGS's orbit is about thirteen and a half hours. We're shaving off about 6 minutes with each drag-pass.

[ Sandy/NASAChatHost - 47 - 11:05:36 ]
RE: [Andrew-Elaine/EncinalSchool] Encinal school is here and is very excited
Welcome Encinal School! Good to see you here :-)

[ Rich/LMA/Denver - 49 - 11:07:26 ]
RE: [MrsTsurunagasClass-Nancy/WoodlandHillsElementaryLAUSD] Also, Rich. If you suspected that there might be water on Mars, why didn't you include a drilling module with the MGS?
A drilling module is an interesting idea, but it requires actually getting down to the surface of the planet. MGS, Mars Global Surveyor, is a remote sensing spacecraft, like weather satellites and others in orbit around Earth. The Mars Polar Lander mission carries "penetrators", as I recall, which will do exactly what you suggest.

[ Rich/LMA/Denver - 51 - 11:09:54 ]
RE: [Kye-Carl/homeschooled] Hi Rich - I'm interested in your work with pointing the High Gain Antenna and Solar Arrays. I am putting activities together for my web site for children to do to better understand how we use right triangle in science and engineering. They use a quadrant (made from my pages) to measure different things, using tangents to find the unknowns. Do you have suggestions for things to do along these lines?? (pun intended on the "lines")
Wow, Kye! Right off the top of my head I'm finding it hard to jump from all the three-dimensional vectors I worked with in my spreadsheet to 2D triangle exercises. Tell you what, please send me an email (including the URL for your educational web site) and I'll think about that off-line.

[ Rich/LMA/Denver - 53 - 11:13:40 ]
RE: [Nick-Nicholas/IronHorse] How do you control the MGS now?
That's a pretty broad question, Nick, and a good one. MGS has a computer onboard with software running that diagnoses it's health and performs routine "autonomic" functions, kind of like a heartbeat and breathing. When we need it to do more, we send "sequences" to it. Sequences are essentially scripts, like a checklist or a recipe, saying, "do this thing at this time". Working out the order of events and the timing is actually very important and care has to be taken, so we have special software on the ground that performs all the right checks for MGS. There's more to it, but that's the general idea of how we control the spacecraft.

[ Rich/LMA/Denver - 56 - 11:17:34 ]
RE: [MrsTsurunagasClass-Nancy/WoodlandHillsElementaryLAUSD] Can you explain how "drag pass" works?
A "drag pass" is what happens when the periapsis of MGS (the point in the orbit closest to Mars) is low enough to subject MGS to atmospheric drag, the same kind of drag that holds up kites or that you feel when you ride a bicycle. On the way into a drag pass, the "sequence" tells the spacecraft to do several things: turn your solar panels this way so we can pre-charge the batteries, then stop rotating and point the instrument deck this way, pull the solar panels up and back for stability in the "wind", then start rotating this way, ..., and then on the way out do the reverse.

[ Rich/LMA/Denver - 57 - 11:18:10 ]
RE: [Kye-Carl/homeschooled] Rich - Nice web site! Who's brain is in the vat?
Ah, that's the question, isn't it?

[ Rich/LMA/Denver - 61 - 11:24:17 ]
RE: [MrsTsurunagasClass-Nancy/WoodlandHillsElementaryLAUSD] How does aerobraking work?
Another fine and yet very broad question. Through experiments, scientists over the years have learned how to use certain mathematical equations to represent the drag (frictional) forces caused by fluids, like atmospheric gases. An extension of that is our collective experience with global climate and weather modelling. Also, with experience building aircraft and rockets, engineers and scientists use the fluid models to design things that flow through the air more easily, with less drag. (look at old automobiles and compare them with newer, more aerodynamically efficient ones) So, Dr. Bill Willcockson at Lockheed Martin thought, "why not use a weather model of Mars, the fluid drag equations and an aerodynamically stable spacecraft to use the atmospheric drag of Mars to slow the spacecraft down, remove energy from it's orbit, without requiring fuel?" In the past, atmospheric drag was thought of as a problem to be overcome, but gradually people like Bill turned it into a useful tool.

[ Rich/LMA/Denver - 64 - 11:28:22 ]
RE: [MrsTsurunagasClass-Nancy/WoodlandHillsElementaryLAUSD] Here's your chance to go out on a limb, Rich. Do you believe we'll find life on Mars?
Well, you know, every time I think about it I convince myself that it's possible we'll find life on Mars, or evidence of past life, then I think further and I realize it's also possible that either we'll never find it or that it doesn't exist to be found. Unless we have evidence either way, it's perfectly alright to have a "suspended belief", neither way. I _do_ believe that the question is extremely interesting and incredibly important to humanity, and I don't squelch my wonder and awe the question and the possiblities.

[ Rich/LMA/Denver - 65 - 11:30:14 ]
RE: [Kye-Carl/homeschooled] Rich - I'm a mostly self-taught programmer (basic, C, C , JAVA). What kind of programming do you use for communicating with the spacecraft, and what kind of programming do you do the shareware in?
Our main sequence building tool is an Excel spreadsheet written by my esteemed colleague Wayne Sidney. At JPL there are other pieces of software that we use but do not "own", so I have no idea what language their written in. My shareware was written in Delphi, which is "visual object pascal".

[ Rich/LMA/Denver - 68 - 11:33:15 ]
RE: [Nick-Nicholas/IronHorse] What kinds of data are you collecting from the MGS?
We receive two kinds of data, engineering data and science data. All the data is stored on two database servers, and those who need it run queries to retrieve what they need. The Spacecraft Team works exclusively with engineering data (monitoring and trending the health of the spacecraft), except in the case of the Mars Horizon Sensor Assembly (MHSA), which is a science instrument being used to watch the deflection of the broken solar panel. The scientists query their respective science data. For details on that, please visit the MGS home page and step through the great slide show they have in the images area.

[ Rich/LMA/Denver - 72 - 11:40:19 ]
RE: [MrsTsurunagasClass-Nancy/WoodlandHillsElementaryLAUSD] Jonathan would like to know what the surveyor will be looking for when it reaches its final orbit around Mars.
MGS will be looking for all kinds of data in the final orbit, the same kind of data it was collecting earlier in aerobraking before we had to stop performing science observations. (that was necessary to allow us to keep the spacecraft alive -- you can't do anything with a dead spacecraft) The difference is that in the final orbit the geographical resolution ("level of detail") will be highest. The instruments are collecting data on everything about Mars, which is why it's called "Surveyor", things like: images of the geology, altitude of geological features, mineral types and distributions, atmospheric density and composition, gravity map of the planet, magnetic field and charged particle measurements, etc. It's pretty amazing what creative scientists can get out of a single data set. They'll be analyzing MGS data for a long time.

[ Rich/LMA/Denver - 73 - 11:42:25 ]
RE: [MrsTsurunagasClass-Nancy/WoodlandHillsElementaryLAUSD] Spencer would like to know how the solar panel wing broke, and how will you try to fix it?
The panel broke when a "damper" failed. The damper was supposed to slow the panel down during deployment, so it wouldn't just "snap" straight and break itself. The damper broke and "ate into" part of the panel, which is why the panel couldn't fully deploy for a long time. There's no way to fix it now that MGS is so far from our reach.

[ Rich/LMA/Denver - 74 - 11:43:06 ]
RE: [SpencerK-Elaine/EncinalSchool] What spacecraft were you most proud of to work on?
This is my first spacecraft-related job, so MGS is the one! (some expert I am, eh?)

[ Rich/LMA/Denver - 75 - 11:43:43 ]
RE: [Kye-Carl/homeschooled] Rich - My last Live From Mars email newsletter (#67) talks about the radio science team using transmissions from MGS just before it goes behind the planet to learn more about Mars' atmosphere from the distortions in the radio signals while they pass through it. Would a decent demonstration of distorted radio signals be the old AM/FM radio receiver with the aluminum foil lined umbrella in front of it? Or would more of a visual demonstration like the way water bends light be appropriate?
Let's talk about such details off-line.

[ Sandy/NASAChatHost - 77 - 11:46:11 ]
RE: [MrsTsurunagasClass-Nancy/WoodlandHillsElementaryLAUSD] Thanks for answering our questions, Rich. The lunch bell is ringing!
Thanks so much for your great questions and for participating in today's chat! Hope you can join us again for the upcoming chat!

[ Rich/LMA/Denver - 78 - 11:46:40 ]
RE: [Nick-Nicholas/IronHorse] How long will the MGS remain in orbit around Mars?
The plan, as I understand it, is to reach final mapping orbit in April, or so, 1999, then do mapping for a Martian year (two Earth years). When that's done, MGS will fire it's thrusters to push the spacecraft into a higher orbit that will not decay for at least 50 years. There is an international agreement to not allow spacecraft debris to get into the Mars system where it might confuse our measurements while we learn about the planet.

[ Rich/LMA/Denver - 79 - 11:47:35 ]
RE: [Sandy/NASAChatHost] Thanks so much for your great questions and for participating in today's chat! Hope you can join us again for the upcoming chat!
You're quite welcome.

[ Sandy/NASAChatHost - 80 - 11:47:37 ]
EVERYONE: Just another 10 minutes and then we have to let Rich go and get back to his REAL work! A few more questions and then we'll call it a day...

[ Rich/LMA/Denver - 84 - 11:52:50 ]
RE: [DarianS-Elaine/EncinalSchool] How did Space Exploration attract you as a child?
It started with television, then as I started to learn about how the world works I saw more and more how wonderful and awesome and beautiful it is, and that happened at the same time we were all starting to realize how fragile our biosphere is because the Apollo and Skylab photos of Earth gave us a larger perspective. There isn't any one or two things I can point to, but I do know that the more science I learned the more wonderful the universe became, and once you realize that you're on a small planet living in a very thin, fragile and precious biosphere, you can't go back, you start thinking in "the big picture".

[ Sandy/NASAChatHost - 85 - 11:52:51 ]
RE: [Nick-Nicholas/IronHorse] Thanks a whole lot Rich and Sandy for telling us about Mars and the MGS
Nick, you're most welcome :-) Hope you can join us for the next chat!

[ Rich/LMA/Denver - 86 - 11:53:09 ]
RE: [Nick-Nicholas/IronHorse] Thanks a whole lot Rich and Sandy for telling us about Mars and the MGS
You're welcome!

[ Rich/LMA/Denver - 87 - 11:53:35 ]
RE: [Kye-Carl/homeschooled] Rich - Thanks for your time! You are really good at explaining these things. Also, your advise in your bios is great. Knowing how to go find out about something (research and learn) is so much more important than memorizing facts! Thanks again, and good luck with your mission.
You're welcome! And thanks.

[ Rich/LMA/Denver - 89 - 11:55:46 ]
RE: [Doug/ArapahoeHigh-Doug/ArapahoeHigh] Rich, does Lockheed-Martin have a webb site that might show some data from MGS, or is it best to go to a JPL site? Thanks-keep up the great job!
Yes, we have a public telemetry page if you want to see engineering data. Send me email and I'll get you the URL. As for science data, your best bet is the JPL pages. (you're welcome and thanks for joining us)

[ Sandy/NASAChatHost - 90 - 11:58:06 ]
Everyone: It looks like today's chat has come to an end. thanks to all the participants! You did your homework and asked some really good, thoughtful questions :-) And Rich, a special thank you to you for taking time out of your day to spend with us today. Your answers were very informative and I actually learned a few new things today! Thank you :-)

[ Rich/LMA/Denver - 91 - 11:58:50 ]
RE: [Sandy/NASAChatHost] Everyone: It looks like today's chat has come to an end. thanks to all the participants! You did your homework and asked some really good, thoughtful questions :-) And Rich, a special thank you to you for taking time out of your day to spend with us today. Your answers were very informative and I actually learned a few new things today! Thank you :-)
My pleasure. Thanks for setting up the MTO program!

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