Sandy/NASA Chat Host: . . . . Wed, Jan 8, 8:56AM PDT (-0700 GMT). . . [281 ] Hello everyone and welcome back after the holidays! Our guest today is Steve Stolper from NASA's Jet Propulsion Laboratory in Pasadena, California. Steve is a flight software engineer for the Mars Pathfinder spacecraft. One of his many jobs is to write the program that allows the computer to control the spacecraft. This is very challenging because the computer must fly the spacecraft during the seven-month cruise to Mars as well as control the atmospheric entry, descent and landing on the surface of the planet. Steve has been at work since 4:30 this morning, using the Deep Space Network antenna is Australia to communicate with the Pathfinder. Welcome Steve!

Melanie@RoseRock in Cal.: . . . . Wed, Jan 8, 8:56AM PDT (-0700 GMT). . . [282 ] Hi everyone

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 8:57AM PDT (-0700 GMT). . . [283 ] Welcome all students and teachers!

Andrea/NASA/Moderator: . . . . Wed, Jan 8, 8:57AM PDT (-0700 GMT). . . [284 ] Hi Josh/Strath -- you may want to move your name into the box below the chat window called "Your Handle" this way you don't have to retype it.

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 8:57AM PDT (-0700 GMT). . . [285 ] Steve: Can you tell us what you've up to since 4:30 this morning?

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 8:58AM PDT (-0700 GMT). . . [286 ] Thank you Sandy. I'm excited to be here.

Eric@RoseRock in Cal: . . . . Wed, Jan 8, 8:58AM PDT (-0700 GMT). . . [287 ] Hi

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 8:59AM PDT (-0700 GMT). . . [291 ] We are preparing for our first big manuever. We must steer the spacecraft to Mars. We do this by turning to a certain attitude. Then we burn the thrusters to put the spacecraft on the proper path.

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 8:59AM PDT (-0700 GMT). . . [292 ] Hello LMA in Portugal, welcome to the chat!

lma@portugal/europe: . . . . Wed, Jan 8, 9:00AM PDT (-0700 GMT). . . [293 ] Hi Sandy, Allone in the chat room?

Melanie@RoseRock in Cal.: . . . . Wed, Jan 8, 9:01AM PDT (-0700 GMT). . . [294 ] what programing language do you use

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:01AM PDT (-0700 GMT). . . [295 ] Hello, LMA! You are not alone.

Megan: . . . . Wed, Jan 8, 9:01AM PDT (-0700 GMT). . . [296 ] How long did it take to program everything?

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:02AM PDT (-0700 GMT). . . [297 ] We program the spacecraft in the 'C' programming language. This language is very popular. Many schools are teaching 'C' now instead of Pascal. Melanie, what languages do you program in?

Eric@RoseRock in Cal: . . . . Wed, Jan 8, 9:02AM PDT (-0700 GMT). . . [298 ] Steve:Are you going to continue to program Pathfinder while it is on Mars?

Josh/Strath Haven Middle School: . . . . Wed, Jan 8, 9:03AM PDT (- 0700 GMT). . . [299 ] What language do you write your programs in?

Mark Stokes: . . . . Wed, Jan 8, 9:03AM PDT (-0700 GMT). . . [300 ] Philbert - pls. go to Hallway.

Jaime/CJHS: . . . . Wed, Jan 8, 9:03AM PDT (-0700 GMT). . . [301 ] How did they choose who would be working on a computer to control the pathfinder?

Tim McCollum/CJHS: . . . . Wed, Jan 8, 9:03AM PDT (-0700 GMT). . . [302 ] Good Morning Steve, Andrea and Sandy - Charleston Jr. High in Charleston, IL is online.

John W/cjhs: . . . . Wed, Jan 8, 9:04AM PDT (-0700 GMT). . . [303 ] What are you going to do if the pathfinder stops responding to commands on mars?

Josh/Strath Haven Middle School: . . . . Wed, Jan 8, 9:04AM PDT (- 0700 GMT). . . [304 ] Sorry!:)

John N/CJHS: . . . . Wed, Jan 8, 9:04AM PDT (-0700 GMT). . . [305 ] How long did it take you to program the computer on the Mars Pathfinder?

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:04AM PDT (-0700 GMT). . . [306 ] Hi Eric, My job has changed. I "fly" the spacecraft now. Since I helped design it, I know how it works in great detail. This is very useful if anything goes wrong during the mission.

David/CJHS: . . . . Wed, Jan 8, 9:04AM PDT (-0700 GMT). . . [307 ] How did you get teh airbags to inflate at just the right time?

Jim/CJHS: . . . . Wed, Jan 8, 9:04AM PDT (-0700 GMT). . . [308 ] How much ram does it take to run everthing?

Joey/CJHS: . . . . Wed, Jan 8, 9:04AM PDT (-0700 GMT). . . [309 ] How powerful is the computer on Mars Pathfinder compared to a common personal computer?

Mike S\CJHS: . . . . Wed, Jan 8, 9:04AM PDT (-0700 GMT). . . [310 ] What computer programs do you use for the pathfinder?

Melanie@RoseRock in Cal.: . . . . Wed, Jan 8, 9:04AM PDT (-0700 GMT). . . [311 ] I've only learned Basic but we have "C" books and my dad can teach me.

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 9:04AM PDT (-0700 GMT). . . [312 ] Josh: Steve answered your question in response # [297].

lma@portugal/europe: . . . . Wed, Jan 8, 9:04AM PDT (-0700 GMT). . . [313 ] I saw in the specifications your processor is very simple. is the program very simple too? to you take too much time perfecting it?

Josh/Strath Haven Middle School: . . . . Wed, Jan 8, 9:05AM PDT (- 0700 GMT). . . [314 ] About how many lines of code are your programs?

Mark Stokes: . . . . Wed, Jan 8, 9:05AM PDT (-0700 GMT). . . [315 ] Hi Steve - I'm curious about what kind of software and hardware you use to control spacecraft.

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:06AM PDT (-0700 GMT). . . [316 ] Jaime, We asked to chosen. We were picked depnding on our experience and skills. It was even important how well we did in school!!!

Dustin/cjhs: . . . . Wed, Jan 8, 9:06AM PDT (-0700 GMT). . . [317 ] How does the mars pathfinder send information back without anybody programing it?

Jenny/CJHS: . . . . Wed, Jan 8, 9:06AM PDT (-0700 GMT). . . [318 ] How did you become a Flight Software Engineer?

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 9:06AM PDT (-0700 GMT). . . [319 ] Everyone: Hold off for about 3-4 mins. while Steve tries to answer all 10 questions that just came in. He is typing as fast as he can!

Alex/CJHS: . . . . Wed, Jan 8, 9:06AM PDT (-0700 GMT). . . [320 ] If the NASA computer downloads a virus and it wipes out the database how would you reprogram it?

Megan: . . . . Wed, Jan 8, 9:06AM PDT (-0700 GMT). . . [321 ] How long did it take to program the computer on the MPF?

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 9:07AM PDT (-0700 GMT). . . [322 ] Good Morning Tim in Illinois! Welcome to the chat!

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:07AM PDT (-0700 GMT). . . [323 ] OK. Let me spend a second discussing the computer because there are several questions about it. Then I will answer the airbag question.

JOHN SCOTT: . . . . Wed, Jan 8, 9:07AM PDT (-0700 GMT). . . [324 ] Just a test

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 9:08AM PDT (-0700 GMT). . . [325 ] We read you John Scott, loud & clear. Welcome!

Marvin the Martian: . . . . Wed, Jan 8, 9:08AM PDT (-0700 GMT). . . [326 ] How many years of schooling does it take to do what you do.?

Brian/CJHS : . . . . Wed, Jan 8, 9:08AM PDT (-0700 GMT). . . [327 ] What would you do if the power went out where you were working and all the ground computers went out?

JOHN SCOTT: . . . . Wed, Jan 8, 9:09AM PDT (-0700 GMT). . . [328 ] Question: What kind of air is in the airbag balloons?

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:09AM PDT (-0700 GMT). . . [329 ] The computer is a lot like the PCs you find on your desk - except much more powerful. The computer processes 2 million instructions per second and has 128 megabytes of memory [continued...]

Jaime/CJHS: . . . . Wed, Jan 8, 9:09AM PDT (-0700 GMT). . . [330 ] Did you ever sell any of the video games you programmed?

Stephanie G/CJHS: . . . . Wed, Jan 8, 9:09AM PDT (-0700 GMT). . . [331 ] Would there be any other way to get to other planets without the use of computers?

Mark: . . . . Wed, Jan 8, 9:10AM PDT (-0700 GMT). . . [332 ] Steve - while you're pondering the computer question, here's another one: when you say you 'fly' the spacecraft, does that mean you have a slot at a computer at Mission Control, and you advise Flight as to status?

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:10AM PDT (-0700 GMT). . . [333 ] The entire computer fits on a small circuit board the size of a small text-book. [continued...]

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:11AM PDT (-0700 GMT). . . [335 ] The computer also has 6 megabytes of programmable ROM. This is special memory that holds data even if there is no electricity on the spacecraft. This is useful when we go to sleep at night on Mars.

Joey/CJHS: . . . . Wed, Jan 8, 9:11AM PDT (-0700 GMT). . . [336 ] About what size is the computer in Mars Pathfinder?

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:12AM PDT (-0700 GMT). . . [337 ] Let me answer the airbag question because it was very good. "How do you know when to inflate the airbags?"

JOHN SCOTT: . . . . Wed, Jan 8, 9:12AM PDT (-0700 GMT). . . [338 ] Do you remember my airbag question?

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:12AM PDT (-0700 GMT). . . [339 ] We plunge through the atmosphere of Mars and slow down from 1,500 MPH to 300 MPH using a parachute. [continued...]

lma@portugal/europe: . . . . Wed, Jan 8, 9:12AM PDT (-0700 GMT). . . [340 ] what computer are yuo talking about? the mars pathfinder computer? or the controling computer?

David/CJHS: . . . . Wed, Jan 8, 9:12AM PDT (-0700 GMT). . . [341 ] Were you involved with the mission that failed in the early 90's ,if so what do you think happened ?

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 9:12AM PDT (-0700 GMT). . . [342 ] John: Your airbag question will be answered momentarily...

anita/glencliff: . . . . Wed, Jan 8, 9:13AM PDT (-0700 GMT). . . [343 ] Hi- Right now we're just testing to see if this message goes through.

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:13AM PDT (-0700 GMT). . . [344 ] But, we must use the airbags to cushion us from our crash with the ground. This is very tricky! Here is how we do it: [continued]

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 9:13AM PDT (-0700 GMT). . . [345 ] Welcome Anita. Your message has come through!

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:14AM PDT (-0700 GMT). . . [346 ] We have a device called a radar altimeter. It beams radar waves at the ground and listens for "echos" as the beams bounce off of the ground and return to the spacecraft. This is just like the way bats navigate in dark caves! [continued]

JOHN SCOTT: . . . . Wed, Jan 8, 9:14AM PDT (-0700 GMT). . . [347 ] Thank ya!

lma@portugal/europe: . . . . Wed, Jan 8, 9:14AM PDT (-0700 GMT). . . [348 ] how do you prevent form the airbag gas to contaminate the martin surface?

David/CJHS: . . . . Wed, Jan 8, 9:15AM PDT (-0700 GMT). . . [349 ] How did you get teh airbags to inflate at just the right time?

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:15AM PDT (-0700 GMT). . . [350 ] By measuring how long it takes the radio waves to travel to the ground and bounce back, we know how high we are! Right before we hit the ground, we inflate the airbags!

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:17AM PDT (-0700 GMT). . . [351 ] LMA: how do you prevent form the airbag gas to contaminate the martin surface? The gas is CO2 (carbon monoxide). This gas is present on Mars already. So releasing a very small amount into the atmosphere will not contaminate the planet.

JOHN SCOTT: . . . . Wed, Jan 8, 9:17AM PDT (-0700 GMT). . . [352 ] Does the MGS later help "Sojourner" by orienteering?

Micah/CJHS: . . . . Wed, Jan 8, 9:17AM PDT (-0700 GMT). . . [353 ] Is programming computers for spacecrafts as fun or exciting as it is for video games?

Joey/CJHS: . . . . Wed, Jan 8, 9:17AM PDT (-0700 GMT). . . [354 ] What is the most disasteris malfunction that could happen to Mars Pathfinders computer?

Josh/Strath Haven Middle School: . . . . Wed, Jan 8, 9:18AM PDT (- 0700 GMT). . . [355 ] How long does it take a transmission to get from the Earth to Mars?

David/CJHS: . . . . Wed, Jan 8, 9:18AM PDT (-0700 GMT). . . [356 ] Were you involved with the mission that failed in the early 90's ,if so what do you think happened ?

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:18AM PDT (-0700 GMT). . . [357 ] Micah: Is programming computers for spacecrafts as fun or exciting as it is for video games? It is just as fun but very different [continued]

JOHN SCOTT: . . . . Wed, Jan 8, 9:19AM PDT (-0700 GMT). . . [358 ] Do you remember the MGS question?

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:19AM PDT (-0700 GMT). . . [359 ] A spacecraft does something very unique and will change history and the way people view the universe. That makes it very exciting. Designing video games is a different kind of excitement. [continued]

lma@portugal/europe: . . . . Wed, Jan 8, 9:20AM PDT (-0700 GMT). . . [360 ] carbon monoxide is CO isn't it? not CO2 How can you know the presence of CO/2?

Megan: . . . . Wed, Jan 8, 9:20AM PDT (-0700 GMT). . . [361 ] How long did it take to program the computers on the MPF?

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 9:20AM PDT (-0700 GMT). . . [362 ] John: Could you please reask your question? Thanks!

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:20AM PDT (-0700 GMT). . . [363 ] When you design a video game, you get to see people all over the world using something that you thought up and built. That is a different kind of excitement!

Micah/CJHS: . . . . Wed, Jan 8, 9:21AM PDT (-0700 GMT). . . [364 ] What's the next mission you're goin to help program?

JOHN SCOTT: . . . . Wed, Jan 8, 9:21AM PDT (-0700 GMT). . . [365 ] My question: Does the MGS help the "Sojourner" later orienteering?

David/CJHS: . . . . Wed, Jan 8, 9:21AM PDT (-0700 GMT). . . [366 ] Were you involved with the mission that failed in the early 90's ,if so what do you think happened ?

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:22AM PDT (-0700 GMT). . . [367 ] Megan: How long did it take to program the computers on the MPF? It took 7 of us 3 years to program the computer. Three years is a long time to spend working on just one thing.

John W./CJHS: . . . . Wed, Jan 8, 9:22AM PDT (-0700 GMT). . . [368 ] What are you going to do if the pathfinder stops taking commands on mars?

Rick: . . . . Wed, Jan 8, 9:23AM PDT (-0700 GMT). . . [369 ] How many computer programmers compose the team that worked on this project?

anita/glencliff: . . . . Wed, Jan 8, 9:23AM PDT (-0700 GMT). . . [370 ] Steve- How large are the airbags? Anita

JOHN SCOTT: . . . . Wed, Jan 8, 9:23AM PDT (-0700 GMT). . . [371 ] Now, does the MGS help the Sojourner or not?

Joey/CJHS: . . . . Wed, Jan 8, 9:23AM PDT (-0700 GMT). . . [372 ] What is the most disasteris malfunction that could happen to Mars Pathfinders computer?

John N/CJHS: . . . . Wed, Jan 8, 9:23AM PDT (-0700 GMT). . . [373 ] How long did it take you to program the computer on the Mars Pathfinder?

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:23AM PDT (-0700 GMT). . . [374 ] Hi John Scott: MGS does not help the rover because it does not arrive until after most of our mission is accomplished. Because of this, we designed the rover to operate on its own - even after the orbiter arrives at Mars.

David/CJHS: . . . . Wed, Jan 8, 9:24AM PDT (-0700 GMT). . . [375 ] Were you involved with the mission that failed in the early 90's ,if so what do you think happened ?

lma@portugal/europe: . . . . Wed, Jan 8, 9:24AM PDT (-0700 GMT). . . [376 ] What computer are you talking about? MPF's ?

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 9:25AM PDT (-0700 GMT). . . [377 ] lma: Steve is talking about MPF's.

JOHN SCOTT: . . . . Wed, Jan 8, 9:25AM PDT (-0700 GMT). . . [378 ] Well, I thought that Sojourner would operate more than 2 years!

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:26AM PDT (-0700 GMT). . . [379 ] Joey: What is the most disasteris malfunction that could happen to Mars Pathfinders computer? That is a scary question! The worst thing that can happen is that the computer stops working. This would happen because the hardware malfunctioned, or because the software had a "bug" in it. Most spacecraft have 2 computers in case one breaks! Ours only has one to save money since computers are usually very reliable.

Brian/CJHS: . . . . Wed, Jan 8, 9:26AM PDT (-0700 GMT). . . [380 ] What would you do if the power went out where you were working and all the ground computers went out?

Jaime/CJHS: . . . . Wed, Jan 8, 9:26AM PDT (-0700 GMT). . . [381 ] Did you ever sell any of the video games you programmed?

MikeS/CJHS: . . . . Wed, Jan 8, 9:26AM PDT (-0700 GMT). . . [382 ] What program do you use for the Pathfinder?

Jim/CJHS: . . . . Wed, Jan 8, 9:26AM PDT (-0700 GMT). . . [383 ] How much ram does it take to run everything?

JOHN SCOTT: . . . . Wed, Jan 8, 9:27AM PDT (-0700 GMT). . . [384 ] Thank ya again!

Megan: . . . . Wed, Jan 8, 9:27AM PDT (-0700 GMT). . . [385 ] Thanks for the Answer! When you programed the MPF computers, what did you have the most trouble with?

Dustin/cjhs: . . . . Wed, Jan 8, 9:27AM PDT (-0700 GMT). . . [386 ] How does the mars pathfinder send information back without anybody programing it?

Jenny/CJHS: . . . . Wed, Jan 8, 9:28AM PDT (-0700 GMT). . . [387 ] How did you become a Flight Software Engineer?

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:28AM PDT (-0700 GMT). . . [388 ] Hi Josh: How long it takes for a transmission from Earth to reach the spacecraft depends on how far the spacecraft is from Earth. Right now it is 31.9 seconds. This is a minor delay compared to the delay at Mars. The delay is 15 Minutes!!!

Marvin the Martian: . . . . Wed, Jan 8, 9:28AM PDT (-0700 GMT). . . [389 ] test

Stephanie G/CJHS: . . . . Wed, Jan 8, 9:28AM PDT (-0700 GMT). . . [390 ] Would there be any other way to get to other planets without the use of computers?

JOHN SCOTT: . . . . Wed, Jan 8, 9:28AM PDT (-0700 GMT). . . [391 ] Who has created Sojourner?

Joey/CJHS: . . . . Wed, Jan 8, 9:28AM PDT (-0700 GMT). . . [392 ] Is there any type of malfunction that could cause Mars Pathfinder to explode?

Alex/CJHS: . . . . Wed, Jan 8, 9:29AM PDT (-0700 GMT). . . [393 ] If the NASA computer downloads a virus and it deletes the database how do you reprogram it?

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:30AM PDT (-0700 GMT). . . [394 ] Hi David! The mission that failed in the early 90's was Mars Observer. Nobody knows for sure why it disappeared but we have a good idea [continued]

JOHN SCOTT: . . . . Wed, Jan 8, 9:30AM PDT (-0700 GMT). . . [395 ] I'm interested in the name of MPF's following spacecraft (after MGS)

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:31AM PDT (-0700 GMT). . . [396 ] To make the rockets powerful, we mix two chemicals that explode on contact. We mix these chemicals in the thrusters and the explosion propels the spacecraft. [continued]

Marvin the Martian: . . . . Wed, Jan 8, 9:31AM PDT (-0700 GMT). . . [397 ] We have heard that it takes 20 minutes to send a message from Earth to the Mars computer. Is this true? If so, how does it affect the airbag? Do you have to tell it to deflate 20 minutes before you actually get close to the ground?

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:32AM PDT (-0700 GMT). . . [398 ] We believe that Mars Observer had a valve that let one of the chemicals leak into the fuel lines where it accidently mixed with the other chemical. The explosion happened in the wrong place and the spacecraft was lost.

lma@portugal/europe: . . . . Wed, Jan 8, 9:32AM PDT (-0700 GMT). . . [399 ] How does the mpf comnunicate, since the mgs is not present? directly to Earth? there is not a "dark side" ?

lma@portugal/europe: . . . . Wed, Jan 8, 9:33AM PDT (-0700 GMT). . . [400 ] How does the mpf comnunicate, since the mgs is not present? directly to Earth? there is not a "dark period" ?

JOHN SCOTT: . . . . Wed, Jan 8, 9:33AM PDT (-0700 GMT). . . [401 ] That about Mars Observer is really interesting!

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:33AM PDT (-0700 GMT). . . [402 ] Stephanie: Would there be any other way to get to other planets without the use of computers? In the "old days" before computers, spacecraft were controlled by simple mechanical systems and 'analog' electrical circuits. The spacecraft were very primitive and could not do the things that modern spacecraft do for us.

Mark Stokes: . . . . Wed, Jan 8, 9:33AM PDT (-0700 GMT). . . [403 ] Steve - how do you *control* a chemical explosion?

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:35AM PDT (-0700 GMT). . . [404 ] Hi Rick: You had asked about the number of programmers on the project. Seven (7) people worked very hard for three years to design, write, and test the software for the pathfinder computer.

: . . . . Wed, Jan 8, 9:35AM PDT (-0700 GMT). . . [405 ] Are there aliens on Mars?

Tim McCollum/CJHS: . . . . Wed, Jan 8, 9:35AM PDT (-0700 GMT). . . [406 ] Steve, Sandy & Andrea - End of class here. Thanks again for allowing us to participate. On to Mars!

JOHN SCOTT: . . . . Wed, Jan 8, 9:36AM PDT (-0700 GMT). . . [407 ] What's the name of the following spacecraft after MGS and MPF

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:36AM PDT (-0700 GMT). . . [408 ] Mark: Steve - how do you *control* a chemical explosion? Joey: Can Pathfinder explode? These questions are related [continued]

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:38AM PDT (-0700 GMT). . . [409 ] We control the explosion by mixing the chemicals in the proper proportions in the proper places. Pathfinder is different from Mars Observer it only has one gas that it shoots out [cold] from the thrusters to propel the spacecraft. It is not as good as having a chemical explosion, but it is much safer. [continued]

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 9:38AM PDT (-0700 GMT). . . [410 ] To Whoever Wrote the Question: "ARe there aliens on Mars?" Please write your name, or any name in "The Handle" so that we can direct an answer to you!

anita/glencliff: . . . . Wed, Jan 8, 9:38AM PDT (-0700 GMT). . . [411 ] what is mpf going to do to follow up on the rock they found in antarctica that contained the indications of life

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:39AM PDT (-0700 GMT). . . [412 ] The only way Mars Pathfinder can explode is if a valve gets stuck "ON." The way the valve works is that electricity is applied to a coil to produce a magnet. You can build one in your classroom [continued]

5th/Morris MN: . . . . Wed, Jan 8, 9:39AM PDT (-0700 GMT). . . [413 ] How long does it take you to program a computer.

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 9:40AM PDT (-0700 GMT). . . [414 ] 5th/Morris MN: Can you be more specific? Program a computer to do what?

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:40AM PDT (-0700 GMT). . . [415 ] If the electricity stays on too long, the spacecraft can get very hot and the fuel will explode. The software I designed will shut off the electricity before this can happen. SOFTWARE TO THE RESCUE!!!

: . . . . Wed, Jan 8, 9:40AM PDT (-0700 GMT). . . [416 ] This is McMurray Middle School on Vashon Island, Mr. Stopler how long have you worked on the Mars Pathfinder.How long until humans inhibate Mars.

John Scott: . . . . Wed, Jan 8, 9:41AM PDT (-0700 GMT). . . [417 ] So, what's the name of the 1998 missions, if there are really some?

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 9:41AM PDT (-0700 GMT). . . [418 ] Welcome McMurray Middle School! Where is Vashon Island? Steve is answering a backlog of questions right now, but he will get to yours soon! Hang tight!

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:41AM PDT (-0700 GMT). . . [419 ] Hi Alex: You asked about a virus in our computer. This cannot happen. First, the virus would have to get into the computer. But, the computer is out in space! When the computer was on the ground it was carefully protected so nobody could introduce a virus.

Megan: . . . . Wed, Jan 8, 9:42AM PDT (-0700 GMT). . . [420 ] When you programed the MPF computers, what did you have the most trouble with?

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:43AM PDT (-0700 GMT). . . [421 ] Marvin the Martion asked about the 20 minute delay and the airbags. How do we get everything to happen at the right time? The answer is simple.... SOFTWARE [continued]

John Scott: . . . . Wed, Jan 8, 9:43AM PDT (-0700 GMT). . . [422 ] What's the name of the 1998 missions to mars?

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 9:43AM PDT (-0700 GMT). . . [423 ] Hang in there John Scott, we'll get to you. As you can see there are a lot of people who want their questions answered :-)

5th/Morris MN: . . . . Wed, Jan 8, 9:43AM PDT (-0700 GMT). . . [424 ] For a computer to control a spacecraft.

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:43AM PDT (-0700 GMT). . . [425 ] Mars is soooo far away that the ground cannot command the spacecraft to do the right thing at the right time. The spacecraft must decide what to do on its own. [continued]

Mustangs: . . . . Wed, Jan 8, 9:44AM PDT (-0700 GMT). . . [426 ] What previsions are available for trouble shooting deployment failiars?

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 9:44AM PDT (-0700 GMT). . . [427 ] 5th/Morris MN: It took 7 people three years to program the Mars Pathfinder computer.

John Scott: . . . . Wed, Jan 8, 9:44AM PDT (-0700 GMT). . . [428 ] That's all right. Thank you very much

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:45AM PDT (-0700 GMT). . . [429 ] In order to make the spacecraft behave intelligently, we must write clever computer programs that take in data and act intelligently. We are trying to build a spacecraft as smart as a person.

toby /glencliff: . . . . Wed, Jan 8, 9:45AM PDT (-0700 GMT). . . [430 ] steve-what kind of education/college did you go through to get where you're at now?

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:46AM PDT (-0700 GMT). . . [431 ] LMA: How does Pathfinger communicate with Earth? Good question. [continued]

Melanie@RoseRock in Cal.: . . . . Wed, Jan 8, 9:47AM PDT (-0700 GMT). . . [432 ] Mr. Stolper, we have learned a lot today! Apparantly the software is very important. You say you use C Programming language. Do you use add-ons or just plain C. It sounds like you can do a lot of sophisticated stuff with C.

Mustangs: . . . . Wed, Jan 8, 9:47AM PDT (-0700 GMT). . . [433 ] Vashon is in the bottom of the Puget Sound, in Washington State.

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:47AM PDT (-0700 GMT). . . [434 ] We communicate directly from the surface of Mars to the surface of the Earth using a ping-pong paddle sized antenna. As Mars rotates, the Earth rizes and sets just like Earth's moon. During those periods, we do not talk to the spacecraft. It must be smart enough to take care of itself.

Marvin: . . . . Wed, Jan 8, 9:48AM PDT (-0700 GMT). . . [435 ] Steve, does programming for MPF seem like the video games you used to program? You must love your job if it does.

cindy/glencliff: . . . . Wed, Jan 8, 9:48AM PDT (-0700 GMT). . . [436 ] I am very fasinated from your background as a computer scientist and as an inventor. I am interested in the computer science field also. Do you have any advice for interested minds like myself? Also have you created or designed any other software or spacecrafts.

John Scott: . . . . Wed, Jan 8, 9:48AM PDT (-0700 GMT). . . [437 ] My question (1998) isn't answered yet!

5th/Morris MN: . . . . Wed, Jan 8, 9:48AM PDT (-0700 GMT). . . [438 ] Did you ever think that the things that happend in Star Trek would come true?

Megan: . . . . Wed, Jan 8, 9:48AM PDT (-0700 GMT). . . [439 ] When you programed the MPF computers, what did you have the most trouble with?

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:49AM PDT (-0700 GMT). . . [440 ] Hi Anita: You had asked about Pathfinder and the Mars Rock... We are exploring an area where a catastrophic flood has brought different kinds of rocks from all over the planet. [continued]

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 9:49AM PDT (-0700 GMT). . . [441 ] John: There are a couple hundred kids out there sending in questions! We're trying to get to everyone at least once!

5th/Morris MN: . . . . Wed, Jan 8, 9:49AM PDT (-0700 GMT). . . [442 ] Do still like the Star Wars movies?

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:50AM PDT (-0700 GMT). . . [443 ] We will analyze these rocks. But, most of the mission was designed before the rock was discovered. So, we do not have all of the equipment necessary to look for life.

anita/glencliff: . . . . Wed, Jan 8, 9:51AM PDT (-0700 GMT). . . [444 ] is nasa planning to send any plobes to pluto

Marvin: . . . . Wed, Jan 8, 9:51AM PDT (-0700 GMT). . . [445 ] If a person were in outer space without a spacesuit, would he blow up without any pressure?

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 9:51AM PDT (-0700 GMT). . . [446 ] EVERYONE: STEVE IS WILLING TO STAY ON FOR AT LEAST ANOTHER 30 MINUTES! WE'VE NEARLY FINISHED ANSWERING THE BACKLOG OF QUESTIONS. THANK YOU FOR BEING SO PATIENT :-)

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:52AM PDT (-0700 GMT). . . [447 ] Hi Mustangs: I have worked on Pathfinder since it was only an idea someone wrote on a piece of paper three years ago. I do not know when humans will inhabit Mar, but I belive that it is possible within the next 25 years.

Megan: . . . . Wed, Jan 8, 9:52AM PDT (-0700 GMT). . . [448 ] When you programed the MPF computers, what did you have the most trouble with?

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:54AM PDT (-0700 GMT). . . [449 ] Hi Toby: You asked about my school background. After high-school, I went to an Engineering College called Rensselaer Polytechnic Institute (RPI) in New York. I wanted to study computers but did not know WHAT I wanted to do with them. [continued]

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:55AM PDT (-0700 GMT). . . [450 ] It was not until after I reached college and tried business computing, scientific computing, and computer graphics that I decided I wanted to program real-time control systems.

: . . . . Wed, Jan 8, 9:56AM PDT (-0700 GMT). . . [451 ] What do you plan to work on in the future?

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:56AM PDT (-0700 GMT). . . [452 ] Hi Cindy: I'm glad that you like computers as much as I do! I have worked on Galileo which went to Jupiter and several other spacecraft. I have even worked on an instrument that flew on a Japanese spacecraft last year. [continued]

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 9:58AM PDT (-0700 GMT). . . [453 ] The advice that I have for people who want to learn more about computers is to: 1. Have fun 2. Take interesting computer programming courses 3. learn the fundamentals of computer programming (data structures and algorithms} 4. Have Fun!

Megan: . . . . Wed, Jan 8, 9:58AM PDT (-0700 GMT). . . [454 ] I have to leave now - Thanks for another great webchat!

Mark Stokes: . . . . Wed, Jan 8, 9:58AM PDT (-0700 GMT). . . [455 ] Steve - I have a sense that my question about your role at Mission control (telling Flight what is happening) might have been inapropriate - security and all that. Yes?

Eric@RoseRock in Cal.: . . . . Wed, Jan 8, 9:59AM PDT (-0700 GMT). . . [456 ] Sorry, I didn't know I was anonymous. My question was: What do you plan to work on in the future?

John Scott: . . . . Wed, Jan 8, 9:59AM PDT (-0700 GMT). . . [457 ] Is somebody like you, who directly works with spacecraft, still so fascinated of space travelling (or more?)

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 9:59AM PDT (-0700 GMT). . . [458 ] Bye Megan. Thanks for joining us again :-) I hope we were able to answer most of your questions! Hope to "see" you next week!

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 10:00AM PDT (- 0700 GMT). . . [459 ] Hi John Scott: After Pathfinder, an orbiter and lander combination are going to be launched to Mars. The project is called Mars Surveyer. It will not have a rover, but will have a giant robot arm to dig into the soil and look for life. It will land in the polar regions of Mars. Maybe on snow!

5th/Morris MN: . . . . Wed, Jan 8, 10:00AM PDT (-0700 GMT). . . [460 ] We have to leave very, VERY soon. Please answer our question.

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 10:01AM PDT (- 0700 GMT). . . [461 ] Hi Morris! I think many things on Star Trek have already come true. We talk to computers, we have personal communicators (cell phones), we have data cartridges (disks) and many others.

luis alves /lma/portugal: . . . . Wed, Jan 8, 10:02AM PDT (-0700 GMT). . . [462 ] I'm back again

John Scott: . . . . Wed, Jan 8, 10:02AM PDT (-0700 GMT). . . [463 ] Thank you for answering!

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 10:03AM PDT (- 0700 GMT). . . [464 ] Hi Melanie! We use ANSI standard C. We do this so we can use our programs on other computers in the future. We use functions the operating system provides because we plan to use the operating system on our future computers.

Megan: . . . . Wed, Jan 8, 10:03AM PDT (-0700 GMT). . . [465 ] Bye Sandy! And thanks to everyone again! (And yes, you'll "see" me next week!)

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 10:04AM PDT (-0700 GMT). . . [466 ] Welcome back Luis! Nice to "see" you again :-)

5th/Morris MN: . . . . Wed, Jan 8, 10:04AM PDT (-0700 GMT). . . [467 ] What was the first brand of computer you used?

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 10:04AM PDT (- 0700 GMT). . . [468 ] Hi Eric! I do not know what I plan to work on in the future. There are so many exciting things! Not just spacecraft, but new inventions that are controlled by computers! But, I think I might return to college and learn more about computers so that I can do my job better.

Melanie@RoseRock in Cal.: . . . . Wed, Jan 8, 10:05AM PDT (-0700 GMT). . . [469 ] Thank you for the chat session, Mr. Stolper. It was very interesting. I learned quite a bit. I have to go now though!

Eric@RoseRock in Cal.: . . . . Wed, Jan 8, 10:05AM PDT (-0700 GMT). . . [470 ] Thank you for the information. It gave me a very good idea what your job is like! Bye.

luis: . . . . Wed, Jan 8, 10:05AM PDT (-0700 GMT). . . [471 ] i' had problems with the refresh rate, sandy. how can i turn it off?

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 10:06AM PDT (-0700 GMT). . . [472 ] Bye Melanie and Eric. Thank you for joining us! Please come back next week!

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 10:06AM PDT (- 0700 GMT). . . [473 ] Anita, NASA is considering sending a probe to Pluto because it is the only planet in the solar system not visited by a spacecraft. The problem is that Pluto is soooo far away from the sun that we cannot use solar panels for electricity. Until we figure out how to solve this problem, we are not ready to send a spacecraft to Pluto.

luis: . . . . Wed, Jan 8, 10:08AM PDT (-0700 GMT). . . [474 ] why do not use a quimical or nuclear eletricity generator?

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 10:08AM PDT (- 0700 GMT). . . [475 ] Hi Marvin: Would a person blow up if he was in space without a spacesuit? I will try to answer but this is not really my area of expertise. A person would probably not explode. But, his blood would boil (fluids boil at lower temperatures), and he would get a TERRIBLE SUNBURN!

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 10:09AM PDT (-0700 GMT). . . [476 ] Luis: There is a "Refresh Rate" box in my WebChat screen. If there is one on your screen, put a zero in it.

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 10:10AM PDT (- 0700 GMT). . . [477 ] Morris: What was the first brand of computer I used? When I was very young, the first popular personal computer was the IBM PC. This computer was so new, that adults did not know how to use them! I worked in high school teaching adults how to use this computer. It was a good way to earn extra money.

5th/Morris MN: . . . . Wed, Jan 8, 10:10AM PDT (-0700 GMT). . . [478 ] Do you hope that some day you will send a spacecraft that will land on Pluto?

luis: . . . . Wed, Jan 8, 10:10AM PDT (-0700 GMT). . . [479 ] i have put it, but it did not work ! I had to close the browser.

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 10:12AM PDT (-0700 GMT). . . [480 ] Andrea or Mark: ARe you still "out there"? If so, can you answer Luis's question about turning refresh off? Thanks!

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 10:12AM PDT (- 0700 GMT). . . [481 ] Hi Luis! We can not use chemical electricity generators to reach Pluto at this point because they are not efficient enough and powerful enough. We could use radio- isotope-thermal-electric-generators like the Voyager spacecraft did, but the nuclear power sources are so expensive that nobody builds them anymore!

Andrea/NASA/Moderator: . . . . Wed, Jan 8, 10:13AM PDT (-0700 GMT). . . [482 ] Sure - type 0 in the "Refresh Rate" box and hit the chat button.

John Scott: . . . . Wed, Jan 8, 10:13AM PDT (-0700 GMT). . . [483 ] I have put "10" into the box. It doesn't refresh.

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 10:14AM PDT (- 0700 GMT). . . [484 ] Morris: Do you hope that some day you will send a spacecraft that will land on Pluto? I do not know if I will do that or choose something entirely different. It might be challenging to catch a comet, or build robots that fly airplanes or drive cars.

5th/Morris MN: . . . . Wed, Jan 8, 10:15AM PDT (-0700 GMT). . . [485 ] We would appreciate it if you would answer are ? in the next 6 minutes.

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 10:15AM PDT (-0700 GMT). . . [486 ] EVERYONE: STEVE NEEDS TO GET BACK TO "SPACECRAFT DUTY" SOON, SO WE'RE GOING TO GO FOR 10 MORE MINUTES AND THEN SAY GOODBYE.

Andrea/NASA/Moderator: . . . . Wed, Jan 8, 10:15AM PDT (-0700 GMT). . . [487 ] John - try putting in a higer number and then hit the chat button

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 10:16AM PDT (-0700 GMT). . . [488 ] 5TH/Morris: Anymore questions in your last 6 minutes?

John Scott: . . . . Wed, Jan 8, 10:17AM PDT (-0700 GMT). . . [489 ] Do you remember my question about "fascinated of space travelling"

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 10:17AM PDT (- 0700 GMT). . . [490 ] John Scott: Can you ask me again?

5th/Morris MN: . . . . Wed, Jan 8, 10:18AM PDT (-0700 GMT). . . [491 ] Thank you for anwering our question, and yes we do hope that some day we will send a spacecraft that will land on Pluto.

luis: . . . . Wed, Jan 8, 10:18AM PDT (-0700 GMT). . . [492 ] Andrea: I've tryed it. May be not the right time to solve this small problem. Later if you want. Low bandwith? (portugal-us)

John Scott: . . . . Wed, Jan 8, 10:19AM PDT (-0700 GMT). . . [493 ] I do so now: Is somebody like you after you started to do hat you do still fascinated of space travelling? )(or more?)

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 10:21AM PDT (- 0700 GMT). . . [494 ] John Scott: Yes! Every project is new and exciting. On this project we have pushed things out of helicopters and dropped them from cranes. I got to hug our rocket and see a Space Shuttle launch while I was in Florida. I learned many new thing and played with fun toys. So, I am just excited now as I was when I started.

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 10:23AM PDT (-0700 GMT). . . [495 ] Good bye John Scott, Luis, Mark, Andrea and anyone still listening! Thank you for joining us! A special thank you to Steve! Your responses were terrific. We hope you will join us again in the future! Good luck with Pathfinder :-)

John Scott: . . . . Wed, Jan 8, 10:23AM PDT (-0700 GMT). . . [496 ] So, do you also read Sci-Fi stories?

John Scott: . . . . Wed, Jan 8, 10:24AM PDT (-0700 GMT). . . [497 ] Thank you very much!!!

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 10:24AM PDT (- 0700 GMT). . . [498 ] John Scott: I love to read Sci-Fi stories but am very picky about what I read. It needs more than gadgets. It needs to have a good story and be well written. If it is, I can not put the book down until I read the whole thing.

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 10:24AM PDT (-0700 GMT). . . [499 ] Hang on John...

Andrea/NASA/Moderator: . . . . Wed, Jan 8, 10:25AM PDT (-0700 GMT). . . [500 ] luis - what type of browser are you using and what version is it?

luis/lma: . . . . Wed, Jan 8, 10:25AM PDT (-0700 GMT). . . [501 ] Steve: i wish you luck to your project. Thank you for this moment.

Andrea/NASA/Moderator: . . . . Wed, Jan 8, 10:25AM PDT (-0700 GMT). . . [502 ] Steve Thank you! I learned some great stuff!

Steve Stolper (Mars Pathfinder): . . . . Wed, Jan 8, 10:25AM PDT (- 0700 GMT). . . [503 ] Unfortunately, I have to leave at this time. I had a great time speaking to everyone and I hope we can do this again. - Steve

Sandy/NASA Chat Host: . . . . Wed, Jan 8, 10:26AM PDT (-0700 GMT). . . [504 ] Bye Luis! I'm glad you were able to join us this week! I hope we can figure out your refresh problem.

luis/lma: . . . . Wed, Jan 8, 10:27AM PDT (-0700 GMT). . . [505 ] Andrea: windows internet explorer 3.0 , w95, I can test it with you for more 15 minutes. Thank you.