Transcript from the National Engineers Week Webchat: Phoenix Mars Mission Engineering

3:30 p.m. PT on Wednesday, February 20, 2008


H__ <Q>Do you build/use any robots in your spare time, at home ?
Erik_Bailey <A>Yes... I fool around with Lego Mindstorms when I get free time, and have a Roomba - if that counts!

Cassie_Bowman <Q>Here's another question via email for both our engineers: Do you have any hobbies?
Erik_Bailey <A>Yup. Sport Kiting, Bicycling (road), Music Composition, Audio Recording, and Video Editing.

Cassie_Bowman <Q>Via email: What other classes besides math and science would you recommend for students interested in engineering?
Erik_Bailey <A>Any kind of hands-on construction class, such as drafting, wood shop, and metal shop. Computer programming is also a must.

Aikin_Elementary <Q>How fast can the rovers go?
Erik_Bailey <A>The MER rovers move at about the speed of a tortoise.

Aikin_Elementary <Q>How many robotic systems can you control at one time?
Erik_Bailey <A>We can control as many as the Deep Space Network can communicate to at once. Google "Deep Space Network" for more information.

bulldog08 <Q>What is each of your specific jobs at NASA?
Erik_Bailey <A>I am a Guidance, Navigation, and Control Systems Engineer. Translation: I work with the parts of the spacecraft that tell the spacecraft how it is pointed, and how it is moving. I've specialized in Entry, Descent, and Landing systems since I started at JPL 7.5 years ago.

Cassie_Bowman <Q>Another email question: How long will it take Phoenix to get to Mars?
Erik_Bailey <A>Just over 9.5 months. We launched on August 4, 2007, and we land on May 25, 2008.

Aikin_Elementary <Q>Do you think it is possible that a human can walk on Mars?
Erik_Bailey <A>Absolutely, provided he has a space suit so he/she can breathe! The gravity is roughly double that of the moon, so things will accelerate faster in Mars gravity. Astronauts would hop like the lunar astronauts, but not as high or as far.

Cassie_Bowman Thanks for joining our National Engineers Week webchat! We'll get started at 3:30 PT. In the meantime, one of our participating engineers is posting answers to questions received earlier today, so feel free to read through.

Aikin_Elementary <Q>Is it hard to control robots on Mars from here on Earth?
Erik_Bailey <A>The short answer, yes. Imagine this: You have a remote control car, but when you command it, the car doesn't "hear" your command until a minimum of 6.5 MINUTES later, and then you don't see it respond until 6.5 MINUTES later after it "hears" your command. Given this situation, you can't just "joystick" spacecraft on Mars around. What we do is send up sequences, which the spacecraft then interpret and execute within their autonomous fault protection. Think of it as creating a list of things to do, which we then monitor remotely.

Erik_Bailey Hi all. I'm answering questions that are in our queue while I wait to start.

Cassie_Bowman <Q>Via email: "What subjects would you suggest a student interested in a career in robotics take in High School and college?"
Erik_Bailey <A>That will vary on the curricula available, but I'd suggest the following for High School students: Math & Physics to as high of levels as you can obtain, computer programming, wood & metal shop, drafting, and as many hands-on activities (like FIRST Robotics) as you can get into that are engineering-oriented.

EDL <Q>Airbags have apparently reached their limit, so what is the maximum payload that a Phoenix/Viking type lander can deliver to the surface?
Erik_Bailey <A>First off, Airbags have only reached their limit in terms of existing design for Pathfinder/MER. With re-design I think that they can be stretched to do more than they already have. Remember, that MER was originally supposed to use the Pathfinder Entry/Descent/Landing system AS-IS... but as the mass grew during the design/build phase, we had to alter the system, adding layers and an extra bladder to the airbags to make the work with the MER landed mass.

TADO_slo_ <Q>what is this disc with names on it?I mean send name to mars...
Cassie_Bowman <A>Hi, If you're taking about the disc on Phoenix, you can read about it at http://www.planetary.org/special/fromearth/phoenix

EDL <Q>Airbags have apparently reached their limit, so what is the maximum payload that a Phoenix/Viking type lander can deliver to the surface?
Erik_Bailey <A>Secondly, the Phoenix/Viking type lander is a bit of a misnomer... Viking had different engines than Phoenix has, and that architecture can be scaled up... a modified version of the Viking engines are being used on the Mars Science Lab for their powered descent. The only difference being that MSL is landing a rover that is the size of a small car, so the loads required for the driving system can also handle the range of soft landing. That's why we developed the sky crane architecture: suspending the rover beneath the Viking-engine-derived "descent stage" via a rope so we could eliminate the egress problem that plagued MER during the first week of surface ops. MSL does not have to drive out or off of any other structure... and it uses similar "powered, controlled" descent like Viking and Phoenix.

EDL <Q>Airbags have apparently reached their limit, so what is the maximum payload that a Phoenix/Viking type lander can deliver to the surface?
Erik_Bailey <A>Lastly, Phoenix is using a control scheme designed for the Mars Polar Lander, which uses pulsed descent engines - they turn on/off 10x per second at varying pulse lengths (we call them "duty cycles"), rather than running continuously like Viking with a throttle valve to regulate the thrust. MSL uses Viking-like throttled engines, whereas MPL and Phoenix are the only spacecraft landers sent to mars using the pulsed descent engine scheme.

Cassie_Bowman <Q>Here's another great question that came via email: If you didn't work on space missions, what would you do?
Erik_Bailey <A>I'd most likely be working in the defense industry on military applications.

Cassie_Bowman Welcome to the Robotics Alliance Project National Engineers Week webchat! Our focus is on Phoenix Mars Mission engineering. I'd like to welcome our engineering participants: Erik Bailey, Jacob Egan and Rigel Woida and ask them to each give a brief introduction about themselves.

TADO_slo_ <Q>its phoenix rotating on the way?
Erik_Bailey <A>No. Phoenix is what we call 3-axis-stabilized, meaning that the spacecraft maintains a preferred attitude about all three body axes (X,Y,Z).

TADO_slo_ <Q>its phoenix rotating on the way?
Erik_Bailey <A>MER was a spinner, though.

Cassie_Bowman <Q>When you were in high school, what did you know about engineering?
Erik_Bailey <A>Very little. I just knew I liked building things, and applying math/science to that. I only knew that they called that "engineering" in the "real world" at the time. It wasn't until I got to college that I got a better grasp of what the profession encompassed - which is a lot more than what I thought it did in high school!

Cassie_Bowman <Q>Welcome to the Robotics Alliance Project National Engineers Week webchat! Our focus is on Phoenix Mars Mission engineering. I'd like to welcome our engineering participants: Erik Bailey, Jacob Egan and Rigel Woida and ask them to each give a brief introduction about themselves.

Jacob_Egan <A>Hello! My name is Jacob Egan and I am part of the Education and Public Outreach group for the Phoenix Mission. I am also a graduate student in Optical Science and Engineering at the University of Arizona in Tucson.

Cassie_Bowman <Q>Welcome to the Robotics Alliance Project National Engineers Week webchat! Our focus is on Phoenix Mars Mission engineering. I'd like to welcome our engineering participants: Erik Bailey, Jacob Egan and Rigel Woida and ask them to each give a brief introduction about themselves.

Rigel_Woida <A>I am 26, a grad school at the U of A in Optical Sciences and a senior ISE for the SSI and RAC. The ISE's job for the SSI and RAC is to control the imaging on Mars.

PJ <Q>Type hereThe "air bag" landings of the Mars Rovers were so successful, why didn't you use that method instead of what looks like a very risky rocket landing?
Erik_Bailey <A>This Scout mission was selected to fly the hardware that was not used but was built to fly to Mars in 2001 to accompany the Mars Odyssey orbiter. The proposal for this mission was to "resurrect" the hardware from that cancelled lander mission.

Cassie_Bowman <Q>Rigel, would you mind spelling out what ISE SSI and RAC mean?
Rigel_Woida <A>Becasue everyone wants to talk fast and seem smart we use alot of acronyms for the project.

Erik_Bailey I'm 32 and am a Guidance, Navigation, and Control Systems Engineer at NASA's Jet Propulsion Lab. I've been working on Entry, Descent, and Landing systems for almost 8 years now, including both MER rovers and proof-of-concept testing of the MSL skycrane architecture as well as my current job on the Phoenix EDL team. I have both my SB and SM from MIT in Aeronautics and Astronautics.

Cassie_Bowman <Q>Here's another question we received via email: Do you have any hobbies?
Jacob_Egan <A>Definitely, when I'm not working or at school I like to go rock climbing. Tucson has some great places to go climbing and I like to take advantage of that. I also just got my amateur radio license. Not to mention relaxing and playing video games.

Cassie_Bowman <Q>Rigel, would you mind spelling out what ISE SSI and RAC mean?
Rigel_Woida <A>The SSI is the Stereo Surface Imager and it job is to be the eyes of Phoenix

Rigel_Woida <A>The RAC is the robitic arm camera and its job is to look at the ground soil that we are digging up and delieving to the other instruments.

Rigel_Woida <A>There are two main roles for the instruments on Phoenix:
Cassie_Bowman <Q>Via email: What did your family think when you told them you wanted to be an engineer?

Erik_Bailey <A>Quite honestly, they didn't really know what it meant - but my professors helped them "see the light" when they came to visit my department in college. Neither of my parents have technical carreers.

Cassie_Bowman <Q>Via email: What did your family think when you told them you wanted to be an engineer?
Jacob_Egan <A>My family was very supportive of my decision to study engineering. My dad is a hardware/electrical engineer so I grew up enjoying science and technology.

Cassie_Bowman For those who just joined, feel free to submit your questions and our engineers Erik, Jacob, and Rigel will answer them!
Cassie_Bowman <Q>Rigel, would you mind spelling out what ISE SSI and RAC mean?
Rigel_Woida <A>The ISE and IDE: The ISE is the Instrument Sequencing Engineer and the IDE is the Instrument Downlink Engineer. The ISE focuses on commanding the instrument, where as the IDE recover the data and helps with the next day plans

Cassie_Bowman <Q>A member of our email audience asks: How old were you when you knew you wanted to be an engineer?
Jacob_Egan <A>I didn't know for sure that I wanted to be an engineering until I started college (roughly 18) but I had a general idea since high school.

Cassie_Bowman <Q>Another email question: Do you interact with scientists in your job? What is that like?
Erik_Bailey <A>Absolutely! Our job as engineers for a mission like Phoenix is to provide the vehicle and instruments for scientists to conduct science on Mars. They tell us what they need to explore Mars, and we tell them what we can build for them - there's a give and take until we come up with the best solution that accomplishes the scientists' goals. In general, scientists discover new phenomena and knowledge about our universe - engineers take that knowledge and use it to create real-world applications. For us, the real-world applications serve the very scientists that discover new things for us... it is quite fulfilling.

Cassie_Bowman <Q>Participants earlier today wanted to know: "What's the best part of your job?"
Erik_Bailey <A>The best part of being an engineer is being posed a difficult, unsolved problem that you can really sink all your "mental teeth" into. When you solve that problem, it's a feeling like no other.

Cassie_Bowman <Q>Another email question: Do you interact with scientists in your job? What is that like?
Rigel_Woida <A>The interacting with the scientists is a large part of our job. We have PI or Principle Investigators, (like Peter Smith) who are in charge of the science that is done with the instrument. So, from design, to fabracation, to calibration and final in the use of the camera. We interact a great deal. Every PI i have ever worked with on this project has been inspiring and passionate. And a lot of fun.

Cassie_Bowman <Q>Question from our email audience: When you were in high school, what did you know about engineering?
Jacob_Egan <A>Looking back now, I actually knew very little. In high school I basically thought of engineers as people who built things. In reality, engineers build things but they are also problem solvers. They look for ways to explore new technology or improve existing items to (hopefully) better society. It is very rewarding to find a problem and see it through to a solution.

Cassie_Bowman <Q>Participants earlier today wanted to know: "What's the best part of your job?"
Rigel_Woida <A>The best part of my job is being able to excite people and tell them what we are doing. I tend to wear my Phoenix ID around town and people are always coming up to me and asking. "Are you working on Phoenix ?" and they are so excited about it and it pumps me up. I find myself spent large amounts of time just talking about the possiblities and goals. So in reality I am doing the best part of my job, right now.

James <Q>Hello?

Cassie_Bowman <A>Hi, Do you have any questions for our engineers?
Cassie_Bowman For those of you interested in student opportunities at NASA, check out https://university.gsfc.nasa.gov/application/ http://nasajobs.nasa.gov/ (student opportunities) Or, if you have a NASA Center near you, take a look at their Center webpage.

Erik_Bailey Hi James.

Cassie_Bowman <Q>A previous participant wanted to know: "Was there one specific event or moment that inspired you to become an engineer?"
Rigel_Woida <A>There was no one momment for me. I always loved looking at the stars and I spent a good amount of time doing it as a kid. As i got older I start hanging out more and more with amateur astronomers and at 14 got a job working on telescopes. One thing lead to another and here I am. (PS i also watched alot of Star trek and Star Wars :) )

Cassie_Bowman <Q>A previous participant wanted to know: "Was there one specific event or moment that inspired you to become an engineer?"
Erik_Bailey <A>Not really - it was kind of something that built slowly over time as I learned more about science, math, and worked on projects in various classes and after-school activities.

Cassie_Bowman <Q>Jacob and Rigel, you mentioned that you're students. Can you talk a bit about what it's like to work on a real Mars mission while you're still a student?
Jacob_Egan <A>It is probably one of the coolest jobs that I could think of. Everyone here is very friendly and they are always willing to answer questions whenever you have them. I can walk into Peter Smith's (the mission PI) office and talk with him if I have a question. That really speaks volumes about the mission if a student can walk into the office of the mission PI.

Cassie_Bowman We've got about 5 more minutes for our chat this afternoon--please submit any last questions you have for our engineers.

James <Q>Will they attemt to wake Phonix up after the winter season?
Erik_Bailey <A>While I cannot speak for the ops team and have no clue if the mission is funded to do that, I'd think that we should at least try to talk to the vehicle and see if it survived the Martian winter... Jacob? Rigel? do you know any more about this one?

Jose <Q>Does NASA work with all different types of Engineers?
Rigel_Woida <A>Yes, we have a very large number of difference engineers here on Phoenix and in NASA in general. We have optical, electrical, mechincal, computer, networking, civil and chemical engineers. And that just the people around me right now.

TADO_slo_ <Q>what is chache in % that some meteor crash into phoenix?
Erik_Bailey <A>While I do not know the percentage, I can say that we track all known objects and the navigators do analysis to see if there are any proximity problems with them. As for yet-discovered objects, we don't know that they exist, so we cannot track them and analyze the risk.

Jacob_Egan <Q>James...I don't know to much more but I was told there was no mission plan past the scheduled 90 sols. That doesn't mean we can't try I suppose.

Cassie_Bowman <A>See answer above.

Cassie_Bowman Okay, That's all the time we have. Thanks very much for our engineering participants and those who logged in to ask questions!

Cassie_Bowman The log of this chat will be online later today or sometime tomorrow, so check back.

James <Q>Will Phoenix be communicating with the orbiters....MRO or Mars Express?
Erik_Bailey <A>Yes. Phoenix uses MRO, ODY, and MEX as UHF relays.

Cassie_Bowman <Q>A previous participant wanted to know: "Was there one specific event or moment that inspired you to become an engineer?"
Jacob_Egan <A>For me, I think it was a gradual process. I always liked legos/building stuff when I was a kid so I'm sure that helped.

James <Q>Thanks alot...that was really interesting....GOOD LUCK!

Cassie_Bowman <A>Thanks for participating!

Erik_Bailey You're welcome.

Cassie_Bowman <Q>Jacob and Rigel, you mentioned that you're students. Can you talk a bit about what it's like to work on a real Mars mission while you're still a student?
Rigel_Woida <A>It is wonderful, hard, long, challenging work. But at the end of everyday you feel an overwhelming sense of accomplishment. The team is made up of people who 10 or 20 years ago were like us, student working to try something new. In fact Peter Smith went to the same department for school as Jake and myself.