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ATO #122 - November 6, 2000

PART 1: Upcoming Chats
PART 2: Test NASA's Astroventure Website
PART 3: Working on the 2003 Mars Plane Mission


QuestChats require registration. You can register at

-Wednesday, November 8, 2000, 11 AM Pacific Planetary Flight Chat with Andy Hahn Andy Hahn is a conceptual airplane designer. He has worked on some conceptual designs for planetary planes. Read his profile at http://quest.nasa.gov/aero/team/hahn.html

-Tuesday, November 21, 2000, 9 AM Pacific
Planetary Flight Chat with Peter Gage

Peter Gage is a design engineer. He has worked on the design of some Mars entry vehicles.
Read his profile at http://quest.nasa.gov/aero/team/gage.html

-Tuesday, December 5, 2000, 10 AM Pacific
Aerospace Team Online Design, Manufacture and Test of a Planetary Entry Model

During this special Web cast, students will meet the engineers, machinists and facility managers who are responsible for the design and test of the planetary entry models. Students can ask questions via chat. Mark your calendar! More info will be available at http://quest.nasa.gov/aero/events

Help Test NASA's New Astro-Venture Web Site on Astrobiology and NASA Occupations (Grades 5-8)

We are inviting classrooms to Test the Astronomy Training Module Astro-Venture, http://astroventure.arc.nasa.gov is an educational, interactive, multimedia Web environment highlighting NASA careers and astrobiology research in the areas of Astronomy, Geology, Biology and Atmospheric Sciences.

Students in grades 5-8 are transported to the future where they role-play NASA occupations and use scientific inquiry, as they search for and build a planet with the necessary characteristics for human habitation. Supporting activities include chats with real NASA scientists, online collaborations, classroom lessons, a student publishing area and occupations fact sheets and trading cards.

We are seeking classroom, science center, museum, after-school and home-school educators and career guidance counselors interested in pilot testing the Astronomy Training multimedia Module and the lesson plans that accompany the module. In this module, students observe the effects of changes to star type, Jupiter's orbit, Earth's mass and Earth's orbit in our solar system and how those changes affect Earth's habitability for humans. The lessons address prerequisite concepts before completing the module as well as four occupation lessons.

What is Required to Participate? Pilot testing the Astro-Venture Astronomy Training Module means using the module and at least five of the accompanying lessons with your students during the month of January, 2001. During the pilot test, you are expected to provide feedback from yourself and your students on the module, the Web site and at least five lessons. This will require a minimum of 10 hours of classroom/instruction time. If you elect to do all of the lessons, instruction time should not exceed 35 hours. You will be given a five-week time frame in which to complete the lessons and submit the evaluations.

As a pilot tester, you will be contributing to the development of exciting quality educational curriculum for which you will receive recognition in the product as well as a certificate of appreciation from NASA. In addition, you will be among a select group of educators who will have access to the lesson plans and student materials for the Astronomy Training Module. As a part of this select group, you will be a part of an evaluation e-mail list that will provide technical support and suggestions from fellow piloting educators. Finally, to show our appreciation, you will receive a packet of NASA educational CD's, posters and a complete color set of Astro-Venture trading cards. Upon the completion of all nine Astro-Venture modules, you will receive a CD-ROM of the entire Astro-Venture Web site, materials and multimedia modules.

To learn more information on how to apply, visit http://astroventure.arc.nasa.gov/is/evaluate.html or contact Christina O'Guinn at NASA Ames Research Center coguinn@mail.arc.nasa.gov (Please mention where you saw this posting).


Virtual Skies is an air traffic management project for students and teachers in Grades 9-12. It will be a "project based learning activity" with hands on multimedia to enhance student decision making and problem solving skills. Topics to be covered include Aviation Navigation, Aviation Weather, Communication Air Traffic Management, Airport Design, and Air Traffic Research. Materials will be tied to the National Standards in Mathematics, Science, Technology, Geography and Language Arts.

Planetary Flight is an aerospace project for Grades 5-8. We know how to fly on Earth but what will it take to fly on Mars. This will be an inquiry based learning project to design an airplane to fly on Mars. The stuff dreams are made of!!

[Editor's Note: Andy Hahn is a conceptual designer. That means thinks about the kind of aircraft that would suit a certain mission at the very early stages. Read his bio at http://quest.arc.nasa.gov/aero/team/hahn.html ]


by Andrew Hahn

November 7, 2000

Most people don't know that NASA is actually made up of several centers, with varying amounts of overlap in terms of responsibility and capability. When our Administrator, Daniel Goldin, decided that it would be neat to send a powered airplane to Mars to commemorate the 100th anniversary of the Wright brothers' first flight, he asked groups at the Langley, Dryden, Glenn, and Ames Research Centers for proposals. This journal covers the early efforts of the Ames proposal.

Initially, Dave Kinney and I were tapped to do a feasibility study for Ames. We were told to start at 4:00 p.m. on Friday, 5 February 1999 and needed "something" to support our management in a meeting at Headquarters the following Thursday. It was a long weekend. Dave and I had done many conceptual designs before, but nothing like this. The deadline was very short, the task wasn't well defined, and the vehicle operated under conditions that were foreign to us. In short, we weren't quite sure where to begin. On top of that, all of our design tools pretty much assumed that airplanes flew on earth. Mars has a different gravitational constant (g), a very different atmosphere, and no oceans. Really fundamental questions like how much does it weigh, how much lift or drag does it have and how high up is it couldn't be answered with our existing design codes. We had to start from scratch, questioning everything we thought we knew and we had to do it fast.

Right away, we decided to use the metric system for everything. Normally, we use the English measure system because a great deal of our basic design data are in English units and over the years, we have gotten a feel for the scale of answers we get, which alerts us to really big errors. Unfortunately, this project is particularly sensitive to keeping mass and force distinct, which English units are less conducive to doing, and the scale of the plane meant that our wealth of experience was not going to be applicable. So, there was a potentially bad outcome if we stayed with English units and no really good reason to stick with them.

We also decided to prototype a new design code for Extraterrestrial Flyers in a spreadsheet. We didn't have any time to do sophisticated analysis, the task didn't require sophisticated analysis, and we didn't think we could find all the "g's" in our sophisticated analysis. Also, this problem was so uncharted that we didn't know what needed to be calculated first, calculated second, etc. We really needed the flexibility in calculation flow that spreadsheets are really good at. Once our methodology settled down into a useful progression, Dave coded a Fortran program that mimicked the spreadsheet at first, but grew over time to include much more sophisticated analyses.

We did get some guidance from the space folks that the maximum mass (not weight) allowable for the Mars Plane was about 24 kg. and that it had to fit into a re-entry shell of about one meter diameter. They also told us that the gravity was about 3/8 that of Earth's and that the atmosphere where we wanted to fly was similar to the Earth's at 100,000 feet altitude.

We then had to make a number of assumptions about speed, airfoils, materials, propulsion, and range to see how easily an airplane could be made that met even the most basic requirements. What we found out was that the most important design constraints were the mass and volume available on the space vehicle that carries the plane to Mars. Early results indicated that we wanted the biggest plane that we could fit into the re-entry vehicle, which in turn wanted to be the biggest we could fit onto the launch vehicle, the Ariane 5. Our initial concept looked very much like a radio control model airplane that folded up into a compact re-entry shell and while it looked feasible, we wanted more. This prompted our looking at some very strange ideas for fitting a flight vehicle into a re-entry vehicle. We did a qualitative look at a folding wing with only two hinges, a folding wing with eight hinges, a cable braced roll up wing, a flexible membrane sailwing (kind of like a bat wing) and a parafoil (like a square parachute). In the end, we wound up choosing the folding wing with the fewest hinges for a lot of practical reasons.

Given our assumptions, it appeared that the most attractive mission from the standpoint of performance feasibility was the relatively low altitude Canyon Flyer. It turned out that the Mars scientists liked the same mission because they were very interested in getting a look at the walls of the huge Valles Marineris Canyon over as long of a stretch as they could. As an added bonus, the primary scientific instrument, a video camera, would provide really cool pictures for the public as well as document the really risky deployment from the re-entry shell. It was beginning to look like things were coming together.

In just five days, Dave and I had concluded that the Mars Plane mission was difficult, but doable. We had given our management enough information for them to make important, early decisions, and started a relationship with the space side of NASA. Over the next nine months, many more people were called in to flesh out the design and make an integrated proposal. Specialists in aerodynamics, communications, power systems, structures, missions, science, fabrication, and contracting turned our simple study into something quite impressive. Steve Smith was called on to lead this much larger team of some 40 people with a lot of programmatic support from Julie Pollitt. Leading researchers is a little like herding cats, but they managed pull the many specialties together. Steve also added key insights into how best to solve the problem of generating the most lift with the smallest wing while avoiding compressibility problems and how best to deploy the plane from the re-entry shell.

We found that our initial assessment was somewhat optimistic, but that as we found problems with our assumptions, our specialists were able to minimize the impact through clever, detailed solutions. Even so, there were several critical areas of uncertainty that could only be managed through very sophisticated analysis and testing. Cost and schedule would have been very tight. In the end, the project would have required either pulling resources from other projects to "do it right" or taking on too large of a risk of failure and so the project was cancelled.


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