Spacecraft Design 101
Spirit, the most sophisticated Mars rover ever made, landed safely on the red planet’s surface on January 3, 2004, seven months after it was launched from Earth. Above a dry crater south of the Martian equator, the vehicle parachuted toward the Mars surface. Just before touch down, it was enveloped by giant protective airbags which allowed the craft to bounce safely until it stopped.
The story of Spirit is an amazing one. The rover had to go through a long process of planning, designing, building, testing, final check, and launch. The brainchild of scientists, it was designed and built by engineers who had to deliver what the scientists asked for. Teams of people combined their expertise in various specialties to make sure that the device would actually work as intended. It was not an easy task, and there were design difficulties that had to be overcome.
The rover is remote-controlled from millions of miles away via radio signals that take at least ten minutes to reach Mars. But during entry, descent, and landing, the spacecraft was on its own. The rover had to unfold itself and call home to say it had arrived. Because of the time delay, it also has to be smart enough to make decisions independently, such as how to move around a hazard. While all of this would be difficult enough to do on Earth, the rover has to perform in an extreme environment besides. Just a little Martian dust in the wrong spot could ruin a circuit, for example.
Even when everything looked like it would work on paper, the testing phase brought unexpected problems. First, the airbag got a gaping hole in it upon impact and had to be redesigned. Then the parachute had to be redesigned twice, first because it tore apart, and the next time it wouldn’t open. To add to the stress level, the teams had to magically find more time to fix these things in an already tight schedule, as there was an important deadline to meet. This is because every 26 months, Mars comes close enough in its orbit to launch a spacecraft there from Earth. If the rover didn’t make it to launch this time, their window of opportunity would be gone. They would have to wait another two years and waste millions of dollars as a result.
With its payload of fragile components, delicate circuits, and scientific instruments, any number of things could go wrong with the rover. If just one electrical or mechanical device were to fail, it would jeopardize the whole mission. In fact, a potentially catastrophic electronic problem on the Spirit turned up at the last minute. During final check when the finished product was awaiting launch, the circuit boards were found to be faulty. In order to replace them, the whole thing had to be taken apart and painstakingly put back together again.
Only half of all the Martian probes that were attempted actually worked when they got there. Human error may be a significant contributing factor to consider. In 1999, two NASA probes arriving at Mars were lost without a trace. The reason for the failure of one of the probes remains unexplained. The other probe’s loss was caused by a simple mathematical error, a mix-up between English and metric units.
The Mars Pathfinder mission in 1997 successfully tested the airbag-landing technique and proved that a rover could work. It was criticized, however, for not bringing back enough scientific data. So this time around, as much equipment as possible was packed into the Spirit including radios, antennas, radar, a robotic arm, power tool, cameras, infrared sensor, spectrophotometer, microscope, onboard computer, solar collectors, and a heater.
As the ultimate off-road, off-Earth mobile science lab, Spirit’s mission is to undertake the most comprehensive search for evidence of liquid water ever attempted on Mars. Spirit is now on site in Gusev Crater, a possible former lake, and its twin rover Opportunity will land in late January at Meridiani Planum, where minerals were detected that normally form in the presence of water.
Some scientists theorize that liquid water was once abundant on Mars's surface but has since vanished. When Viking found no evidence of life on Mars in the 1970’s, it was such a disappointment that there were no more Mars missions for twenty years afterwards. Perhaps this time the questions – Was there ever liquid water on the red planet? Were conditions ever suitable for life? – will finally be answered. The future of NASA's Mars exploration program itself hangs in the balance.
Honeywell Fiesta Bowl Aerospace Challenge
Hundreds of schoolchildren from around the state recently got to participate in a spacecraft design project. In doing so, they experienced some of the tension and anticipation that real scientists and engineers feel. The Honeywell Fiesta Bowl Aerospace Challenge lasted from September to December, culminating with the final competition during the week of the Fiesta Bowl. In this case, students in grades 5-8 had to design their own space station.
The Honeywell Fiesta Bowl Aerospace Challenge was developed to enhance the knowledge of space technology, as well as promote team building, communication, problem solving, and critical decision making skills while integrating the subjects of math, science, social studies, language and fine arts. This was a great opportunity for children who are interested in space, like to work numbers, enjoy drafting floor plans, making models, or planning simulated communities.
Contest teams utilized current knowledge of the International Space Station (ISS) to design and build a "new" generation ISS complete with a physical scale model. While still under construction, the ISS is in operation with its fifth three-man crew in residence. Once completed in 2006, the ISS is expected to operate for at least ten years supporting a crew of generally six members for 90 days at a time. With this in mind, contest teams were given the task of redesigning the current ISS to accommodate a crew of 100 for a period of two years.
The teams had to determine every last detail such as how they would get water, dispose of waste, and supply food for their crews. In addition to structural design, docking port, gravity, air and power supply, other topics included shielding, communications, arts and entertainment, recreation, medical, economics, politics, culture and international involvement. The children even got to design their own mission patch and vote on an appropriate name for their space station.
One station was called the “Space Oasis,” named for all of the hydroponic gardens on board. The Space Oasis team was made up of five 7th and 8th grade homeschool students – Megan Barlow and Chris Minsky of Desert Hills, Aaron MacInnis and Dominic Martel of Glendale, and Peter Olsen of New River.
These students took their project seriously, spending many hours and late nights researching their topic in books and on the internet, and learning all about space station design. They met weekly, kept in touch via e-mail, and went on fact-finding field trips to the ASU Mars Lab, ASU Photovoltaic Lab, and APS Solar Test and Research Center.
The Space Oasis team’s report on the daily operation of their station was over 30 pages in length. They also made detailed diagrams and floor plans, and finally they put the model together. Their physical model incorporated both new and recycled materials including a hula hoop, wooden dowels, mesh screen, and plastic film.
The Space Oasis team was one of four homeschool teams, and they ranked in the top 10 out of 66 teams from many schools around the state. A homeschool team from the West Valley was the final winner. The coach of the winning team had complimented the Space Oasis earlier, saying “I read the papers for many other projects and theirs stood well above the field. Many teams had only a paragraph or two on each topic and their entire paper was only a few pages long. Also the scale interior drawings [of the Space Oasis] were very well done.”
The space station contest was judged by professional engineers from the Honeywell Aerospace division. It was apparent that the high caliber of the top projects made the decisions difficult and set a high standard for the rest of the competitors. It was too bad, however, that the judges did not thoroughly read each and every written report. This was rather disappointing to the children who had worked particularly hard in an effort to impress the judges with all of the research they had done. After all, a well-researched report will contain a lot more information, scientific details, and creative ideas which may not be obvious by simply looking at a model.
Upon seeing a copy of the Space Oasis report afterwards, a senior Aerospace Engineering student majoring in Spacecraft Design and Propulsion at Embry-Riddle Aeronautical University in Prescott commented, “Overall, the report is creative and interesting, and exemplifies that the students did a great deal of research. Thought processes of each student indicated clever thought.”
Congratulations, team, on a job well done! Next week on this page we will publish some excerpts from their report.
Did You Know…? The International Space Station (ISS) can often be seen in orbit over Arizona. Visit www.heavens-above.com to find out when and where to look for the ISS. A fairly bright evening ISS fly-over for the Phoenix area will occur on Sunday, January 18th from 7:14 PM to 7:17 PM. This passage will be a nice one to watch as it should be easy to see. The ISS will rise in the southwest and pass below Mars through the constellations Pisces and Aries, finally disappearing almost overhead. Viewing times are approximate.
http://pbs.org/nova/mars (Log onto Nova’s website and see images of the Martian surface, watch an animation of a rover's journey from Earth to Mars, and design a parachute that will safely slow the rovers in their descent to Mars. Plus, access lesson plans related to the Mars mission.)
www.space-education.org (The Florida Space Research Institute in cooperation with Embry-Riddle Aeronautical University offers web-based introductory courses in Space Science. This is a great program for high school students in anticipation of engineering-related professions or anyone with a casual interest in spacecraft design.)
http://my.execpc.com/~culp/space/space.html (Boy Scout Space Exploration Merit Badge Home Page. Learn about the history of space travel, how rockets work, design a spacecraft, and more.)
www.childrensmuseum.org/cosmicquest/spacestation/index2.html (A fun interactive website on space station design.)
www.sciencemaster.com/jump/index_jump_space.php (Jump start to space science.)
http://voyager.cet.edu/iss/intro/about.asp (Internet-based engineering and design curriculum supplement for high school students. Learn about new and emerging technologies while experiencing ISS design, construction, assembly, and operational processes.)
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These pages are a continuous work in progress.