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- January 27, 2014, Sonoma State University lecture by Kevin Zack, a student, presented a program that launched the SSU satellite on November 13, 2013. It operated for 8 weeks, all systems working, and then suddenly stopped communicating 4 days ago. Not sure what caused the failure, but, 8 weeks of operation was a great success.
-. The satellite was 100% SSU student designed , develop, and built. Called a “pocket cube” design, it was a small box 5 x 5 x 15 centimeters. It contained a magnetometer, 3 temperature sensors, and a torque coil, plus radio and computer software. The magnetometer and torque coil could sense the Earth’s magnetic field.
-. The satellite was designed and tested by SSU students for a total cost of $200 in materials, not including the solar cells that were gifted. The ground station costs another $500. The launch itself was a stowaway. The satellite was shipped to Italy where it was packaged with 31 other cube satellites. This payload was shipped to Russia where a ballistic missile launched out of the silo shot it into space. All 32 satellites were flung into the same polar orbit together. The drags on each individual satellite allowed them to separate over time.
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- The satellite was put into a north-south polar orbit, 700 kilometers altitude, traveling at 7.5 kilometers per second. (435 miles altitude, traveling 16,800 miles per hour.) This gives the satellite a kinetic energy, (mass * velocity^2), equal to a 100 watt lightbulb being on for 33 hours. This kinetic energy with the drag associate with the satellite calculated to allow the satellite to stay in orbit for 39 years. NASA has rules that every satellite launched must be the de-orbited in less than 25 years. Therefore , the students modified the satellite to include open transparency kites attached to the dipole antenna. The dipole antenna function like a folded tape measure that snapped out when it exited the missile package. The kite’s additional drag kept the satellite within the NASA restrictions. The missile launch put the satellite through 6G’s of acceleration to reach this orbit.
-. The rectangular cube was surfaced in solar cells that were gifts to the project. They were premium cells because they operated at 27% efficiency. RadioShack and residential installations normally operate at 12 to 15 percent efficiency.
-. The satellites contained a RadioShack radio transmitter that operated at 100 milliwatts. A normal cell phone operates at 400 milliwatts. It's frequency was 437.465 megahertz in the 70 centimeter, HAM, amateur radio band. The range of the transmitter proved to be 2,700 kilometers, (1,700 miles).
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- The ground station costs $500 for HAM radio receivers ,transmitters and 2 yagi antennas mounted at 90 degrees to each other. This system could listen to all 32 satellites’ data. The SSU satellite had to use its unique HAM call letters to meet the FCC HAM licenses requirements.
-. The communication of one’s and zero’s measured magnetic fields and temperatures. The cube design meant the satellite had two panels always facing towards the Sun. The torque coil measured the Earth's magnetic field. Because NASA has already mapped the Earth’s magnetic field at that elevation the measurements could determine the location of the satellite and it's spin rate, one rotation every 20 seconds.
-. The temperature measurements were varying with 60 minutes of daylight and 30 minutes of nighttime for each 90 minute orbit. Varying from 272 Kelvin to 291 Kelvin, that is comfortable for astronauts, -1 C to 18 C, or, 64 degrees Fahrenheit, (my current room temperature).
-. The magnetometer had a resolution of 0.015 micro-Tesla. The magnetic field of the Earth is about 50 micro-Tesla. Again magnetic field measurements mapped on the NASA magnetic field map accurately located the satellite in orbit.
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- The nickel-cadmium batteries were the same as those used in power tools. They put out 4.5 volts and 150 milliamps.
-. In north-south polar orbit the satellite moved east-west one degree per day. The polar orbit put the satellites through rigorous magnetic fields and solar radiation. Cosmic ray collisions are likely what put the satellite out of commission 4 days ago, although the cause is still unknown.
-. The noteworthy achievement is the student’s use of micro-logo programming language that allowed them to reprogram the satellite while it was in orbit. NASA would never allow this on one of their missions, that is way too much flexibility. The programming worked flawlessly. 12 individual measurements were continuously transmitted every 20 seconds. This is the first satellite to ever operate with this ground based programming flexibility.
-. Even the printed circuit board was designed and assembled by the students. The soldering of 12 millimeter traces proved to be a challenge. But, the secret was continuously testing. A small vacuum chamber was used. A garden glow heat lamp serve to be the Sun.
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- The rigorous testing paid off. The logo cube operated flawlessly for 8 weeks which is a record for this type of endeavor.
-. The students are busy building another satellite for launch. They plan to add an X-ray measurement capability. 100% student design, built, and tested on campus. This one will go up to the International Space Station and be flung into orbit using the ISS Canadian throwing arm.
-. When I was in college the school’s public address system broadcast the beep- beep-beep of the first Sputnik satellite. That was meant to be a motivator for those young engineering students. Today the students launch their own satellites. What a motivator that is! There is such a wide range of physics that is learned and experienced. True engineering to follow through and achieve valued results. An announcement will be made shortly, stay tuned.
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(1) The satellite operated at room temperature, 291 Kelvin. Heat and temperature are interesting phenomena. Temperature is how fast particles are vibrating, on average. Particles could actually be oscillating at 2,000 degrees Kelvin in space, but, the rarefied , scarcity of particles in space means few actually make contact with the satellite. The density of particles (atoms) as well as their thermal energy determine the heat. Temperature of air and water can both be at 212 degrees Fahrenheit. The air will feel warm, but, stick your hand in the water and it will get scalded. Water density means more particles with the same kinetic energy are making contact with your skin at any moment. Don’t try this at home.
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