Making Space Shuttle Tiles
(Video)
Download and ShareScientists and engineers often work on the same teams and think about similar questions, but scientists and engineers are guided by different (but related) processes. The Scientific Process has an engineering analog - the Engineering Design Process:
For a satellite or an instrument heading into space, testing and re-design are especially critical because, once launched, a satellite can’t be easily repaired or re-designed. That’s why NASA engineers subject all space-bound instruments to a wide variety of engineering tests. Some of those tests include g-forces, vibrations, acoustic/sound, EM interference, and extreme temperature change.
G-forces arise when an object (or a person) undergoes an extreme acceleration, like speeding up or braking in a car or whipping around a turn so fast you’re pinned to the wall. When you get pushed back into your seat while taking off in an airplane, you’re experiencing increased g-force. Some roller coasters subject riders to forces greater than 5g – even more than a rocket launch. When g-forces arise, objects can be compressed, stressed, ruined and deformed.
During liftoff and launch, vibrations travel through the launch vehicle and the payload bay where a new instrument might be cradled. Though installed securely and precisely, the instrument still experiences the transmitted vibrations, so engineers must run vibration tests to see if the materials and parts are durable enough. Though sound isn’t visible, its effects can be very powerful – and sometimes destructive. Sound waves, after all, transmit energy. Loud, prolonged sound can impact sensitive instruments, disrupt calibrations, and even cause physical change. Another variable that engineers consider when testing an instrument for space-readiness is EM interference. Without the security blanket that is our atmosphere, instruments in space must be able to function in radiation environments very different than those on the ground. Sensors, receivers, communication devices, and the physical frame must hold up to intense radiation testing. One of the most destructive forces a space-based satellite or sensor can face is wild fluctuations in temperature. Extreme temperature changes – melting to freezing and back again – can quickly deform or decay materials, interfere with electrical properties, and cause cracks or breaks.
When engineers design a system or an object, the process will always include some kind of testing, the results of which will feed back into ongoing phases of design improvement - until the product is optimized for use.
Students break into groups and choose an object to test and critique – cell phone, laptop bag, backpack, etc. (If supplies are available, students can design and build a new object to test and critique.) Groups create a list of two or three parameters they will test and discuss. Students outline the tests they will perform and how they will measure results. Then they conduct the tests in their groups. Based on their results, students come up with re-design recommendations they would make before a future round of tests. Each group has a chance to present to the class and, if time allows, running additional tests with the whole class.
Discussion QuestionsStudents collect a series of articles, radio pieces, podcasts, or other media segments that relate to or describe situations in which the engineering design process played a major role. Based on those, students create an overview piece – written or oral or video – to summarize the engineering “current events” they discovered. Questions: Were there some common threads through all the stories? What was the scale for each – small-scale nano, everyday, or large-scale? Were the topics newsworthy because of engineering successes – or because of failures? What were some common terms or vocabulary words you saw / heard in all the stories?
NARRATOR: Welcome to NASA's spacecraft chamber of horrors.
Here spacecraft and components suffer through a grueling battery of tests, all in an effort to see if they are truly handle their mission and surviving the rigors of spaceflight.
As this centrifuge whips them around, they experience the kind of G-forces or gravitational forces that they can expect to see on launch. Now, this centrifuge is not for human use. It can go up to 30 Gs which is way more than a human being can stand.
They get shaken on any number of vibration tables to simulate the vibrations during launch.
There is no sound in space, but the ride up can be noisy enough to break things.
Inside this acoustics chamber, the instruments are blasted with noise in order to make sure they can survive the rocket trip to space.
Some, like the new SLIC carrier, come here to the static load test facility. Some call it "the rack." Inside this frame, hydraulic actuators operated by a team of engineers push and pull the new composite payload carrier, testing it's ability to withstand the stresses of launch and re-entry. Based on the results from the 1000 strain gages placed on the carrier - it passed.
In the Electromagnetic Interference test chamber, radio waves are blasted at the instrument to see if they any will disrupt its operations. The instruments are also tested to see if they produce any radio waves that could interfere with other instruments or systems.
This is the Space Environment Chamber.
Inside this enormous tank, spacecraft and instruments like the new Wide Field Camera 3 experience the harshness of space. The air is pumped out to simulate the vacuum of space and then the real testing begins. This chamber can heat to a blazing 300 degrees above zero Fahrenheit, and then drop to minus 310 degrees Fahrenheit. In here, the spacecraft must endure the huge temperature extremes it will experience in orbit, as it travels from full sunshine to the darkenss of Earth's shadow. A typical test can take many weeks.
If the spacecraft survives the torture here, it's pretty much ready for space. If not, better it breaks here than after launch. Here we have the ability to understand the problem, correct it, and test again. All this testing helps reduce the risk of failure on orbit and increase the spacecraft's potential for scientific success.
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