Samples of the Future
The advanced space ships of tomorrow will be crafted
from far-out materials with extraordinary resistance to the harsh
environment of space.
The successors to the Hubble Space Telescope have been in space for decades -- longer than today's satellites can usually survive -- taking breathtaking photos of the cosmos and helping unravel the history and workings of our Universe. Dozens of Earth-observing satellites with long-lived mirrors and lenses provide scientists with daily global maps of deforestation, urban sprawl, stratospheric ozone, and other environmental factors -- bringing unprecedented scientific knowledge to the political arena.
Huge orbiting solar collectors as big as a dozen football fields generate gigawatts of power that are beamed down to the energy-hungry civilization below. Space-based radio antennas hundreds of meters long listen for the faintest of signals from civilizations elsewhere in our galaxy. And spacecraft propelled by vast billowing solar sails stand poised to carry their first passengers across interstellar space.
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Above: This tray of material samples may look a bit like the ultimate children's watercolor set, but the contents of these trays certainly aren't child's play. Scientists and engineers will use this palette to paint the future of space utilization. Click on the image for ashowing how these materials will be mounted to the ISS for exposure to the space environment.
The Materials International Space Station Experiment, or MISSE for short (pronounced "Missy") consists of two suitcase-like containers, each holding hundreds of advanced materials that might someday be used to build solar sails, large antennas, super-spaceships, or thousands of other far-out devices.
During a spacewalk slated for Thursday, August 16th, shuttle crew members Dan Barry and Patrick Forrester will attach the "suitcases" to the outside of the space station and open them up, exposing the material samples to the harsh environment of space. MISSE will be the first externally-mounted science experiment on the ISS. Once opened, the suitcases will require no attention from the ISS crew until a year later, when they will be returned to Earth, where scientists will examine the materials and see how well they fared.
"Materials are really the enablers for all future technology," says Bill Kinard, senior research scientist at NASA's Langley Research Center (LaRC). Researchers at LaRC manage the experiment, which is a cooperative venture involving NASA, the U.S. Air Force, and members of the aerospace industry.
"[With] MISSE, we're testing the candidate materials and components that people are planning to use in the future," Kinard says. "The first question is, 'Are they stable? Will they survive for a long period of time in space?'"
Many people think of space as completely empty. If that were true, choosing materials for spacecraft would be easy! But space is far from empty, and many types of materials don't survive for long in the harsh space environment.
"In space, there are high-energy protons and electrons, ultraviolet radiation, atomic oxygen, high and low temperature extremes, hard vacuum, galactic cosmic radiation, micrometeors, man-made debris and a lot of other things as well," says Sheila Thibeault, LaRC's principal investigator for MISSE.
Right: The two "suitcases" -- officially called Passive Experiment Containers, or PECs -- will be attached to the exterior of the recently installed airlock and high-pressure gas tanks during a spacewalk on Wednesday. Click the image for a.
Here on Earth, the oxygen we breathe is molecular. It consists of two oxygen atoms chemically bonded together (O2). Molecular oxygen is fairly stable and safe, but in the upper atmosphere, radiation often splits molecular oxygen into atomic oxygen (O). Many of these oxygen atoms recombine to form ozone (O3). However, some of the oxygen atoms drift up to LEO, where they pose a serious threat to spacecraft.
Atomic oxygen is highly chemically reactive. When it encounters other materials, it can steal atoms of carbon, hydrogen, nitrogen, and other elements from the surface. Over time, this will erode the material away.
A dramatic example of this erosion was provided by the Long Duration Exposure Facility. LDEF was a bus-sized materials exposure experiment similar to MISSE launched in 1984. LDEF orbited for more than 5 1/2 years before it was finally recovered.
Researchers can simulate atomic oxygen exposure in the laboratory, but to see how materials are affected when they're exposed to all the elements of the space environment simultaneously, nothing but space itself will do.
Above: Some of the materials on MISSE may someday be used to build vast, ultra-lightweight solar sails that would use the pressure of sunlight to propel humans across interstellar space. With areas exceeding that of a small farm here on Earth, these sails must be able to withstand the inevitable impacts of micrometeors -- dust- and sand-sized grains zipping through space at high speed. MISSE will help determine if candidate materials are indeed durable enough.
LaRC invited the other NASA centers as well as the larger aerospace community to submit materials to fly on MISSE.
"This time we're primarily using the space station to perform experiments to benefit other people in other programs, as opposed to just supporting the station," Kinard says. About 1500 total samples were approved for the mission, roughly half of which are being installed on August 16, 2001. The rest will go up in two more suitcases scheduled to fly in about 18 months.
Right: Great care went into deciding which materials to include on MISSE and into preparing the individual samples for flight, to ensure that the results from the mission have the maximum possible scientific value. In this picture, Rachel Kamenetzky (shown holding the tray) and Miria Finckenor -- both from NASA's Marshall Space Flight Center -- examine one of the trays to be loaded into the "suitcases." [more]
The samples represent a wide range of materials. New solar cell materials promise to improve the lifetime of satellites, including commercial communications satellites. Lightweight radiation-shielding films may someday help protect astronauts on their long trip to Mars. Optical materials that can better withstand atomic oxygen will improve the reliability of Earth-observing satellites. Thin, micrometeor-resistant polymers could allow the construction of huge, fold-up antennas, as well as inflatable mirrors and lenses for solar power collection. And ultra-lightweight polymers flying on MISSE could someday be used to build the solar sails that finally take humans sailing to another star.
All of this from two modest, suitcase-like containers affixed to the outside of the ISS -- and, of course, the dedicated work of thousands of researchers with a vision of what space technology 50 years from now could be.
August 15, 2001
presented by ThursdaysClassroom.com
These activities are based on the Science@NASA article
"Samples of the Future"
- Discussion Questions: Sample these thought-provoking discussion questions about far-out materials. [lesson plan] [questions]
- Do-it-Yourself MISSE: In this exercise, which reinforces creative thinking and the scientific method, kids build their own toy spacecraft from assorted household materials. [lesson plan]
|Use this button to download the story with lessons and activities in printer-friendly Adobe PDF format:|
This episode of Thursday's Classroom was produced for Science@NASA
by Bishop Web Works under the direction of Dr. Tony Phillips.
Materials International Space Station Experiment (MISSE) -- home page, from NASA's Langley Research Center.
MISSE background information -- from NASA's Marshall Space Flight Center
Virtual Reality Spacewalking -- Astronauts Patrick Forrester and Daniel Barry, who will install MISSE on the outside of the ISS, prepared for their spacewalk using virtual reality training gear.
Long Duration Exposure Facility (LDEF) -- archive of results from the LDEF project, which subjected hundreds of materials to the environment of space for almost 6 years.
Living in Space is Tough, Even for Spaceships -- Science@NASA article: Life in space can be tough not just on humans. Spaceships have to weather a svere environment, too, as they endlessly circle the globe.
Buck Rogers, Watch Out! -- Science@NASA article: NASA researchers are studying insects and birds, and using "smart" materials with uncanny properties to develop new and mindboggling aircraft designs.
Radiation Shielding from Mars or Moon Dirt? -- Science@NASA article: Lunar and Martian dirt could provide radiation shielding for crews on future missions.
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