In many of the earliest science-fiction imaginings,
gleaming structures of glass and steel rise from the surface of the moon
and into the
surrounding darkness as intrepid colonists zip about them in jet packs
and flying cars.
While those nifty space-age modes of transportation have yet to
materialize in the real world, the long-envisioned idea of establishing
colony on the moon might actually become a reality in the near future.
That's the grand scheme, at least, as outlined in President
George W. Bush's "Moon, Mars and Beyond" space-exploration initiative.
The idea is to return to the moon by 2020 and create a self-sustaining
research outpost somewhere on its surface. At first, a few
astronauts will make several week-long visits until their power systems,
rovers and living quarters are functional. NASA then plans to
extend the missions to two weeks, then two months and eventually to 180
Within a decade or so, the theory goes, lunar explorers should have
enough extraterrestrial experience and skill to make the next giant
leap to Mars and perhaps planets beyond.
Of all the many challenges NASA faces in this ambitious endeavor, one of
the most critical is providing habitats that will allow humans to
live and work safely in the lunar or other harsh space environments. Not
only will the structures have to be comfortable enough for long
stays, they will have to shield their inhabitants from cosmic rays and
radiation while withstanding micrometeorites, moonquakes and
surface temperatures that fluctuate day to night from about 224 degrees
to minus 243 degrees Fahrenheit. Thus, it will be critical to
continuously monitor the dynamic shape of deployable space structures
such as lunar habitat and microwave antennas.
Designing such deployable space structures will require engineers to
rethink what constitutes a structure, and the methods and
materials necessary to build them. That's where University of Maine
researchers are hoping to play an important role.
Initial funding by the Maine Space Grant Consortium led to a $1.5
million grant from the NASA Experimental Program to Stimulate
Competitive Research (EPSCoR) and UMaine. UMaine electrical and computer
engineers Ali Abedi and Mauricio Pereira da Cunha have
teamed up with mechanical engineers Vince Caccese and Mohsen Shahinpoor,
as well as University of Southern Maine computer engineer
Mariusz Jankowski to develop a first-of-its-kind wireless sensor network
system to monitor the structural integrity of inflatable space
structures after they've been deployed in space.
Easy-to-assemble inflatable structures are considered to be one of the
most promising of the habitation concepts now on NASA's
drawing board. They're ultra light when compared with building materials used in large earthbound structures, and that's a big plus when
launch costs are running about $10,000 a pound and getting one pound of
supplies from the Earth to the moon requires 125 pounds of
hardware and fuel.
One UMaine graduate student is now working with Caccese to build
computer models of how certain flexible materials work, while
another is researching a new way to make them rigid once the inflatable
structure is deployed.
"NASA is extremely concerned about human safety," Caccese says. "I
picture myself being up there, too, and I ask myself what would I
like to live in and what would make me feel safe."
It was work by Abedi and Pereira da Cunha on wireless sensing, and Caccese's and Shahinpoor's past experience with smart structures,
that convinced NASA to make the UMaine project one of 13 in a nationwide
competition to receive funding.
Abedi says this system would also allow NASA to reduce the miles of
bundled sensor wires and connectors that now add so much
unwanted weight, expense and potential for failure to every space
As innovative and valuable as that battery-free wireless system may
prove to be, Abedi says, the UMaine team's latest efforts in the
advancement of space exploration will require technology that goes a
step beyond anything that currently exists.
"Today, what we have for sensors, wireless systems and algorithms, none
of them can address this new system," says Abedi, who is
leading the UMaine team. Once the new sensors are developed, the
challenge will be to find a way to embed them into a multi-layer
fabric that a leading aerospace contractor in Delaware will use to build
a prototype inflatable structure for UMaine researchers.
By sensing the coordinate positions of an array of key points on the
inflatable's surface, the wireless system will allow the researchers
to visualize the shape of the structure after it is deployed. That final
shape data, when compared with computer modeling data, can be
used to assess how successfully the structure was inflated and
eventually to help in correcting any troubling deformations.
"If there is damage to the deployed space structure from a
micrometeorite, for example, we have to be able to determine where that
impact occurred, and what kind of damage it caused," Pereira da Cunha
says. "That's the first step in this investigation, but once we
enable this system, we will be able to expand our research to include
other relevant NASA monitoring needs, such as gas, temperature,
changes in pressure, etc."
As important as shape constraints are for lunar habitats, they are even
more critical to the proper functioning of inflatable antennae. If
an antenna is not shaped exactly as its designers intended, its
microwave transmission signals are distorted and attenuated, and,
ultimately communication may be interrupted.
"The beauty of this project is that wireless technology gives us a
powerful mechanism to determine how an inflatable structure has been
deployed, and what dimples or wrinkles need to be corrected," says
Shahinpoor, chair of the Mechanical Engineering Department, who
will use his expertise in smart materials for the rigidization work.
"Right now, NASA can't detect or correct these deficiencies."
Although NASA has long been interested in inflatable structures, the
educational opportunities such research could provide for students,
as well as its economical development potential, have so far gone
largely unexplored at most universities. This project, according to
Caccese, could change that quickly for UMaine, USM and the state.
The researchers plan to involve 15 undergraduate and four graduate
students in the three-year project. They will be trained in campus
laboratories, as well as at NASA's Johnson Space Center in Houston,
Texas, and Glenn Research Center, Cleveland, Ohio, which are
collaborating on the UMaine research and development work.
The UMaine team also intends to create new course materials pertaining
to the research and to hold seminars for the public at high
schools in the state.
"It helps the university and the whole state to get students excited
about this," Abedi says. "I think this will put UMaine on NASA's
by Tom Weber
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