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A D V A N C E D
M A T E R I A L S
&
P R O C E S S E S |
M A R C H
2 0 1 6
1 1
or suffers a scratch, stress, or fracture,
the capsules break open. The dye reacts
with the epoxy, causing a dramatic
color change from light yellow to bright
red—with no additional chemicals or
activators required. The deeper the
scratch or crack, the more microcap-
sules are broken and the more intense
the color. The team is now exploring
further applications for the indicator
system, such as applying it to fiber-
reinforced composites, as well as
integrating it with previous work in
self-healing systems. .
FINAL MIRRORS INSTALLED
ON JAMES WEBB SPACE
TELESCOPE
In February, the 18th and final
primary mirror segment was installed
on the James Webb Space Telescope
at NASA’s Goddard Space Flight Center
in Greenbelt, Md. Using a robotic arm,
the team installed all of Webb’s primary
mirror segments onto the telescope
structure. Each hexagonal-shaped seg-
ment measures just over 4.2 feet across
and weighs approximately 88 pounds.
Once in space and fully deployed, the
segments will work together as one
large 21.3-foot-diameter mirror.
MirrorswerebuiltbyBall Aerospace
& Technologies Corp., Boulder, Colo.,
the principal subcontractor to Northrop
Grumman for the optical technology
and optical system design. The new
telescope is the scientific successor to
NASA’s Hubble Space Telescope and will
be the most powerful space telescope
ever built. Webb is targeted to launch
from French Guiana aboard an Ariane 5
rocket in 2018.
Inside a massive clean room at NASA’s Goddard Space Flight Center, a robotic am is used to
install the 18th mirror segment onto the Webb telescope structure. Courtesy of NASA/
Chris Gunn.