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simulation.” Due to more sophisticated
modeling and ever-improving super-
computers, the team is on the way to
doing just that. Elisberg recently ran
hundreds of processors for 72 hours
to simulate an extensive series of ther-
mal test cycles—a feat that would have
been impossible just two years ago.
sandia.gov.
WHO’S THE THINNEST OF
THEM ALL?
Scientists at NASA’s Goddard
Space Flight Center, Greenbelt, Md.,
created and proved for the first time a
technique for manufacturing high-res-
olution, x-ray mirrors using single-crys-
tal silicon. The development points to
lightweight, super-thin mirrors that
offer significantly larger collection
areas and dramatically improved reso-
lution over traditional mirrors—all at a
reduced cost.
To create the mirrors, which must
be curved and nested inside a can-
ister-like assembly to collect highly
energetic x-ray photons, astrophysi-
cist William Zhang and his team heat a
block of silicon and cut it to shape with
a band saw. After its surface is ground
and refined with machining tools and
chemical methods, a substrate a frac-
tion of an inch thick is sliced off. The
surface is polished, and individual
segments are coated with iridium to
improve reflectance. Unlike typical
optics materials that suffer from high
internal stress when cut or shaped—
especially as they become thinner—
single-crystal silicon’s lattice structure
prevents it from deforming, and it is
inexpensive and abundantly available,
thanks to the semiconductor industry.
Zhang and his team are perfecting
techniques for aligning and bonding
6000 mirror segments to form meta-
shells to be integrated into a mirror
assembly; their goal is to create six
meta-shells and automate the align-
ment process
. nasa.gov.Scientist Will Zhang created a manufacturing facility to build a new-fangled
x-ray optic made of silicon. Image shows the buffing machine used o re-
move imperfections from the mirror’s surface. Courtesy of NASA/W. Hrybyk.