Page 9 - Pakistan Link - November 19, 2021

OPINION NOVEMBER 19, 2021 – PAKISTAN LINK – P9

Inspirations…

Muslim Contribution to the NASA Hubble Space Telescope

n By Professor Nazeer Ahmed it. When we opened the truck
Concord, CA door, water came gushing out of
the truck and with it there was
uslims have enriched a little frog. To this day I do not
America. This is a story know if the frog was inside the
Mthat needs to be told, and truck or came from the outside!
told loud and clear, especially in In any case, the Main Ring had to
the current environ- be vacuum-baked at 220 degrees
ment when vitriolic F for several days to dry it out.
Islamophobia rages Good thing it was built of Tita-
in the land and cor- nium. If it was any other material,
rupts the social land- the 8-million-dollar item would
scape. have to be scrapped. The lessons
The story of a for scientists are obvious: No mat-
group of Pakistani doctors in Ap- ter how careful you are, you can-
palachian Virginia provides an ex- not avoid the intrusion of nature
ample. About thirty-five years ago, (the Divine Laws) or the frivolities
I was invited to visit and speak in of human behavior.
Roanoke, a town located deep in
the coal mining area of Appala- The Advanced Composites
chian Mountains that straddle Metering Truss
the eastern states and extend into The Primary Mirror, Second-
southwest Virginia and Tennes- ary Mirror, Focal Plane and the
see. Poverty stalks the land. Most Fine Guidance Sensor have to be
people in the region subsist on was a research project in itself ed. The optics is a Ritchey–Chré- it runs across conceptualization, kept in a stable configuration with
coal mining, although in recent that stretched the limits of tech- tien reflector (invented as early as systems definition and analysis, respect to one another. Thermal
years it has attracted some white- nology. The lessons learned were 1910). Light from far field (deep design, manufacture, assembly, fluctuations (the heat and cold of
collar jobs. According to available later used in advanced systems in space) is collected by a convex test and post-launch operations. space) and launch dislocations
statistics, the per capita income both in the civilian and other sec- primary mirror which reflects it can change the distance of one
in the region is approximately tors. This is a brief non-technical onto a concave secondary mirror. The Zero Gravity Float component from another. Weight,
$17,000 as compared to $35,000 note on that exciting project al- The reflection from the secondary The next challenge is to grind stiffness, and stability are ma-
in Northern Virginia. though some technical jargon mirror passes through a hole in the mirror so that it has the de- jor drivers. On the Hubble, each
Until recent years, medical is unavoidable while discussing the primary mirror and is “seen” sired shape in the weightless- pound of extra weight added fifty
facilities in the region were scarce. such a highly specialized subject. by a focal plane located at the fo- ness of space. When you polish a thousand dollars in launch costs
People were dying of lung disease The illustrative pictures are from cus of the secondary mirror. Light mirror on earth, it will “sag” due at 1980 prices. A tubular Meter-
from breathing the dust in the open source. shields are used on both mirrors to gravity. This sag has to be cor- ing Truss, built of graphite ep-
coal mines. In the 1970s a group The Hubble was one of the to minimize stray radiation. rected so that the mirror has the oxy advanced composites is used
of Pakistani doctors moved into most precise instruments built in The primary mirror of the correct shape after launch in space to keep the two mirrors in fixed
the area, providing much needed the twentieth century. It expand- Hubble is 2.4 meters in diameter. where there is no gravity. configuration (distance and tilt)
medical services to the poverty- ed the horizons of humankind Why? This size is dictated by the The construction of a zero- with each other. The advantage of
stricken people and building and provided deep insights into size of the bay in the Space Shut- gravity float was one of the re- composites is that you can “build”
world class medical facilities. The the universe that we are a part of. tle which carried the telescope sponsibilities of my group. An these materials unlike the natu-
health standards of the region im- Specifically, it enabled us to know into space. The primary mirror is ultra-precise mechanism was de- rally occurring materials such
proved, and the people were grate- with greater certainty the location ground to 1/70th of a wavelength signed to “float” the mirror and as metals. High strength GY 300
ful. It is a success story of Muslim of black holes at the centers of of red light (0.63 micrometer). The achieve zero gravity on earth. The fibers with tensile strength in ex-
doctors serving the United States, galaxies, improved the precision secondary mirror is 14 inches in 1,800 pound hogged out (light- cess of 300,000 psi were used on
transforming the health and wel- of the time of origin of our uni- diameter and is ground to 1/700th ened) fused silica mirror was the Hubble. The composites were
fare of an entire region and this verse, enabled us to witness stars of a wavelength of red light. Why? conceptually divided into 132 designed to have high stiffness ra-
story needs to be told. of magnitude 8 (formed as early as The precision of the mirrors is segments and the weight of each tio, high specific strength and very
Many are the doctors, engi- a hundred million years after the dictated by the wavelength of op- of these segments was precisely low coefficient of thermal expan-
neers, scientists, architects, artists, Big Bang) and provided us pic- eration which is chosen depend- calculated using finite element sion. The measurements required
professors, sportsmen and other tures of distant stars and galaxies ing on mission requirements. In structural analysis. An ultra-fine for the characterization of these
professionals who have enriched with awe-inspiring resolution. general, you can tell a great deal balance was built to apply an up- innovative materials were so small
this great country. It is not just about a telescope or a sensor just ward thrust on each individual (10 E-7 ins/in) that they exceeded
household names like Moham- Why the Hubble? from the wavelength of its opera- segment, precisely equal to the the capability of interferometers
med Ali and Kareem Abdul Jab- Astronomical observations tion. The long wave infrared tele- calculated weight of that segment. then available and required the
bar who have set a mark of ex- depend on the signal to noise ra- scopes are used for surveillance It was a major achievement to so invention of novel methods of
cellence in their fields and have tio (SNR). The higher the signal and tracking. The short-wave balance the large mirror and at- measurement.
brought honor to their country. to noise ratio, the greater is the infrared telescopes are used for tain zero gravity on earth. The advanced composite
There are literally hundreds, per- resolution (clarity) with which we homing devices and missiles. The tubes were fabricated at Boeing
haps thousands of others, some can see the stars and galaxies. The visible and ultraviolent telescopes The Main Ring Aircraft Company in Seattle. Do
well-known, others obscure, who electromagnetic waves from the are used for celestial observations. The Optical Telescope As- not be so awed by these fascinat-
have made their contributions stars and deep space objects con- The shorter the wavelength, the sembly of the Hubble is divided ing new materials. A visit to fab-
and have made America richer, stitute the signal. All else is noise. greater the precision of the mir- into four major subsystems: The rication facilities in one of these
safer and a better place to live. The stray light from earth and rors and the greater the stress on Primary Mirror Assembly, the big-name companies reminds one
The stories of these contributions from the atmosphere are sources design. The other reason is cost. Secondary Mirror Assembly, the of grandma’s kitchen. Their fabri-
must be collected and told again of noise that reduce the SNR. The greater the precision, the Focal Plane Assembly and the cation is still more of an art than
and again so that future genera- Space-based telescopes are free higher the cost. The mirrors of Fine Guidance Sensor. All of these a science. Defects in manufac-
tions remember and are inspired from earth-bound noise and offer the Hubble are ground to operate systems are supported on the ture are commonplace and, have
to excel and serve. ideal platforms for astronomical from 0.35 to 0.75 micrometers. In Main Ring, a doughnut shaped ti- to be patched up, or they have to
This article is about the observations with a high SNR. other words, they operate in the tanium structure. go through a Materials Review
NASA Hubble Space Telescope. The proposal for a space tele- ultraviolet to the short-wave in- Let me tell you a story here. Board for acceptance. The Hubble
As Senior Staff Project Manager scope was advanced as early as frared spectrum. The Main Ring was manufactured advanced the state of the art in
at Perkin Elmer Corporation in the 1950s by the physicist Lyman The performance of a space in Upstate New York and was advanced composites. The lessons
Danbury, CT, I had the privilege of Spitzer (1914-1997) and others. telescope is limited by the diffrac- shipped to Danbury, Connecticut, learned about the limits of com-
being a member of the core team In the 1970s, when the American tion of space particles. As a rule a distance of about two hundred posite material usage under vari-
that designed, built, assembled, space program was at its zenith, of thumb, diffraction limited per- miles. This kind of specialized ous load conditions, their stability
tested and delivered the Hubble. the US Congress allocated the formance is about 1/18th of the hardware is specially packed and when subject to temperature vari-
I was responsible for delivering funds to conceptualize and build selected wavelength. Each of the sealed in air bags to prevent dam- ations, moisture (water and vola-
diffraction limited performance the Hubble (named after the as- components of a telescope con- age in transportation. On the way, tile condensable matter) and the
for the Secondary Mirror Assem- trophysicist Edwin Hubble). The tributes an “error” (inaccuracy) the truck carrying the Main Ring environment, were used in other
bly at 1/700th of a wavelength of thrust was the advent of the Space because of the limits with which ran into severe rainstorms and advanced systems in later years.
light in the visible (0.63 microm- Shuttle which offered new means it can be designed, manufactured had to pull out of the highway.
eters). It included the Metering of deployment of payloads like the and assembled. In the Hubble, all Accelerometers attached to the The Strain Free Mounts of
Truss, the Secondary Mirror and Hubble. the “errors” from all the compo- truck showed 5g loads, meaning the Mirrors
its Strain Free Mount, the stray nents statistically add up to less the trucker had hit big pits on the The mounting of the mirrors
light Baffles, Figure Control Ac- The Concept than 1/18th of a wavelength of off ramp. In any case, the truck without distorting their fine shape
tuators, the Advanced Compos- The core of the Hubble is red light. Management of the “er- arrived at our facility in the early is a specialized research issue. The
ite Structures as well as the Zero the Optical Telescope Assembly ror budget” is a major challenge in hours of the morning and I was Secondary Mirror, for instance,
Gravity Float. Each one of these (OTA) with which I was associat- a complex project such as this as one of the team asked to receive HUBBLE, P24
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