Tahukah Anda bahwa baik tragedi Challenger belasan tahun lalu maupun tragedi Columbia
kemarin-kemarin ini, keduanya terjadi pada Hari Raya Imlek?
Wah, padahal saya sudah sempat menduga kecanggihan mujahidin Palestina sudah sampai
bisa mengirim bom bunuh diri mengejar kolonel Israel hingga ke outer space..., ha ha
ha.
Lalu, ngomong-ngomong tentang Palestina, tahukah pula Anda bahwa, percaya tidak
percaya, pada hari-hari pertama setelah musibah, di media TV Amerika diberitakan bahwa
reruntuhan Columbia tersebar di antara kota San Augustine, PALESTINE dan Nacogdoches!!
Tetapi, dasar Amerika, besok-besoknya nama kota Palestine tidak pernah disebut-sebut
lagi oleh media TV Amerika, bahkan dalam tayangan gambar petanya, kota Palestine lalu
(ter/di)hapus...
Well, itu bagian "bodor"-nya, sekarang seriusnya dalam konteks profesi kita sebagai
engineer.
Pesawat ulang alik ("SS", Space Shuttle) adalah sebuah wahana yang rumit.
Penyebab terjadinya musibah SS Columbia pasti tidak mudah ditemukan. Data yang ada
tidaklah lengkap. Menghubung-hubungkannya dengan Cina (Imlek) dan Palestina (kolonel
Israel) tentulah absurd.
Jadi bagaimana cara para insinyur bekerja untuk mengungkap misteri penyebab musibah
ini?
Artikel di New York Times yang terlampir di bawah ini mengupasnya.
Katanya teori yang sama juga diterapkan oleh Made Mangku Pastika...
Wasalam.
------------
Catatan:
Artikel ini mengesankan sepertinya NASA itu kerjanya runut sekali.
Tetapi jangan lupa, dalam berbagai textbooks tentang Engineers' Code of Ethics, contoh
kasus pelanggaran kode etik insinyur yang selalu disebut-sebut justru adalah apa yang
terjadi di NASA dalam kaitan dengan musibah SS Challenger.
Seorang insinyur yang berkerja pada suatu kontraktor NASA yang terlibat dalam
penyiapan peluncuran sebetulnya telah mengetahui adanya kerapuhan O-ring pada tangki
bahan bakar, yang kemudian menjadi penyebab meledaknya SS Challenger.
Tetapi atasan langsungnya yang dilapori hal itu, memutuskan untuk tidak meneruskan
laporan itu ke pimpinan peluncuran, karena penundaan peluncuran yang mungkin terjadi
kalau kelainan itu dilaporkan, akan menyebabkan financial loss yang besar pada
berbagai pihak yang terlibat, termasuk para kontraktor-kontraktor NASA.
==================================================
February 6, 2003
Engineers List All the Ideas, Striking Them One by One
By WILLIAM J. BROAD and ANDREW C. REVKIN
Ron D. Dittemore of NASA described yesterday how an engineer responds to a mysterious
event. Start with what you know, in this case that the shuttle Columbia was lost as it
returned to Earth.
Then list every conceivable scenario of what could have caused of the problem, no
matter how remote. Later, gather up all the available evidence and see which outlines
have more or less support, an engineering process of elimination known as fault-tree
analysis.
A fault-tree provides a map.
Everything on the tree is considered legitimate until solid evidence rules it out.
If the process works correctly, its final stages will disclose the likeliest cause of
the puzzling event.
Yesterday, Mr. Dittemore, the shuttle program manager, said the process was far from
finished in the question of what destroyed Columbia.
"We are continuing to build the fault-tree," he told reporters in Houston.
"And we have many areas to investigate. We have not narrowed down to any one
particular conclusion or any one favorite topic."
A major branch of the tree centers on the left wing, in particular the wheel well,
where sensors recorded unexplained temperature increases shortly before the craft
broke up.
The increases were small, not large enough to melt through the structure, but
nonetheless unusual. What could have caused them? Was there an unseen fire nearby? If
so, what caused it?
Mr. Dittemore described how NASA was making and testing models, hypothetical outlines,
to sift through the branches of the wing fault tree.
"What we're trying to do is understand what would cause a 30-to-40-degree rise in the
wheel well," he said.
"Where does the heat source have to be within the wing or somewhere else to have a
resultant 30-to-40-degree rise in the wheel well and a 60-degree rise on the side wall
of the orbiter above the wing?"
By studying the aluminum frame and the locations of warm spots and areas that showed
no change, investigators hope to home in on perhaps just a few initial conditions that
could explain the readings.
"NASA has the capability to model the transport of heat in the shuttle structure
components," said Dr. A. J. Baker, a former NASA scientist who is a professor of
engineering at the University of Tennessee in Knoxville.
The absence of sharp warming in other parts of the craft, although confounding in some
ways, at least eliminates many other possibilities, experts said.
The situation is somewhat akin to a blind person's feeling rising warmth from a fire
and trying to judge where the flames are.
Mr. Dittemore said concrete clues on the ground might not, in the end, offer the
solution.
"As you focus your attention on the debris," he said, "we are focusing our attention
on what we did not see."
Mr. Dittemore said investigators were trying "to back out where the heat source had to
be in order for this temperature rise to be reflected."
The senior systems integration manager for the shuttle at NASA headquarters in
Washington, Parker Counts, said, "With the orbiter, we are trying to create that with
all the available intelligence and
imagery and everything else."
A similar analysis focuses on the shuttle's last movements, particularly sideways ones
before it began to tumble and fall apart.
The flight control system, including small jets, was struggling to compensate for a
mysterious force that was dragging at the left wing.
Mr. Dittemore said NASA was modeling what drag forces "would be required in order to
cause the aerosurfaces to react and the jets to fire."
NASA is also generating evidence that will bear on the fault tree, possibly
strengthening some branches and eliminating others. One area concerns what had been
the leading theory - the idea that a chunk of insulation that flew off the 15-story
external fuel tank and hit the left wing might have caused enough damage to doom the
spacecraft.
Mr. Dittemore said NASA was planning to test the range of possible damage from foam
impacts, as well as tile strength, "just so we can have a better understanding of the
capabilities of the tile and the
foam."
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