James Webb Space Telescope (JWST):
The JWST idea was first launched for scientific purposes that included knowing what happened after the big bang. The main goals of JWST can be concluded as follows:
1. Reionization and first light.
2. Knowing how galaxies formed and the assembly of galaxies.
3. To know and get more details about the birth of stars and planets.
4. To know more about planets and the origin of life and if life is possible on other galaxies and planets.
5. To know what and where other earth-like planets are there.
The mission drives basic requirements can be concluded as recognizing the faint objects, distant -old- objects, and through dust clouds. This can be achieved using a telescope that has the following properties in sequence:
A high redshift is when galaxies move in respect together with low velocity and at high speed in relative to themselves.
Requirements of JWST:
To make this mission a successful one, several requirements were set as requirements. The requirements include the following:
· Large Light-Collecting Area:
· Deployable system (Deformable).
· Lightweight materials (thin mirrors, films and membranes, and composites).
· Stable structures and materials (beryllium mirrors &low creep composites).
· Infrared observations:
· A cryogenically compatible system (beryllium mirrors & carbon fiber composites).
· Cryogenic telescope and science instrument:
· Deformable beryllium mirrors (can deform in 6° of freedom).
· Bonded carbon fiber campsites structures.
· Four infrared optimized science instruments.
Composites were chosen for this mission because they are basically plastics that can deform under load and retain their original shape and dimensions upon unloading them. Carbon fiber, however, was chosen because its unique properties that include the high strength-to-weight ratio and extreme temperatures resistance.
Components of the JWST:
· The Sunshield:
A multi-layer sunshield was developed for this very mission and consisted of light-tight materials that are capable of resisting the damage that might be caused by sunlight (which is not filtered like the sunshine on earth). Also, the membranes are infrared-tight; which means that they won’t develop damages when an IR beam hit them. Note that the membranes are deployable.
The sunshield was coated with aluminum on both sides in layers 3, 4, & 5. However, layers 1 and 2 were coated with aluminum on top and silicon on bottom. It is worth mentioning that the size of the shield is almost the size of a tennis court. Two of the biggest challenges in the design of the sunshield are coming up with a concept to fold it in the rocket and the wide temperature range between the top and bottom.
The membranes are coated with kapton to withstand the high temperature range. The calculation of the temperature difference between the top and bottom resulted in realizing that the temperature on top (away from sun) is around 50 K (= -370 °F) and on bottom (facing sun) is ar ...
TataKelola dan KamSiber Kecerdasan Buatan v022.pdf
James Webb Space Telescope (JWST)The JWST idea was first laun.docx
1. James Webb Space Telescope (JWST):
The JWST idea was first launched for scientific purposes that
included knowing what happened after the big bang. The main
goals of JWST can be concluded as follows:
1. Reionization and first light.
2. Knowing how galaxies formed and the assembly of galaxies.
3. To know and get more details about the birth of stars and
planets.
4. To know more about planets and the origin of life and if life
is possible on other galaxies and planets.
5. To know what and where other earth-like planets are there.
The mission drives basic requirements can be concluded as
recognizing the faint objects, distant -old- objects, and through
dust clouds. This can be achieved using a telescope that has the
following properties in sequence:
A high redshift is when galaxies move in respect together with
low velocity and at high speed in relative to themselves.
Requirements of JWST:
To make this mission a successful one, several requirements
were set as requirements. The requirements include the
following:
· Large Light-Collecting Area:
· Deployable system (Deformable).
· Lightweight materials (thin mirrors, films and membranes, and
composites).
2. · Stable structures and materials (beryllium mirrors &low creep
composites).
· Infrared observations:
· A cryogenically compatible system (beryllium mirrors &
carbon fiber composites).
· Cryogenic telescope and science instrument:
· Deformable beryllium mirrors (can deform in 6° of freedom).
· Bonded carbon fiber campsites structures.
· Four infrared optimized science instruments.
Composites were chosen for this mission because they are
basically plastics that can deform under load and retain their
original shape and dimensions upon unloading them. Carbon
fiber, however, was chosen because its unique properties that
include the high strength-to-weight ratio and extreme
temperatures resistance.
Components of the JWST:
· The Sunshield:
A multi-layer sunshield was developed for this very mission and
consisted of light-tight materials that are capable of resisting
the damage that might be caused by sunlight (which is not
filtered like the sunshine on earth). Also, the membranes are
infrared-tight; which means that they won’t develop damages
when an IR beam hit them. Note that the membranes are
deployable.
The sunshield was coated with aluminum on both sides in layers
3, 4, & 5. However, layers 1 and 2 were coated with aluminum
on top and silicon on bottom. It is worth mentioning that the
size of the shield is almost the size of a tennis court. Two of the
biggest challenges in the design of the sunshield are coming up
with a concept to fold it in the rocket and the wide temperature
range between the top and bottom.
3. The membranes are coated with kapton to withstand the high
temperature range. The calculation of the temperature difference
between the top and bottom resulted in realizing that the
temperature on top (away from sun) is around 50 K (= -370 °F)
and on bottom (facing sun) is around 360 K (=185 °F).
To make sure that the sunshield will be fine in space, several
tests were performed that include the abrasion test, which
resulted in less than 0.03& damage in shield. Also, a meteoroid
impact test was performed and it was successful (a tear was
developed but didn’t really affect the performance of the
shield).
· Warm Spacecraft Bus:
Another interesting part in JWST is the “Warm Spacecraft Bus”.
This part works as the brain of the telescope. It also generates
power for the structure and launches vehicle interface.
· The Mirror:
Mirrors can be made of glass, however, since glass is very
heavy, fragile, and hard to produce in big dimensions, it was
replaced by beryllium. Basically, JWST mirror is bigger than
the Hubble mirror. The mirror consists of 18 hexagonal
segments that are 6.5 m (21.4 ft.) across; each of is 1.34 m (4.4
ft.) flat to flat. There are 6 motors that are responsible for
adjusting the curvature of the mirror with 6° of freedom
(correctable structure). Also, there is a 7th motor in the center
to make sure that the mirror is in the correct curvature.
Beryllium is one of the strangest elements on earth. It is very
toxic and causes lung cancer on the long term of being exposed
to it. Also, this element is hard to handle; however, its unique
properties qualified it for manufacturing the mirror. Beryllium
is very light and has high melting point (around 1280 °C).
4. The process by which the mirrors were manufactured is that
they were first consolidated (HIP), then machined and polished,
and afterwards, they were gold coated. Note that the mirror is
gold coated because gold is the only element that is capable of
reflecting all of the infrared beams that might cause damage to
the telescope.
How to Make Sure That Mirrors Survive Launch & Mission:
Several test were developed specifically to make sure that the
mirror is capable of withstanding the harsh conditions in space.
Those tests include:
1. Cryogenic temperature cycling.
2. Iterative polishing.
3. Vibration testing.
And afterwards, the mirrors were checked to notice any
imperfections of deformation in the materials.
Note that the impact of radiation is very important. The optical
absorption and emissivity is performance critical; because
radiation may cause changes, which will affect the performance
negatively. The samples were exposed to low speed electrons
and low speed neutrons. The JWST shield was tested in a 7-year
storage simulation and the coating remained well adhered and
the optical properties didn’t degrade significantly.
Also, a high temperature exposure was performed under a
temperature of 600 K. the results showed that the coating
remained well adhered and the optical properties didn’t degrade
significantly.
The Plan:
The JWST is planned to be launched in 2018. The observatory
5. time is estimated to be 5 years knowing that the fuel is
supposed to last long for 11 years.
Large Collecting Area
Long Observations
High Redshift
Infrared Observations
Evaluation of Long-Term Structural Shading for Use in
Djibouti, Africa (harsh environments):
There is an American military base that is located in Djibouti
where housing is basically containerized (in containers). The
goal of this project was basically to provide a super CLU-S for
the containers living units. Those tents are supposed to protect
the containers from the harsh environment factors like the
sunlight, high temperatures, and wind. To achieve this, several
samples of fabrics for manufacturing tents were obtained and
tested in conditions that are very similar to those in Djibouti.
Goals of the Project:
There are mainly two goals for this project, which are for the
tents to be durable and have high performance at the same time.
6. The following table shows the sub goals of each of the main
goals of the project:
Durability
Performance
Strength
Heat transmissivity
Wind resistance
Breathability
Abrasion resistance
Thermal resistance
Testing the Fabric Materials:
There were 16 different samples from different manufacturers
(the navy manufactured one of those). The fabric samples were
tested in similar conditions to those in Djibouti where the base
is located. The wind test was performed with wind speeds of 60
Mph and under an average temperature of 85 °F. This section
analyzes the performed tests:
· Strength Test:
A tensile test was performed in order to know how well the
fabric lasts in a tension situation. This test was performed to
know if the fabric will develop any tears. Also, the fabric
should yield when loaded and not develop any tears or deform
plastically. The tensile test was performed according to an
ASTM standard.
Note that the fabric is woven in a form of wrap and woof. The
results of the test varied from sample to sample and the samples
strength varied from 1.5 ksi to 7 ksi.
7. · Wind Testing:
This test took place in a wind tunnel where the samples were
exposed and tested under a wind speed of 60 Mph and above.
This speed simulates what the tents will be exposed to in the
field. The wind test was followed by a tensile test to see the
effect of wind on the strength of the fabric and how much
degradation in strength that is caused by wind. Note that the
maximum wind speed that test were performed at was 70 Mph
for 45 minutes.
The strength test results were almost the same in all of the
samples as before the wind test. This test was performed to look
at the lifetime effect as much as possible.
· Abrasion Testing:
Abrasion can be defined as the process of scraping or wearing
away. The fabric samples were sandblasted for 30 seconds to
see the effect on the life and strength of the materials
· Thermal Testing:
It is known that temperature can degrade the materials
performance and strength. For that a thermal test was developed
for this very purpose to know the effect of heat on tents
samples. The test settings included two plates on top and bottom
of the fabric sample that are heated to a temperature of 85 °F.
The samples were held between the plates for 45 days. Note that
the plates gave uniform temperature distribution.
The heat that each sample was exposed to can be calculated
8. using the following equation:
Where q is the heat added to the tested sample, h is the
enthalpy, A is the area of fabric exposed to the surfaces of the
heating tool.
The results carried out by this test showed some degradation in
the strength of the samples except the navy one, which showed
better strength after the test.
Conclusion:
A variable factor in the test that wasn’t included in determining
the best fabric material for harsh environments was the cost.
This factor wasn’t included because it can’t be accurately
determined. Note that the best performance sample with lowest
price was sample G.