Hubble Space Telescope
Introduction
Throughout time, telescopes grew in size, complexity, accuracy and
ofcourse power. Edwin Hubble, for whom the Hubble Telescope is named, used the
largest telescope of his day in the 1920s at the Mt. Wilson Observatory near
Pasadena, Calif., to discover galaxies beyond our own. Hubble's launch and deployment in April 1990 marked the most
significant advance in astronomy since Galileo's telescope. This was one of the
greatest millstones in astronomical history of advancement.
Important facts about Hubble Space
Telescope
NASA's
Hubble Space Telescope was officially launched on April 24, 1990 on the space
shuttle Discovery from Kennedy Space Station. It is important to know that
Hubble does not travel to stars, planets or galaxies, instead it takes pictures
of them as it whirls around Earth at 17,500 mph. Hubble has circled Earth and gone more than 3
billion miles along a circular low earth orbit of 340 miles altitude. Also, Hubble has no thrusters. It uses
Newton’s third law by spinning its wheels in the opposite direction in order to
change into various different angles. It turns at about the speed of a minute
hand on a clock, taking 15 minutes to turn 90 degrees. It’s has the accuracy of .007 arc seconds,
and ouutside the haze of our atmosphere, it can see astronomical objects with
an angular size of 0.05 arc seconds. Hubble
generates about 10 Terabytes of new data per year, and weighs 24,500 pounds,
which is equivalent to two full-grown elephants. Hubble's primary mirror is 2.4 meters in
which is measured as 7 feet, 10.5 inches across, while it is 13.3 meters
(43.5 feet) long which is equivalent to the length of a large school bus. Hubble has made more than 1 million
observations since its mission began in 1990, and astronomers using Hubble data
have published more than 12,700 scientific papers, making it one of the most
productive scientific instruments ever built.
Chief Goals Assigned
There are
3 main chief goals assigned in terms o the purpose of the Hubble Space
Telescope.
1. Galaxy
Evolution: With the
WFC3’s panchromatic imaging, astronomers can follow galaxy evolution backward
in time from our nearest neighboring galaxies to the earliest times when
galaxies had just begun to form.
2. Detailed
Studies of Star Populations in Nearby Galaxies: The high UV-Blue sensitivity over a wide
field within the WFC3’s panchromatic coverage will enable astronomers to filter
out details within the various population of stars in nearby galaxies to learn
when they were formed, and what their chemical composition consists of.
3.
Dark Energy and Dark Matter: WFC3’s mapping of gravitational lenses
can help determine the character and distribution of dark matter within galaxy
clusters. WFC3 plus ACS is capable of
conducting systematic searches for Type la Supermovae to measure the expansion
history of the universe and get a handle on dark energy.
How the Hubble Space Telescope Works
All of the functions captured
by Hubble are powered by sunlight. Every
97 minutes, Hubble completes a spin around Earth for every 97 minutes, moving
at the speed of about five miles per second (8 km per second). As it travels, Hubble's mirror captures light
and directs it into its several science instruments. Hubble is a type of telescope referred to as
a Cassegrain reflector. Light hits the telescope's primary mirror, which then
bounces off the to a secondary mirror.
The secondary mirror focuses the light through a hole in the center of the
primary mirror, which then leads to the telescope's science instruments. Hubble's primary mirror is 94.5 inches (2.4
m) in diameter, but Hubble's location beyond the atmosphere gives it extremely
high clarity. Once the mirror captures
the light, Hubble's science instruments work together or individually to
provide the observation. Each instrument is designed to examine the universe in
a different way. There are 6 main
instruments involved.
1.
Wide
Field Camera 3 (WFC3) in which
is a fairly new instrument, sees three different kinds of light: near
ultraviolet, visible and near-infrared, though not simultaneously. Its
resolution and field of view are much greater than that of Hubble's other
instruments.
2.
The Cosmic Origins Spectrograph (COS) is the other new instrument,
which is a spectrograph that sees exclusively in ultraviolet light. This
instrument provides a wavelength "fingerprint" of the object being
observed, which identifies information regarding its temperature, chemical
composition, density, and motion. COS will improve Hubble's ultraviolet
sensitivity at least 10 times, and up to 70 times when observing extremely
faint objects.
3.
The Advanced Camera for Surveys (ACS) sees visible light, and is
designed to study some of the earliest activity in the universe. ACS helps plot
the distribution of dark matter, detects the most distant objects in the
universe, searches for massive planets, and studies the evolution of clusters
of galaxies.
4.
The Space Telescope Imaging Spectrograph (STIS) is a spectrograph that sees
ultraviolet, visible and near-infrared light, and is known for its ability to
hunt black holes. While COS works best with small sources of light, such as
stars or quasars, STIS can map out larger objects like galaxies.
5.
The Near Infrared Camera and Multi-Object
Spectrometer (NICMOS) is
Hubble's heat sensor. Its sensitivity to infrared light, so it observes objects
hidden by interstellar dust, like stellar birth sites, and gaze into deepest
space.
6.
Finally, the Fine
Guidance Sensors (FGS) are
devices that lock onto "guide stars" and keep Hubble pointed in the
right direction. They can be used to accurately measure the distance between
stars, and their relative motions.
Problems Regarding the
Hubble
There were 2 main problems after the launch of the Hubble
regarding the main mirror, which primarily focused on two key instruments the
ACS and the STIS. Regarding the advanced
camera for surveys (ACS), it partially stopped working in 2007, due to an
electrical short but was repaired soon later in May 2009 during the Servicing
Mission. Another problem that was
encountered post the launch of Hubble was when the Space Telescope Imaging Spectrograph
(STIS) stopped working as well due to the technical failure on August 3, 2004,
but that too was also repaired during the same servicing mission 4.
3 Great Moments of
Hubble
1.
NASA’s Hubble Discovers Four
Images of Same Supernova Split by Cosmic Lens
Astronomers using NASA’s Hubble Space Telescope, have spotted
a distant supernova split into four images, which has happened for the very
first time. It is shown that the
multiple images of the exploding star are caused by the powerful gravity of a
foreground elliptical galaxy embedded in a massive cluster of galaxies. The reason why I have chose this great
moment of Hubble is because this observation will definitely help astronomers
refine their estimates of the mass of dark matter in the lensing galaxy and
cluster, as it is listed as one of their 3 main goals regarding the Hubble.
Dark matter is an invisible form of matter that makes up most of the mass of
the universe, and this is a great milestone within that topic of interest. This phenomenon happened on March 5, 2015.
2. Hubble Space Telescope Sees Evidence of Water Vapor Venting
off Jupiter Moon
NASA’s Hubble Space Telescope has observed and identified water
vapor above the frigid south polar region of Jupiter's moon Europa on December
12, 2013. Previous scientific findings
from other sources already point to the existence of an ocean located under
Europa's icy crust. However, researchers
are not yet fully certain whether the detected water vapor is generated by
erupting water plumes on the surface, but they are confident from this
discovery. The reason as to why I chose
this particular finding is because, this finding shows that this capture by
Hubble is the first strong evidence of water plumes erupting off the moon's
surface, and this would make Europa the second moon in the solar system known
to have water vapor plumes.
3. NASA Hubble Finds New Neptune Moon
On July 15, 2013, NASA's Hubble Space Telescope has
discovered a new moon orbiting the distant blue-green planet Neptune. This is now the 14th known to be circling the
giant planet. The moon, designated S/2004 N 1, is estimated to be no more than
12 miles across. It is extremely small and dim that it is roughly 100 million
times fainter than the faintest star that can be seen with the naked eye. It
even escaped detection by NASA's Voyager 2 spacecraft, which flew past Neptune in
1989 and surveyed the planet's system of moons and rings. The reason why I have chosen this phenomenon
is because this finding of Hubble proves that this moon is the smallest known
moon in the Neptunian system.
References:
http://www.nasa.gov/mission_pages/hubble/story/index.html#.VRyHczvF8vNhttp://www.nasa.gov/content/nasa-hubble-finds-new-neptune-moon/
http://hubblesite.org/the_telescope/hubble_essentials/
http://www.nasa.gov/mission_pages/hubble/servicing/SM4/main/WFC3_FS_HTML.html
