Darksky: Hubble Space Telescope-english

[Hubble Space Telescope]

Hubble Space Telescope, is the name given for an space telescope operated by NASA. This telescope had been designed since the 1970. In the 1977, this project gets approval from United States congress, and name " Hubble" given in 1984 as respect to astronomer, Edwin Hubble.

Hubble launched from Discovery shuttle on 15 April 1990. From the planning stage until launched, Hubble needs time until 20 years, including a few years postponement as result of disaster Challenger ( January 1986). Long time required also as result of level of fund for this project reaching 1,55 billions USD.

Hubble is in the form of an alumunium cylinder as wide as 4,3 m with length 13 m with two solar panel along the length of 12 metre attached at each side as source of power. Solar panel at Hubble is design to be able to rotate free angle so the solar panel always receives sunshine fully.

[Hubble Structure]

Secondary mirror at Hubble attached at main mirror focus having diameter 2,35 m ( 8 feet) reflect light by five instrument residing in Hubble. Each instrument attached at separated place, so the instruments can be moved as according to requirement. a camera with narrow sight area made by European Space Agency ( ESA) applied for visual observation and also observation to radiation of ultra violet ray and infra-red from spectrum an object. Other camera has approach area 40 scale wider, but with lower resolution. Also available Fotometer and Spektograf capable to observe gloomy object with high resolution.

Camera attached at Hubble doesn't use film as conventional camera which we recognized. Standard camera that called CCD ( Chart Coupled Device) works by collecting light at electronic detector, like a principle work of digital camera. Spektograf dissociates starlight to become certain colors, same as prism elaborating sunshine to become variegation of rainbow. With analyzing color result of decomposition by spektograf, the astronomers can estimate temperature, movement, composition and also age of a star.

Every day, Hubble sends data between 3 to 5 GB (gigabytes), and distributes between 10 to 15 GB data to the astronomers in the world. An radio antenna enables Hubble to communicate with mission controller that located in Goddard Space Flight Center. From facility Space Telescope Operations Control Center (STOCC), the technicians controls Hubble during 24 hours one day, 7 day one week, along the length of 20 years duration of operation of this telescope.

With a program called Control Center System (CCS), mission controller sends instruction detail several times in one day. More than 100.000 instructions sent to Hubble every week. This instructions converted in the form of code which can be processed by mainframe computer at Hubble. When Hubble observes a target, the computer will change information become digital data which then will be sent through radio wave to communication satellite then will be received by mission controller. From here, data is sent to Space Telescope Science Institute in Baltimore for further processing. Pictures taken by Hubble kept in optical disk. Observation by Hubble in one day yields the same data like an encyclopedia!

Hubble orbit

[Hubble Telescope in Earth Orbit]

Hubble is a low orbit satellite (Low Earth Orbiting, LEO). Hubble orbits at height of 600 km to earth surface. In that height, Hubble can orbit earth average of once every 97 minutes at speed around 27.200 km/h with orbit inclines towards equator with angle 28,5º.

Not like most people assumption, Hubble (as well as other low orbit satellite) actually doesn't orbit in space that is really vacuum. Orbit area occupied by Hubble known as thermosfer or exterior atmosphere. In this area, gas forming atmosphere there are still exist although very thin. Satellite orbiting in this area can experience existence effect of atmosphere in the form of aerodynamic pressure.

Existence of this effect causes an low orbit satellite can lose height in a few years after launching. If is not done something to improve orbit height, then the satellite can enter earth atmosphere (deorbit) and finally annihilate combustible. This event known as Orbital Decay. when lower orbited a satellite, then also bigger strength of aerodynamic pressure that received. To avoid it, so satellite must be put down at orbit as high as possible.

Atmosphere layer that cause this aerodynamic pressure also increases as result of warm-up by sun. Thermal energy from sun has variety intensity in a certain cycle every 11 years. When this intensity reach the top that’s known " solar maximum". When the happening of solar maximum, atmosphere density at all of height improved, and resistance effect received by satellite bigger than the usual. Solar energy can measure variously. One other most commonly is through counting of the sunspots and measurement of radio emission (solar flux).

[Lyman Spitzer, “Father” of Space Telescope]

Hubble very susceptible to danger of orbital decay, in consequence either orbit and also the sun temperature intensity received always monitored. If satellite experience losing of height, then must be returned to normal height. Some satellite types has an special impeller rocket applied to increase height. Hubble doesn't have impeller rocket machine, in consequence the only way to return height of orbit Hubble is by catching and disposition it directly. This thing done by shuttle mission in service missions and term as "reboost". At Hubble, reboost have been done three times, and last done by shuttle mission Columbia in the early of March 2002.

Contact lens

After launched, known that main mirror at Hubble doesn't function properly. Main mirror filings of Hubble made too flat by Perkin-Elmer company so that light falling at the surface cannot be reflect in focused. Sky objects picture gotten tends to disseminates so that seems to be not focus. As a result, all astronomers required more time to be able to analyst consignment pictures Hubble. Other problem also met at one of solar panel from Hubble which not suitable because thermal of sunshine. Meanwhile, 3 gyroscope damaged and some measurement equipments nor can function.

[Hubble Take Space Picture]

Of course this thing disappoints the astronomers and the member team. people of United States also disappoints because they fund billion Dollar applied to finance project of Hubble comes from tax which they pay to exchequer. During few days this failure becomes big news everywhere.

Then the experts involving in this project has solution to overcome problem at main mirror of Hubble, that is with installing a kind " contact lens", the principle same as to man who is experiencing myopy eye handicap (myopia). In 1991, NASA prepares flash program to prepare correction mirror to overcome the problem. Correction mirror which called COSTAR (Corrective Optics Space Telescope Axial Replacement) consisted of 10 silver mirror measure like a metal money in such a manner so that after attached will assist focused light reflect by surface of main mirror that having problem at Hubble.

Mirror with value of USD 625 million attached by the shuttle crews of Endeavour that launched on 6 December 1993. Besides installing lens COSTAR, the Endeavour crew also replace one of solar panel and three damaged gyroscopes at Hubble. Installation of COSTAR done at seventh day after launching by astronaut Kathryn Thornton. This is not easy mission because installation of correctional lens placed in box as heavy 272 kg was only tolerance inaccurate 0,005 inch ( 0,125 mm).

This repair operation takes place with success and obtains gladdening result. Two months after Hubble can send pictures sharper than when before repair.

Looks Into Past

Till now, observation bases on earth, although done from highest top of the mountain, always pursued by earth atmosphere layer. Not to mention light pollution problem by lamp in urban that is now becomes serious problem for most of observatory. Usage space telescope like Hubble assumed as the answer to this problem.

Without annoyed by cloud and atmosphere dirt, observation through Hubble telescope penetrative apart seven times farther and detects object 50 times darker compared to the best telescope that existing in Earth. Hubble even can catch sky objects image apart 15 billion light years from Earth. Then what is the meaning of this distance?

Looks into sky is look into past, pierces space and time. when in one seconds a light particle can pass through over 300000 km, hence distance gone through in one year is trillion 9 km. Can be imagined how far of distance 15 billion light years. Because velocity of light is constant, hence at the same time we can know that light from object as far as that requires 15 billion years to be able to up to Earth. When the light up to Earth, possible itself object have been annihilate, but light caught able to bring cosmos past story that invaluable price.

Calculation of the cosmology indicates that the universe age is not too far from number 15 billion years. By observing object as far as that, the astronomers hopes can find the cosmos past secret, even obtains image of about " creation" process of the universe.

Furthermost objects which can be detected through telescope non-visual till now is objects kuasi stellar that transmitting very powerful energy of which is consisted of active core galaxy that estimated has gigantic black hole in its central (this estimation then proven its truth based on observation of Hubble in 2002). Many between this object apart 12 - 13 billion light years. estimated this objects located " edge" of cosmos space-time meaning save cosmos mystery is not too long after creation of universe.

Observation through Hubble telescope is expected can assist the astronomers in defining cosmos scale, expansion speed of cosmos also means the age, even opens secret "dark matter" what believed the astronomers to fill approximant 90% cosmos mass.

Pictures taken by hubble telescope