A SEMINAR ON HUBBLE SPACE TELESCOPE PRESENTED BY: HARI OM ELECTRONICS & COMMUNICATION REG NO SECTION-C ROLL NO.– 123

CONTENTS Overview Spacecraft System Operation Parts Outer structure Pointing control system Optical assembly Scientific instruments Colours & filters Application fields Features Limitations Conclusion References

OVERVIEW Hubble—a space telescope 600km above earth Excellent pointing precision,powerful optics,state of the art instruments Designed -1970s & launched-1990 Moduler design Goal—knowledge of our cosmic roots

SPACECRAFT SYSTEM POWER COMMUNICATIONS STEERING- To remain fixed on an object HST has three onboard systems: Gyroscopes-Sense small to large motions Reaction Wheels-Move the telescope FGS-Sense fine motion COMPUTING STRUCTURE

OPERATION

INTERNAL OPERATION Electronic eyes Cameras--collect light with electronic detectors Spectrographs—separate starlight into rainbow of colours Mirrors to focus & magnify light

PARTS

OUTER STRUCTURE Solar arrays(2)—12m in length,2400 watts Communication antennae(2)—transmit information to TDRSS Computer support systems module—for communications,navigation,power management,etc. Electronic boxes—houses much of the electronics Aperture door—just like camera’s lens Light shield—shaft for blocking surrounding light Pcs—for pointing towards the target

POINTING CONTROL SYSTEM(PCS)

PCS CONT… Fine guidance sensor(3) Coarse sun sensor(2) Magnetic sensing system Rate sensor unit(2) Fixed head startrackers(3)—electro- optical detector Reaction wheel actuators(4) Magnetic torquers(4)

OPTICAL ASSEMBLY Primary mirror—2.4m in diameter, concave shape Secondary mirror—0.3m in diameter Focal plane—for examining the light

SCIENTIFIC INSTRUMENTS AXIAL BAYS(4)- Four instruments aligned with the main optical axis & are mounted just behind the primary mirror. 1>ACS--wide field of view,better light sensitivity 2>NICMOS—infrared instrument 3>STIS—separates light into component wavelengths 4>COSTER—for correction of spherical aberration WFPC2(Wide Field/Planetary Camera 2)- It is responsible for taking nearly all of HUBBLE’s famous pictures FINE GUIDANCE SENSORS(3)- It measures relative positions,providing data to the spacecraft’s targeting system

LIGHT & FILTERS

COLOUR AS A TOOL

FEATURES 3 observations/hour Each observation requires 100 computer functions 2 observations at a time 100,000 instructions/week Generates 10 billion bits of scientific data/week Can move 90 degrees/15 minutes 17,000mph around the earth

APPLICATION FIELDS Best view of mars Proof of black holes Quasars—active galactic nuclei in distant galaxies Gamma rays origins The expanding universe The birth of stars The death of stars Comet collision Auroras & electricity

LIMITATION Can’t observe the sun—intense light & heat Can’t observe mercury or venus Can’t observe some stars—too bright Orbit of HST—target obstructed by earth Van allen radiation belt—charged particles from solar winds trapped by earth’s magnetic field

CONCLUSION Despite its flawed early history, the HST has performed well, yielding much scientific data and beautiful images. However, the HST will not last forever. Plans are underway for a new space telescope, called the Next Generation Space Telescope (NGST). NGST will be even more sensitive than HST and provide better images of even more distant objects.The age of optical space telescopes started by HST promises to revolutionize astronomy as much or more than Galileo's first use of the telescope did long ago.

REFERENCES

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