Britannica Illustrated Science Library: Space Exploration by Encyclopedia Britannica

Author:Encyclopedia Britannica [Britannica, Encyclopedia]
Language: eng
Format: epub
Published: 2011-10-29T23:50:40+00:00

58 PERMANENT EXPLORATION

SPACE EXPLORATION 59

Spying on the Universe

HOW IMAGES ARE

IMAGES

The Hubble can photograph a large variety of objects—from galaxies and clusters TRANSMITTED

of galaxies to stars on the verge of exploding (such as Eta Carinae) and planetary nebulae (such as the Cat's Eye).

S

1 HUBBLE

pace telescopes such as the Hubble are artificial satellites put into orbit for observing Instructions for the

desired observation are

different regions of the universe. Unlike telescopes on Earth, space telescopes are above uploaded to the

telescope, which then

the Earth's atmosphere. Therefore, they avoid the effects of atmospheric turbulence, transmits the image or

other observational

which degrades the quality of telescopic images. Moreover, data after the

observation

the atmosphere prevents the observation of the is completed.

stars and other objects in certain wavelengths (especially the infrared), which substantially STAR ETA

SUPERNOVA

CAT'S EYE

CARINAE

NEBULA

decreases what might be seen in the

SHUTTER

Because it is outside the atmosphere, Hubble photographs are sharper than heavens. Space telescopes do not have to

During observations

those taken by terrestrial telescopes.

it opens to allow

contend with light pollution, which is a

light to enter.

2 TDRS SATELLITE

Receives the data from

problem for observatories near urban areas.

Hubble and sends them

to a receiving antenna at

3 EARTH

Other Telescopes

SECONDARY MIRROR

the White Sands Test

From New Mexico, data are

Located inside the

Facility in New Mexico.

transmitted to the Goddard

telescope tube. Light

Space Flight Center in

The Spitzer telescope, launched in

reflects from the

Greenbelt, Maryland, where

August 2003, was designed to

secondary mirror to the

the information is analyzed.

photograph very distant objects. It is

The Hubble Space Telescope

camera.

expected to be deactivated in 2008. SOHO,

developed jointly by NASA and ESA, shows

HIGH-GAIN ANTENNA

The Hubble was put into orbit on April 25, 1990, by NASA and ESA. It is an artificial satellite receives orders from the Earth

in detail the interactions between the Sun

whose instruments are directed toward outer space. The telescope can be remotely controlled and sends back as TV signals the

and the Earth. Chandra, launched in 1999,

by astronomers at different locations. The telescope's computers point the telescope in the desired photos that the Hubble takes.

carries instruments that provide

direction, and sensitive light detectors and cameras make the desired observations, in many cases information about the position and energy

producing impressive vistas of the cosmos. In 1993, because of a fault in the primary mirror, a of celestial X-ray sources.

corrective lens called COSTAR had to be installed to correct the focus of the telescope.

TECHNICAL SPECIFICATIONS

Launch date

April 25, 1990

Orbital altitude

370 miles (600 km)

24,250

Orbital period

97 minutes

Type of telescope

pounds

Ritchey-Chretien Reflector

46 feet

SOLAR PANEL

NASA and ESA

(14 m)

PRIMARY, OR

Organization

(11,000 kg)

Energy is provided by

PRINCIPAL, MIRROR

Useful life

SPITZER

20 years (until 2010)

WEIGHT ON EARTH

is 8 feet (2.4 m) in

directional solar

antennas that convert

observes the universe

Launch cost

$2 billion

diameter; captures and

in infrared.

focuses the light.

sunlight into electricity.

Primary mirror diameter 8 feet (2.40 m)

14 feet

(4.26 m)

HOW IT CAPTURES IMAGES

KEY

COSTAR

The Hubble uses a system of mirrors that receive the light and cause it to converge until it reaches a focus.

The optical device that

Direction

corrected the defective

of the light

EXTERNAL LAYER

original mirror of the

protects the telescope

Hubble. The device was put

Secondary

Secondary

from external damage.

in place by space shuttle

SOHO

Mirror

Mirror

During repair missions,

astronauts in 1993.

Put into orbit in 1995, it

takes images of the Sun.

the astronauts inspect it

to look for particles and

A scientific

debris to be removed.

instrument where

the image

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