Satellites And Spaceprobes

AUGUST 2005: ROVER ON A RED PLANET

Turning the gaze of its panoramic camera downwords, the Mars Exploration Rover Spirit photographs itself amid the dust of a Martian desert. After almost 20 months on the surface of Mars, the rover's solar arrays - providers of its energy and life - are still gleaming through only a thin veneer of dust.

THE SPACE AGE HAS TRANSFORMED our understanding of our own world and others. In 50 years, artificial satellites have gone from propaganda weapons to vital tools of humanity, watching over the Earth. They have gathered information on everything from hidden mineral deposits to long-term climate change, provided a new view of the Universe from beyond the atmosphere, and triggered a global revolution in communications that has helped to make the world a smaller place.

And while manned exploration of space has gone no further than our own Moon, our robot servants have gone much further. Spaceprobes have explored all the other major worlds that orbit the Sun, in addition to a number of the smaller objects that clutter the Solar System. They have ventured into environments that would quickly prove fatal to astronauts and to distant regions that would take decades for a manned mission to reach. The images and data they have sent back have not only revealed previously unseen worlds but also aided understanding of our own.

4 October 1957

The satellite age begins with the launch of Sputnik 1.

31 January 1958

Explorer 1 becomes the first satellite to return scientific data from orbit.

25 June 1959

The US launches its first spy satellite, Discoverer 4, though it fails to reach orbit.

7 August 1959

Explorer 6 returns the first television pictures from orbit.

1 April 1960

NASA launches the first successful weather satellite, TIROS 1.

7 March 1962

NASA launches Orbiting Solar Observatory 1, arguably the first astronomical satellite.

16 August 1964

Syncom 3, the first successful geostationary comsat, is launched.

23 April 1965

The Soviet Union launches Molniya 1-01, the first comsat with a highly elliptical orbit.

23 July 1972

NASA launches ERTS-1, the first remote-sensing satellite.

Orbiting the Earth

In the decades since Sputnik 1 first sent a simple radio signal back to Earth, artificial satellites have transformed not only our view of Earth and the wider Universe but also many aspects of everyday life.

As with many revolutionary technologies, it took some time for the full potential of the artificial satellite to be recognized. The wave of apprehension that greeted news of Sputnik 1 in the West was born of a fear that satellites might be used as weapons platforms to rain down missiles on a defenceless enemy. The military on both sides were also aware that satellites could act as spies in the sky, beyond the range of ground-based weapons. Indeed, many early US experimental satellites, such as Discoverer and Corona (see p.249), and some of the Soviet Cosmos series were in fact orbiting spy cameras.

It took longer for scientists to realize the potential of satellite-borne cameras for studying the Earth in general - an application known today as remote sensing. In fact, it was only when Gordon Cooper reported seeing roads and buildings from his Mercury capsule Faith 7 in 1963 that NASA started to wonder about the possible applications.

Today, remote-sensing satellites are used to study many aspects of our planet's geology, oceanography, climate, and ecology. Looking the other way, astronomers have also made use of spaceflight - a location above the Earth's atmosphere holds obvious advantages for any instrument needing a clear view into deep space. One other predicted application was the communications satellite, or comsat - an orbital

POLAR COSMODROME

Russia's northern cosmodrome at Plesetsk near Archangel is an ideal site for launching satellites into polar orbits and also into the highly inclined Molniya orbits used by Russian comsats.

inclined, highly elliptical Molniya-type orbit

ORBITAL VARIETY

Some of the most commonly used types of satellite orbit are shown here (though not to scale). Other, more exotic paths are also technically orbits of our planet - they ore used by spaceprobes or observatories that require a great deal of distance from the Earth.

inclined, highly elliptical Molniya-type orbit

ORBITAL VARIETY

Some of the most commonly used types of satellite orbit are shown here (though not to scale). Other, more exotic paths are also technically orbits of our planet - they ore used by spaceprobes or observatories that require a great deal of distance from the Earth.

Geostationary Orbit Polar Orbit

geostationary orbit above the equator polar orbit typically used by remote-sensing sote/lites geostationary orbit above the equator polar orbit typically used by remote-sensing sote/lites

POLAR COSMODROME

Russia's northern cosmodrome at Plesetsk near Archangel is an ideal site for launching satellites into polar orbits and also into the highly inclined Molniya orbits used by Russian comsats.

platform that bounces signals between distant places on Earth, overcoming the line-of-sight limitation of radio signals (see over). However, even enthusiasts would not have foreseen the communications revolution that comsats would trigger.

Was this article helpful?

0 0
100 Photography Tips

100 Photography Tips

To begin with your career in photography at the right path, you need to gather more information about it first. Gathering information would provide you guidance on the right steps that you need to take. Researching can be done through the internet, talking to professional photographers, as well as reading some books about the subject. Get all the tips from the pros within this photography ebook.

Get My Free Ebook


Post a comment