Vol.1, No.6

Nasa expeditions to uranus

Voyager 2 and its visit to the planet Uranus.

A satellite sent to Uranus
Photo Credit: NASA
Uranus is the seventh planet from the sun in our solar system, and one of the furthest away from planet Earth. Uranus was discovered in 1781 by William Herschel and Herschel discovered the two largest moons of the planet, Titania and Oberon in 1787. The atmosphere of Uranus is 83% hydrogen, 15% helium and 2% methane. The methane in the atmosphere absorbs red light giving the planet an attractive blue-green color. Uranus is also known as the "tilted," planet as it has an unusual axis that lies almost level with its rotation around the sun. Many astronomers think that a planet the size of the Earth collided with Uranus shortly after its birth causing the odd tilt.

Uranus has at least 27 moons, as of October 2003 and there may be more yet to be discovered. The planet is very far away from Earth making exploration more challenging than other exploratory space missions.

Voyager 2 was launched on August 20th 1977 and is the only spacecraft so far, to reach the distant planet. Voyager was launched to take advantage of an unusual arrangement of the planets in our solar system. Jupiter, Saturn, Uranus and Neptune were lined up in a way that made it possible for a spacecraft to skip from one planet to the other without an abundance of fuel. The planets position only occurs once every 175 years and Voyager was to use each planets gravitational pull as momentum to reach the next planet in line. Using this technique the flight time to Neptune, for instance, was reduced from 30 years to 12.

Voyager 2 did a fly-by of Uranus on January 24th, 1986 coming within 56,000 miles of the planet's atmosphere. No spacecraft had reached the distant planet before this date and the visit had an immediate impact on current knowledge about Uranus. There were only five known moons circling Uranus prior to the arrival of Voyager 2. The probe quickly discovered ten small moons disrupting all prior information scientists had about Uranus. Voyager 2 also discovered nine rings around Uranus, some of them being strangely incomplete drawing the name ring-arc. The theory is the remains of a destroyed moon may have created the rings. Atmospheric turbulence on Uranus is causing huge lighting strikes Voyager 2 discovered. Scientist were able identify the lightning by listening to the static crashes the planet was generating and comparing them to similar static that the lightning on Earth causes.

NASA's Hubble Space Telescope obtained the only other close up view of Uranus in August of 1994. Uranus was 1.7 billion miles for the Earth at that time and the telescope was able to take pictures of the planet that had only been possible before when Voyager 2 visited.

NASA plans no future missions to Uranus at this point in time. The European Space Agency and Japan are both expanding their space programs and with the rest of the world joining the exploration of space. The distant planet is sure to draw some more interest.