Happy 10th Year Birthday for Cassini spacecraft

William Atkins
Tuesday, 16 October 2007 20:14

Science - Space

The Cassini spacecraft is ten years old and continues to successfully carry out its mission to explore the planet Saturn and its natural satellites (moons). Do you remember the controversy for its October 15, 1997 launch?          

The power source for the Cassini spacecraft, which is a joint effort of NASA, the European Space Agency, and the Italian Space Agency, is three radioisotope thermoelectric generators (RTGs) that use the natural decay of plutonium to produce heat in order to generate electricity to power the spacecraft.

RTGs have been used for the Galileo, Ulysses, and New Horizons space missions to Jupiter, the Sun, and Pluto, respectively.

Environmental groups and individuals protested the launch because of the chance that the spacecraft could explode during launch and later during its swing around the Earth on its way to Saturn and spew radioactive materials down onto the surface of the Earth.

NASA estimated that the chance for radioactive contamination was about 1 in 1,400 immediately after launch and about 1 in 476 during its flight into space. Only a 1 in ten million chance was present later in its mission (according to the NASA Final Environmental Impact Study)—during its gravitational slingshot maneuver around Earth.

Protestors stated that the chances for contamination were much greater and the mission should be scrubbed.

Some of the articles protesting the Cassini launch are found below:

The Baltimore Chronicle: “Countdown to Cancel the Cassini Space Probe”.

CNN: “Dozens arrested in protest of plutonium-fueled space mission”

A response from a pro-Cassini launch group is found here:

National Space Society: “Responding to Concerns That Might Be Raised, NUCLEAR RTGs & CASSINI MISSION TO SATURN, What you Should Know and What You Can Do”

During its ten years exploring the Saturnian system, Cassini has looked under the haze that hides the moon Titan—discovering large lakes of liquid methane among a frozen hydrocarbon surface.

Cassini has also photographed a hexagonal structure in Saturn's atmosphere, found that the moon Enceladus contains organic materials and liquid water, and discovered a bulging equatorial ridge on the moon Iepetus, which looks like a walnut.

A multitude of discoveries have been made to aid human knowledge of the solar system and of Earth, itself.

Whatever humans do, risks are involved. We have to consider the risks to determine if we want to take the chance. If we always say 'no' to risks, we will never accomplish anything in life. Yes, some things are too risky. But, we should rationally weigh the risks versus the benefits to decide what we should do, whether it is in our daily lives or on a distant space mission to Mars, Saturn, Jupiter, or Pluto.

The NASA Jet Propulsion Laboratory’s home webpage for the Cassini-Huygens mission is: http://saturn.jpl.nasa.gov/home/index.cfm. Take a look at all the discoveries the Cassini robotic probe has safely made over the past ten years.

Look at some of the dramatic images taken by Cassini over the past ten years: http://saturn.jpl.nasa.gov/multimedia/images/index.cfm.

Check out the Cassini website from NASA at: http://www.nasa.gov/mission_pages/cassini/main/index.html. Archives of past articles are included on the website.