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This clip shows tense scenes in Mission Control at the National Aeronautics and Space Administration’s (NASA’s) Jet Propulsion Laboratories on 30 June 2004 as the Cassini spacecraft is about to enter a crucial stage of its voyage to Saturn. The clip begins with an external view of the Laboratories but cuts almost immediately to inside Mission Control. Close-up views of scientists and engineers are intercut with a series of animated graphics showing the spacecraft initiating the move that will take it through the plane of Saturn’s rings so that it can enter orbit, captured by the planet’s gravity. Narrator Dr Richard Smith is shown in the media room explaining the potential dangers of Cassini’s approach through the plane of Saturn’s rings.

Educational value points

• The goal of the Cassini-Huygens mission was to travel to and orbit Saturn to explore Saturn’s large and complex ring system and 34 moons. Once there, it would carry out a detailed study of the clouds, atmosphere and surface of Titan, the largest of Saturn’s moons. The mission involved collaboration between three space agencies: NASA, the European Space Agency (ESA) and the Italian Space Agency (ASI Agenzia Spaziale Italiana) and was 14 years in the planning. The Huygens probe, which rode piggyback on Cassini, was released in January 2005, collecting data during its descent and in the short time it spent on the surface of Titan.

• At the time of writing the Cassini spacecraft was the largest interplanetary spacecraft ever built. NASA was responsible for the orbiter, ASI for the communications antenna (images of the orbiter and its antenna form part of the graphics seen in the clip), and ESA for the Huygens probe. Overall, 17 nations were involved in the construction of the 5.6-tonne spacecraft.

• Following its launch from Cape Canaveral, USA, on 15 October 1997, the Cassini spacecraft undertook a 7-year, 3 billion-km journey to Saturn, the final critical stages of which are shown in the clip. As such a journey could not be achieved by launch velocity alone, four gravitational slingshots, known as 'gravity-assist swing-by manoeuvres’, were needed to propel the spacecraft: two from Venus in April 1998 and June 1999, one from Earth in August 1999, and one from Jupiter in December 2000. ESA calculates that the first three swing-bys provided Cassini with thrust equivalent to that of 68,040 kg of rocket fuel.

• Described by the narrator as 'Cassini’s moment of truth’, the spacecraft’s passage through the plane of the rings of Saturn placed the craft in immense danger. The rings are composed of innumerable pieces of ice and rock, some huge and some minute, with any one capable of destroying a spacecraft approaching at more than 70,000 km per hour. In the final set of graphics shown in the clip Cassini is depicted approaching the rings from below to attempt to pass through the gap between the outer F and G rings. At the time of Cassini’s passage, the gap was clear of debris and Cassini survived to begin its planned 74 orbits of Saturn over a period of 4 years.

• The clip includes images of Saturn, many of which were created from data sent by the spacecrafts Voyager I and II in their fly-bys of 1980 and 1981. Since entering orbit in 2004 Cassini has sent back 3 gigabytes of data a day, which is enabling more comprehensive and detailed images to be created than those shown in the clip.

• A range of techniques are used to build suspense in the clip, including rapid cuts from one scene to another; close-ups of the scientists and engineers looking anxious, swallowing and rocking; commentary that employs evocative words and phrases and a particularly suspenseful scene where the narrator whispers to the camera.

• Cassini has proved to be a much-needed public relations success for NASA’s space program as NASA, like all US federal agencies, must generate support to facilitate its budget being passed annually by the US Congress. NASA’s overall budget for 2004 was US$15.4 billion, less than 1 per cent of the US federal budget.

• The clip demonstrates the importance of programs such as the Australian Broadcasting Corporation (ABC)’s Catalyst in enhancing the public’s understanding of science, and the contribution of the narrator Dr Richard Smith, a marine biologist turned filmmaker, in making science exciting.