video record
Media not available in the Digital Archive
This programme, narrated by Dr John Guest of the University of London, looks at craters throughout the solar system and what we can learn by studying them. It begins with a brief historical resume ...of the impact/volcanism crater formation argument, which was finally settled by nuclear tests after the Second World War. It then looks in detail at an experiment specially done for the programme at NASA's Vertical Gun facility, in San Francisco. Dr Peter Schultz, of the Lunar & Planetary Institute, Houston, creates a lunar crater in the laboratory by firing an aluminium ball into a sand target in an evacuated chamber. We see the crater, and slow motion film of its formation, described in detail by Dr Schultz. Prof Ronald Greeley of Arizona State University, then discusses the crater record on Mars, and shows a simulation of it on film firing into a fluid mud target. This raises the question of planetary composition and atmosphere: whether observed craters on Mars are formed by ejecta travelling through an atmosphere or by volatiles in the planet's crust. The answer to this is provided by the Galilean satellites of Jupiter. Rostrum stills and animations illustrate Io and Europa, the two innermost of them:then Prof Bob Strom, University of Arizona, talks about the two outer, Callisto and Ganymede. A third experiment, firing into waoi on water, seems to prove volatiles are the key to martian and galilean cratering. Prof. Strom then goes on to discuss cratering on some of the saturnian satellites, and raises the question of where the impacting objects come from. This can be determined from a size frequency distribution curve of craters, and Hyperion is proposed as one of the sources of impacting bodies in the Saturnian system.
Metadata describing this Open University video programme
Module code and title: S237, "The Earth, structure, composition and evolution"
Item code: S237; 14; 1983
First transmission date: 19-08-1983
Published: 1983
Rights Statement:
Restrictions on use:
Duration: 00:24:00
+ Show more...
Producer: Nick Brenton
Contributors: John Guest; P Schultz
Publisher: BBC Open University
Keyword(s): Craters; Ejecta; Galilean satellites; Impact events; NASA; Palimpsests; Planets; Regolith; Size-frequency distribution; Solar system
Master spool number: HOU4278
Production number: FOUS255E
Videofinder number: 1603
Available to public: no