Aurora '93, a simulated operational dive to 450/470 metres, took place at the National Hyperbaric Centre in Aberdeen, Scotland during April and May 1993. The primary objective of the programme was to demonstrate productive, safe and cost-effective manned subsea intervention at 450 metres with excursions to 470 metres The programme further allowed equipment manufacturers to test their equipment under realistic yet safe conditions.
Oil exploration and production in Northern Europe is moving into ever deeper water and this has further stimulated the development of subsea production systems with remote operation and maintenance precluding the dependence on manned intervention at ambient pressure It has, however, also been realised that a manned intervention capability will be required, if only in a secondary mode. This has defined a requirement, therefore, for manned intervention and the consequent procedures and technology to permit safe and productive deep saturation diving. Therefore, while the requirement may not be immediate, the future likelihood of one-off deep saturation dives is strong. The ethical concerns that may still persist are best answered during well-controlled and well-monitored deep simulation dives so that the divers can be safeguarded both dunng the dive and during the post-dive phase all in accordance with standard industry practice. Comprehensive neurological, neuropsychological and pulmonary investigations have been carried out as part of Aurora '93, as indeed they have as part of many previous deep dive programmes.
Statistically significant changes can always be found and any insult resultant from the dive causing either transient or more long term dysfunction needs to be assessed in the context of other diving populations and any qualitative effects on daily life.
Aurora '93 was designed with the primary objective of demonstrating safe and cost effective manned subsea intervention at 450 metres. The project was 35% funded by the EC Thermie programme (Hydrocarbons) with additional support, primarily in kind, from the oil and subsea industries and research institutes. Thirty different companies participated representing 6 countries thus demonstrating the confidence not only in the efficacy of manned subsea intervention but also in the potential future markets.
Four divers (2 French and 2 British) from the Stolt Comex Seaway Group were pressurized to a storage depth of 450 metres on April 18/19 The storage PO2 was 400 mb with the balance being helium Figure 1 illustrates the compression profile used during Aurora '93 The profile was evolved from the results of many deep simulated dives over the last 20 years. The compression profile from Igloo '88, a dive to 450 metres in 1988 at the National Hyperbaric Centre, has been overlaid to highlight the different philosophies of the profiles. The Igloo '88 profile resulted in significant and debilitating HPNS in the 6 divers for the first 3 days of the 10 day bottom phase.
