was to actually measure the size of a crater on the moon). "Aerial Surveyor": Build a device with a camera that could survey a large area from the air. Find the center of one of the largest earthquakes to hit America that took place back in 1872 in California, and estimate what it measured on the Richter scale. Mike creates a system that filters carbon dioxide, just as the astronauts of Apollo 13 were forced to do when an explosion ruptured an oxygen tank. "Rocket": Design rockets that can launch an egg into the air and return it safely to earth. Three different rockets are attempted by three of the scientists, while the remaining two work on a parachute system. Series 5 This series takes place on the coast of Zanzibar and has a strong ecological theme running through the challenges. The line-up of scientists is Ellen McCallie, Jonathan Hare, Mike Bullivant, and Kathy Sykes. The episode challenges for this series are: "Shipwrecked" – Design and build a submersible exploration vehicle to explore a shipwreck, determine when low tide occurs for the best chance at getting to the wreck, and how to purify the scientists' water supply. "Lost at Sea" – Build a distress flare, make an emergency flotation device, and create a warning light activated by seawater. "Call of the Wild" – Const an underwater hydrophone, an underwater viewing device, and create mosquito repellent. "To the Lighthouse" – Build a lighthouse by creating a light source visible from great distances while at sea, as well as create the lighthouse infrastructure and make the light flash. "The Reef" – Create a system to protect a coral reef by alerting approaching boats that they're entering a protected area. "Beneath the Waves" – Build a SCUBA device that can safely be used to a depth of 5 meters and still provide freedom for exploration. Series 6 This series, shown in 2005, takes place in the San Juan Mountains in Colorado. For this series, geomorphologist Hermione Cockburn replaced Kathy Sykes. "Power" – Supply electricity and natural gas to their basecamp, located in an old mill. "Safety" – Build a fire extinguisher (using carbon dioxide) and a water treatment plant. "Mountain" – Calculate the height and weight of a mountain and make sunglasses to protect the eyes at high altitudes. "Clean" – Build a washing machine with washing soap, and create antiperspirant and deodorant.