Case Study - Liberty Bell 7 mission
Date: July 21, 1961
American astronaut Gus Grissom was inside a small capsule that splashed down safely in the Atlantic Ocean upon successful completion of the mission. While he was waiting for helicopters to take him back, he was recording flight data
Unfortunately, an incorrect command in the capsule’s explosives system caused the hatch of the capsule to pop out, causing water to flow inside. Moreover, Grissom forgot to close a valve in his spacesuit, leading to water flowing into the suit as well. He survived the experience in the end
First crewed splashdowns
Date: 1961 USA’s Project Mercury used conical capsules for splashdowns
- Before safe landing, the returning spacecraft has to slow down
- Atmospheric drag and friction can greatly heat up the spacecraft and slow it down
- Still not slow enough!
- Atmospheric drag and friction can greatly heat up the spacecraft and slow it down
- NASA uses parachutes with bright colours (in order for them to be easily noticed from afar) to slow the craft down
- Diameters are usually ~30.48 m
- More than one parachute is used for better stability
- Drogue parachutes are deployed first before the main ones when the craft has slowed to 700 m/s. This is done to increase stability and control
- Water is a good shock absorber unlike hard ground
- Water has low viscosity and density
- 70% of Earth is water, so the landing area is higher
- Returning spacecraft are splashed down in water for this reason
- Crashworthiness phenomena - The degree of damage a craft takes after hitting a surface
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