A semi spherical parachute 
A cross shaped parachute.
The following calculations can be performed when working on the parachute design. You may need to read the following sections on descent physics and parachute designs in order to do these calculation.
- Calculate the impact speed of the can without a parachute (when released from 1 kilometre altitude). (The answer to this question gives you an idea of why a parachute is nescessary!)
- Calculate the minimum required area for your parachute when you use a cross shaped parachute. What size should the squares be on the parachute?
- Perform the same calculation for a semi spherical parachute. What is the radius?
- Test the descent velocity of your parachute with a soda can with same mass as your CanSat.
- Try out different solutions for the parachute. A parachute with some holes in it or perhaps multiple small parachutes? Both will enhance the stability of the CanSat.