Challenge Mission 1: Stay Young
In the first Asteroid challenge mission, Stay Young, you are tasked with keeping your rock within a large circle drawn in space while wave after wave of piles of asteroids are thrown at you and inside the ring in general. The trick here is that you have to keep from evolving to a Small Planet for as long as possible, made difficult by having to avoid collisions with other asteroids in order to do so.
Easy Score: 15 seconds
Medium Score: 25 seconds
Hard Score: 40 seconds
The general idea to beating the hard score in Stay Young is to move in a circular pattern, taking advantage of your quick acceleration while still a small rock to dodge the incoming waves. The asteroids will come at you in a spiral pattern that centers on your current location when the wave spawns. Pick either clockwise or counter-clockwise rotation for your path and duck and dodge as necessary. If you become to large of an asteroid, you will find yourself having a progressively more difficult time preventing further collisions due to your size and gravity well. Finally stay away from any planets that manage to spawn, which can happen at the center of the spirals where the asteroids all collide with each other, as their gravity will pull you in and throw off the precise movements you need to pull off.