6
Launch/Landing
	6.1	Launch Vehicle
The proposed launch vehicle for the mission is the Delta II 7925H. This vehicle was chosen because it was the largest rocket which was covered by the Discovery program. The Delta II rocket can mount three different payload fairings - 2.4m, 2.9m and 3.0m. The 2.9m fairing was chosen because it provides almost as much room as the 3.0m, but is capable of launching a larger payload mass. A drawing of the 2.9m fairing with dimensions is included in Appendix ?. With this configuration, the rocket is capable of launching a 1500kg payload to the Moon.
	6.2	Landing
Icebreaker calls for the design of an innovative landing strategy. To obtain the terrainability and functionality required by the mission, Icebreaker must be a large robot. This leaves very little space or mass in the rocket for a landing craft. To overcome this problem, it is proposed that Icebreaker be a combined lander/rover. 
Traditionally a robot rides on top of a landing vehicle. The landing vehicle has the propulsion system and shock absorbing structure to land on a planetary surface. Typical landing velocities are on the order of 3m/s. Once landing is complete ramps are deployed to allow the robot to roll off and start its mission. The landing craft is not needed again.
In the combined lander/rover, propulsion systems are connected directly to the robot. This is combined with advanced control techniques to allow the lander/rover to land at very small velocities. Rocks and other hazards can be avoided at the landing site with a vision system. This increased controllability allows the amount of shock absorbing structure to be minimized and removes the need of a landing craft. By eliminating the landing craft structure, which is not used after landing, the effective payload can be increased. Also, the complex ramp structures are eliminated, removing the complexity of deploying the robot from the landing craft.
Icebreaker will have a total of three propulsion systems to remove the energy of descent. The initial deceleration is performed by a solid rocket motor. The proposed model is the Thiokol STAR 37XFP. A picture of the rocket motor is included in Appendix ?. As shown on ???, the solid rocket motor fires at approximately 50km above the surface of the Moon. It burns out after 56s.
Final deceleration is controlled by the main hydrazine thrusters and the attitude control system. The main hydrazine thrusters consist of 12 34lbf thrusters, mounted in 4 groups of 3. Each group of thrusters has a 39L fuel tank mounted directly beside it. This reduces the amount of pipes needed to bring the fuel to the thrusters.
The third propulsion system consists of small thrusters mounted perpendicularly to the main hydrazine thrusters. The purpose of these thrusters is to ais in the control of the attitude of Icebreaker during landing. While the main hydrazine thrusters can control pitch and roll, they cannot remove any spin or yaw which may be present during the final descent. The attitude control system can do this. As well it is capable of aiding in translation manoevers so that maximum vertical deceleration may continue.
This is still pretty bad, but I assure you that I will spend more time making this presentable over the weekend and start of next week. Sorry to waste your time.