RocketSTEM Issue #14 - March 2017 | Page 50

The Refueling Craft itself is almost ex- ternally identical to the Interplanetary Spacecraft, sharing the same superstruc- ture which cuts down on development costs. At the base are six vacuum-opti- mized Raptor engines set around a set of three gimbled engines (each engine sits on controllable hydraulics to control the direction of the thrust). Before departing to Mars, the spacecraft will take on fuel from three to eight times, depending upon the mass of the payload. Once the craft has begun its journey, two solar panels will be deployed and supply the craft with 200 kilowatts of electricity. It will coast away from Earth at 100,800 kilometers an hour towards Mars, before aerobraking in the Martian air as it prepares for landing. The craft is designed as a “lifting-body”, echoing that of the now retired Space Shuttle, providing the lifting force during atmo- spheric entry to slow down the craft to 48 48 launch The Refueling Craft is the key to the system, compared to a Saturn V, for example, which used a three-stage rocket that maximized the payload, but increased both the cost and complexity of the mission. Refueling means that you don’t have to bring as much mass with you in the first place, as you can simply launch the craft multiple times, which reduces mission complexity and vehicle size. Not refueling in orbit would require building a three-stage rocket at five to 10 times the size and cost. Once the Booster has delivered the Interplanetary Spacecraft to low Earth orbit, it will turn around and begin its de- scent back to Earth. Utilizing the method that SpaceX has become so famous for, the Booster will use its grid fins and engines to land back near the launch platform. At this point, the Booster can be refueled and the Refueling Craft is loaded on top for its next departure. draw any connections. The launch height of the ITS is 122 meters, compared to the 111 meters of the Saturn V. Addi- tionally, the Saturn V was designed as a single use vehicle, delivering it’s payload into orbit using an expendable three stage setup, meaning that after each use the hardware is simply dropped into the ocean. On the other hand, the Inter- planetary Transportation System is a two stage vehicle and is designed to be fully reusable. www. RocketSTEM .org