Reusable Solar Stage Rocket

The third and the final reusable rocket stage is the solar stage. This stage would circulate the earth and a planet close to the sun (Venus or Mercury). It will look like a folded umbrella. It will be assembled from smaller pieces on the LEO orbit. The first section will be the liquid propulsion rocket’s engine section with a propellent tank group. The subsequent sections will add more propellent tank groups to the rocket. Then, high voltage ion thruster section with a gas tank will be added. The outside of this section will have the folded solar panels which double as solar sail. The subsequent sections will have more gas tanks for the ion thruster and folded solar panels. The nose of the rocket will carry the payload of the rocket.

Once the addition of sections is complete, the rocket will fire its liquid rocket engine to increase its altitude and reach the escape velocity. The consumed propellent tank groups will be ejected as the rocket accelerates and will decompose like the second stage’s tanks. When all the propellent is consumed, the liquid rocket section will eject itself from the remaining rocket assembly. The ejected rocket section will be at the escape velocity and can be programmed to crash on to the moon.

The remaining solar stage will unfold its solar panels to generate maximum electricity which will be used by the high voltage ion thrusters to accelerate the rocket further. While the rocket is distant from the sun, the panels can be fully extended and the solar wind would have minimum effect on it. As the rocket approaches the sun, the solar panels would be slightly folded back to reduce the solar drag. Additionally, close proximity to the sun would generate more power, negating the need for fully extended panels. This approach will accelerate the rocket to very high speeds and reduce the travel time to Venus and Mercury. The consumed gas tanks of the ion thruster will be ejected during the journey to reduce the weight. At a certain distance from the target location, the engines will be stopped and the solar sail will be fully extended to decelerate the rocket with the help of solar wind.  This will allow the payload to be released at a slower speed to help it safely land on the planet.

Once the payload is released, the rocket will circle around the planet and fire it’s ion thrusters once more for the return trajectory. The solar panels and the sail will remain extended so that the solar wind would contribute to the acceleration as well. The rocket will fold the solar panels back, as it approaches the earth to minimize the drag on the ionosphere. Hopefully, it will settle back on a LEO orbit where it will be serviced with new payload, ion thruster gas tanks and a new liquid propulsion rocket.