Examples using different propellants

Given that nuclear propulsion is be considered unsafe, the alternative of a purely chemical fueled rocket will be considered together with other options for a mixed system. Because the lander’s engines will only be fired on Mars, very far away from Earth and any potential nuclear hazard, a purely nuclear fueled rocket for the lander might also be considered.

Option 1

Earth to Mars

Crew cab/Lander

Trans Mars Injection 3 km/s
Mars Orbit                5 km/s
                                 8 km/s

Chemical propulsion              Isp 450s  M/Mo=6

Nuclear Thermal Propulsion   Isp 900s  M/Mo=2.5

(The lander/crew habitat would in this case be considered dead cargo for the Mars cab.)

Lander

Mars Landing  5 km/s
Mars Takeoff  5 km/s
                     10 km/s

Chemical propulsion            Isp 450s M/Mo=9.63

Nuclear Thermal Propulsion Isp 900s M/Mo=3.10

Return Trip

Trans Earth Injection 3 km/s

Chemical propulsion            Isp 450s M/Mo=1.97

Nuclear Thermal Propulsion Isp 900s M/Mo=1.4

Option 2 (MSR- Mars Surface Rendezvous)

Earth to Mars

(the difference with option 1 is that as in this case the ascent vehicle is awaiting at the surface it will not need to be taken on as dead weight)

Crew cab

Trans Mars Injection  3 km/s
Mars Orbit                5 km/s
                                 8 km/s

Chemical propulsion            Isp 450s M/Mo=6

Nuclear Thermal Propulsion Isp 900s M/Mo= 2.5

Lander

Mars Landing 5 km/s

Chemical propulsion            Isp 450s M/Mo=3.1

Nuclear Thermal Propulsion Isp 900s M/Mo=1.76

Ascent/Return Trip

Mars Takeoff            5 km/s
Trans Earth Injection 3 km/s
                                 8 km/s

Chemical propulsion            Isp 450s M/Mo=6

Nuclear Thermal Propulsion Isp 900s M/Mo= 2.5