How Fast Could (Should) We Go to Mars?

Comparing Nuclear Electric Propulsion (NEP) with the Nuclear Thermal Rocket (NTR) and Chemical Rocket for Sustainable 1-year human Mars round-trip mission

The human habitat must allow good health and strength for surface work on arrival: 62,000 kg per DRA 5.0. Helio transfers must be fast enough to allow at least 30 days on the surface. Propellant requirements practically eliminate all options except for nuclear electric.

NEP vs NTR for a long-stay DRA-5.0-like mission. In flight round-trip mission time from low Earth orbit (LEO)

Reducing the round-trip in-flight time on a human mission to Mars reduces the radiation dose to the crew (vertical arrow), which increases with trip time. The green curves show the total round-trip in-flight time vs the NEP rocket’s power for various values of α ranging from 1 to 10 (α is a measure in kg/kW of how “light” the nuclear reactor and engine package could be). For each α there is a minimum trip time and a corresponding power level that satisfies the mission requirements. The horizontal red dashed line shows round-trip time using an NTR. Nuclear electric space reactors with α <10 do not yet exist, but compelling designs have been proposed by recognized experts worldwide . These must be developed to enable fast missions to Mars and a robust human exploration of the solar system.