A proposed propulsion concept called the synchronal bimodal nuclear rocket, or S-BNR, would combine nuclear thermal and electric propulsion in a single reactor system. The design is described in IEEE Spectrum as a joint effort by NASA and industry engineers to cut travel times around the solar system.
In nuclear thermal mode, the reactor would provide high thrust for departures and major course changes. Once underway, the rocket would shift to an electric propulsion mode that uses the reactor's energy more efficiently over long stretches of flight. Because both modes share one reactor, the concept could avoid the weight penalty of carrying separate nuclear power and propulsion systems.
The most direct payoff, according to the report, is shorter trips to Mars and other destinations. Faster transits would mean less time for crews in deep space, though the summary does not specify exact timelines. Since only one source was available, there are no contrasting findings to note here.