According to a February 27, 2014 story in Space News, the House Science Committee held a hearing discussing the possibility of an interplanetary flyby mission of both Venus and Mars with a launch in 2021. The consensus of the four witnesses, which included former NASA officials, was that the project was feasible, but would be risky and likely expensive. The 2021 date is a hard date because of the alignment of the planets.
However, Scott Pace, one of the witnesses and the Director of Space Policy Institute at the Elliott School of International Affairs, George Washington University, attempted to place a Mars/Venus flyby mission in the context of an overall space exploration plan for the 21st Century. In his written testimony he suggested the following timeline:
“International Space Station -- continue to 2024 and possibly beyond
Mars Flyby with crew -‐ 2021
Cis lunar operations – mid-‐2020s, building up as ISS operations ramp down
Human lunar landing – late 2020s, lander development after SLS completed
Human missions to an asteroid, Mars orbit – 2030s
Mars Expedition to the surface – late 2030s
Human mission to the moons of Jupiter and Saturn – 2040s?”
The interesting thing about this timeline is that Pace, who is often on a short list to be NASA administrator in a future Republican administration, is a warm advocate of a return to the moon. But even he finds the idea of a Mars/Venus flyby mission so attractive, he suggests pursuing the mission before returning to a campaign to return to and explore the moon.
If the Mars/Venus flyby mission were to be undertaken, it would be the riskiest, most spectacular thing that NASA has ever attempted, even including the moon landings. It would be an obvious leadin to going back to the moon, save as a stress test for life support and anti radiation technology. However the psychological significance of such a mission cannot be underestimated. If successful it would reestablish the United States as the preeminent space power and boost American pride in advance of a new age of space exploration.