Because we want to launch our spacecraft during Mars opposition, and Mars opposition happens every 2 years + 2 months. A Hohmann transfer orbit also determines a fixed time required to travel between the starting and destination points; for an Earth-Mars journey this travel time is about 9 months. The first ideas a spacecraft traveling between Earth and Mars are nearly a century old. The Hohmann transfer orbit, as it came to be known, relies on Earth and Mars to be in the right positions relative to each other so that a spacecraft in a Hohmann orbit. Phase 4b: Mars Human Landing Missions Ends with testing, research and demos complete* Asteroid RedirectCrewed Mission Marks Move from Phase 1 to Phase 2 Ends with one year crewed Mars-class shakedown cruise Today Mid-2020s 2030 * There are several other … In 1925 Walter Hohmann proposed an elliptical orbit between the two worlds. Artificial gravity (AG) Mars transfer vehicle (MTV) concepts are presented that utilize both conventional NTR, as well as, enhanced “bimodal” nuclear thermal rocket (BNTR) propulsion. The model is based on empirical data for astronauts, consumables, and spacecraft components. When transfer is performed between orbits close to celestial bodies with significant gravitation, much less delta-v is usually required, as Oberth effect may be employed for the burns. The reason to launch a mission to Mars during opposition is pretty obvious – this is the time when Earth is nearest to Mars. The Hohmann transfer is known as a two-impulse transfer because it consists of two primary bursts of propulsion: once in the departure orbit to set the spacecraft on its way, and once at the destination to match orbits with the target; the remainder of the transit time is primarily spent coasting, apart from occasional corrective maneuvers. Now we know how Elon Musk plans to get 1 million people to Mars.. At a conference in Mexico today (Sept. 27), the SpaceX founder and CEO unveiled the … This paper presents a parametric design model and a design study for a crew transfer vehicle designed to transfer humans between Earth or Mars and a spacecraft on a cyclic Earth–Mars trajectory. Deep Space Transport (DST) and Mars Mission Architecture John Connolly NASA Mars Study Capability Team October 17 2017. SpaceX's Starship spacecraft and Super Heavy rocket (collectively referred to as Starship) represent a fully reusable transportation system designed to carry both crew and cargo to Earth orbit, the Moon, Mars and beyond. The NTR is a proven technology that generates high thrust and has a specific impulse (I sp) capability of ~900 s – twice that of today’s best chemical rockets.