The Planetary Society today released a study that calls for the planned Crew Exploration Vehicle (CEV) to be built in two steps - the first allowing completion of the International Space Station (ISS) core assembly and retirement of the shuttle, the second permitting human space transportation beyond Earth orbit.
The report, "Extending Human Presence into the Solar System," outlines a strategy for the proposed U.S. Space Exploration policy and was drafted by an independent study group chaired by former astronaut Owen Garriott and aerospace veteran Mike Griffin and convened by The Planetary Society.
The CEV would be launched on a new human-rated vehicle based on the existing shuttle solid rocket motor (SRM), augmented with a new liquid oxygen (LOX)-hydrogen upper stage. Such a system could be available by 2010, allowing the shuttle orbiter to be retired as planned. If ISS assembly has not been completed by that date, the remaining international modules can be deployed on the heavy-lift launch vehicle (HLLV) that must be developed to support the proposed exploration initiative, or on suitable international vehicles such as Ariane or Proton. The study group supported the use of foreign launch vehicles in the space station assembly.
"The Planetary Society has put forward a human space exploration plan with regular, significant, and publicly appealing milestones," said Griffin, "while at the same time respecting the political and programmatic constraints inherited from the past and the fiscal constraints likely to exist in the future."
The group considered the entire architecture for a Moon-Mars program and estimated its cost, stating, "A Mars Exploration Program starting in 2014, launching a first mission in 2024 and a mission every 26 months thereafter through 2044, is estimated to have a total cost of no more than $129 billion over that period, or about $4.3 billion per year."
Louis Friedman, Executive Director of The Planetary Society, stated, "That is less than the current year-by-year cost of the shuttle program."
The study recommends a three-stage strategy to send humans to the Moon and Mars:
Stage 1 would establish Earth orbital capabilities with a new CEV capable of carrying four to six persons to and from low-Earth orbit (LEO), including the ISS, by 2010. It requires an appropriate launch vehicle, which could be based on a single SRM augmented with a new LOX-hydrogen upper stage. With this system in place, and with the agreement of the international partners, the shuttle orbiter could be retired after ISS assembly reaches the milestone "U.S. Core Complete."
Stage 2 of the exploration program should focus on robotic missions to interesting destinations within the solar system, such as the Moon, near-Earth objects, the Lagrange points, and Mars, including the Martian moons Deimos and Phobos. Each of these locations offers the potential of fascinating scientific return and broad public interest, while remaining within reasonable fiscal bounds.
Stage 3 would encompass human landings on the Moon and Mars.
Wesley T. Huntress, Jr., President of The Planetary Society, thanked the independent study group, "The report outlines bold, innovative steps that must be taken to enable the new vision for human space flight." He added, "The recommended strategy is also resilient to inevitable schedule delays and technical problems."
The study report cites the need to retire the shuttle by 2010 or 2011, after reaching the "U.S. Core Complete" stage with the space station. To continue using the shuttle until ISS is totally completed would take more than 20 additional flights, which would stretch the program too far. The report also strongly endorses international cooperation in the new Moon-Mars program.
"The proposed US exploration policy was developed without any international or broad political input," notes Friedman. "But all of the international partners share the space transportation problems, most specifically completing the assembly of the space station. Beyond that, China and India have joined the US, Europe and Japan in planning lunar exploration."
The study group recommended that the heavy-lift launch vehicle (developed in Stage 2) be a design that utilizes existing space shuttle components (e.g., the solid rocket motor and external tank). Some proposed Shuttle-derived HLLVs could have a payload capacity in excess of 100 metric tons and offer a near-term approach to meeting exploration requirements with a minimum of non-recurring investment.
The Planetary Society commissioned the study as part of its support for the proposed re-direction of the human spaceflight program to exploration beyond Earth orbit. The Society has also commissioned two other studies: one on how Russia would approach the Moon-Mars strategy, conducted by Russian aerospace organizations; and a second on a specific first step preparing for a Mars Outpost- an International Lunar Way-Station.
The Society is conducting the Aim For Mars! Campaign to encourage public support of the proposed policy: The studies commissioned by the Society are part of this campaign.