Exploration Systems Architecture Study
The Exploration Systems Architecture Study (ESAS) is the official title of a large-scale, system level study released by the
Scope
NASA Administrator Michael Griffin ordered a number of changes in the originally planned Crew Exploration Vehicle (now Orion MPCV) acquisition strategy designed by his predecessor Sean O'Keefe. Griffin's plans favored a design he had developed as part of a study for the Planetary Society, rather than the prior plans for a Crew Exploration Vehicle developed in parallel by two competing teams. These changes were proposed in an internal study called the Exploration Systems Architecture Study,[1] whose results were officially presented during a press conference held at NASA Headquarters in Washington, D.C., on September 19, 2005.
The ESAS included a number of recommendations for accelerating the development of the CEV and implementing
Originally slated for release as early as July 25, 2005, after the "Return to Flight" mission of Discovery, the release of the ESAS was delayed until September 19, reportedly due to poor reviews of the presentation of the plan and some resistance from the Office of Management and Budget.[2]
Shuttle based launch system
The initial CEV “procurement strategies” under Sean O’ Keefe would have seen two “phases” of CEV design. Proposals submitted in May 2005 were to be part of the Phase 1 portion of CEV design, which was to be followed by an orbital or suborbital fly-off of technology demonstrator spacecraft called FAST in 2008. Downselect to one contractor for Phase 2 of the program would have occurred later that year. First crewed flight of the CEV would not occur until as late as 2014. In the original plan favored by former NASA Administrator Sean O'Keefe, the CEV would launch on an
However, with the change of NASA Administrators, Mike Griffin did away with this schedule, viewing it as unacceptably slow, and moved directly to Phase 2 in early 2006. He commissioned the 60-day internal study for a re-review of the concepts—now known as the ESAS—which favored launching the CEV on a shuttle-derived launch vehicle. Additionally, Griffin planned to accelerate or otherwise change a number of aspects of the original plan that was released last year[when?]. Instead of a CEV fly-off in 2008, NASA would have moved to Phase 2 of the CEV program in 2006, with CEV flights to have commenced as early as June 2011.[citation needed]
The ESAS called for the development of two shuttle-derived launch vehicles to support the
The crew would be launched in the CEV atop a five-segment derivative of the Shuttle's
Cargo would be launched on a heavy-lift version of the Space Shuttle, which would be an "in-line" booster that would mount payloads on top of the booster. The in-line option originally featured five throw-away versions of the
The infrastructure at
CEV configuration
The ESAS recommended strategies for flying the crewed CEV by 2014, and endorsed a
The CEV re-entry module would weigh about 12 tons—almost twice the mass of the Apollo Command Module—and, like Apollo, would be attached to a service module for life support and propulsion (
Accelerated lunar mission development was slated to start by 2010, once the Shuttle retired. The Lunar Surface Access Module, which would later be known as Altair, and heavy-lift booster (Ares V) would be developed in parallel and would both be ready for flight by 2018. The eventual goal was to achieve a lunar landing by 2020, the Artemis Program is now targeting a lunar landing in 2024. The LSAM would be much larger than the Apollo Lunar Module and would be capable of carrying up to 23 tons of cargo to the lunar surface to support a lunar outpost.
Like the Apollo LM, the LSAM would include a descent stage for landing and an ascent stage for returning to orbit. The crew of four would ride in the ascent stage. The ascent stage would be powered by a
Lunar mission profile
The lunar mission profile was a combination of
Both the LSAM and the lunar CEV would carry a crew of four. The entire crew would descend to the lunar surface, leaving the CEV unoccupied.[5] After the time on the lunar surface had been spent, the crew would return to lunar orbit in the ascent stage of the LSAM. The LSAM would dock with the CEV. The crew would return to the CEV and jettison the LSAM, and then the CEV's engine would put the crew on a course for Earth. Then, much like Apollo, the service module would be jettisoned and the CEV would descend for a landing via a system of three parachutes.
Ultimately a
Extension to Mars
The use of scalable CEVs and a lander with methane-fueled engines meant that meaningful hardware testing for Mars missions could be done on the Moon. The eventual Mars missions would start to be planned in detail around 2020 and would include the use of Lunar ISRU and also be "conjunction-class", meaning that rather than doing a Venus flyby and spending 20–40 days on the Martian surface, the crew would go directly to Mars and back and spend about 500–600 days exploring Mars.
Costs
The ESAS estimated the cost of the crewed lunar program through 2025 to be $217 billion, only $7 billion more than NASA's current projected exploration budget through that time.
The ESAS proposal was originally said to be achievable using only existing NASA funding, without significant cuts to NASA's other programs, however, it soon became apparent that much more money was needed. Supporters of Constellation saw this as a justification for terminating the Shuttle program as soon as possible, and NASA implemented a plan to terminate support for both Shuttle and ISS in 2010. This was about 10 years earlier than planned for both programs, so must be considered a significant cut. This resulted in strong objections from the international partners that the US was not meeting its commitments, and concerns in Congress that the investment in ISS would be wasted.
Criticism
Beginning April 2006 there were some criticisms on the feasibility of the original ESAS study. These mostly revolved around the use of methane-oxygen fuel. NASA originally sought this combination because it could be "mined" in situ from lunar or martian soil – something that could be potentially useful on missions to these celestial bodies. However, the technology is relatively new and untested. It would add significant time to the project and significant weight to the system. In July, 2006, NASA responded to these criticisms by changing the plan to traditional rocket fuels (liquid hydrogen and oxygen for the LSAM and
However, the primary criticism of the ESAS was based on its estimates of safety and cost. The authors used the launch failure rate of the Titan III and IV as an estimate for the failure rate of the Delta IV heavy. The Titan combined a core stage derived from an early ICBM with large segmented solid fuel boosters and a hydrogen-fueled upper stage developed earlier. It was a complex vehicle and had a relatively high failure rate. In contrast, the Delta IV Heavy was a "clean sheet" design, still in service, which used only liquid propellant. Conversely, the failure rate of the Shuttle SRB was used to estimate the failure rate of the Ares I, however only launches subsequent to the loss of Challenger were considered, and each shuttle launch was considered to be two successful launches of the Ares even though the Shuttle SRBs do not include systems for guidance or roll control.
The Delta IV is currently launched from Cape Canaveral Air Force Station Complex 37, and the manufacturer, United Launch Alliance, had proposed launching human flights from there. However, in the estimation of costs, the ESAS assumed that all competing designs would have to be launched from Launch Complex 39, and that the Vehicle Assembly Building, Mobile launcher Platforms and pads A and B would have to be modified to accommodate them. The LC-39 facilities are much larger, more complex, older, and more expensive to maintain than the modern facilities at Complex 37 and are entirely inappropriate for the Delta, which is integrated horizontally and transported unfueled. This assumption was not justified in the report and greatly increased the estimated operational cost for the Delta IV. Finally, the decision in 2011 to add an uncrewed test of the Orion on a Delta IV clearly contradicts the ESAS conclusion that this was infeasible.
Review of United States Human Space Flight Plans Committee
The Review of United States Human Space Flight Plans Committee (also known as the HSF Committee, Augustine Commission, or Augustine Committee) was a group convened by
The Committee judged the 9-year old
The proposed "ultimate goal" for human space flight would appear to require two basic objectives: (1) physical sustainability and (2) economic sustainability. The Committee adds a third objective: to meet key national objectives. These might include international cooperation, developing new industries, energy independence, reducing climate change, national prestige, etc. Therefore, the ideal destination should contain resources such as water to sustain life (also providing oxygen for breathing, and hydrogen to combine with oxygen for rocket fuel), and precious and industrial metals and other resources that may be of value for space construction and perhaps in some cases worth returning to Earth (e.g., see asteroid mining).
See also
- Crew Exploration Vehicle
- Crew Space Transportation System
- Liquid Rocket Booster
- Reusable launch system
- Shuttle-derived vehicle
- Space Shuttle Solid Rocket Booster
References
- ^ "Crew Exploration Vehicle Procurement". NASA. Archived from the original on 2008-04-03. Retrieved 2008-03-26.
- ^ a b "NASA Studying Unmanned Solution to Complete Space Station as Return to Flight Costs Grow". spaceref.com. 24 July 2005. Retrieved 2008-03-26.
- ^ "NASA Plans to Build Two New Shuttle-derived Launch Vehicles". spaceref.com. July 2005. Retrieved 2008-03-26.[permanent dead link]
- ^ "Surface Landing Site Weather Analysis for NASA's Constellation Program" (PDF). Retrieved 2011-06-24.
- ^ "Remarks for AIAA Space 2005 Conference & Exhibition" (PDF). NASA. Archived from the original (PDF) on 2005-09-08. Retrieved 2008-03-26.
- ^ "NASA makes major design changes to CEV". nasaspaceflight.com. Archived from the original on 2008-02-03. Retrieved 2008-03-26.
External links
- NASA's Exploration Systems Architecture Study Archived 2016-10-04 at the Wayback Machine
- Official Constellation NASA Web Site
- Official Orion NASA Web Site
- Official Ares NASA Web Site Archived 2009-08-11 at the Wayback Machine
- White House: A Renewed Spirit of Discovery
- President's Commission on Implementation of United States Space Exploration Policy
- NASA: Exploration Systems
- Apollo 2.0: Moon Program on Drugs
- National Space Society
- NASA formally unveils lunar exploration architecture Archived 2005-12-02 at the Wayback Machine
- NASA Revives Apollo - While Starving Space Life Science
- Full Resolution Photos of NASA's New Spaceship
- ESAS Fact sheet
- ESAS Presentation
- Full ESAS report Archived 2007-11-20 at the Wayback Machine
- ESAS Appendix with launch vehicle configurations
- QuickTime animation
- Spacedaily on ESAS