Exploration Systems Architecture Study

The Exploration Systems Architecture Study (ESAS) is the official title of a large-scale, system level study released by the National Aeronautics and Space Administration (NASA) in November 2005 in response to American president George W. Bush

George W. Bush

George Walker Bush is an American politician who served as the 43rd President of the United States, from 2001 to 2009. Before that, he was the 46th Governor of Texas, having served from 1995 to 2000....

's announcement on January 14, 2004 of his goal of returning astronauts to the Moon

Moon

The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

and eventually Mars

Mars

Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...

— known as the Vision for Space Exploration

Vision for Space Exploration

The Vision for Space Exploration is the United States space policy which was announced on January 14, 2004 by President George W. Bush. It is seen as a response to the Space Shuttle Columbia disaster, the state of human spaceflight at NASA, and a way to regain public enthusiasm for space...

(and unofficially as "Moon, Mars and Beyond" in some aerospace circles, though the specifics of a manned "beyond" programme remain vague).

Scope

Recent (2005–2009) NASA Administrator Michael Griffin

Michael D. Griffin

Michael Douglas Griffin is an American physicist and aerospace engineer. From April 13, 2005 to January 20, 2009 he served as Administrator of NASA, the space agency of the United States...

ordered a number of changes in the originally planned Crew Exploration Vehicle

Crew Exploration Vehicle

The Crew Exploration Vehicle was the conceptual component of the U.S. NASA Vision for Space Exploration that later became known as the Orion spacecraft...

(CEV) acquisition strategy designed by his predecessor Sean O'Keefe

Sean O'Keefe

Sean O'Keefe is the CEO of EADS North America, a subsidiary of the European aerospace firm EADS, a former Administrator of NASA, and former chancellor of Louisiana State University . O'Keefe is also a former member of the board of directors of DuPont...

. 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

Crew Exploration Vehicle

The Crew Exploration Vehicle was the conceptual component of the U.S. NASA Vision for Space Exploration that later became known as the Orion spacecraft...

developed in parallel by two competing teams. These changes were proposed in an internal study called the Exploration Systems Architecture Study, whose results were officially presented during a press conference held at NASA Headquarters in Washington, D.C.

Washington, D.C.

Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....

on September 19, 2005.

The ESAS includes a number of recommendations for accelerating the development of the CEV and implementing Project Constellation

Project Constellation

Constellation Program is a human spaceflight program within NASA, the space agency of the United States. The stated goals of the program were to gain significant experience in operating away from Earth's environment, develop technologies needed for opening the space frontier, and conduct...

, including strategies for flying manned CEV flights as early as 2012 (now pushed back to at least 2015) and methods for servicing the International Space Station

International Space Station

The International Space Station is a habitable, artificial satellite in low Earth orbit. The ISS follows the Salyut, Almaz, Cosmos, Skylab, and Mir space stations, as the 11th space station launched, not including the Genesis I and II prototypes...

(ISS) without the use of the Space Shuttle

Space Shuttle

The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...

, using cargo versions of the CEV.

Originally slated for release as early as July 25, 2005, after the "Return to Flight" mission of Discovery

Space Shuttle Discovery

Space Shuttle Discovery is one of the retired orbiters of the Space Shuttle program of NASA, the space agency of the United States, and was operational from its maiden flight, STS-41-D on August 30, 1984, until its final landing during STS-133 on March 9, 2011...

, 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.

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 manned 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 Evolved Expendable Launch Vehicle (EELV), namely the Boeing

Boeing

The Boeing Company is an American multinational aerospace and defense corporation, founded in 1916 by William E. Boeing in Seattle, Washington. Boeing has expanded over the years, merging with McDonnell Douglas in 1997. Boeing Corporate headquarters has been in Chicago, Illinois since 2001...

Delta IV

Delta IV rocket

Delta IV is an active expendable launch system in the Delta rocket family. Delta IV uses rockets designed by Boeing's Integrated Defense Systems division and built in the United Launch Alliance facility in Decatur, Alabama. Final assembly is completed at the launch site by ULA...

Heavy or Lockheed Martin

Lockheed Martin

Lockheed Martin is an American global aerospace, defense, security, and advanced technology company with worldwide interests. It was formed by the merger of Lockheed Corporation with Martin Marietta in March 1995. It is headquartered in Bethesda, Maryland, in the Washington Metropolitan Area....

Atlas V

Atlas V is an active expendable launch system in the Atlas rocket family. Atlas V was formerly operated by Lockheed Martin, and is now operated by the Lockheed Martin-Boeing joint venture United Launch Alliance...

Heavy EELVs.

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. 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.

The ESAS called for the development of two shuttle-derived launch vehicles to support Project Constellation; one derived from the space shuttle’s solid rocket booster

Space Shuttle Solid Rocket Booster

The Space Shuttle Solid Rocket Boosters were the pair of large solid rockets used by the United States' NASA Space Shuttle during the first two minutes of powered flight. Together they provided about 83% of liftoff thrust for the Space Shuttle. They were located on either side of the rusty or...

(SRB) to launch the CEV, and an in-line heavy-lift vehicle using SRBs and the shuttle’s external tank

Space Shuttle external tank

A Space Shuttle External Tank is the component of the Space Shuttle launch vehicle that contains the liquid hydrogen fuel and liquid oxygen oxidizer. During lift-off and ascent it supplies the fuel and oxidizer under pressure to the three Space Shuttle Main Engines in the orbiter...

to launch the Earth Departure Stage and Lunar Surface Access Module. The performance of the Cargo Shuttle Derived Launch Vehicle (SDLV) would be 125 to 130 metric tons to Low Earth Orbit

Low Earth orbit

A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...

(LEO). An SDLV would allow a much greater payload per launch than an EELV option.

The crews that would be launched in the CEV atop a five-segment derivative of the Shuttle's Solid Rocket Booster and a new liquid-propellant upper stage based on the Shuttle's External Tank. Originally to be powered by a single, throw-away version of the Space Shuttle Main Engine

Space Shuttle main engine

The RS-25, otherwise known as the Space Shuttle Main Engine , is a reusable liquid-fuel rocket engine built by Pratt & Whitney Rocketdyne for the Space Shuttle, running on liquid hydrogen and oxygen. Each Space Shuttle was propelled by three SSMEs mated to one powerhead...

, it was later changed (as noted on a space.com article dated on January 20, 2006) to a modernized and uprated version of the J-2

J-2 (rocket engine)

Rocketdyne's J-2 rocket engine was a major component of the Saturn V rocket used in the Apollo program to send men to the Moon. Five J-2 engines were used on the S-II second stage, and one J-2 was used on the S-IVB third stage. The S-IVB was also used as the second stage of the smaller Saturn IB...

rocket engine (known as the J-2X) used on the S-IVB

S-IVB

The S-IVB was built by the Douglas Aircraft Company and served as the third stage on the Saturn V and second stage on the Saturn IB. It had one J-2 engine...

upper stages used on the Saturn IB

Saturn IB

The Saturn IB was an American launch vehicle commissioned by the National Aeronautics and Space Administration for use in the Apollo program...

and Saturn V

Saturn V

The Saturn V was an American human-rated expendable rocket used by NASA's Apollo and Skylab programs from 1967 until 1973. A multistage liquid-fueled launch vehicle, NASA launched 13 Saturn Vs from the Kennedy Space Center, Florida with no loss of crew or payload...

rockets. This booster would be capable of placing up to 25 tons into low Earth orbit. The booster would use components that have already been man-rated.

Cargo would be launched on a heavy-lift version of the Space Shuttle, which would be an "in-line" booster which would mount payloads on top of the booster. The in-line option originally featured five throw-away versions of the SSMEs on the core stage, but was changed later to five RS-68

RS-68 (rocket engine)

The Pratt & Whitney Rocketdyne RS-68 is a liquid-fuel rocket engine that burns liquid hydrogen with liquid oxygen . It is the largest hydrogen-fueled engine in the world. Development of the engine started in the 1990s with the goal of producing a simpler, less-costly, heavy-lift engine for the...

rocket engines (currently in use on the Delta IV rocket), with higher thrust and lower costs, which required a slight increase in the overall diameter of the core. Two enlarged five-segment SRBs would help the RS-68 engines propel the rocket's second stage, known as the Earth Departure Stage

Earth Departure Stage

The Ares V Earth Departure Stage was a rocket stage which NASA planned to design at its Marshall Space Flight Center in Huntsville, Alabama as part of Project Constellation...

(EDS), and payload into LEO. It could lift about 125 tons to LEO, and is estimated to cost $540 million per launch.

Therefore, the infrastructure at Kennedy Space Center, including the Vehicle Assembly Building

Vehicle Assembly Building

The Vehicle Assembly Building, or VAB, at NASA's Kennedy Space Center was used to assemble and house American manned launch vehicles from 1968-2011. It is the fourth largest building in the world by volume...

(VAB) and Shuttle launch pads LC-39A and 39B would be maintained and adapted to the needs of the future giant launch vehicle, with an option of constructing two new pads (LC-39C & LC-39D) or resurrecting the former LC-34 or LC-37A pads at the nearby Cape Canaveral Air Force Station

Cape Canaveral Air Force Station

Cape Canaveral Air Force Station is an installation of the United States Air Force Space Command's 45th Space Wing, headquartered at nearby Patrick Air Force Base. Located on Cape Canaveral in the state of Florida, CCAFS is the primary launch head of America's Eastern Range with four launch pads...

used by the Saturn IB for the early Apollo earth orbital missions.

CEV configuration

The ESAS recommends strategies for flying the manned CEV by 2014, and endorses a Lunar Orbit Rendezvous

Lunar orbit rendezvous

Lunar orbit rendezvous is a key concept for human landing on the Moon and returning to Earth.In a LOR mission a main spacecraft and a smaller lunar module travel together into lunar orbit. The lunar module then independently descends to the lunar surface. After completion of the mission there, a...

approach to the Moon. The LEO versions of the CEV would carry crews four to six to the ISS. The lunar version of the CEV would carry a crew of four and the Mars CEV would carry six. Cargo could also be carried aboard an unmanned version CEV, similar to the Russian Progress cargo ships. The contractor for the CEV will be Lockheed Martin

Lockheed Martin

, which was selected by NASA in September, 2006 and is the current contractor for the Space Shuttle's External Tank and the Atlas V EELV.

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. The CEV will be an Apollo-like capsule, with a Viking

Viking program

The Viking program consisted of a pair of American space probes sent to Mars, Viking 1 and Viking 2. Each spacecraft was composed of two main parts, an orbiter designed to photograph the surface of Mars from orbit, and a lander designed to study the planet from the surface...

-type heat shield

Heat shield

A heat shield is designed to shield a substance from absorbing excessive heat from an outside source by either dissipating, reflecting or simply absorbing the heat...

, not a lifting body

Lifting body

A lifting body is a fixed-wing aircraft configuration in which the body itself produces lift. In contrast to a flying wing, which is a wing with minimal or no conventional fuselage, a lifting body can be thought of as a fuselage with little or no conventional wing...

or wing

Wing

A wing is an appendage with a surface that produces lift for flight or propulsion through the atmosphere, or through another gaseous or liquid fluid...

ed vehicle like the current Shuttle. It would land on land rather than water, similar to the Russia

Russia

Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

n Soyuz spacecraft

Soyuz spacecraft

Soyuz , Union) is a series of spacecraft initially designed for the Soviet space programme by the Korolyov Design Bureau in the 1960s, and still in service today...

, though it would be capable of a water recovery if an emergency splashdown were needed. Possible landing areas that have been identified include Edwards Air Force Base

Edwards Air Force Base

Edwards Air Force Base is a United States Air Force base located on the border of Kern County, Los Angeles County, and San Bernardino County, California, in the Antelope Valley. It is southwest of the central business district of North Edwards, California and due east of Rosamond.It is named in...

, California, Carson Flats (Carson Sink

Carson Sink

Carson Sink is a playa in the northeastern portion of the Carson Desert that was formerly the terminus of the Carson River. The sink is currently fed by drainage canals of the Truckee-Carson Irrigation District...

), Nevada, and the area around Moses Lake, Washington

Moses Lake, Washington

Moses Lake is a city in Grant County, Washington, United States. The population was 20,366 as of the 2010 census. Moses Lake is the largest city in Grant County.-Background:...

state. Landing on the west coast would allow the majority of the reentry path to be flown over the Pacific Ocean

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

rather than populated areas. The CEV would have an ablative (Apollo-like) heat shield that would be discarded after each use, and the CEV itself could be reused about 10 times.

Accelerated lunar mission development is slated to start by 2010, once the Shuttle is retired. The Lunar Surface Access Module (LSAM) and heavy-lift boosters would be developed in parallel and would both be ready for flight by 2018. The eventual goal is to achieve a lunar landing by 2020. The LSAM would be much larger than the Apollo Lunar Module

Apollo Lunar Module

The Apollo Lunar Module was the lander portion of the Apollo spacecraft built for the US Apollo program by Grumman to carry a crew of two from lunar orbit to the surface and back...

and would be capable of carrying up to 23 tons of cargo to the lunar surface to support a lunar outpost. This weight in cargo is greater than the mass of the entire Apollo Lunar Module (LM).

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 methane

Methane

Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...

/oxygen

Oxygen

Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

fuel for return to lunar orbit (later changed to liquid hydrogen and liquid oxygen, due to the infancy of oxygen/methane rocket propulsion). This would allow a derivative of the same lander to be used on later Mars missions, where methane propellant can be manufactured from the Martian soil in a process known as In-Situ Resource Utilization

In-Situ Resource Utilization

In space exploration, in-situ resource utilization describes the proposed use of resources found or manufactured on other astronomical objects to further the goals of a space mission....

(ISRU). The LSAM would support the crew of four on the lunar surface for about a week and use advanced roving vehicles to explore the lunar surface. The huge amount of cargo carried by the LSAM would be extremely beneficial for supporting a lunar base and for bringing large amounts of scientific equipment to the lunar surface.

Lunar mission profile

The lunar mission profile will be a combination of earth orbit rendezvous

Earth orbit rendezvous

Earth orbit rendezvous is a type of space rendezvous and a spaceflight methodology most notable for enabling round trip human missions to the moon...

and lunar orbit rendezvous

Lunar orbit rendezvous

(LOR) approach. First, the LSAM and the EDS will be launched atop the heavy-lift, Shuttle-derived vehicle. The EDS would be a derivative of the S-IVB

S-IVB

The S-IVB was built by the Douglas Aircraft Company and served as the third stage on the Saturn V and second stage on the Saturn IB. It had one J-2 engine...

upper stage used on the Saturn V

Saturn V

rocket and will use a single J-2X engine similar to that used on the SRB-derived booster (originally two J-2X engines were to be used, but the RS-68 engines for the core stage will allow NASA to only use one). The crew will then be launched in the CEV on the SRB-derived booster, and the CEV and LSAM will dock in Earth orbit. The EDS will then send the complex to the Moon. The LSAM will brake the complex into lunar orbit (similar to the Block D

Block D

Blok D is an upper stage used on Soviet and later Russian expendable launch systems, including the N1, Proton-K and Zenit. There were plans to use it for some other rockets as well ....

rocket on the failed Soviet moonshot

Soviet Moonshot

The Soviet manned lunar programs were a series of programs pursued by the Soviet Union to land a man on the Moon in competition with the United States Apollo program to achieve the same goal set publicly by President John F. Kennedy on May 25, 1961...

attempt in the 1960s and 1970s), where four astronauts will board the LSAM for descent to the lunar surface for a week of exploration. Part of the LSAM could be left behind with cargo to begin establishment of a long-term outpost.

The article says that both the LSAM and the lunar CEV would carry a crew of four. Griffin has subsequently stated that the entire crew would descend to the lunar surface, leaving the CEV unoccupied. After the time on the lunar surface has 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. Two parachutes are enough for landing (although in the western United States rather than the Ocean). The article says that the ESAS contains a recommendation for at least two missions to the moon each year, starting no later than 2018.

Ultimately a base would be built, possibly near the Moon's south pole. But this decision has not yet been taken and might depend on potential international and commercial participation to the exploration project.

Extension to Mars

The use of scalable CEVs and a lander with methane-fueled engines means that meaningful hardware testing for Mars missions could be done on the Moon (though these have since been changed to hydrogen/LOX, losing commonality). 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

Venus

Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus, the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows...

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 estimates the cost of the manned lunar program through 2025 to be $217 billion, only $7 billion more than NASA's current projected exploration budget through that time. This estimate may be high because it includes the cost of developing a new engine for the EDS, whereas the current plan is to use a J-2 derivative.

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 hypergolics for the CEV). This has reduced the weight and shortened the project's timeframe.

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 form 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. Since 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.

External links

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