Crew Exploration Vehicle

From Free net encyclopedia

Image:Mergefrom.gif It has been suggested that Orbital Space Plane be merged into this article or section. ([[{{{2|: talk:Crew_Exploration_Vehicle}}}|Discuss]])
Image:Cev with lander.jpg

Image:Cev landing.jpg Image:Cev rockets.jpg The Crew Exploration Vehicle is NASA's proposed series of human spaceflight spacecraft, intended to supersede the space shuttle system. Together with the Earth Departure Stage, the Lunar Surface Access Module, and the associated launch infrastructure, the CEV is one of the elements of Project Constellation. There is a report that the CEV has been christened Altair<ref name="Altair">Template:Cite web</ref> — named after a variable double star in the constellation Aquila (see Nomenclature below).

Contents

[edit]

Origin

The proposal to create the CEV is partly a reaction to the Space Shuttle Columbia disaster, the Columbia Accident Investigation Board report and the White House's review of the American space program; the CEV replaces the Orbital Space Plane program.

On January 14 2004, President George W. Bush announced the CEV as part of the Vision for Space Exploration:

"Our second goal is to develop and test a new spacecraft, the Crew Exploration Vehicle, by 2008, and to conduct the first manned mission no later than 2014. The Crew Exploration Vehicle will be capable of ferrying astronauts and scientists to the Space Station after the shuttle is retired. But the main purpose of this spacecraft will be to carry astronauts beyond our orbit to other worlds. This will be the first spacecraft of its kind since the Apollo Command Module."
[edit]

Design

The CEV Crew & Service Modules (CSM) consists of two main parts--a conical crew module shaped similarly to the Apollo Command Module and capable of holding three to six crew members, and a cylindrical service module which will hold the spacecraft's onboard supplies. The CSM will be built on the designs of the Apollo CSM, but with the technologies introduced on the Space Shuttle in the past 25 years of operation.

Such technologies will include, but are not limited to: the "glass cockpit" technologies; improved waste management (the use of a minaturized camping-style toilet instead of plastic bags for fecal disposal, and a unisex "relief tube" for urine elimination); and an oxygen-nitrogen atmosphere at sea level or slightly reduced pressure instead of a pure oxygen atmosphere, the latter being extremely flammable as was the case in the Apollo 1 fire.

The main feature that will be introduced in the new crew module will be a new recovery system that will employ the use of a combination of parachutes and airbags for capsule recovery. This will allow retrieval of the CEV crew module on land, like the Soyuz descent module, and eliminate the expensive naval recovery fleet employed on Mercury, Gemini and Apollo.

Another feature will be the partial reusability of the CEV crew module. Each crew module will be able to be reused for up to 10 flights, thus allowing NASA to construct a fleet of CEVs like that of the current Shuttle fleet. To allow the CEV to service the International Space Station, it will use a simplified version of the Russian-developed docking ring currently in use on the remaining Shuttle fleet, but with the ability of being discarded upon the ending of the mission. The docking adapter will be covered over with a Launch Escape System identical in design to that found on the Apollo spacecraft.

The CEV service module is identical in shape (but not in size) to its Apollo predecessor, but unlike the Apollo SM, the new CEV SM, which will be shorter in height, will feature a pair of deployable Soyuz-like solar panels, eliminating the need to carry fuel cells and hydrogen tanks. Instead, the new SM will have tanks containing liquid oxygen (LOX) and liquid methane (LCH4), the latter being the fuel for both the onboard service propulsion system and reaction control system.

The choice of liquid methane was simple: 1. It eliminates the hazards associated with the use of hypergolic system similar to that found on Apollo and the Shuttle, and 2. it can be mined on methane-rich bodies such as Mars, Titan, Pluto, and most of the trans-Neptunian objects in the Kuiper Belt. Also, liquid methane, which can be produced with normal liquified natural gas (LNG) methods, is cheaper to store on site and can be transported with normal transportation methods (trucks, trains, ships, or even by pipeline), while hypergolics require special hazmat permits.

The CEV crew/service module will be launched into low earth orbit using a new Crew Launch Vehicle (CLV). This Shuttle Derived Launch Vehicle (SDLV), based mostly on the solid rocket boosters (SRBs) and external tank (ET) of the Shuttle, will consist of a solid-fueled first stage, using a five-segment booster instead of the current four-segment version, with the second stage being a liquid-fueled upper stage using LOX and liquid hydrogen (LH2) and powered by an uprated Apollo J-2 engine (the Shuttle's main engine was originally proposed, but an air-startable engine was never produced or tested while the Saturn-based J-2 was designed from the beginning to start in mid-air).

An unmanned version, using a pressurized crew module stripped of all crew-required equipment, can be used for resupply mission to the ISS in a fashion similar to that of the Progress supply ships in current use, with old scientific and engineering equipment being sent back to Earth for ground analysis (the Progress spacecraft cannot do this as the entire ship burns up in the atmosphere).

[edit]

Exploration Systems Architecture Study

For details of this NASA system activity conducted during the summer of 2005, see Exploration Systems Architecture Study

[edit]

Competition

Image:CEV Lockheed Martin.jpg Image:A-northrop.jpg

The Draft Statement of Work for the CEV was issued by NASA on December 9, 2004, and slightly more than one month later, on January 21, 2005, NASA issued a Draft Request For Proposal. The Final RFP was issued on March 1, 2005, with the potential bidders being asked to answer by May 2, 2005.

NASA had planned to have a suborbital or an Earth orbit fly-off called Flight Application of Spacecraft Technologies between two teams' CEV designs before September 1, 2008. However, Administrator Griffin has indicated that NASA will select one contractor for the CEV in 2006 to permit an earlier date for the start of CEV operations. He states that this will both help eliminate the currently planned four-year gap between the retirement of the Shuttle in 2010 and the first manned flight of the CEV in 2014 (by allowing the CEV to fly earlier), and save over $1 billion for use in CEV development. [1]

On June 13, 2005, NASA announced the selection of two consortia, Lockheed Martin Corp. and the team of Northrop Grumman Corp. and The Boeing Co. for further CEV development work. Each team has received a $28 million contract to come up with a complete design for the CEV and its launch vehicle until early 2006, when NASA will award one of them the task of building the CEV. The teams will also have to develop a plan for their CEV to take part in the assembly of a lunar expedition, either in EOR, LOR, or in a direct mode. The two teams are composed of:

Another announced team was t/Space, a consortium including such groups as Burt Rutan's Scaled Composites, Elon Musk's SpaceX, and Red Whittaker[2] of the Carnegie Mellon Robotics Institute. Some news reports in mid-March 2005, stemming from an interview with New Scientist had reported that t/Space intended to withdraw from the competition, citing a high paperwork burden; however, no announcement of a withdrawal had been made by t/Space. NASA has not gone public about who did finally submit a bid. Therefore, either t/Space did not submit a bid, or its bid was not selected by NASA.

Each contractor-led team will include subcontractors that will provide the lunar expedition astronauts with equipment, life support, rocket engines and onboard navigation systems. The planned orbital or suborbital fly-offs under FAST would have seen the competition of a CEV built by each team, or of a technology demonstrator incorporating CEV technologies [3]. Under FAST, NASA would have chosen the winner to build the final CEV after actual demonstration of this hardware. Fly-offs are often used by the U.S. Air Force to select military aircraft; NASA has never used this approach in awarding contracts. However, as Administrator Griffin has indicated he will abandon the FAST approach, it is likely NASA will pursue the more traditional approach of selecting a vehicle based on the contractors' proposals.

[edit]

Proposals

Image:Boeing-CEV-Concept.jpg

[edit]

Original designs

Lockheed's proposed craft was a small shuttle-shaped lifting-body design, big enough for six astronauts and their equipment. Its airplane-shaped design makes it easier to navigate during high-speed returns to Earth than the capsule-shaped vehicles of the past, according to Lockheed Martin. According to the French daily Le Figaro and the publication Aviation Week and Space Technology, EADS SPACE Transportation would be in charge of the design and construction of the associated Mission Module. The head of the Lockheed team is Cleon Lacefield. The Lockheed Martin design is quite similar to their OSP design, but has some slight changes, mainly the presence of the mission module.

The Lockheed Martin CEV design included several modules in the LEO (low earth orbit) and manned lunar versions of the spacecraft, plus an abort system. The abort system is an escape tower like that used in the Mercury, Apollo, Soyuz, and Shenzhou craft (Gemini, along with the Space Shuttles Enterprise and Columbia [until STS-4] used ejection seats). It would be capable of an abort during any part of the ascent phase of the mission. The crew would sit in the Rescue Module (RM) during launch. According to the publication Aviation Week and Space Technology, the RM would have an outer heat shield of reinforced carbon-carbon and a redundant layer of felt reusable surface insulation underneath in case of RCC failure. The RM comprises the top half of the Crew Module (CM), which comprises the RM and the rest of the lifting-body structure. The CM includes living space for four crewmembers. In an emergency the RM separates from the rest of the CM. The RM would seat up to six crewmembers, with two to a row, and the CM has living space and provisions for four astronauts for 5–7 days. EVAs could be conducted from the CM, which could land on land or water and could be reused 5–10 times.[4]

The mission module would be added to the bottom of the CEV for a lunar mission, and would be able to hold extra consumables and provide extra space for a mission of lunar duration. It would also provide extra power and communications capabilities, and include a docking port for the LSAM. On the bottom of the lunar CEV stack would be the Propulsion or Trans-Earth Injection Module would provide for return to Earth from the Moon. It would probably incorporate (according to Aviation Week) 2 Pratt & Whitney RL-10 engines. Together, the RM/CM, MM, and TEIM make up the Lockheed Martin lunar stack. The original idea was to launch the CM, MM, and TEIM on three separate EELVs, with one component in each launch. This vehicle would need additional modules to reach lunar orbit and to land on the Moon. However, this plan will be altered according to the CFI (Call for Improvements), described below.

Unlike the well-publicized Lockheed Martin CEV design, virtually no information is publicly available on the Boeing/Northrop Grumman CEV design. However, it is instructive to note that most publicly released Boeing designs for the cancelled Orbital Space Plane resembled the Apollo capsule. Lockheed Martin's CEV design is in many ways a derivative of their OSP [5]; therefore it is possible that the Boeing CEV is a capsule rather than a lifting body or plane design. [6]

[edit]

Changes to original bids

Sean O'Keefe's strategy would have seen the CEV development in two distinct stages, or Phases. Phase I would have involved the design of the CEV and a demonstration by the potential contractors that they could safely and affordably develop the vehicle. Phase I would have run from bid submissions in 2005 to FAST and downselect to one contractor. Phase II would have begun after FAST and involved final design and construction of the CEV. However, this schedule is unacceptably slow to Mike Griffin, and the current plan is that NASA will issue a "Call for Improvements" (CFI) after the release of the ESAS for Lockheed Martin and Boeing to submit Phase II proposals. [7] NASA will choose the winning consortium in August 2006.[8] [9] Therefore, the CEV bids already submitted and described here are not necessarily representative of the final CEV design, as they will be changed in accordance with the CFI and any findings of the ESAS that are put into the CFI. For example, as described above, the ESAS recommends an Apollo-like capsule for the CEV, which would necessitate major changes to the Lockheed Martin proposal.

[edit]

Spiral development and schedule

Under Administrator Sean O'Keefe, NASA planned to acquire the CEV in the style of United States Department of Defense procurements, by first conducting the FAST fly-off competition, and by designing the CEV ships in a series of "spirals." These spirals were announced as:

  • Exploration Spiral One (CEV Earth Orbit Capability). By 2014, Spiral 1 equipment will test crew transportation elements in Low Earth Orbit, in preparation for human missions to the Moon. As new elements are developed, they will be tested in space with the Spiral 1 CEV.
  • Exploration Spiral Two (Extended Lunar Exploration). By 2015 or 2020, Spiral 2 gear will put humans on the Moon for at least four days.
  • Exploration Spiral Three (Long Duration Lunar Exploration). After 2020, Spiral 3 gear will allow routine human long-duration missions on the surface of the Moon to test out technologies and operational techniques for sending humans to Mars and beyond. Missions in Spiral 3 will last up to several months, serving as an operational analog of short-stay Mars missions.
  • Exploration Spiral Four (Crew Transportation System Mars Flyby). After 2020, (by 2032 [10]) Spiral 4 gear will allow a Mars flyby mission using elements of the Human-Mars Crew Transportation System.
  • Exploration Spiral Five (Human Mars Surface Campaign). After 2020, (by 2034 [11]) Spiral 5 gear will send humans to Mars.

However, after the appointment of Administrator Michael Griffin and a reshuffling of upper-level management personnel, it is now clear that neither the FAST competition nor the spiral development schedule will be followed. In testimony to the House Science Committee on 28 June 2005, Griffin stated,

"You asked, what we will be doing different? First of all, I hope never again to let the words spiral development cross my lips. That is an approach to acquisition for large systems very relevant to DoD acquisition requirements, but I have not seen the relevance to NASA and I have preferred a much more direct approach, and that is what we will be recommending and implementing."

He later said,

"What else will be different? I hope that you will see, as we bring it forward, a very straightforward plan to replace the shuttle and a very straightforward architecture for a lunar return, that, on the face of it, will seem to you that if we are to do these things, that the approach being recommended is a logical, clean, simple, straightforward approach. You mentioned, sir, in your opening remarks postponing the arrival date at Mars in order that we can do the proper things now. And I agree."[12]

Spiral development is associated with large DoD projects such as the F-35 Joint Strike Fighter; indeed, Rear Adm. (ret) Craig Steidle, appointed by Sean O'Keefe to head the Exploration Systems office, had led the F-35 effort in the past. However, it had been pointed out that spiral development was not a logical approach to building the CEV; that the proposed CEV spirals did not effectively build on each other; and that Spirals 2 and 4 were unnecessary [13]. Through his disavowal of the spiral development system, Administrator Griffin appears to assent to this viewpoint. The ESAS as described in the Orlando Sentinel [14] also contains no mention of spiral development.

NASA is also looking into building rockets with nuclear propulsion and developing space nuclear power reactors under Project Prometheus. This will not be part of the initial phase of building the Crew Exploration Vehicle.

NASA hopes to follow this schedule in development of the CEV:

  • 2006 - (August) NASA selects one team to build CEV.
  • 2006–2007 - Engineering review of selected CEV design
  • 2008–2010 - First unmanned flight of CEV in Earth orbit.[15]
  • 2011 - (June) First manned flight of CEV in Earth orbit.
  • 2015–2018 - First unmanned flight of Lunar Surface Access Module (LSAM).
  • 2016–2018 - First manned flight of LSAM.
  • 2018 - First manned lunar landing with CEV/LSAM system.
  • 2020 - Start of planning for Mars missions

It has been rumored that the ESAS will support a phased retirement of the Space Shuttle, which would begin by retiring one orbiter (probably Atlantis), as early as 2007. Under this plan, Discovery would likely be retired in 2009, followed by the retirement of Endeavour prior to September 30, 2010 (the last day of fiscal year (FY) 2010). In the meantime, NASA engineers would work to upgrade the current launch facilities to work with the next generation shuttle-derived launch vehicles. [16] Such a plan would allow lunar mission development to begin much earlier than currently planned, as additional funding will be available earlier.

[edit]

Possibilities for future CEV development

After the replacement of Sean O'Keefe, NASA's procurement schedule and strategy has completely changed, as described above. In July 2004, before he was named NASA administrator, Michael Griffin participated in a study called "Extending Human Presence Into the Solar System"[17] for The Planetary Society, as a co-team leader. The study offers a strategy for carrying out Project Constellation in an affordable and achievable manner. Since Griffin was one of the leaders of the study, it can be assumed that he agrees with its conclusions, and it is therefore instructive to review the study to gain insight into possible future developments regarding the CEV. Indeed, as described below, the actions he has taken thus far as administrator support the goals of the plan.

According to the executive summary, the study is built around "a staged approach to human exploration beyond low Earth orbit (LEO)." [18] It recommends that Project Constellation be carried out in three distinct phases, called "Stages." These are:

  • Stage 1 - "Features the development of a new crew exploration vehicle (CEV), the completion of the International Space Station (ISS), and an early retirement of the Shuttle Orbiter. Orbiter retirement would be made as soon as the ISS U.S. Core is completed (perhaps only 6 or 7 flights) and the smallest number of additional flights necessary to satisfy our international partners’ ISS requirements. Money saved by early Orbiter retirement would be used to accelerate the CEV development schedule to minimize or eliminate any hiatus in U.S. capability to reach and return from LEO." [19]
  • Stage 2 - "Requires the development of additional assets, including an uprated CEV capable of extended missions of many months in interplanetary space. Habitation, laboratory, consumables, and propulsion modules, to enable human flight to the vicinities of the Moon and Mars, the Lagrange points, and certain near-Earth asteroids." [20]
  • Stage 3 - "Development of human-rated planetary landers is completed in Stage 3, allowing human missions to the surface of the Moon and Mars beginning around 2020." [21]
[edit]

Stage I

Rather than designing a CEV solely for the earliest lunar landing possible, the report recommends developing the CEV in two Blocks. The Block I CEV would be suitable for LEO missions only and would be developed as quickly as possible to avoid the gap between the currently scheduled Shuttle retirement in 2010 and CEV flights starting in 2014. It would carry a crew of 4–6 astronauts. The report recommends the development of a shuttle-derived CEV launch vehicle based on the "Shuttle Solid Rocket Motor with a new liquid propellant upper stage" [22] for CEV launch, rather than man-rating an EELV. This approach would allow the advantages of using a proven, man-rated design (the Solid Rocket Motor), plus the ability to continue using Shuttle infrastructure to support CEV operations.

Indeed, as described above, the upcoming Exploration Systems Architecture Study is thought to contain an endorsement of exactly this option — the construction of an SRM-based SDLV, plus a heavy-lift launch vehicle derived from the Shuttle, in addition to options for expediting CEV development to permit earlier manned flight. [23] Therefore, the idea that the Planetary Society report could shed light on future CEV development is supported by these new developments. In other words, the very recommendations contained in the report for the beginning of Stage I — namely, the expedited CEV development and the SRM-derived launch vehicle — appear to have materialized.

Under the rest of Stage I, the Shuttle would be retired as soon as possible after completing the "U.S. Core Complete" configuration of the International Space Station, an option that also appears to have gained support within NASA and the Bush administration [24]. The report makes no specific mention of a manned Hubble Space Telescope servicing mission, although Administrator Griffin has instructed Hubble managers at NASA Goddard Space Flight Center to make preparations for such a mission [25], and the report refers to Hubble as "world-class astronomy". [26] The report suggests the use of expendable launchers, either foreign vehicles such as the Ariane and Proton, or a new Shuttle-derived, heavy-lift launch vehicle to complete the ISS after Shuttle retirement. The Block I CEV could also act as an ISS Crew Return Vehicle, allowing crews of more than three to be supported. Stage I is to be implemented by 2010.

[edit]

Stage II

Under Stage II, a new Block II CEV would be developed, suitable for interplanetary flight. The report states that the new CEV should keep the same mold lines as the Block I, making the selection of an appropriate Block I CEV extremely important to the successful implementation of the plan. The report states that the Block II CEV would need to have capability to conduct interplanetary cruises of at least several months in duration. It suggests the development of other modules, specifically modules called "Hab," "Lab," "Propulsion," and "Consumables" to support longer-duration flights. The use of ISS module derivatives for the Hab and Lab modules is suggested but not explicitly endorsed.

Four destinations are suggested for CEV exploration in Stage II. They are (probably, although not necessarily, in the order that they would be visited):

The goal would be to conduct flights to each of these destinations but without a human-rated lander for the Moon and Mars. The use of SEL2 is described as important to demonstrate the capability of servicing future space telescopes (such as the James Webb Space Telescope) there and also for staging interplanetary flights. After the flights to SEL2, a flight to a NEO could be attempted; due to its extremely low surface gravity a landing module would not be needed and the astronauts could "walk" on it with MMU-like equipment. Finally, a mission to orbit Mars and possibly land on its moons is suggested. All these flights would be accomplished with one CEV design supported by the various modules, as necessary. Stage II would take place from about 2015 onward. However, according to the current descriptions of the ESAS, a landing on the Moon appears to be the first priority of Project Constellation and will occur by 2018 [27].

[edit]

Stage III

In Stage III, human-rated landers are developed to allow landings on both the Moon and Mars. Since the Block II CEV should be capable of flights to both these destinations, lunar and Mars landings could begin simultaneously, with the experience gained from exploring the four destinations referenced in Stage II. These landings would begin in 2020.

[edit]

Summary

Although CEV development is still in an extremely early stage and it remains to be seen what form it will finally take, NASA is apparently taking exactly the steps recommended for the implementation of Stage I of the report. Therefore it is not unlikely that the three-stage plan suggested in this report could be the plan for the actual Project Constellation. Although it now appears that the plan will not be followed exactly, it is possible that elements of it could still be used as a baseline for Constellation exploration strategies (for example, Stage I appears to have become a NASA strategy). Although the plan would not allow for lunar landings as early as 2015, as suggested in the Bush vision, it does permit an early Mars landing in 2020, contemporaneous with lunar landings by that date.

[edit]

Funding

President Bush's budget request for Fiscal Year 2005 included: "$428 million for Project Constellation ($6.6 billion over five years) to develop a new crew exploration vehicle." The budget for FY2005 was confirmed by the Congress in November 2004 with full funding for the CEV.

The FY2006 budget request includes $753 million for continuing development of the CEV. As of 2005 the total development costs of the CEV are estimated at $ 15 billion. [28]

Although to date the exploration systems have received full funding and a House endorsement[29], there is a possibility that rising Shuttle return to flight costs will make funding of CEV development extremely difficult. There has been discussion of either obtaining a special supplemental from Congress to pay for the extra Shuttle costs, or of involving private industry in CEV development and operations. [30] The total funding of Project Constellation through 2025, inflation-adjusted and without any other increases to NASA's budget, is estimated at $210 billion; the ESAS estimates the cost of the program through that date at being only $7 billion more, at $217 billion [31]. This cost may in fact end up lower as it includes developing new engines for the EDS instead of the newer idea of using J-2 derivatives[32].

[edit]

Nomenclature

There is a great deal of speculation as to what the final name for the CEV/CLV Human Space Transport will be. A new name should be announced in 2006.

As of February 28, 2006, reported naming is: <ref name="Altair" />

  • Altair: Crew Exploration Vehicle (CEV).
  • Ares I: Crew Launch Vehicle (CLV).
  • Ares V: Cargo Launch Vehicle (CaLV).
  • Artemis: Lunar Surface Access Module (LSAM).
[edit]

See also

Template:Wikinews

[edit]

References

<references/>

[edit]

External links


Template:US manned space programsde:Crew Exploration Vehicle eo:Crew Exploration Vehicle fr:Crew Exploration Vehicle it:Crew Exploration Vehicle hu:Crew Exploration Vehicle ja:Crew Exploration Vehicle nl:Crew Exploration Vehicle pl:Crew Exploration Vehicle ru:Crew Exploration Vehicle fi:Crew Exploration Vehicle sv:Crew Exploration Vehicle

Retrieved from "http://www.netipedia.com/index.php/Crew_Exploration_Vehicle"