Encyclopedia Astronautica

CEV's Compared
Credit: © Mark Wade
CEV Command Modules compares
Credit: © Mark Wade
NASA's manned spacecraft for the 21st Century, a throwback to the Apollo capsule, a shuttle replacement with an uncertain future.

The Space Shuttle was sold by NASA to America in the early 1970's as a low-cost, reusable spaceship that would replace all existing boosters and manned spacecraft. The Apollo capsule and Saturn launch vehicles were scrapped. Production of all other expendable boosters would be discontinued once the Shuttle was 'fully operational'. The myth of its lower cost was maintained in the face of mounting evidence to the contrary until the shuttle Challenger exploded on the way to orbit in 1986. In the post-mortem that followed, it was discovered that the shuttle was actually more expensive and very much more operationally constraining in delivering satellites to orbit than the expendable boosters it was supposed to replace. So the American government abandoned use of the Shuttle for satellite launches and allowed production of expendable launch vehicles to resume.

But the Shuttle was now the only American manned spacecraft, so a new mission was found for it. It was claimed it was now safe after billions of dollars of post-Challenger fixes. It was also claimed that only its unique design would allow NASA to assemble a space station. The space station project stretched out, until it was taking decades. The shuttle was getting old, and America had no lifeboat - a manned re-entry vehicle - that it could use to rescue crews from the space station if the balky shuttle was unavailable. On the other hand, NASA saw development of any other manned spacecraft as a threat to the very existence of the Shuttle. Various suggested supplemental projects suggested in the 1980's and 1990's were decisively squelched. The X-38 lifting body was to be developed as a Crew Rescue Vehicle, and perhaps as a Shuttle alternative. But the initially simple skunk-works approach to the program was overwhelmed by NASA gold-plating, and it finally was quietly killed off 'due to cost over-runs'. The X-33 single-stage-to-orbit was NASA's true vision for a shuttle successor, but after spending a huge sum NASA decided SSTO was actually not attainable using existing technology, and canceled that. Given that NASA's lead-time for developing new spacecraft had gone from a few years in the 1960's to a few decades by the 1990's, NASA decided it would be prudent to start the long definition process for the Orbital Space Plane, a shuttle successor that would be launched by an expendable launch vehicle.

Then in 2003 the space shuttle Columbia was lost during re-entry. The final shuttle myth - that it was safer than alternatives - was demolished. Flights of the shuttle would have to end by 2010, it was decided, and therefore a successor ready for flight before then.

Meanwhile President Bush had been convinced by the NASA administrator O'Keefe to back yet another in-the-future grandiose manned space exploration program. The Orbital Space Plane was renamed the Crew Exploration Vehicle. Now the requirements for the spacecraft would be extended by requiring it to be the manned return vehicle not just from earth orbit, but from the moon and Mars. In the original 2003-2004 concept a CEV program would have been developed in three phases, to support NASA's then-planned three spirals of space exploration development:

  • Spiral 1 systems would be available by 2014 at the latest. They would provide the hardware to replace the space shuttle in support of manned operations in low Earth orbit. NASA hoped this capability might be available as early as 2010, when the shuttle was schedule to be retired. Otherwise only the Russian Soyuz spacecraft would be available to support International Space Station operations between 2010 and the station's planned retirement in 2016. Spiral 1 systems would also allow renewed robotic exploration of the moon.
  • Spiral 2 systems would allow a human landing on the moon, followed by extended duration manned lunar exploration and robotic exploration of Mars in the period 2015-2020.
  • Spiral 3 systems would allow establishment of a near-permanent lunar base and continued robotic exploration of Mars. Lunar surface habitation and power systems would be developed, and the CEV would have to be capable of long-duration lunar-surface or lunar-orbit storage between crew rotations or expeditions.

In Phase 1 of the CEV program (different from Spiral 1 of the overall program!) two contractors would develop competing CEV designs and demonstrate these in unmanned flight tests in 2008. Design of the definitive manned CEV would at the same time be taken up to the Preliminary Design Review stage. A single prime contractor would be selected to continue with Phase 2 in late 2008. That contractor would develop, test, and deploy a man-rated CEV system capable of supporting Spiral 2 requirements by 2014 (and hopefully capable of supporting Spiral 3 requirements without further modification). After completion of phase 2 the contractor would provide sustaining engineering services and production capability to support additional flights and additional CEV spacecraft.

The CEV requirements included:

  • Support a minimum crew of four (NASA preferred six) from the Earth's surface through mission completion on the Earth's surface.
  • Mass less than 15 to 18 tonnes (the precise value to be determined in preliminary contract studies).
  • Abort capability during all phases of flight. Preferably such abort capability would be available continuously and independent of Launch Vehicle (LV) or Earth Departure Stage (EDS) flight control.
  • Integrate with the Constellation Launch Vehicle (LV) to achieve low earth orbit.
  • Integrate with the Earth Departure Stage (EDS) to achieve lunar orbit.
  • Integrate with the Lunar Surface Access Module (LSAM) to achieve lunar surface mission objectives. Preferably the CEV would be capable of transferring consumables to and from the EDS and the LSAM.
  • Maximum use of existing technology.
  • Open Systems Architecture and use of common hardware and software between equipment built for acceptance testing of the flight system and the ground support equipment used to process the vehicle at the launch site.
  • Simple interface between the CEV and Launch System to optimize integration.
  • Certification by test to the maximum extent possible.

On 4 September 2004, NASA announced selection of contractors for initial Crew Exploration Vehicle studies. The contracts were awarded for a six-month base period. A six-month option would be exercised on a case-by-case basis. The selected companies and the value of their contracts were:

  • Andrews Space Inc., Seattle -- Base: $2,999,988; Option: $2,999,941
  • Draper Labs, Cambridge, Mass. -- Base: $2,988,083; Option: $2,945,357
  • Lockheed Martin Corp., Denver -- Base: $2,999,742; Option: $2,999,920
  • Northrop Grumman Corp., El Segundo, Calif. -- Base: $2,958,753; Option: $2,999,473
  • Orbital Sciences Corp., Dulles, Va. -- Base: $2,998,952; Option: $2,994,259
  • Schafer, Chelmsford, Mass. -- Base: $2,999,179; Option: $2,997,804
  • The Boeing Co., Huntington Beach, Calif. -- Base: $2,998,203; Option: $2,998,346
  • t-Space, Menlo Park, Calif. -- Base: $2,999,732; Option: $2,939,357

Although each contractor conducted thousands of pages of rigorous trade studies against NASA's proposed requirements, they came to very different conclusions. However there were some common themes identified by more than one contractor:

  • The optimum CEV would have a mass of under 9 tonnes and a crew of four or less.
  • The lowest cost launch solution would be to use existing expendable launch vehicles (Atlas V and Delta IV) or derivative. This would allow launch of the CEV on earth-orbit missions by a single booster existing ELV. Three-booster versions of existing ELV's could orbit elements of lunar or Mars expeditions.
  • The most flexible and logical lunar exploration architecture was to assemble lunar expedition components at the L1 Earth-Moon Lagrangian point. This allowed unconstrained launch and landing schedules, and provided a permanent way station for not only lunar, but Martian exploration.

By the time the final CEV proposals were received, Mike Griffin had been appointed the new NASA Administrator. He saw that the CEV plan would realistically leave NASA with a half-decade gap between the retirement of the shuttle and the commencing of CEV flights. Griffin obtained White House backing to reject all of the contractor's proposals abandon the long, expensive, 'spiral' development process, and plunge ahead using existing technology and NASA's best judgment. On June 13, 2005, NASA announced the down-select of two contractors: Lockheed Martin and the team of Northrop Grumman and Boeing. However the selected contractors would only build a CEV to NASA's own design.

Phase 1 was now accelerated so that a single contractor would be selected without prototyping or flight-test in 2006, so that the spacecraft could be available by 2010 as a shuttle replacement. The crew requirement was increased to six, and CEV launch mass to 30 tonnes, meaning the CEV could only be launched atop a Shuttle-derived, NASA-operated launch vehicle. NASA's CEV configuration, as finally made public in late 2005, was called 'Apollo on steroids'. The CEV would be used initially to provide access to the International Space Station after the retirement of the Space Shuttle in 2010. Thereafter it would provide the earth return vehicle for missions to the moon (by 2020) or Mars (by 2030+?).

It looked like the errors of the original Apollo program would be repeated. A three-module spacecraft, as used successfully on Soyuz and Shenzhou, was rejected. Instead the sole crew habitat space would be the re-entry vehicle, which would be a 41% scaled up version of the Apollo command module. This would have over three times the internal volume and double the surface area of the Apollo capsule, but NASA claimed its mass could be limited to only 50% more than the Apollo design. Despite the increase in volume and mass, it would provide accommodation for only four to six crew (versus three to five in Apollo).

The service module was stubbier and lighter than the Apollo CSM, and powered by a liquid oxygen/methane engine. The same propellant combination would be used in the reaction control systems of both the command and service modules, the ascent stage of any later lunar lander, and the ascent stages of any Mars landers. The choice of this untried rocket propellant was driven by NASA plans to - maybe - generate methane from the Martian atmosphere on future manned expeditions. For NASA's lunar landing scenario, the CEV would be required to make only the Trans-Earth injection maneuver to bring the crew home. In the Apollo scenario, the CSM had to brake both the CSM and lunar module into lunar orbit, as well as make Trans-earth injection for the CSM.

The CEV would be launched into earth orbit by the Crew Launch Vehicle, a shuttle-derived two-stage rocket consisting of a single Shuttle RSRM solid booster as the first stage and a new second stage, 5.5 m in diameter, using Lox/LH2 propellants and powered by a single SSME.

By January 2006 NASA still had not released its revised baseline so that the prospective contractors could begin working on their final proposals for the down-select. The contradictions in NASA's homegrown design had become apparent even before the final specification could be released. Reportedly, the liquid oxygen/methane engines would be eliminated, replaced instead by toxic but proven storable propellant engines as used on Apollo and the Shuttle. The CEV's first flight had slipped to 2011 or 2012. NASA had lost one its main political supporters, Tom DeLay.

The selection of an Apollo-type configuration for the re-entry vehicle represented a step back sixty years. The original Apollo design, a NASA in-house concept, was inferior to contractor alternatives. The Soviets selected the Soyuz configuration (identical to the losing General Electric Apollo design) and had a configuration still in production fifty years later - and likely to continue to the middle of the 21st Century in the Chinese Shenzhou. Apollo, by comparison, remained in production only five years. In 2005, Northrop-Grumman again proposed a Soyuz-type design.

Other alternatives for Apollo were a variety of ballistic, lifting-body and winged configurations, any of which would have provided a fine basis for a manned spacecraft that could be recovered with horizontal landings. At least the excuse given in 1961 - that there was no time to pursue development of a winged vehicle and still make the end-of-the-decade lunar landing deadline - may have had some validity. But this made less sense in 2005, when Lockheed proposed a winged design based on forty years of intervening lifting body research and shuttle hypersonic flight experience.

Incredibly, NASA made the same mistake again, fifty years later. The same approach was used. First, proposals from industry were solicited. In both the Apollo and CEV cases these were imaginative, innovative, and incorporated all of the lessons of hundreds of millions of dollars of advanced research funded not just by NASA, but also by industry and the US Air Force. Superior contractor designs using the Soyuz-type separate orbital module or a winged spaceplane approach were made in both cases. In both cases the contractors were thanked, and NASA then proceeded with its own in-house government design. This was then suitably tweaked until it will passed the Congressional pork test.

After the Apollo decision, it was apparent that a two-man Apollo or Gemini direct lunar mission would have been much more logical, economical, and less risky. In the CEV decision, it was apparent that a design with a re-entry vehicle and service module under 8 tonnes that could be launched by an existing heavy-lift EELV rather than NASA's shuttle-derived hardware would be much more economical. But again the decision was made primarily on political grounds, and to keep NASA government jobs.

The following table compares NASA's CEV design and mission plan with those recommended by its subcontractors:

ContractorCEV ConceptCrewRV FormCargo LVLunar Scenario
AndrewsMM+CM+SM6ApolloELV 40tL1
BoeingMM+CM+SM4ApolloELV 20 + ELV 40tEOR/L1
Draper MITIntegral6SoyuzHLV 60tDirect
LockheedMM+CM+SM4Lifting BodyELV 70tEOR + LOR Equatorial
Northrop-GrummanMM+CM+SM4SoyuzSDV 20t + ELV 55tEOR/L1
OrbitalIntegral4ApolloSDLV 141tLOR
RaytheonIntegral3ApolloELV 25tL1
SAICIntegral4SoyuzELV 10 to 30tEOR + LOR Polar
SchaferIntegral4DiscovererELV 25tEOR/L1
SpacehabMM+CM+SM4ApolloELV 15tEOR/LOR
t/SpaceIntegral4DiscovererQuick Reach 5 tEOR/LOR/EOR
NASAIntegral6ApolloSDLV 25t/SDLV 136tEOR + LOR Polar

More... - Chronology...

Associated Spacecraft
  • CEV Spacehab American manned spacecraft. Study 2005. The final Spacehab CEV concept was a three-module spacecraft using a slightly enlarged Apollo command module for return of the crew to earth. More...
  • CEV Andrews American manned spacecraft. Study 2005. The Andrews Crew Exploration Vehicle (CEV) design adopted NASA's preferred Apollo CM re-entry vehicle shape, but combined it with a mission module crew cabin to minimize the CEV's mass. More...
  • CEV American manned spacecraft. Study 2006. The Crew Exploration Vehicle (CEV) was NASA's planned manned spacecraft intended to carry human crews from Earth into space and back again from 2012 on. More...
  • CEV SAIC American manned spacecraft. Study 2012. SAIC's notional CEV was a Soyuz-shaped aeroshell, enclosing a common pressurized module, and accommodating a crew of four. More...
  • CEV Lockheed American manned spacecraft. Study 2012. The Crew Exploration Vehicle first proposed by Lockheed was a lifting body with a total mass of 18 metric tons and a crew of four. More...
  • CEV Boeing American manned spacecraft. Study 2012. Boeing's CEV consisted of a four-crew Apollo-type capsule, a service module, and a pressurized mission module. More...
  • CEV Orbital American manned spacecraft. Study 2012. Orbital's nominal CEV was an Apollo-derived capsule. The CEV's service module would take the capsule from low earth orbit, to lunar orbit, and back to earth. More...
  • CEV Raytheon American manned spacecraft. Study 2012. Raytheon's CEV was a low L/D capsule, designed for three crew, sized so that an existing EELV Heavy could send it towards L1. More...
  • CEV Northrop American manned spacecraft. Study 2012. Northrop Grumman kept its CEV final proposal very secret, citing competitive concerns. More...
  • CEV Schafer American manned spacecraft. Study 2012. Schafer proposed a lightweight 11 metric ton integral CEV, staged from L1. More...
  • CEV Draper MIT American manned spacecraft. Study 2012. The Draper-MIT CEV proposal was an 8-metric ton integral ballistic capsule. More...
  • CXV American manned spacecraft. Study 2012. Crew Transfer Vehicle proposed by `t/Space and Burt Rutan's Scaled Composites for NASA's Crew Exploration Vehicle requirement. More...

Home - Browse - Contact
© / Conditions for Use