Orion's current design has been optimized to support relatively short duration missions to the moon, but also sized to function as an emergency get-home vehicle for a six-person crew on the ISS. As such, Orion, with its service module, is too heavy for earth-to-ISS travel, and is poorly suited for other potential human exploration missions beyond LEO.

The Orion capsule is too small for any mission longer than about 10 to 14 days. Imagine three or even four people living in an Orion-sized space of about 10x10x6 ft for several weeks or months. Control panels and operating systems protrude into the limited space.

Crews get stinky and crowded. Waste management in such a small space is a real problem and privacy is non-existent. Crew performance deteriorates. It would be possible to contain crews in the small Orion capsule for longer missions, but this is certainly not desirable.

The exploration program needs a Crew Exploration Module (CEM), which could be described as "a small, self-contained space station", or an Orion Crew Exploration Vehicle (CEV) with more living space. In either case, the CEM would need nearly all the systems and subsystems now planned for Orion, e. g., life support, attitude control, communications, navigation, docking capability, hygiene facilities, electric power, radiation protection and thermal control.

Two or more of these modules docked together may be considered for long missions. Propulsion for maneuvering could be provided by a separate service module which is launched separately and docked to the CEM. Of course, main propulsion for missions beyond LEO will require a heavy lift launcher and/or a propellant depot.

The Shuttle could deliver a CEM to LEO of up to 14 feet in diameter and more than 50 feet long, containing more than 30 times the pressurized volume of an Orion capsule, and weighing less than 50,000 pounds.

Systems in the CEM should be mounted on swing-out panels for easy access to both sides for maintenance, and access to the interior of the pressurized shell to enable quick repair of potential micrometeoroid penetrations. Lessons from the ISS, Apollo 13 and the Mir station illustrate the vital requirement to accommodate unscheduled maintenance and repair.

Crews could travel between Earth and LEO on other transportation vehicles, such as Soyuz, the proposed US commercial crew vehicle or eventual crew carrying vehicles from ESA, India, China, or Japan.

It can be expected that each one of these entities will have an operational means for transporting people to and from the ISS by about 2020. Return from long missions beyond LEO may require expendable CEMs and propulsion modules, plus a minimal reentry capsule that could be stored during the mission and used only for reentry.

A summary of the advantages of a CEM (call it a reconfigured Orion CEV) are:

+ Access to the inside of the pressure shell for repair of micrometeoroid penetrations

+ Access to systems for maintenance and repair

+ Relatively small CEM's will permit two or more CEM's to travel together and provide backup for each other on long missions

+ Relatively clean interface for international partners who might want to build their own CEM to travel in tandem with the U.S. CEM

+ Space (and mass capability) for radiation protection

+ Ability to qualify crews and systems for long duration missions while docked safely to the ISS

+ More living volume

International partners (IP) need and want the ISS and Shuttle to continue. The ISS is a perfect place to develop and qualify people and systems for much longer human missions.

IP's would welcome that opportunity. Major IP's could even develop and build their own CEM, as long as utilities (power, atmosphere, comm., etc) are compatible. This would be viewed as a great opportunity for an International Partner. And, it provides a clean interface between the U.S. and it partners.

Opportunities exist on the ISS to develop ways to make future human exploration missions safer, faster and more efficient. These include radiation protection for astronauts, recyclable water and food, ion and other advanced propulsion, electric power generation, better hygiene systems, recyclable environmental systems, in-flight repair techniques, advanced robotics, etc.

The ISS is a perfect test bed for those systems. Test and qualification of a Mars transit module at the ISS would be a fantastic and inspiring job for the station.

A CEM qualification test article could be built, docked and launched using the ISS. The hatch would be kept closed, except in case of emergency, and the crew and systems would simulate long missions to destinations beyond LEO and back. This would be viewed as a very important job for the ISS and Shuttle.

The ISS may eventually become inoperable without Shuttle to replace large or heavy elements, like complete modules and solar arrays. The ISS is also critical to the development of advanced space transportation, such as plasma or ion propulsion requiring large and/or heavy elements.

Furthermore, the Shuttle is the only practical way to service future major scientific satellites in LEO. Retaining the current Earth-to-LEO capability may be the only way to avoid the serious gap in U.S. space launches that may space more than seven years. Such a gap could lead to a serious loss of experienced technical personnel in space operations within NASA.

The current NASA budget could support continuation of ISS and Shuttle, reinvigorate science and technology programs and continue very important work on a reconfigured Crew Exploration Module.

Most of the systems planned and designed for Orion would probably work for the CEM, avoiding a possible waste of funds already spent on Orion. The current Orion contract could perhaps continue, but with a redesigned configuration. Furthermore, an inflatable structure should be considered for part of the CEM.

Regardless of changes in the configuration or schedule of Orion or CEM, the Shuttle should be extended through the life of the ISS.

The Shuttle/ISS combination is a unique, versatile, and useful system. At some point in the next several years, if Shuttle and ISS have been retired, we may well find ourselves saying, "We had it. How could we have been so short-sighted as to have thrown it away?"

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