8-Jul-2011Placating rather than innovating?
Much of what would normally be expected to be available from NASA in terms of design details seems to lean, instead, toward non-specific "considerations" placating current contractors associated with NASA through the shuttle-- rather than developing better and newer technologies.
A recent CNN report, Beyond Atlantis, on the end of the NASA Space Shuttle era, contained a brief mention of the next US manned spacecraft for NASA. Already well into development, the former deep space crew capsule under the Constellation project was quickly adjusted to meet the needs of the Obama Administration's new tasking of the space agency; and with the mandated changes came also the name change from Orion Crew Exploration Vehicle (CEV) to Multi Purpose Crew Vehicle (MPCV). Unlike Mercury, Gemini, Apollo and the Space Shuttle, NASA's next generation space vehicle is almost unknown to the general public.
|Lockheed Martin photo of MPCV, via NASA|
Scanning what little specific information is available, the advertisement theme from NASA begins to deepen as a marketing technique, rather than the technological reporting which is more typical of the agency.
In one NASA press release (here), it is said:
- Spacecraft to serve as the primary crew vehicle for missions beyond LEO
- Capable of conducting regular in-space operations (rendezvous, docking, extravehicular activity) in conjunction with payloads delivered by SLS for missions beyond LEO
- Capability to be a backup system for ISS cargo and crew delivery.
Low Earth Orbit is variously defined, but is most usefully understood to be within the Van Allen Radiation Belt, for two reasons:
Crossing through the radiation belt subjects the crew to a risk of high doses of X-Ray and Gamma radiation. NASA did it successfully each time Apollo crossed the belt on the way to the moon, flying through the known weakest portions of the belt and passing through it as quickly as possible (http://lsda.jsc.nasa.gov/books/apollo/S2ch3.htm).
Secondly, the belt protects the Earth from dangerous radiation. Outside of that belt, any unanticipated major solar event could easily become deadly to any persons beyond the Van Allen Belt without proper shielding. In addition to x-ray and gamma ray radiation, the Van Allen Belt also shields the Earth from cosmic rays which are far more difficult-- perhaps impossible-- to suppress or absorb.
Elsewhere is found other mention of the vehicle's deep-space ability to make possible a manned visit to some future and unnamed passing asteroid (e.g., the CNN report, mentioned above, referred to this possibility). Much more vaguely mentioned are suggestions of its being used as a step toward returning to the moon and manned exploration of Mars. Yet, there is no lander, no habitat for extended voyages, and no significant information about the shielding required for a deep space vehicle.
So, on balance, the missions are defined, at best, as a back-up to the Russian Soyuz supply missions to the International Space Stations (ISS), and then only potentially for missions which are neither planned nor funded. It seems, therefore:
- The main purpose is to simply keep the US current in technology and preserve the brain-power already in place in NASA and its contractors, and / or
- To replace the Soyuz because the best guess is that Russia cannot afford to keep it up. It would be understandable that the US would not wish to state, publicly, such a lack of confidence in Russia.
It seems NASA does not wish to state the obvious: That the MPCV is a big Apollo capsule with modern avionics and other electronics. However, that is what it seems to be. There is nothing wrong with that-- the Apollo was a great design; but saying so seems to be taken as a negative from a marketing (think: Congressional Funding) approach.
- The heat-shield seems to be the same design of fiberglass honeycomb impregnated with the an ablative material (Avcoat) as was used with Apollo.
- The crew safety system seems to be the same technology, or a close variant ,used in Apollo-- an escape tower. From this beefed-up Max Launch Abort System test (video, below), it appears that the Service Module may also be part of the escape system.
|Boeing's PICA heat shield.|
- The "deep-space" radiation shielding is (apparently) the water which is carried anyway in the Service Module aft of the capsule, and polyethylene-- hardly new technology.
It is known that the aluminum exterior of a spacecraft can actually aggravate crew hazards when exposed to the impact of particles from Cosmic Rays. Water and polyethylene tend to be the most absorbent of these particles which are available for spacecraft, but the dampening effects are limited.
Aluminum, while helpful for minimizing x-ray and gamma ray exposure, tends to increase the potential for the crew being damaged at the cellular level, by adding part of its own matter to the already ultra-high-speed particle rays. Like hiding under a bridge which is being bombed from the air, one may escape the bomb shrapnel only to be killed by the pieces falling from the bridge.
Alone, the radiation shielding of the MPCV seems inadequate for consideration for extremely long deep space journeys such as the more than 400 day minimum expected for a Mars voyage.
Safety, Safety, Safety
NASA is very aware of the public expectations of crew safety, and as if the public may doubt it, press releases concerning the MPCV leave one with the impression that the vehicle's development is primarily a reaction to the Challenger and Columbia disasters. It is not.
Many are aware of NASA's contrition for the loss of those two Shuttle crews and of the agency's subsequent and earnest commitment to crew safety. But the ghosts appear. The literature and press releases currently available emphasize crew safety technology while remaining silent as to what a crew will be accomplishing using the vehicle.
Meanwhile, the MPCV not only lacks a place to go, it also lacks the ability to get there.
Space Launch System
The rocket to be used to boost the crew vehicle into orbit (and beyond?) does not exist. While still under development, is heavily weighted toward using Shuttle launch technology, and according to the CNN report, even reusing left over fuel tanks. Current expectations are for he final design to be ready in 2016. Certainly NASA has an indebtedness to the contractors who have kept the US manned space program flying over the decades; but there may be a cost in crew safety as well as in payload limitations if recovered solid rocket motor casings and liquid fuel tank re-usability drives the design decisions.*
NASA is tasked and funded to continue to develop a manned craft capable of re-supply of crew and cargo for the ISS and that same vehicle is to be capable of deep space missions. This may be the highest accomplishment NASA might be expected to achieve at this time. The desire to continue with older technology and familiar contractors is a fair compromise in the present economic environment.
In the five or six years between today's final Space Shuttle launch and the next available manned launch from NASA, specific project missions will certainly be developed and proposed for feasibility and for funding. Once once final equipment design is formalized, NASA's customer base can begin payload designs, just as has been done with the Shuttle.
Perhaps it will be, by 2016, men and women will board a new spacecraft with an appropriately godly name, and again capture the imagination and the hopes of human endeavor.
- Crew of four
- 21 day mission capability with out additional supply.
- Advanced shielding for deep space work
- Integrated docking hardware (for ISS and future modules to be designed)
*Aerojet with Teledyne Brown announced its intent to design a competitive all-liquid-fuel rocket for the MPCV based upon its NK-33.