« AnteriorContinuar »
KEY CONSIDERATIONS IN FUTURE SPACE PROGRAMS
The American Institute of Aeronautics and Astronautics is the
technical society whose membership of 25,000 engineers, scientists,
and students represent all the disciplines of the aerospace profession. Clearly, space is our business. We have frequently presented
testimony on future space programs before subcommittees of this com
mittee and elsewhere, and we appreciate this further opportunity to
express our views to the full Committee on this 20th anniversary of
our nation's first successful space flight.
In the past two decades, the U. S. space program has come nearly
Our initial efforts were of necessity exploratory, seek
ing to develop the technology and capability needed for more ambitious
The manned lunar missions demonstrated how success
fully we accomplished that phase. In the decade of the 1970's, we have turned more and more to the utilization of our space capabilities
to improve the quality of life here on Earth.
Applications to communi
cations, meteorology, resource detection and education, and the develop
ment of new scientific knowledge about the Earth, Sun, solar system, and the stars have become the principal focus of space activities.
Now, we are preparing to begin again the process of maturing a
whole new gamut of capabilities. The advent of the space shuttle both enlarges our ability to perform applications-oriented missions and opens
news vistas of what we can accomplish in space.
Other witnesses at
these hearings will describe some of these prospective new missions,
many of which are described in previous AIAA publications which have
been placed in the records of this Committee's activities. Many AIAA
members believe that whereas we are devoting adequate attention to
the applications (including scientific exploration)
and these are
certainly both excellent and necessary
we are not preparing properly
for the potential expansion of space activities which is made possible by the introduction of reusable space transportation systems. These
concerns were expressed by members of our Technical Committee on Space
Systems, and endorsed by our Board of Directors, in our critique of
NASA's "Outlook for Space" study several years ago.
they are still applicable today.
Our concerns fall into two categories: technical and managerial.
We can dispose of the managerial concern quickly: it is simply that
one of NASA's basic purposes
research and development of new space
technologies, systems, and capabilities
should not be allowed to
become secondary to the operation of applications programs, with the consequent deemphasis on advanced programs designed to support future
We recognize, of course, the need for someone to operate our
Earth resources, space transportation, astronomical
and scientific satellites, and so on
but we should not foreclose
on our preparation for the future in order to do so.
We believe this Committee should initiate the exploration of the various approaches to implementing the operational aspects of space activities. Possible options are to expand NASA's charter, as was
suggested by former AIAA President Daniel Fink in Astronautics &
Aeronautics back in 1973; to set up new federal agencies; to transfer
operational activities to an existing cognizant federal agency (as was done with weather satellite operations); to encourage private industry to take over operations, as was the case with communications satellites; or, when operations have a multinational application, to
organize an international consortium such as Intelsat.
shuttle, once it has reached operational status, should perhaps be operated by an entity more like a commercial airline. It is a
transportation system, and NASA's job should be improving it and developing follow-on capability, not selling tickets or performing
engine and airframe maintenance.
The forthcoming competition of the
ESA Ariane launch vehicle for shuttle payloads emphasizes the need for careful thought on this question.
I would like to turn now to our most serious concern: the lack
of technology programs directed at the fulfillment of the promise of
Note that in concentrating on technologies, I do not mean to
ignore the important task of defining new space missions for the
However, there are a number of AIAA publications already in
the record of this Committee and its Subcommittees which suggest new
missions; many more are suggested by other witnesses at these hearings.
But without the basic technological capabilities, none of these new
missions will be viable.
Although the general attitude of emphasing applications to the detriment of future capability development prevails almost across the board at NASA, I will limit myself in this paper to only three examples of technologies which we believe are essential to our future in space,
and which are not now receiving adequate attention.
These three areas
are propulsion, power, and large space structures.
The lack of a sound NASA rocket propulsion technology program, identified over three years ago by NASA's own Research and Technology
Advisory Council, is already beginning to affect plans for proper
shuttle utilization. Many of the shuttle's prospective customers re
quire higher energy orbits than the shuttle orbiter can provide; especially geosynchronous orbits and Earth-escape trajectories.
projected interim upper stage and spin-stabilized upper stage do not
begin to meet the capabilities required of a standardized orbital
and the principal lack is that of a good, advanced
liquid-propellant rocket engine, which in the long run could reduce
transportation costs and make the shuttle system economically more
As a consequence, the shuttle may suffer a serious loss
of potential business; e.g., to the ESA Ariane launch vehicle I
But the lack of an active and viable rocket propulsion technology program has even more serious consequences: a loss of intrinsic cap
ability in this area.
Our impressive past successes in space were
in no small measure the result of several decades of building propul
sion capability: test facilities, production facilities, support
facilities, propulsion hardware, and, most important, people. NASA's cadre of experienced rocket propulsion personnel is dwindling rapidly,
(as are key NASA cadres in other space technologies).
There are no
new people coming along to replace them, because there are few programs
for them to work on.
The industry cannot develop new engines on their
own; such high-risk efforts classically are performed by government
And because virtually all space activities require pro
pulsion, the absence of a strong, continuing program of research and
technology implies an approaching obsolescence in our entire future
space program, which is what these hearings are, hopefully, aimed at
The weakness of NOW's space power technology program will not
be felt quite so soon
in propulsion, but it could turn out to be
more serious a limitation in the long run.
It is already evident
that even the shuttle's fuel-cell powerplant, basically an Apollo
derivative, will limit several projected Spacelab and other missions.
And fuel cells are only short-term power sources.
The next commercial
phase of space activity generally recognized as the development of new and improved comunications functions will require substantially
greater power than the maximum of a few kilowatts now available from
current photovoltaic power supplies. Projections to more ambitious programs in the industrialization of space, which I will touch on
later, identify on-board electric power as one of the principal limita
Photovoltaic supplies might be able to be used up to perhaps
50 kW, but higher power levels, such as are needed, for example, by
the space-based propellant processing system which General Dynamics has suggested as a means for expanding shuttle capabilities, probably
require more compact systems.
Yet, aside from one extremely high-risk
400 kWe heat-pipe-cooled reacter design employing even higher-risk thermionic converters, there are no nuclear reacter space power sources
under active consideration today.
And even the high-risk 400 kWe
system study does not include a reacter technology development effort.
The final point of technical concern I wish to bring to your attention is the lack of a responsible, coherent research and technology program aimed at understanding the fabrication, deployment, utilization, evaluation, and maintenance of large structures in space. The preponderance of space activities which have been suggested for the late 1980's and 1990's will require not only the higher levels of onboard power I have already mentioned, but also the use of much larger