On April 29-30, 2003, The Planetary Society, the Association of Space
Explorers, and the American Astronautical Society held a workshop at the George
Washington University’s Space Policy Institute about the future of human space
transportation. The following conclusions have been endorsed by The Planetary
Society and the American Astronautical Society and by a number of astronauts
present at the workshop.

CONCLUSIONS

Human space exploration is a great and unifying enterprise of planet Earth.
The loss of Columbia reminds us that astronauts are the emissaries of humankind
as part of our civilization’s aspirations for great achievements and new
discoveries. The United States’ commitment to human exploration reflects
humankind’s movement outward from Earth, to become eventually a multi-planet species.
We do this to understand and cope with the limits of Earth, its finite
resources and indeed its finite lifetime, and to satisfy the innate desire of people
to advance civilization and understand their place in the universe. We do this
not just for our own country, but also for all our planet’s citizens.
Furthermore, the space enterprise provides a unique means of building national
intellectual, technical and personal capabilities. It is a commitment to a positive
future.

The Planetary Society, the Association of Space Explorers- USA, and the
American Astronautical Society convened a group of experts at a workshop, in memory
of the Columbia space shuttle crew, to assess launch vehicle requirements to
meet the needs of human space exploration beyond Earth orbit. Our conclusions
from this assessment are:

THE IMPERATIVE

There are strong societal imperatives for exploring space. The natural
curiosity to explore new frontiers coupled with an instinctive desire to preserve
the future of humankind motivates our continued exploration of space. Space
exploration will provide new knowledge and resources for a more prosperous and
secure future.
There are fundamental questions concerning our cosmic origin, our future and
whether or not we are alone in the universe. Science in pursuit of these
questions can provide a credible goal-oriented strategy for an evolutionary
approach to exploring deep space destinations with both robots and humans.
The exploration of deep space by humans will be energized by the goals of
individual nations woven into an international enterprise and infused with a
sense of human destiny in space.

THE DESTINATIONS

The most important scientific destinations for human explorers are the Moon,
Mars, Near-Earth Objects and the Sun-Earth Lagrangian point L2[1] (for
astronomical observatories).

Mars is the ultimate destination for human explorers in the foreseeable
future. Consequently the robotic Mars exploration program should progress beyond
sample return to robotic outposts in preparation for human presence.

A STRATEGY

By adopting a phased approach to human exploration beyond Earth orbit, we can
develop a cost-effective program that is exciting, scientifically rewarding
and for which the risks can be measured and managed.

The initial stages of a robust human exploration architecture can proceed
using existing and currently planned propulsion technologies.

We see no essential role for continuing flight of the shuttle orbiter beyond
its immediate goal of completing construction of the International Space
Station and early transport of crewmembers to and from the Station. As soon as an
alternate mode of human transport into and from low Earth orbit (LEO) is
available, which should be accomplished as soon as possible, the shuttle orbiter
should be retired.

Crew and cargo should be transported separately to increase flexibility,
reduce cost and reduce risk associated with human space exploration.

The underutilized fleet of existing expendable launch vehicles should play a
major role in the next stages of human space exploration, as well as in human
and cargo transportation into LEO.

Increased investment in on-orbit operations and in-space propulsion
technologies is required.

INTERNATIONAL COOPERATION

Exploration beyond Earth orbit is an intrinsically global enterprise. It is
unlikely that any nation acting alone will commit the necessary resources for a
major human exploration mission initiative beyond Earth orbit.

International partnerships provide tangible benefits for human space
exploration. These include broadening public and political support, sharing of the
cost and risk, adding resiliency and enriching the scientific and technological
content.

To this end all space faring nations should strengthen mechanisms for
exchanging information on human exploration activities and plans, increase
international participation in robotic exploration missions, and explore mechanisms for
sharing critical roles among partners.

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1)Lagrangian points (L1-L5) are points in space where the gravitational
forces from the two most nearby influential gravitational masses (in this case the
Sun and Earth) are in equilibrium.