Download Don`t Limit the Reach of Space Exploration Humans explore. We

Don’t Limit the Reach of Space Exploration
Humans explore. We have explored unceasingly throughout history, continually advancing the
frontiers of our knowledge and understanding as well as our geographical frontiers. Inspired by the feats
of such explorers as Columbus and Magellan, Lewis and Clark, Perry and Shackelton, Gagarin and
Armstrong, we tend to equate exploration with human exploration—with “boldly going where no one has
gone before.” But this definition of exploration is too narrow. It ignores a different mode of exploration,
one that uses technology to extend the human senses to places inaccessible or inhospitable to the human
presence.
Now, human exploration is embarking on an ambitious journey to the nearest planet, Mars. It is a
long-term and expensive endeavor, which may well turn out to be worth the effort. But, should other
forms of space exploration be cancelled or curtailed to make this new, but limited, exploration vision
possible? We think and hope not. Space exploration has never been limited to places where it is feasible
to send only humans.
The balance between the two modes of exploration, human and robotic, is now threatened. NASA
appears poised to shut down seven of its satellites that study the space environment and to considerably
reduce funding for the supporting branches of science: solar physics, space physics, atmospheric physics,
and astrophysics. The impact of these cuts will limit future robotic and scientific exploration. They will
also limit the ability of our community of space scientists to aid human exploration by defining and
learning to forecast the serious hazards in space.
The Aldridge report, which considered how to implement the Exploration Vision, found that “the
space exploration vision will be enabled by scientific knowledge, and will enable compelling scientific
opportunities to study the Earth and its environs, the solar system, planetary systems, and the universe”1.
History supports this approach. Exploration builds knowledge, which, in turn, enables expansion of the
human frontier. It is critical, as we prepare to move into new frontiers, that we continue to explore
broadly. Retreating from the frontiers of robotic exploration to send humans forth would not be wise.
The consummate early space explorer is Galileo, who probed the heavens with the newly invented
telescope, discovering sunspots and the moons of Jupiter and inaugurating a new era in study of the
cosmos. The modern equivalents to Galileo’s simple device are the great ground- and space-based
observatories that have measured the residual radiation from the Big Bang, observed the earliest starforming galaxies, and detected supermassive black holes. They have captured the death of stars and the
birth of planets and, within our solar system, have probed the interior of the Sun, revealed spectacular
auroras on Jupiter and Saturn, and allowed us to glimpse the icy worlds that populate the trans-Neptunian
region.
Technology not only enables us to study the cosmos remotely; it also allows us to sample the stuff of
the cosmos directly—through measurements by robotic spacecraft, which, like the telescope, extend our
senses to places where human explorers cannot go. Robotic explorers have given us a detailed knowledge
of Earth’s space environment and of its interaction with the Sun. Unmanned probes have visited all the
planets except Pluto—and a mission to Pluto is now being readied. The Galileo probe recently completed
an extensive 8-year exploration of Jupiter, its moons, and its giant magnetosphere (the largest object in
the solar system), while Cassini has just embarked on its tour of the Saturn system. Imaging from both
orbiting spacecraft and landers have shown us a variety of exotic landscapes—the windswept plains of
Mars, the crevice-riven ice crust of Europa, the sulfurous surface of volcanic Io, and most recently, the
hydrocarbon lakes of smog-shrouded Titan. Robotic probes have charted the heliosphere—the part of the
galaxy dominated by the Sun’s influence—in three dimensions, and soon a solar probe may fly to within
4 solar radii of the Sun, one of the last unexplored parts of the solar system and the birthplace of the
heliosphere itself. This, humankind’s first visit to a star, promises to be a major milestone in our
understanding of the Sun and of other Sun-like stars as well. And scientists and engineers are working to
develop the technology that will someday enable an interstellar probe to cross the boundary of the
heliosphere into the galactic environment beyond.
Although our robotic explorers have, so far, been confined to the heliosphere, what they have taught
us about the rich variety of space environments within the solar system has contributed to our
understanding of the behavior of the universe as a whole. With the advent of the space age, the
heliosphere became a unique laboratory where certain universal physical processes could be explored in
situ. Processes such as magnetic reconnection, energetic particle acceleration, and magnetohydrodynamic
turbulence occur in all astrophysical systems but are accessible for detailed study only in our solar
system.
It is the second mode of exploration—the extension of the human senses through remote sensing
and robotic probes—that, coupled with theoretical and modeling studies, has given us the bulk of our
knowledge and understanding of the universe, the solar system, and the immediate space environment of
our home planet Earth.
Besides its importance as basic science, the understanding that our robotic explorers have given
us of the effects of solar activity on the terrrestrial and planetary space environments has significant
utilitarian value. Solar storms produce disturbances in Earth’s space environment, for example, that can
interrupt power grids and communications and interfere with navigation systems. Satellites may be
damaged or disabled as energetic particles crash through them, while astronauts orbiting Earth or en route
to the Moon and Mars may be exposed to dangerous or even lethal radiation from solar energetic particle
events. As we improve our knowledge of the effects of the Sun’s activity on the Earth, Moon, Mars, and
other planets, we will be better able to specify the conditions and hazards of the space environment and to
keep human technology and astronauts out of harm’s way - from low-Earth orbit all the way to other
planets.
The scientific community has identified the critical problems of Solar and Space Physics in a
recent Decadal Survey by the National Research Council2. To solve these problems we must continue our
robotic exploration of the Sun, the heliosphere, and the space environments and atmospheres of Earth and
the other planets. These critical problems are designed to aid and enhance human exploration and human
technology. These critical problems are:
1. Understand the structure and dynamics of the Sun’s interior, the generation of solar magnetic
fields, the origin of the solar cycle, the causes of solar activity, and the structure and dynamics of
the corona.
2. Understand heliospheric structure, the distribution of magnetic fields and matter throughout the
solar system, and the interaction of the solar atmosphere with the local interstellar medium.
3. Understand the space environments of Earth and other solar system bodies and their dynamical
response to external and internal influences.
4. Understand the basic physical principles manifest in processes observed in solar and space
plasmas.
5. Develop near-real-time predictive capability for understanding and quantifying the impact on
human activities of dynamical processes at the Sun, in the interplanetary medium, and in Earth’s
magnetosphere and ionosphere.
The scientists and engineers involved in this study recommended that the government focus on these
goals to further fundamental understanding of the space environment and its effects on technologies and
human space flight. These individuals continue to believe strongly that by addressing these questions, we
will build beyond a decade-long renaissance in understanding the many physical processes that link the
Sun’s intrinsic dynamics through interplanetary space to the environments of the Earth and other planets.
To solve the critical problems of solar and space physics, new missions are needed that explore
and image critical regions and phenomena. In addition, we now recognize the unprecedented power of the
diverse array of scientific satellites in space and observatories on Earth, which are complemented by
capable computer models that ingest observations to make predictions of increasing value and accuracy.
This collective of observatories - a Great Observatory for our Earth and solar system’s space environment
(just as the Hubble, Chandra, and Spitzer telescopes are for the distant universe) - has grown to be much
greater than the sum of its parts. Extended operation of many existing missions provides an economical
way of advancing the understanding of critical space processes. Operating spacecraft often add
significant value to the measurements anticipated from newly launched spacecraft because spatially
distributed probes are invaluable for understanding the extended spatial domain that influences the Earth,
planets, and the solar system as a whole. Continuity of measurements is often needed because many
processes must be observed over one or two solar cycles before they can be fully understood.
The challenge that NASA faces today is how to advance human exploration while not retreating
from robotic and scientific exploration. We urge NASA to continue to explore broadly as it has since its
creation. The most fruitful interactions between scientific disciplines, those that transform our view of the
world and cosmos, have rarely been planned or foreseen, and they usually were many years in the
making. To narrow our vision now will weaken the very fabric of exploration in the future. In short, we
urge NASA to maintain the reach of robotic and scientific exploration as it readies a new era of human
exploration.
1
A Journey to Inspire, Innovate, and Discover, Finding 7 – Report of the President’s Commission on Implementation
of United States Space Exploration Policy (the “Aldridge Report”), 2004.
2
The Sun to the Earth and Beyond--A Decadal Research Strategy in Solar and Space Physics, National Research
Council, The National Academies Press, Washington, D. C., 2003.
Signatories:
Dr. Nathan Schwadron
Principal Scientist
Southwest Research Scientist
Dr. Richard Anthes
President
University Corporation for Atmospheric Research
Dr. Daniel Baker
Director, Laboratory for Atmospheric and Space Physics
Professor, Astrophysical and Planetary Sciences
University of Colorado
Dr. James L. Burch
Vice-President
Space Science and Engineering Division
Southwest Research Institute
Dr. James F. Drake
Professor, Department of Physics and
the Institute for Physical Science and Technology
University of Maryland
Dr. Lennard Fisk
Thomas M. Donahue Collegiate Professor of Space Science
University of Michigan
Dr. Jeffrey Forbes
Professor, LtCol. USAFR Retired
Department of Aerospace Engineering Sciences
University of Colorado
Dr. Maura Hagan
Acting Director, Advanced Study Program
Senior Scientist, High Altitude Observatory
National Center for Atmospheric Research
Dr. Rod A. Heelis
Cecil and Ida Green Honors Professor of Physics
Director, Hanson Center for Space Sciences
University of Texas at Dallas
Dr. Jack R. Jokipii
Regents' Professor
University of Arizona
Department of Planetary Sciences
Dr. Timothy Killeen
Director
National Center for Atmospheric Research (NCAR)
Dr. Margaret Kivelson
Distinguished Professor of Space Physics
Department of Earth and Space Sciences and
Institute of Geophysics and Planetary Physics
UCLA
Dr. Louis Lanzerotti,
Distinguished Professor of Physics
New Jersey Institute of Technology
Dr. William S. Lewis
Principal Research Scientist
Southwest Research Institute
Dr. Eugene Parker
Professor
University of Chicago
George Siscoe,
Research Professor
Department of Astronomy
Boston University
Karel Schrijver
Astrophysicist
Lockheed Martin Adv. Technology Ctr.,
Solar and Astrophysics Lab