|
||||||||||||||||
|
||||||||||||||||
|
||||||||||||||||
|
| ||||||||||||||||||||||||||||||||
|
||||||||||||||||||||||||||||||||
Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 1
""'~I.-.-
""
NATIONAL RESEARCH COUNCIL
COMMISSIONON PHYSICALSCIENCES,MATHEMATICS,
AND RESOURCES
r 2101Constitution Avenue Washington, D- C. 20418
OFl'ICE LOCATION:
SPACE SCIENCE BOARD
JOSEPH HENRY BUILDING
21ST STREET AND
PENNSYLVANIAAVENVE, N.W.
3 December 1982
Mr. Jesse W. Moore (EL-4)
Director, Earth & Planetary Exploration
Division
NASA Headquarters
Washington, D.C. 20546
Dear Jesse:
The Committee on Planetary and Lunar Exploration
(COMPLEX) in its strategy for the inner planets recommended
"that the triad of terrestrial planets, earth, Venus, and Mars,
should receive the major focus of exploration of the inner
solar system for the next decade. The ultimate goal in this
exploration is to understand the present state and evolution of
terrestrial planets with atmospheres. The comparative
planetology of these bodies is a key to the understanding of
the earth, its atmospheres and oceans, and the physical and
chemical conditions that lead to the origin and evolution of
life." In reassessing the relative balance of our knowledge of
~
this triad of planets following the achievements of the
Pioneer-Venus mission and the recent Venera missions, we have
concluded again that the nature of the surface of Venus remains
the greatest unknown factor. Therefore, we can reaffirm that
obtaining a global map of the topography and morphology of the
surface of the planet at sufficient resolution to allow
identification of the gross processes that have shaped its
surface is of the highest importance per se and in the context
of the inner planet strategy.
COMPLEX finds that the Venus Radar Mapper (VRM) mission,
as described to the committee at its last meeting, will
adequately address our first priority science objective for
Venus (Strategy for Exploration of the Inner Planets:
1977-1987). It is the committee's understanding that both the
images and the resulting topographic map will cover 90\ of the
surface at better than 1.5 km resolution, that the gravity map
will cover 76\ of the surface at 700 km resolution, and that
the altimetry and gravimetry measurements will be accurate to
75 m and 5 mil1iga1s or better respectively.
The images obtained from the Pioneer-Venus orbiter have
demonstrated the feasibility of synthetic aperture radar
techniques to map the surface of Venus. As a result we are
now able to identify the major physiographic features of the
;- r'
surface and, in a limited sense, to characterize global
Tlte N/dio,"d Raearcll Council is tile principal operanng agency of tile National AcaU"'Y of Sciences and tile National Academy of Engineering
to JerfJegwernment and otllerorganiunon.
OCR for page 2
Mr. Jesse W. Moore
22 October 1982
r Page 2
physiographic provinces. However, the resolution obtained by
the Pioneer-Venus orbiter was not sufficient to identify and
characterize the surface processes that have created the
present physiography. In this regard, the data and findings
from higher resolution capability of VRM will build in a
systematic and rational manner on the knowledge acquired from
Pioneer-Venus.
As you will recall, the SSB and COMPLEX gave a similar
endorsement to the Venus Orbiting Imaging Radar (VOIR) mission
before the agency, because of fiscal restraints, was obliged to
reduce the scope of this mission to the more modest level
represented by the VRM. Because the first priority science
objective in the strategy for Venus has been preserved in the
VRM and because it will address adequately the associated
measurement requirements, COMPLEX believes its endorsement of
VOIR can also be applied to the VRM. The committee notes
that the capability to acquire very high resolution of selected
surface areas is now not possible with the VRM. It is our
understanding that the JPL study team would be willing to
consider and study alternatives to achieve this capability
within the present cost magnitude. The committee requests that
it be regularly advised of progress in this effort. Further,
~
since the briefing of VRM to the committee, it now appears that
the Centaur will replace the IUS as the agency's high energy
upper stage. With this added capability, we wish to be kept
apprised of any changes or new opportunities that may be
considered for VRM. Lastly, there is a reasonable difference
of opinion on selection of the Venus latitude for the VRM
periapsis. In the present orbit configuration with periapsis
at -100, imagery will be obtained of the South Pole and the
larger unmapped area in the Southern hemisphere; however, the
resolution over Ishtar Terra will be inferior to
Pioneer-Venus. Since Ishtar Terra may provide the key to
characterizing the tectonics of Venus, there is merit in
consid~ring the case, and its effect, for moving the periapsis
to +30~ to +40. COMPLEX recommends that the scientific
.
arguments for periapsis location should be given ample
opportunity to resolve the issue, and requests that the
committee be kept informed of its progress.
Finally, we would like to express our serious concern
for the planetary program as reflected in the pacing of new
starts and the shrinking level of support for data analysis and
scientific study. Should the VRM be approved, it will be the
first new start in the program since Galileo in 1977. In the
opinion of the committee, a new-start for tbe planetary program
I'
OCR for page 3
~.
Mr. Jesse W. Moore
r 22 October 1982
Page 3
in FY84 must be accompanied by a sustaining baseline support
for research and analysis mission operations and data analysis,
including theory. Such an action is clearly required to
maintain a healthy program, and it would be clearly perceived
as a positive indication for the u.S. planetary program.
The committee would like to express its thanks for your
effort in organizing the VRM review and requests that you
extend our appreciation to the JPL study team and the members
of the science working group.
We will be happy to discuss these issues further at your.
convenience.
Sincerely,
o.~~~......
D. M. Hunten
Chairman
/'-,"""
~
