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Assessment of Solar System Exploration Programs 1991 (Chapter 5)
Assessment of Solar System Exploration Programs
1991
5
Detection and Study of Other
Solar Systems
The committee recently published its first report in this area, Strategy for
the Detection and Study of Other Planetary Systems and Extrasolar Planetary
Materials: 1990-2000 (SSB, 1990d). NASA has not yet had an opportunity to
implement the scientific goals and objectives and related recommendation
established in that strategy. This chapter therefore only summarizes the principal
recommendation from the report's Executive Summary and discusses several
parallel activities at the agency.
Initiate, and maintain for at least a decade, systematic observational
planet searches that encompass the widest feasible domain of the planetary
mass versus semimajor axis exploration space. Specifically,
REPORT MENU
NOTICE
MEMBERSHIP 1. Initiate an astrometric observational survey program designed
FOREWORD to track the reflex motion of 100 or more stars in the solar neighborhood (r
SUMMARY
10 parsecs) with a design goal for relative astrometric accuracy of =
CHAPTER 1
10 microarcsec, sufficient in a search of adequate duration to detect and
CHAPTER 2
track Uranus-mass planets in a solarlike system.
CHAPTER 3
CHAPTER 4
2. Obtain and interpret a record of Doppler shifts in stellar spectral
CHAPTER 5
CHAPTER 6 features due to reflex motion, at or above the current measurement
CHAPTER 7
10 m/s-1 for the velocity of the orbital reflex, in a survey
accuracy of
CHAPTER 8
of the duration and extent specified for the astrometric survey.
CHAPTER 9
REFERENCES
3. Until such systematic searches are mounted, maintain ongoing
ground-based searches at their present best accuracies, and investigate
and implement improvement of these accuracies if technically and
financially feasible.
Augment current observational studies of young stellar systems, and
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Assessment of Solar System Exploration Programs 1991 (Chapter 5)
of the physical properties of circumstellar-interstellar dust systems as precursors
to and products of planetary systems, on a variety of spatial and spectral
resolution scales. Survey a statistically meaningful number of stars of varied
masses and types to detect such systems.
Continue investigations of links between interstellar-circumstellar dust
and isotopically "exotic" grains in solar system materials such as primitive
meteorites, interplanetary dust, and comets. Important elements and objectives of
this effort include collection and curation of rare interplanetary asteroidal-
cometary dust particles (IDPs); laboratory identification and analysis of micron to
submicron presolar dust grains preserved in these meteoritic and IDP materials;
and laboratory simulation and theoretical studies of the astronomical dust cycle,
including the formation and physical and chemical processing of interstellar
grains in preplanetary and planet-forming environments.
Improve the capability of theoretical models and computer experiments
to make specific predictions regarding the observational properties of planetary
systems at all stages of their evolution, and further develop models to aid in the
interpretation of existing data.
Encourage the following multidisciplinary activities between the
responsible divisions at OSSA: participation of planetary scientists in the design
and building of future observatories and facility instruments, and in the allocation
of observing time at existing observational facilities; joint support for
multidisciplinary scientific initiatives; and joint development of instrumentation for
extrasolar observation.
Pursue long-range instrumental and strategic initiatives that are
conceptually applicable and potentially valuable to the investigation of extrasolar
planetary materials in later stages of reconnaissance or in subsequent phases of
exploration and intensive study, but that at present are technologically or
theoretically too undeveloped to be of immediate utility in implementing the short-
term strategy proposed in this report.
Prospects for the detection of extrasolar planetary systems have also
been under investigation by the Planetary Systems Science Working Group
(PSSWG), chartered by the Solar System Exploration Division to explore the
science strategy for detecting other planetary systems. Similar to the
recommendations of COMPLEX listed above, the PSSWG has concluded that
NASA should begin a concentrated, long-term effort to detect extrasolar planetary
systems. The PSSWG envisions an evolutionary approach, starting with current
ground-based astrometric and radial-velocity searches, which are capable of
detecting Jupiter-mass planets around stars in the solar neighborhood. The next
step would be major ground- or space-based instruments, using astrometry,
direct imaging, interferometry, or some combination of these techniques. This
effort could potentially allow detection of Uranus-mass planets around the same
nearby stars, or (for imaging techniques) of relatively fine details (with a
resolution of 1 to 10 AU) in the structure of preplanetary disks in the Taurus or
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Assessment of Solar System Exploration Programs 1991 (Chapter 5)
Ophiuchus molecular clouds. Finally, the ultimate instrument might be a lunar-
based interferometer capable of detecting Earth-mass planets or extremely fine
details (at scales 0.1 to 1.0 AU) in preplanetary disks. The Astrophysics Division
has initiated parallel studies of the capabilities of the Large Deployable Reflector
and the Space Infrared Telescope Facility to detect planetary bodies around
nearby stars. Other activities in astrophysics include theoretical studies of star
formation at a center established for that purpose.
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