Solar Probe - The First Flight Into the Sun’s Corona
Kenneth A. Potocki and Peter D. Bedini
Johns Hopkins University Applied Physics Laboratory
Abstract. The NASA Solar Probe mission to the inner frontier of the heliosphere is a part of the Sun-Earth Connection
theme within the Office of Space Science. A NASA-appointed Science Definition Team has defined a Solar Probe
mission and its scientific objectives. These include making measurements to understand the processes that heat the solar
corona and produce the solar wind, subjects of continuing scientific debate. The Solar Probe mission will accomplish
these objectives with a combination of in situ measurements designed to characterize the local heating and acceleration
of plasma near the Sun and high resolution images to detect small-scale, transient magnetic structures at and around the
Sun. In order to sample the solar corona acceleration region, Solar Probe will fly to four solar radii from the center of the
Sun in an orbit inclined 90° to the plane of the ecliptic. Engineering solutions to design a probe that can withstand the
near-Sun environment have been proposed for several decades. Current status of the Solar Probe concept is provided in
this paper.
objectives into three groups. Listed in priority order,
they are:
INTRODUCTION
NASA’s Sun-Earth Connection Theme seeks to
understand our changing Sun, and its effects on the
solar system, life, and society. Solar activity, including
CMEs, couples into interplanetary space. Only by
exploring the outer coronal regions can we fully
understand this coupling. The solar wind forms
planetary magnetospheres, which shield the Earth and
other planets from interplanetary and galactic particles,
energy, and mass. Solar wind bursts cause magnetic
storms that can damage Earth-orbiting spacecraft,
cause ground power system outages, and create
radiation hazards to man in space. The variability of
the solar wind and embedded magnetic fields controls
magnetospheric/ionospheric dynamics and the aurora
at Earth. The solar wind is the origin of
magnetospheres and of the aurora on Earth, and Solar
Probe will study the origin of the solar wind.
Group 1 Objectives
• Determine the acceleration processes and find the
source regions of the fast and slow solar wind at
maximum and minimum solar activity;
• Locate the source and trace the flow of energy that
heats the corona;
• Construct the three-dimensional coronal density
configuration from pole to pole and determine the
subsurface flow pattern, the structure of the polar
magnetic field, and their relationship with the
overlying corona;
• Identify the acceleration mechanisms and locate the
source regions of energetic particles, and determine
the role of plasma waves and turbulence in the
production of solar wind and energetic particles.
SCIENCE OBJECTIVES
The present Solar Probe study is an engineering
study, and relies solely on the 1999 Science Definition
Team (SDT) findings for any science direction. The
SDT report1 and the associated Mission and Project
Description document2 are the governing documents.
The SDT categorized the Solar Probe science
Group 2 Objectives
• Investigate dust rings and particulates in the nearSun environment;
• Determine the outflow of atoms from the Sun and
their relationship to the solar wind;
CP679, Solar Wind Ten: Proceedings of the Tenth International Solar Wind Conference,
edited by M. Velli, R. Bruno, and F. Malara
© 2003 American Institute of Physics 0-7354-0148-9/03/$20.00
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Group 3 Objectives
The Johns Hopkins University Applied Physics
Laboratory (JHU/APL) has been tasked by the
Goddard Space Flight Center to perform a new
conceptual mission design study of the Solar Probe
Mission with support from the Jet Propulsion
Laboratory.
• Determine the role of x-ray microflares in the
dynamics of the corona; and
Key Technical Challenges
• Establish the relationship between remote sensing,
near-Earth observations at 1 AU and plasma structures
near the Sun.
• Probe nuclear processes near the solar surface from
measurements of solar gamma rays and slow neutrons.
Survive 3000-Sun intensity at perihelion (four
solar radii)
Maintain reliable power over mission life
Protect against hostile near-sun dust environments
Control attitude during flyby for survival imaging
Minimize coronal
communications
scintillation
effects
of
Accommodate in-situ and imaging instruments
New technology is being considered for its
capability to solve these challenges. Solar Probe will
be a mission of totally new discovery, not incremental
science.
FIGURE 1. Ulysses/SWOOPS data overlaid on solar
images provided by the EIT and LASCO/C2 instrument
teams on SOHO and the Mauna Loa coronagraph team from
NCAR’s High Altitude Observatory.
FIGURE 2. Solar Probe Mission trajectory showing the use
of the Jupiter Gravity Assist to achieve a polar solar orbit.
CURRENT STATUS
Solar Probe is now a mission study in the SunEarth Connection Theme.
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FIGURE 3. Solar Probe Perihelion Trajectory with an inset
view of the 16-hour period around perihelion.
ACKNOWLEDGMENTS
Work on this engineering study is supported under
NASA Contract NAS5-01072.
REFERENCES
1. Solar Probe: First Mission to the Nearest Star, Report of
the NASA Science Definition Team for the Solar Probe
Mission, (1999).
2. Solar Probe - Mission and Project Description, NASA
OSS Announcement of Opportunity AO 99-OSS-04
Europa Orbiter/Pluto-Kuiper Express/Solar Probe,
(1999).
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