A HELIOSPHERIC IMAGER FOR SOLAR ORBITER –
LESSONS LEARNED FROM HELIOS, SMEI, AND STEREO
Bernard V. Jackson, Andrew Buffington, P. Paul Hick,
Mario M. Bisi, and John M. Clover
Center for Astrophysics and Space Sciences, University of California,
California, San Diego
9500 Gilman Drive #0424, La Jolla, CA 9209392093-0424, U.S.A
E-Mail: bvjackson@ucsd.edu
Tel: +1+1-858858-534534-3358
Abstract
The Helios photometers, the Solar Mass Ejection Imager (SMEI) on the Coriolis spacecraft, and the Heliospheric
Imagers (HIs) on STEREO all point the way to optimizing remote-sensing Thomson-scattering observations from
Solar Orbiter. Here, we present those instrument specifications and data processing steps required for a successful
heliospheric imager, and the measurements that make the best use of this remote-sensing system. Properly designed
and calibrated, this instrument is capable of determining zodiacal-dust properties, and of three-dimensional
reconstructions of heliospheric electron density over large volumes of the inner heliosphere. Such a system can
measure fundamental properties of the inner heliospheric plasma, provide context for the in situ monitors on board
Solar Orbiter, and enable physics-based analyses of this important segment of the Sun-Spacecraft connection.
HELIOS
Twin
HELIOS
spacecraft:
31º photometer -->
the three
photometers 16º photometer -->
^
are shown
|
90º photometer
as tubes with
blackened ends.
STREAM,
EJECTA
SHOCK A
Solar wind configuration near
Earth inferred from in situ data
from five spacecraft, L. Burlaga
(GSFC).
Carrington
rotation 1681 26
April – 6 June
1979 Helios 2
reconstruction and
density time series
comparison of
time-dependent
model with Helios
2 spacecraft in situ
observations. Only
the northern
hemisphere is
reconstructed.
Solar wind configuration near Earth inferred
from remote sensing data (Helios photometer)
from one spacecraft, B. Jackson ( U. California,
San Diego).
Reconstruction of the
7 May CME at 12 UT
10 May 1979
Brightness of the Sky relative to the Sun’s brightness
with distance from the Sun versus solar elongation
(1.0/R2 Model). Model assumes 10 e- cc at 1 AU,
(Zodiacal cloud and electron brightness measured)
SMEI
28 May 2003 CME event
sequence
(From Jackson et al., 2008.)
Remote observer views
ACE
Halo CME
3D reconstruction brightness
3D Mass determination
Wind
Ecliptic cut
Meridional cut
HAF 3D model brightness
comparison at the same time
24-25 January 2007 direct and
difference image CME analysis
SMEI daily
view of the
Gegenschein
shock
UCSD SMEI Web page http//:smei.ucsd.edu
STEREO
STEREO shows unprecedented ecliptic
detail, and can track CMEs outward
from their origin along the Sun-Earth line.
Spectacular
HI-1A image
24-25 January 2007 CME analysis
20º
SMEI and STEREO HI 1 and HI 2 Comparison
ThreeThree-Dimensional (3D) Reconstructions (CCMC Model)
SMEI Precision Photometry allows the UCSD 3D reconstruction.
Heliospheric Analyses:
The outward-flowing solar
wind structure follows very
specific physics as it moves
outward from the Sun.
Heliospheric ComputerAssisted Tomography
(C.A.T.) analyses (right)
provide the line-of-sight
segment distributions for
consecutive half-day
Carrington Coordinate inner
boundaries for each sky
location during mid-April
2008 from SMEI
observations (right). Lineof-sight weighting and
location are inverted on this
inner boundary to provide a
3D solar wind model to fit
observational parameters.
Heliospheric line-of-sight weighting:
Line-of-sight weighting values for each sky location in
SMEI.
The “traceback” matrix:
In the traceback matrix (depicted below) the
location of the upper level data point (starred) is an
interpolation in x of x2 and the unit x distance –
x3 distance or (1 – x3). Similarly, the value of t
at the starred point is interpolated by the same
spatial distance. Each 3D traceback matrix contains
a regular grid of values x, y, t, v, and
m that locates the origin of each point in the grid
at each time, and its change in velocity and density
from the heliospheric inner solar wind boundary.
The traceback matrix allows any heliospheric model
to be used as a “kernel” in the UCSD 3D analysis.
When SMEI Thomson-scattering data
are used in the current UCSD timedependent inversion, several hundred
thousand lines of sight over a monthlong time interval are used, and
resolutions over the whole heliosphere
at half-day cadences and digital
resolutions of 6.7˚ x 6.7˚ in
heliographic coordinates are available.
Higher resolutions using these data:
Higher 3D resolutions are available
from the SMEI data. Only about 1/50th
of the lines of sight available from
SMEI data are used in current 3D
reconstruction analyses, and this is
predicated by computer processing
time: how well SMEI data can be
cleaned of high energy particle hits,
auroral light, computer memory. At
SMEI launch six years ago, processing
kept up approximately in real time at
these resolutions using a bank of PC
computers. Now a single PC can
process the same data set in less time!
Four
years
ago
Now! One computer
replaces all the others
Photometric images require
extreme attention to noise
levels in an imaging system
Summary and Future
• The UCSD SMEI 3D reconstruction model is currently available and running at the CCMC.
• The USCD SMEI web pages from http://smei.ucsd.edu/ present 3D-reconstuctions of the global
heliosphere since SMEI first light in February 2003 to the present.
• We continue to upgrade our model and these analyses as we learn more about them in comparison with
other data sets as they become available, particularly using multi-point in situ data sets in comparison.
• We expect that the unprecedented results from Thomson-scattering remote sensing imagers will continue
to provide a unique scientific contribution to future spacecraft missions including Solar Orbiter.
• Photometric-quality images require extreme attention to the detail of noise levels from an imaging
system and careful control of stray light from the instrument bus, especially when the large fields of
view required by 3-dimensional analyses near the spacecraft are deemed important.
Primary References:
Buffington, A., Bisi, M.M., Clover, J.M., Hick, P.P., Jackson, B.V., Kuchar, T.A., and Price, S.D., 2009, ‘Measurements of the Gegenschein Brightness from the Solar Mass Ejection Imager (SMEI)’, Icarus (in
press).
Jackson, B.V., A. Buffington, P.P. Hick, R.C. Altrock, S. Figueroa, P. Holladay, J.C. Johnston, S.W. Kahler, J. Mozer, S. Price, R.R. Radick, R. Sagalyn, D. Sinclair, G.M. Simnett, C.J. Eyles, M.P. Cooke, S. J.
Tappin, T. Kuchar, D. Mizumo, D.F. Webb, P. Anderson, S.L. Keil, R. Gold, and N.R. Waltham (2004), ‘The Solar Mass Ejection Imager (SMEI) mission’, Solar Phys. 225, 177.
Jackson, B.V., M.M. Bisi, P.P. Hick, A. Buffington, J.M. Clover, and W. Sun (2008), ‘Solar Mass Ejection Imager (SMEI) 3D Reconstruction of the 27-28 May 2003 CME Sequence’, J. Geophys Res., 113,
A00A15, doi:10.1029/2008JA013224.
D. F. Webb, T. A. Howard, C. D. Fry, T. A. Kuchar, D. Odstrcil, B. V. Jackson, M. M. Bisi, R. A. Harrison, J. S. Morrill, R. A. Howard, and J. C. Johnston, ‘Study of CME Propagation in the Inner Heliosphere:
SMEI and STEREO HI Observations of the January 2007 Events’, Solar Phys., 256, 239-267, DOI: 10.1007/s11207-009-9351-8.