Transcript Slide 1

Solar Space Missions
OSO-1 to OSO-8 launches 3/62 until 6/75 – see OSO viewgraphs
Skylab
5/14/73 – 2/8/74
UV and XUV spectra, EUV/Soft X-ray/XUV imaging, WLCG
P78-1
1979-1985
X-ray spectra, WLCG
SMM
2/14/80 – 12/89
TSI, WLCG, UV and X-ray Instruments
Spacelab2
1985 for 2 wks
UV spectra, high resolution white light imaging
Spartan 201
Flights: 93,94,95,97,98 UV and WL CG’s
Yohkoh
8/30/91 – 12/01
Soft & Hard X-ray Imaging; X- & Gamma-ray spectra
SOHO
12/2/95 – date
UV & WL CG’s, helioseismology, photospheric mag
field, XUV & EUV spectra and imaging
TRACE
4/2/98 – date
High resolution (1”) EUV imaging, movies of corona
RHESSI
2/15/02 –date
Full disk imaging, spectra in hard-X and Gamma Rays
GOES-12
7/23/02 – date
Full disk imaging in soft X-rays
SMEI
1/6/03
Wide field heliospheric imaging
SORCE
1/25/03
Total Solar Irradiance
STEREO
11/05
Stereo imaging using two spacecraft
Solar-B
9/06
High res. vector magnetic field, EUV and Soft X-ray spectra, imaging
SDO
4/08
High resolution (time, space) helioseismology, high resolution EUV
coronal imaging
Solar Probe
> 2010
In situ data in inner heliosphere, imaging to r = 3 Rsun from Sun
Solar Orbiter > 2011
Probe inner heliosphere, insitu data, solar imaging/spectra to r = 0.2 AU
ORBITING SOLAR OBSERVATORIES (OSO’s)
• OSO’s were the first stabilized space platforms for solar-oriented scientific
instruments.
• OSO’s studied the Sun, flares, and other solar activity at X-ray, gamma and
ultraviolet wavelengths. Some OSO’s acquired spectra, others spectra and images
(typical resolution: 30 arc sec to 1 arc min)
• The lower spinning (30 rpm) wheel section acted as a gyroscope to stabilize the
spacecraft. The upper fan-shaped section, the "sail," remained pointed toward the
sun during OSO daytime.
• Experiments in the wheel scanned the sun every 2 sec; those in the sail pointed
continuously at the sun.
• The OSO’s were orbited about 565 km above earth by Delta rockets and circled the
earth every 96 minutes. Each OSO carried up to 9 experiments
OSO Chronology
•
OSO 1 launched March 7, 1962
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OSO 2 launched February 3, 1965 Mass: 247 kg.
Harvard EUV spectrometer/ spectroheliograph
HV failure – not uncommon in early days
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OSO C launched August 25, 1965
Mass: 280 kg
Launch Failure.
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OSO 3 launched March 8, 1967
Mass: 281 kg
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OSO 4 launched Oct. 15, 1967
Mass: 272 kg.
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OSO 5 launched Jan. 22, 1969
Mass: 291 kg.
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OSO 6 launched August 9,1969
Mass: 290 kg.
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OSO 7 launched Sept. 29, 1971
Mass: 635 kg.
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OSO 8 launched June 21, 1975
Mass: 1,066 kg.
Mass: 208 kg.
Harvard Instrument: EUV imaging, spectra, first
model of CH’s -- 1 arc min spatial resolution
Harvard Instrument: 35 arc sec resolution
Demonstrated corona not heated by sound waves.
Skylab Mission
Skylab 1 Launch of Skylab via unmanned Saturn V rocket
Skylab 2 1st astronaut crew, fixed solar panel, installed sun screen, 1
month mission, solar film recovered & returned
Skylab 3 2nd crew, extensive solar data, film returned, 2 month mission
Skylab 4 3rd astronaut crew, extensive solar data, comet data, 3 month
mission
Skylab Apollo Telescope Mount Instrumentation
SO52
White Light Coronagraph (HAO)
Film
SO54
Soft X-ray Telescope (AS&E)
Film
SO55
EUV Telescope Spectrometer (Harvard)
Electronic
SO56
Soft X-ray Telescope (MSFC)
Film
SO82A XUV Spectrometer/imager
SO82B
(NRL)
Film
UV Spectrometer (NRL)
Film
H-alpha Telescope (pointing telescope - Harvard)
Film
Some results:
Skylab coronagraphic photos show how frequent (several times/day) and spectacular
CME’s are – little known about CME’s prior to Skylab.
Long-term observations in soft x-rays show evolution of active regions, CH’s, coronal
bright points – revolutionizing perceptions about coronal structure – loop structure.
High resolution (few arc sec) EUV, XUV, and Soft X-ray images and spectra (UV, EUV,
XUV) provide wealth of data for modeling chromosphere, transition region, and corona.
Excellent multi-wavelength (UV to Soft X-rays) data on flares, leading to major
improvements in understanding of these events.
CH and CME data ’s lead result in much improved understanding of connection
between solar features/events and solar wind.
SO82 A Photo of December 1973 Solar Eruption In He II l304
Owen Garriott at ATM Control Panel -- Skylab-3
Ed Gibson at ATM Control Panel -- Skylab-4
“ATM -- like playing 3 pianos at same time”
Start of Skylab “road” race
Alan Bean doing gymnastics -- Skylab 2 Bean
also flew on Apollo 12, 4th man to walk on moon.
Solar Maximum Mission – December 14, 1980 – December, 1989
SMM carried a battery of instruments designed to study solar flares and the
active solar atmosphere:
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Coronagraph/Polarimeter (CP)
White light coronagraph to detect and observe CME’s and study coronal evolution.
•
Ultraviolet Spectrometer and Polarimeter (UVSP)
Wavelength Range: 1170 - 1800 Å in 2nd order; up to 3600 Å in 1st order. Gregorian telescope
~ 2" resolution, Ebert-Fastie spectrometer, with 5 photomultiplier detectors. Telescope secondary
could be rastered to make image of area up to 256" x 256". Slit wheel gave entrance apertures
ranged in size from 1" x 1" to 125" x 286", and the exit slits ranged from 0.01 to 3.0 Å in second
order. Several of the exit slits biescted by beamsplitter prisms to direct the short- and longwavelength sides of a line profile to different detectors to allow velocity imaging ("Dopplergrams").
A polarimeter could be inserted behind the exit aperture.
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Soft X-Ray Polychromator (XRP)
Hard X-Ray Burst Spectrometer (HXRBS)
Energy Range: 25 - 500 keV in 15 channels, 128ms time resolution. Designed to examine the role
of energetic electrons in solar flares by measuring the variations in intensity and energy of the
hard X-ray fluxes.
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Hard X-ray Imaging Spectrometer (HXIS)
Gamma Ray Spectrometer (GRS)
Energy Range: 10 - 140 MeV for Gamma Rays and neutrons above 20 MeV, and 10 - 140 keV for
hard X-rays. Also measured 7 nuclear lines between 0.3 and 0.9 Mev.
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Active Cavity Radiometer Irradiance Monitor (ACRIM)
Measured total solar irradiance (primarily white light)
SMM payload originally had XUV spectrometer/spectroheliometer, but development terminated
due to cost/development problems.
SMM Coronagraph/Polarimeter
SMM White Light Coronagraph Images of Two Events
Total Solar Irradiance – Shows solar cycle variation of ~0.1%, and
competing effects of sunspots (low values of) and plages (high values)
SMM was rescued and
repaired in a 1984 Space
Shuttle Challenger mission.
Astronaut in
maneuvering
unit
• Yohkoh (“Sunbeam”) was launched August 30, 1991 and obtained data until December
2001. The scientific objective was to observe the energetic phenomena taking place on the
Sun, specifically solar flares in x-ray and gamma-ray emissions.
•
Instruments:
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–
–
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Bragg Crystal Spectrometer (BCS)
Wide Band Spectrometer (WBS)
Soft X-Ray Telescope (SXT)
Hard X-Ray Telescope (HXT).
US and GB
Japan
U.S.
Japan
•
BCS has four bent crystal spectrometers. Each is designed to observe a limited range of soft x-ray
wavelengths containing spectral lines that are particularly sensitive to the hot plasma produced
during a flare. The observations of these spectral lines provide information about the temperature
and density of the hot plasma, and about motions of the plasma perpendicular to the line of sight.
Time resolution one second.
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WBS has three detectors: a soft x-ray, a hard x-ray, and a gamma-ray spectrometer. They provide
spectra from soft x-rays to gamma rays with a time resolution on the order of one sec. Like the
BCS, images are not obtained.
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SXT images x-rays in the 0.25 - 4.0 keV range. It uses thin metallic filters to acquire images in
restricted portions of this energy range. SXT can resolve features down to 2.5 arc sec in size.
Information about the temperature and density of the plasma emitting the observed x-rays is
obtained by comparing images acquired with the different filters. Flare images can be obtained
every 2 seconds. Smaller images with a single filter can be obtained as frequently as once every
0.5 seconds.
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HXT observes hard x-rays in four energy bands through sixty-four pairs of grids. These grid pairs
provide information about 32 spatial scales of the x-ray emission. This information is combined on
the ground to construct an image of the source in each of the four energy bands. Structures with
angular sizes down to about 5 arc seconds can be resolved. These images can be obtained as
frequently as once every 0.5 seconds.
Yohkoh
Spacecraft
Soft X-ray
Telescope
SXT is a glancing incidence telescope of 1.54 m focal
length which forms X-ray images in the 0.25 to 4.0 keV
range on a 1024x1024 CCD detector. A selection of thin
metallic filters located near the focal plane provides the
capability to separate the different X-ray energies for
plasma temperature diagnostics. A companion visible light
telescope provides knowledge of the location of X-ray
images with respect to features observable in visible light.
Yohkoh Hard X-Ray Telescope (HXT)
HXT is a Fourier synthesis type imager with 64 bi-grid modulation
subcollimators (SC's).
Each SC has a different pitch and/or a position angle of collimator
grids, together with a NaI (Tl) scintillation crystal and a detector
photomultiplier located behind the SC.
The number of hard X-ray photons passing through a single SC
is periodically modulated with respect to the incident angle, which
gives a modulation pattern of the corresponding SC, and count
rate data obtained by each detector which can be regarded as a
spatial Fourier component (+ DC level) of a hard X-ray image.
When a flare-mode is triggered, a set of 64 hard X-ray count rate
data is accumulated every 0.5 s (= the highest temporal
resolution) in four energy bands between 14 and 93 keV (L, M1,
M2, and H bands, respectively) and is transferred from HXT to
the Data Processor (DP).
From these data hard X-ray images can be synthesized using
image restoration procedures such as the Maximum Entropy
Method (MEM).
Field-of-view (FOV) of HXT is about 35 by 35 arcminutes (whole
Sun) allowing flares anywhere on Sun to be imaged.
Yohkoh Soft X-ray Image
Yohkoh Soft X-ray Image
Ground-based White Light Image
Back
Page Created by Ryan McWilliams and Piet Martens
Yohkoh Soft X-ray Images from Solar Maximum to Solar Minimum
Solar Science
Report: Yohkoh
Yohkoh observes two sigmoids
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SXT observed two so-called sigmoidal
active regions at similar longitudes north
and south of the equator on May 27, 1999
indicated by the arrows in the figure.

Sigmoidal regions are dominated by “S”
shaped magnetic loops containing hot
plasma. The “S” shape is indicative of a
twisted magnetic field carrying magnetic
free energy capable of powering an eruption.


A major Yohkoh discovery is that sigmoidal regions tend to launch CMEs.
Both of the above regions erupted, confirming the importance of the sigmoidal
structures.
“S” Marks the Spot
Prior to Coronal Mass Ejection
After Coronal Mass Ejection
Yohkoh Hard X-Ray Image & Light Curve of Flare,
Yohkoh WBS
Spectrum