Solar Space MissionsOSO-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

• 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

ORBITING SOLAR OBSERVATORIES (OSO’s)

• OSO 1 launched March 7, 1962 Mass: 208 kg.

• OSO 2 launched February 3, 1965 Mass: 247 kg. Harvard EUV spectrometer/ spectroheliograph HV failure – not uncommon in early days

• OSO C launched August 25, 1965 Mass: 280 kg Launch Failure.

• OSO 3 launched March 8, 1967 Mass: 281 kg

• OSO 4 launched Oct. 15, 1967 Mass: 272 kg. Harvard Instrument: EUV imaging, spectra, first model of CH’s -- 1 arc min spatial resolution

• OSO 5 launched Jan. 22, 1969 Mass: 291 kg.

• OSO 6 launched August 9,1969 Mass: 290 kg. Harvard Instrument: 35 arc sec resolution

• OSO 7 launched Sept. 29, 1971 Mass: 635 kg.

• OSO 8 launched June 21, 1975 Mass: 1,066 kg. Demonstrated corona not heated by sound waves.

OSO Chronology

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 (NRL) Film

SO82B 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 304

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

• 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 long-wavelength sides of a line profile to different detectors to allow velocity imaging ("Dopplergrams"). A polarimeter could be inserted behind the exit aperture.

• 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.

• 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.

• 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 carried a battery of instruments designed to study solar flares and the active solar atmosphere:

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:– Bragg Crystal Spectrometer (BCS) US and GB– Wide Band Spectrometer (WBS) Japan– Soft X-Ray Telescope (SXT) U.S.– Hard X-Ray Telescope (HXT). 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.

• 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.

• 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.

• 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

Soft X-ray Telescope

Spacecraft

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.

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 Hard X-Ray Telescope (HXT)

Yohkoh Soft X-ray Image

                                                                                                                   

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                               Page Created by Ryan McWilliams and Piet Martens

Yohkoh Soft X-ray Image Ground-based White Light Image

Yohkoh Soft X-ray Images from Solar Maximum to Solar Minimum

Solar Science Report: Yohkoh

Yohkoh observes two sigmoids 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