There are currently at least 19 satellite missions that relate to the Earth-Sun system, several of them consisting of multiple satellites.

It is worth noting that satellites are usually divided into two classes, research and operational. Most of the satellites described below are research satellites. They have a specific mission and a timeframe for that mission. Often, the mission is extended to the end of the satellites operational life if it is producing useful data. When the mission ends, the satellite is not replaced.

Operational satellites like GOES and POES provide important data on an ongoing basis. Usually, backup satellites are kept in a parking orbit in the case of geostationary satellites or there may be multiple satellites in the case of POES. New satellites and instruments are being continually developed for the program to provide an uninterrupted flow of  data.

The information presented here is just an overview, condensed from the NASA and NOAA data, so you’ll need to go to the web for the details. Also, be aware that on many of the satellites that carry multiple instruments, there maybe different groups operating each instrument and each instrument may have its own website.

The satellites are presented in alphabetical order.

ACE (Advanced Composition Explorer)

Cluster II


GOES (Geostationary Operational Environmental Satellite)

Hinode (Solar-B)

IBEX (Interstellar Boundary Explorer)

POES (Polar Operational Environmental Satellite)

RHESSI (Reuven Ramaty High Energy Solar Spectroscope Imager)

SDO (Solar Dynamics Observatory)

SOHO (Solar and Heliospheric Observatory)

STEREO (Solar Terrestrial Relations Observatory)

THEMIS (Time History of Events and Macroscale Interactions during Substorms)

TIMED (Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics)

TWINS A & B (Two Wide-Angle Imaging Neutral-Atom Spectrometers)

Van Allen Probes



ACE (Advanced Composition Explorer)

Ace was launched on August 27, 1997. ACE observes particles of solar, interplanetary, interstellar, and galactic origins, spanning the energy range from solar wind ions to galactic cosmic ray nuclei.

Instruments – The Advanced Composition Explorer (ACE) spacecraft carries six high-resolution sensors and three monitoring instruments to sample low-energy particles of solar origin and high-energy galactic particles. CRIS: The Cosmic Ray Isotope Spectrometer, ULEIS: Ultra Low Energy Isotope Spectrometer particle instrument, SWICS: Solar Wind Ion Composition Spectrometer SWIMS: the Solar Wind Ions Mass Spectrometer, EPAM: Electron, Proton, and Alpha Monitor particle instrument, MAG: Magnetometer Instrument, SIS: The Solar Isotope Spectrometer, SEPICA: Solar Energetic Particle Ionic Charge Analyzer, SWEPAM: The Solar Wind Electron, Proton, and Alpha Monitor.

Data – ACE is positioned almost a million miles (1.5 million kilometers) from the Earth, situated in the Earth-Sun libration point called L1. By orbiting the L1 point, ACE stays in a relatively constant position with respect to the Earth as the Earth revolves around the Sun. (For more information on the libration or Lagrangian points, see The location of ACE at the L1 libration point between the earth and the sun enables ACE to give about a one hour advance warning of impending geomagnetic activity. With the approximate one hour lead time, this is a good way to get a “heads-up” on expected (as well as unexpected) geomagnetic disturbances.

The NOAA webpage has real-time data from the ACE satellite. The dial indicates the strength of the Bz component of the interplanetary magnetic field.  This component is parallel to the magnetic axis of the earth and indicates how this incoming magnetic field carried on a CME or the solar wind, will couple with the earth’s field. When the interplanetary magnetic field turns south compared to the Earth’s magnetic field, geomagnetic activity will increase. As the Bz (Southward pointed) value becomes more negative, the associated geomagnetic activity increases.

The dial ranges from -50 to +50 nT. The dial is a linear scale from -10 to +10 nT and a different linear scale from -10 to -50 nT and +10 to +50 nT. For values beyond the maximum and minimum, the arrow will stay pegged at the maximum or minimum. If the magnetic field data is absent, the arrow will not appear. The arrow indicates the actual value of the latest 15 minute average of the Bz component of the magnetic field vector. The letters N and S refer to North and South of the magnetic equator. The color bar indicates green for positive values, yellow for small negative values, and red for large negative values of Bz.

ACE has enough remaining fuel to maintain its orbit thru 2024.

Cluster II

Cluster II was launched on July 16, 2000. The Cluster II mission is an in-situ investigation of the Earth’s magnetosphere using four identical spacecraft simultaneously. It will permit the accurate determination of three-dimensional and time-varying phenomena and will make it possible to distinguish between spatial and temporal variations.

Instruments – Each of the four spacecraft carries an identical set of 11 instruments to investigate charged particles, electrical and magnetic fields. These were built by European and American instrument teams led by Principal Investigators. FGM: Fluxgate Magnetometer, EDI: Electron Drift Instrument, ASPOC: Active Spacecraft Potential Control experiment, STAFF: Spatio-Temporal Analysis of Field Fluctuation experiment, EFW: Electric Field and Wave experiment, DWP: Digital Wave Processing experiment, WHISPER: Waves of High frequency and Sounder for Probing of Electron density by Relaxation experiment, WBD: Wide Band Data instrument, PEACE: Plasma Electron And Current Experiment, CIS: Cluster Ion Spectrometry experiment, RAPID: Research with Adaptive Particle Imaging Detectors, WEC: Wave Experiment Consortium (DWP, EFW, STAFF, WBD, and WHISPER).

Data – There website for this site has extensive resources on the discoveries made by this mission and is updated on an ongoing basis. It’s a good place for the latest findings on the behavior of the magnetosphere.


Geotail was launched on July 24, 1992 and is a collaborative project undertaken by the Institute of Space and Astronautical Science (ISAS) and the National Aeronautics and Space Administration (NASA). Its primary objective is to study the dynamics of the Earth’s magnetotail over a wide range of distance, extending from the near-Earth region (8 Earth radii (Re) from the Earth) to the distant tail (about 200 Re). The GEOTAIL spacecraft was designed and built by ISAS. After fulfilling Its original objective of studying the dynamics of the Earth’s magnetotail over a wide range of distance, extending from the near-Earth region (8 Earth radii (Re) from the Earth) to the distant tail (about 200 Re) its orbit was changed. Since February 1995 Geotail has been in an elliptical 9 by 30 Re orbit where it has provided data on most aspects of the solar wind interaction with the magnetosphere.
Instruments – EFD:, MGF:, LEP:, CPI: Comprehensive Plasma Investigation, EPIC: Energetic Particle and Ion Composition,  PWI:  Plasma Waves Investigation
Data – The websites are not particularly user-friendly, but raw data is available for serious research.

GOES  (Geostationary Operational Environmental Satellite)

The GOES satellites are in a geostationary orbit above the equator. Their primary mission is weather photos, but they also contain sensors to monitor the Space Environment above the earth. The Geostationary Operational Environmental Satellite Program (GOES) is a joint effort of NASA and the National Oceanic and Atmospheric Administration (NOAA).

Currently, the GOES system consists of GOES-13 operating as GOES-East in the eastern part of the constellation at 75° west longitude, and GOES-11 operating as GOES-West at 135° west longitude. These spacecraft help meteorologists observe and predict local weather events, including thunderstorms, tornadoes, fog, flash floods, and other severe weather. In addition, GOES observations have proven helpful in monitoring dust storms, volcanic eruptions, and forest fires.

Instruments – In addition to the imager and sounder used for terrestrial weather and environmental imaging, the GOES satellites have a Solar X-Ray imager and a Space Environment Monitor package. The Space Environment Monitor (SEM) consists of three instrument groups: 1) an energetic particle sensor (EPS) package, 2) two magnetometer sensors, and 3) a solar x-ray sensor (XRS). Operating at all times, the SEM provides real-time data to the Space Environment Center (SEC) in Boulder, Colorado. The five-channel EUV telescope is new on the GOES-NO/P/Q satellites. It measures solar extreme ultraviolet energy in five wavelength bands from 10 nm to 126 nm. The EUV sensor provides a direct measure of the solar energy that heats the upper atmosphere and creates the ionosphere.

Data – The data from these satellites is among the most useful in determining the current geomagnetic state of the near-earth environment. The GOES Hp plot at the SEC Space Weather site contains the 1-minute averaged parallel component of the magnetic field in nano-Teslas (nT), as measured at GOES-12  and GOES-10. The Hp component is perpendicular to the satellite orbit plane and thus essentially parallel to Earth’s rotation axis. This is near real-time data and is a good way to watch for a suspected CME impact with the magnetosphere.

Hinode (Solar-B)

Hinode Solar-B was launched on September 23, 2006. Hinode’s Solar Optical Telescope is the first space-borne instrument to measure the strength and direction of the Sun’s magnetic field in the Sun’s low atmosphere, also called the photosphere.

Instruments – Solar Optical Telescope, X-Ray Telescope, EUV Imaging Spectrometer

Data – Hinode provides solar imaging in the visible, EUV (Extreme Ultra-Violet), and X-Ray spectrums. The images on the site are useful for watching the emergence and progression of sunspots. More detailed data is available from the various partner sites.

IBEX  (Interstellar Boundary Explorer)

IBEX was launched on October 19, 2008. IBEX is the first mission designed to map the entire region of the boundary of our Solar System. IBEX’s sole, focused science objective is to discover the nature of the interactions between the solar wind and the interstellar medium at the edge of our Solar System.

Instruments – The payload consists of two imagers specialized to detect neutral atoms from the solar system’s outer boundaries and galactic medium.

Data – the data gathered by IBEX will, over the long term, help put together a picture of the interactions between the solar wind and interstellar medium at the edge of the solar system. IBEX has already discovered a bright, unexpected ribbon at this boundary that doesn’t quite match any of the proposed models. New theories and discoveries are on the way!

POES  (Polar Operational Environmental Satellite)

Mission –
Like GOES the primary mission of POES is for weather forecsting. Currently, the POES mission is composed of two polar orbiting satellites known as the Advanced Television Infrared Observation Satellites (TIROS) – N (ATN). Operating as a pair, these satellites primarily provide data used for long-range weather forecasting ensuring that infrared and non-visible data for any region of the Earth are no more than six hours old.

The SEM (Space Environment Monitor) package on board the NOAA Polar-orbiting Operational Environmental Satellite (POES) continually monitors the power flux carried by the protons and electrons that produce aurora in the atmosphere. The last POES Satellite was launched in February of 2009. The program is currently in transition with changes in the FY2011 budget. In the future, separate programs with shared data will be run by the Air Force and NOAA. NOAA’s portion will notionally be named the “Joint Polar Satellite System” (JPSS) and will consist of platforms based on the NPOESS Preparatory Project (NPP) satellite. Find more information on the future of this mission at

Instruments – The latest POES satellites have: the Advanced Very High Resolution Radiometer (AVHRR), the High Resolution Infrared Radiation Sounder/4 (HIRS/4), the Advanced Microwave Sounding Units (AMSU-A1 and -A2), the Microwave Humidity Sounder (MHS), and the Solar Backscatter Ultraviolet Radiometer (SBUV/2), the Data Collection System (DCS), the Search and Rescue Repeater (SARR), the Search and Rescue Processor (SARP), and the Space Environment Monitor (SEM).

Data – The POES satellites provide data from the earth’s polar regions which is important if you are monitoring auroral activity or interested in over-the-pole radio propagation.


(Reuven Ramaty High Energy Solar Spectroscope Imager)

Mission –
RHESSI was launched on February 05, 2002

Researchers believe that much of the energy released during a flare is used to accelerate, to very high energies, electrons (emitting primarily X-rays) and protons and other ions (emitting primarily gamma rays). The new approach of the HESSI mission is to combine, for the first time, high-resolution imaging in hard X-rays and gamma rays with high-resolution spectroscopy, so that a detailed energy spectrum can be obtained at each point of the image. This new approach will enable researchers to find out where these particles are accelerated and to what energies. Such information will advance understanding of the fundamental high-energy processes at the core of the solar flare problem.

Instruments – The only instrument on board is an imaging spectrometer with the ability to obtain high fidelity color movies of solar flares in X rays and gamma rays. It uses two new complementary technologies: fine grids to modulate the solar radiation, and germanium detectors to measure the energy of each photon very precisely.

Data – The “Science Nuggets” page provides articles detailing some of the discoveries made by RHESSI.

SDO (Solar Dynamics Observatory)

SDO was launched on February 11, 2010. The Solar Dynamics Observatory (SDO) is the first mission in a fleet of NASA missions to study our sun and is part of a NASA science program called Living With a Star (LWS). SDO will study how solar activity is created and how space weather results from that activity. Measurements of the sun’s interior, magnetic field, the hot plasma of the solar corona, and the irradiance will help meet the objectives of the SDO mission.

Instruments – HMI (Helioseismic and Magnetic Imager), AIA (Atmospheric Imaging Assembly), AIA (Atmospheric Imaging Assembly). This set of instruments does the following: (1.) Measure the extreme ultraviolet spectral irradiance of the Sun at a rapid cadence.  (2.) Measure the Doppler shifts due to oscillation velocities over the entire visible disk. (3.) Make high-resolution measurements of the longitudinal and vector magnetic field over the entire visible disk. (4.) Make images of the chromosphere and inner corona at several temperatures at a rapid cadence. (5.) Make those measurements over a significant portion of a solar cycle to capture the solar variations that may exist in different time periods of a solar cycle

Data – Images are currently available on the website, although the instruments are still being configured. Watch the website for future developments as the satellite should be fully operational by June 2010.

SOHO (Solar and Heliospheric Observatory)

SOHO was launched on December 02, 1995. SOHO, the Solar and Heliospheric Observatory, is a project of international cooperation between ESA and NASA to study the Sun, from its deep core to the outer corona, and the solar wind. Together with two other ESA missions, Cluster and Ulysses, SOHO is studying the Sun-Earth interaction from different perspectives. SOHO’s easily accessible, spectacular data and basic science results have captured the imagination of the space science community.

Instruments –  SOHO has 12 instruments onboard. CDS (Coronal Diagnostic Spectrometer); CELIAS (Charge, Element, and Isotope Analysis System); COSTEP (Comprehensive Suprathermal and Energetic Particle Analyzer); EIT (Extreme ultraviolet Imaging Telescope), ERNE (Energetic and Relativistic Nuclei and Electron experiment); GOLF (Global Oscillations at Low Frequencies); LASCO (Large Angle and Spectrometric Coronagraph); MDI (Michelson Doppler Imager); SUMER (Solar Ultraviolet Measurements of Emitted Radiation); SWAN (Solar Wind Anisotropies); UVCS (Ultraviolet Coronagraph Spectrometer), VIRGO (Variability of Solar Irradiance and Gravity Oscillations). Each instrument has its own website if you are interested in more detailed data and information.

Data – SOHO has been the prime sources of solar images and movies since its launch 15 years ago. The image and other archives is a great source of historical data and the satellite continues to provide a wealth of data. It’s worth spending some time on the website.

STEREO  (Solar Terrestrial Relations Observatory)

STEREO was launched on October 25, 2006. STEREO (Solar TErrestrial RElations Observatory) is the third mission in NASA’s Solar Terrestrial Probes program (STP). This two-year mission will provide a unique and revolutionary view of the Sun-Earth System. The two nearly identical observatories – one ahead of Earth in its orbit, the other trailing behind – will trace the flow of energy and matter from the Sun to Earth as well as reveal the 3D structure of coronal mass ejections and help us understand why they happen. STEREO will also provide alerts for Earth-directed solar ejections, from its unique side-viewing perspective adding it to the fleet of Space Weather detection satellites.

Instruments – The following four instrument packages are mounted on each of the two STEREO spacecraft: Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI); STEREO/WAVES (SWAVES); In-situ Measurements of Particles and CME Transients (IMPACT); and PLAsma and SupraThermal Ion Composition (PLASTIC)

Data – There is a variety of data and images on the various instrument websites. Of particular interest to Natural Radio listeners might be the SWAVES data, which provides daily plots of Solar Radio bursts in the 2.5kHz to 16 mHz range.


(Time History of Events & Macroscale Interactions during Substorms)

THEMIS was launched on February 17, 2007. THEMIS answers longstanding fundamental questions concerning the nature of the substorm instabilities that abruptly and explosively release solar wind energy stored within the Earth’s magnetotail.

Instruments – The five spin-stabilized (spin period = 3 seconds) THEMIS probes carry the comprehensive packages of plasma and field instruments needed to determine the cause of geomagnetic substorms. The instruments being flown are: Electric field instruments (EFI); Fluxgate magnetometers (FGM); Search coil magnetometers (SCM); Electrostatic analyzers (ESA); and Solid state telescopes (SST)

Also, a dedicated array of THEMIS ground observatories (20 all-sky imagers and 21 ground magnetometers) covers North America from Eastern Canada to Alaska, providing the information needed to place THEMIS probe observations within their global context. These instruments are: All-sky white light imagers (ASI) and
Fluxgate magnetometers (GMAGS).

Data – Data and plots are readily available on the websites but would probably appeal more to the serious researcher than the casual hobbyist.


(Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics)

TIMED was launched on December 07, 2001. Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) explores the Earth’s Mesosphere and Lower Thermosphere (60-180 kilometers up), the least explored and understood region of our atmosphere. It is known that the global structure of this region can be perturbed during stratospheric warmings and solar-terrestrial events, but the overall structure and dynamics responses of these effects are not understood. The science payload is allowing scientists to look, for the first time in detail, at composition changes in the upper atmosphere; acquire unique measurements of atmospheric cooling as gases radiate energy back into space; measure the primary energy that’s deposited into the MLTI region; and measure the speed and direction of winds in this region.

Instruments – TIMED’s instruments are the: Global Ultraviolet Imager (GUVI); Sounding of the Atmosphere using Broadband Emission Radiometry (SABER); Solar Extreme Ultraviolet Experiment (SEE); and the TIMED Doppler Interferometer (TIDI).

Data – Current and archived data is available, but it will take a bit of work to find what you are looking for.


(Two Wide-Angle Imaging Neutral-Atom Spectrometers)

TWINS A & B were launched on March 13, 2008. The Two Wide-angle Imaging Neutral-atom Spectrometers missions, TWINS-A and TWINS-B, provide a new capability for stereoscopically imaging the magnetosphere. By imaging the charge exchange neutral atoms over a broad energy range (~1-100 keV) using two identical instruments on two widely spaced high-altitude, high-inclination spacecraft, TWINS will enable the 3-dimensional visualization and the resolution of large scale structures and dynamics within the magnetosphere for the first time. Stereo imaging, as done by TWINS, takes the next step of producing 3-D images, and will provide a leap ahead in our understanding of the global aspects of the terrestrial magnetosphere.

Instruments – The TWINS instrumentation is essentially the same as the MENA instrument on the IMAGE mission. This instrumentation consists of a neutral atom imager covering the ~1-100 keV energy range with 4°x4° angular resolution and 1-minute time resolution, and a simple Lyman-alpha imager to monitor the geocorona.

Data – A variety of images and plots are available. A user manual is available to help you navigate your way through the data.

Van Allen Probes

– The Van Allen Probes were launched from Cape Canaveral Air Force Station in the pre-dawn hours of Aug. 30, 2012. After a successful launch, the probes were released from the upper stage of the Centaur rocket one at a time, and sent off into their different orbits, beginning the two-year mission to study the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time.

The two Van Allen Probes have nearly identical eccentric orbits and identical instrumentation. The orbits cover the entire radiation belt region and the two spacecraft lap each other several times over the course of the mission. With a spaced pair of satellites, the Van Allen Probes can discriminate between spatial and temporal effects, and compare the effects of various proposed mechanisms for charged particle acceleration and loss.

Instruments – The probes carry a number of instruments and instrument suites to support five experiments that address the mission’s science objectives. Because it is vital that the two craft make identical measurements to observe changes in the radiation belts through both space and time, each probe carries the following: Energetic Particle, Composition, and Thermal Plasma Suite (ECT), Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS), Electric Field and Waves Suite (EFW), Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) and the Relativistic Proton Spectrometer (RPS).

Data – The Science Gateway for the Van Allen probes is at It would probably be helpful to visit the sites of each of the spacecrafts’ instruments also.


The twin spacecraft Voyager 1 and Voyager 2 were launched by NASA in separate months in the summer of 1977 from Cape Canaveral, Florida. As originally designed, the Voyagers were to conduct closeup studies of Jupiter and Saturn, Saturn’s rings, and the larger moons of the two planets.

Voyager’s primary mission was completed in 1989, the space craft are now in a new mission, the Voyager Interstellar Mission (VIM). This mission is to extend the NASA exploration of the solar system beyond the neighborhood of the outer planets to the outer limits of the Sun’s sphere of influence, and possibly beyond. This extended mission is continuing to characterize the outer solar system environment and search for the heliopause boundary, the outer limits of the Sun’s magnetic field and outward flow of the solar wind. Penetration of the heliopause boundary between the solar wind and the interstellar medium will allow measurements to be made of the interstellar fields, particles and waves unaffected by the solar wind.

Instruments –  Five of the original ten instruments are currently supported: Plasma Science (PLS) Properties and radial evolution of the solar wind (ions 10 eV – 6 keV, electrons 4 eV-6 keV); Low-Energy Charged Particles(LECP) Energy spectrum of low-energy particles (electrons 10-10,000 keV, ions 10-150,000 keV/n); Cosmic Ray Sub-system (CRS) Energy spectrum of high- and low-energy electrons (3-110 MeV) and cosmic ray nuclei (1-500 MeV/n); Magnetometer (MAG) High (50,000 – 200,000 nT) and low (8-50,000 nT) magnetic field intensity; Plasma Wave Subsystem (PWS) Electrical field components of plasma waves in frequency range of 10 Hz to 56 kHz

Data – Data is available from a variety of sites. You can find a list of locations at:


Mission –
Wind was launched on November 01, 1994 and was positioned in a sunward, multiple double-lunar swing-by orbit with a maximum apogee of 250Re during the first two years of operation. This will be followed by a halo orbit at the Earth-Sun L1 point.

The Wind spacecraft is the first of two U.S. missions of the Global Geospace Science (GGS) initiative, which is part of a worldwide collaboration called the International Solar-Terrestrial Physics (ISTP) program.  Wind, together with Geotail, Polar, SoHO and Cluster, constitute a cooperative scientific satellite project designated the International Solar Terrestrial Physics (ISTP) program that aims at gaining improved understanding of the physics of solar terrestrial relations.

The primary science objectives of the Wind mission are: Provide complete plasma, energetic particle and magnetic field for magnetospheric and ionospheric studies; Investigate basic plasma processes occurring in the near-Earth solar wind; Provide baseline, 1 AU, ecliptic plane observations for inner and outer heliospheric missions.

Instruments –(1.)The Wind Magnetic Field Investigation (MFI) is composed of two fluxgate magnetometers; (2.)WIND Solar Wind Experiment (SWE) Faraday Cup – Ion Data; (3.) WIND Solar Wind Experiment (SWE) Electron Data consisting of two electrostatic analyzers, the vector spectrometer (VEIS) and the Strahl spectrometer; (4.) Wind 3D Plasma Analyzer consisting of six different sensors. There are two electron (EESA) and two ion (PESA) electrostatic analyzers. There are also a pair of solid state telescopes (SST) that measure electrons with energies up to 400 keV and protons with energies up to 6 MeV; (5.) Wind SMS Suprathermal Particle Data composed of three separate instruments. The SupraThermal Ion Composition Spectrometer (STICS); the high resolution mass spectrometer (MASS) and finally, The Solar Wind Ion Composition Spectrometer (SWICS) determines mass, charge, and energy for ions in the energy range of 0.5 to 30 keV/e. (6.) Wind EPACT High Energy Particle Data consisting of multiple telescopes. (7.) Wind WAVES Radio and Plasma Waves Data is composed of the RAD1, RAD2 and Thermal Noise Recivers (TNR), measures electric fields in a wide range of frequencies. (8.) Wind KONUS and TGRS Data consist of two gamma-ray instruments.

Data – There is a vast amount of data here and you’ll want to check out the website for the specific instrument you are interested in. Plots of the WAVES data may be of particular interest to Natural Radio listeners.