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Missions to our star, Sol, in order :
plus nation, launch date, result (bold = success, red = failure, gray = inactive or destroyed, SMALL CAPS = targets/destinations)
vehicle type in parentheses if launch failure
Overall Solar mission success: 62/68 = 91%

  1. Explorer 7 - USA 13 October 1959
    Studied solar X-rays, interaction with ionosphere, composition of cosmic rays, heat emission of Earth. Tx ceased 24Aug1961.

  2. Pioneer 5 - USA 11 March 1960
    Solar flare/cosmic ray observatory studied Forbush Effect. Returned 3 megabits of data. Last tx 26Jun1960 @ 36,200,000 km. In 0.99 AU x 0.80 AU x 3.36 ° solar orbit. See Drew Lepage's article "Exploring the Interplanetary Frontier" in the 20Mar2000 issue of SpaceViews.

  3. Solrad 1 (GRAB 1) - USA 22 June 1960
    1st in series, Galactic Radiation and Background, measured solar & e/m & stellar radiation, decayed ??Apr1961. Was also covert SIGINT bird.

  4. Transit 3A-Solrad 2 (GRAB 2) - USA 30 November 1960 (Thor-Able Star)
    2nd in series, destroyed by range safety, bits recovered in Cuba. Was also covert SIGINT bird.

  5. Injun 1/Solrad 3 (GRAB 3) - USA 29 June 1961
    3rd in series. Primary payload Injun failed to separate in orbit. Solrad returned solar x-ray till late 1961, still in 900? km LEO. Was also covert SIGINT bird.

  6. OSO 1 - USA 07 March 1962
    Wide spectrum Orbiting Solar Observatory in LEO tx'd data on 75 flares. Decayed 09Oct1981.

  7. Solrad 4B (GRAB 4) - USA 26 April 1962. (Scout)
    Launched into submarine orbit. Was also covert SIGINT bird.

  8. Kosmos-8 - USSR 18 August 1962
    scientific purpose? Probable solar radiation monitor; same profile as Kosmos-166. Kap Yar site; SL-7 launcher; 337 kg; 251 km x 591 km x 48.9 ° orbit. Reentered 17Aug1963.

  9. Explorer 18 (IMP-A, IMP-1) - USA 27 November 1963
    First of the Interplanetary Monitoring Program satellites. Radiation observatory in highly elliptical cislunar orbit. Discovered bow shock of solar wind with Earth's magnetic field. Tx stopped ??May1965, decayed 30Dec1965.

  10. Solrad 7A - USA 11 January 1964
    4th payload in manifest, tx'd sol rad data til Jul1966.

  11. Explorer 21 (IMP-B) - USA 04Oct1964
    Magnetic field? or radiation? observatory in highly elliptical cislunar orbit, apogee too low (Delta), ceased tx 13Oct1965, decayed 01Jan1966.

  12. Explorer 26 (IMP?) - USA 21 December 1964
    Failed in space?, still in elliptical orbit.

  13. OSO 2 - USA 03 February 1965
    Wide spectrum Orbiting Solar Observatory in LEO tx'd solar X-ray & UV data until Nov1965. Decayed 09Aug1989.

  14. Solrad 7B - USA 09 March 1965
    4th payload in manifest, tx'd until?.

  15. OSO C - USA 25 August 1965 (Delta)
    3rd stage preemie ignition. In TSO (thalassosynchronous orbit).

  16. Explorer 30 - USA 19 November 1965
    Last IQSY (Int'l Quiet Sun Year) satellite. Monitored solar X-rays and UV. Still in orbit.

  17. OSO 3 - USA 08 March 1967
    Wide spectrum Orbiting Solar Observatory in LEO. Decayed 04Apr1982.

  18. Kosmos-166 - USSR 16 June 1967
    Solar radiation experiments. Reentered 25Oct1967.

  19. Explorer 35 (IMP-E) - USA 19 July 1967
    Earth's magnetic tail observatory, monitors low frequency solar radio emission, micrometeoroids, solar wind, radiation. In lunar orbit (29.5-day).

  20. OVI 12 - USA 28 July 1967
    Flare activated radiological solar observatory in LEO, decayed 22Jul1980.

  21. OSO 4 - USA 18 October 1967
    Wide spectrum Orbiting Solar Observatory in LEO, first pix of Sol in extreme UV. Decayed 15Jun1982.

  22. Explorer 37 (Solar Explorer B, Solrad 2) - USA 05 March 1968
    Suboptimal orbit (Scout), returned solar X-ray data, decayed 16Nov1990..

  23. Kosmos-215 - USSR 19 April 1968
    Solar radiation observatory with 8 telescopes. Reentered 30Jun1968.

  24. Iris (ESRO 2B) - ESRO (now ESA) 17 May 1968
    First satellite launched by ESRO. Returned solar & cosmic radiation data from polar orbit, decayed 08May1971.

  25. Kosmos-262 - USSR 26 December 1968
    DS (Dnepropetrovskoye Sputnik)-U2-DF satellite for heliophysical studies; same profile as Kosmos-215. Reentered 18Jul1969.

  26. OSO 5 - USA 22 January 1969
    Wide spectrum Orbiting Solar Observatory in LEO. Decayed 02Apr1984.

  27. OSO 6 - USA 09 August 1969
    Wide spectrum Orbiting Solar Observatory in LEO, offset raster scanned and solar disk edge scan. Decayed 07Mar1981.

  28. D2-A (Tournesol 1) - France 15 April 1971
    Studied solar UV emissions and distribution of stellar hydrogen in upper atmosphere. Decayed 28Jan1980.

  29. Explorer 44 (Solrad 10) - USA 08 July 1971
    3rd in series, measured solar & e/m & stellar radiation. Decayed 15Dec1979. Were this and later Solrads still covert SIGINT birds?

  30. Shinsei - Japan 28 September 1971
    Studied cosmic rays, hf radio noise from Sun, and measured density & temperature of electrons & ions in Earth's ionosphere. In orbit.

  31. OSO 7 - USA 29 September 1971
    Wide spectrum Orbiting Solar Observatory in LEO. Decayed 09Jul1974.

  32. Aureole-1 (Oreol) - France/USSR 27 December 1971
    French satellite on Soviet launcher to measure electrons in solar wind at 200 eV - 15 keV. In highly inclined elliptical orbit.

  33. HEOS A2 - ESRO 31 January 1972
    Observed particles & fields in highly elliptical orbit. Decayed 02Aug1974.

  34. Prognoz 3 - USSR 15 February 1973
    Solar flare monitor, in highly elliptical earth orbit.

  35. Interkosmos-9 - USSR/Poland/Czech 19 April 1973
    "Copernik-500" solar radiation monitor. Decayed 15Oct1973.

  36. Explorer 50 (IMP-H, IMP-8) - USA 26 October 1973
    Solar flare & radiation monitor, in 12-day cislunar earth orbit. 6 of 12 instruments operative; active for 28 years until retired 28Oct2001.

  37. Aureole-2 (Oreol-2) - France/USSR 26 December 1973
    Studied energy transport from Sun to Earth. In highly inclined elliptical orbit.

  38. Explorer 52 (Hawkeye) - USA 03 June 1974
    Solar wind research, in highly elliptical earth orbit. Decayed 30Apr1978.

  39. Helios 1 - Germany 10 December 1974
    Solar probe, in solar orbit.

  40. Taiyo (SRATS) - Japan 24 February 1975
    Studied solar radiation & thermospheric structure. Decayed 29Jun1980.

  41. Aryabhata - India/USSR 19 April 1975
    First Indian satellite, launched by Soviets from Kapustin Yar. X-ray astronomy, solar physics and aeronomics. Success even though science expts quit after 1 week. Inactive Mar1981, reeentered 11Feb1992.

  42. OSO 8 - USA 21 June 1975
    Orbiting Solar Observatory in LEO, observed Sol @ X-ray, gamma, UV, & IR wavelengths. Last in series. Decayed 09Jul1986.

  43. D2-B (Aura) - France 27 September 1975
    Studied solar UV emissions. Decayed 30Sep1982.

  44. Helios 2 - ESA 15 January 1976
    Solar probe, in solar orbit.

  45. Solrad 11A - USA 15 March 1976
    "solar study".
    Solrad 11B - USA 15 March 1976
    "solar study".
    Same booster & destination, counts as one mission.

  46. ISEE 1 - USA 22 October 1977
    International Sun-Earth Explorer measured interaction betwen solar wind and Earth as part of Int'l Magnetosphere Study. Decayed 26Sep1987.
    ISEE 2 - ESA 22 October 1977
    Int'l Sun-Earth Explorer. Decayed 26Sep1987.
    Although satellites had different builders, both were on same booster & destination, hence counted as one mission.

  47. Solar Max Mission - USA 14 February 1980
    Multispectral (IR, UV, X-ray, gamma) solar observatory, repaired on orbit by STS-41C on 09Apr1984. Decayed 02Dec1989.

  48. Prognoz 8 - USSR 25 December 1980
    Studied interaction betwen solar wind and geomagnetosphere, in highly elliptical orbit.

  49. Hinotori (Astro) - Japan 21 February 1981
    X-ray solar observatory. Decayed 11Jul1991.

  50. China-10 - PRC 19 September 1981
    Reentered 06Oct1982.
    China-11 - PRC 19 September 1981
    Reentered 17Aug1982.
    Studied effect of solar UV and X-rays on upper atmosphere, among other geoscience. Dual science payload on single launcher, counts as one mission.

  51. Aureole-3 (Oreol-3) - France/USSR 21 September 1981
    Studied interaction between the Sunand the Earth. In highly inclined elliptical orbit.

  52. SME - USA 06 October 1981
    Solar Mesosphere Explorer. Observatory decayed 05Mar1981.

  53. Prognoz 10 - USSR/Czech 26 April 1985
    (Project "Magion" or was that on Interkosmos?) Studies magnetosphere and solar wind and shock wave, in very high elliptical orbit.

  54. Ulysses - USA/ESA 06 October 1990
    Solar observatory with 9 expts, launched from Shuttle in LEO (STS-41) on IUS plus gravity assist, flew by JUPITER on 08Feb1992 in order to arrive in 1.3 × 5.4 AU (6 yr) elliptic orbit over SOLAR POLES on xxJun1994. Mission extended 17Apr1998 to observe Solar Max. Mission extended to 2004.

  55. Solar A (Yohkoh) - Japan 30 August 1991
    X-ray imaging solar observatory, in solar orbit. Tumbled out of control Dec 2001. Dead.

  56. SAMPEX - USA 03 July 1992
    Solar Anomalous and Magnetospheric Particle Explorer, in low Earth orbit.

  57. Koronas-I - Russia/USA/multinat 02 March 1994
    Solar activity monitor. In low Earth orbit.

  58. Wind - USA 01 November 1994
    Solar wind physics. In highly elliptical Earth orbit. 32nd flyby of Moon in Aug2000.

  59. Magion-4 - Russia/multinat 02 August 1995
    Solar wind research in conjunction with Interbol-1. In highly elliptical Earth orbit.

  60. SOHO - ESA 2 December 1995
    Solar observatory, in orbit about SUN/EARTH L1 POINT (1.5 million km toward Sun), contact lost due to controller error on 24Jun1998, probe froze, contact regained 16Sep1998, 3 expts OK, will observe Solar Max. Recovering from another safing event on 28Nov1999. As of Feb2000, has discovered 10 random comets plus 92 "Kreutzer sungrazers". This family may be remains of the great comet of 372 BCE observed by Euphorus the Greek, which returned in 1100 AD. Due for a revisit in 2572 AD? Get a free screensaver with realtime imagery from SOHO. Instruments:
    Michelson Doppler Imager (helioseismology)

  61. Cluster I> - ESA 04 June 1996 (Ariane 5) Cluster of four satellites to measure interaction between geomagnetic field and solar wind. Destroyed when Ariane 5 maiden flight failed to orbit. Counts as one mission.

  62. Magion-5 - Czech/Russia/int'l 29 August 1996
    Solar wind research in conjunction with Interbol-2. In highly elliptical Earth orbit.

  63. ACE - USA 25 August 1997
    Advanced Composition Explorer to study solar wind. In orbit about SUN/EARTH L1 POINT.

  64. ACRIMSat - USA 21 December 1999
    Active Cavity Irradiance Monitor Satellite measures total solar output. In LEO.

  65. Cluster II - ESA/Russia 16 July 2000
    Cluster II - ESA/Russia 09 August 2000
    Geophysics. Constellation of four satellites in tetrahedral formation, 2000 km on a side, to measure interaction between geomagnetic field and solar wind with high precision; replacement for first mission. Counts as one mission. In highly elliptical, high Earth orbit.

  66. Koronas-F - ESA/Russia 31 July 2001 First Russian science mission in several years. Follow-on to Koronas-I, solar activity monitor. In low Earth orbit.

  67. Genesis - USA 08 August 2001.
    Discovery-class solar observatory/weather monitor/sample return mission. In heliocentric orbit around Sun-Earth L1 point for 2 years, to collect particles from solar wind, return them to Earth in April 2004 for test of solar & planetary origin theories. Instruments:
    solar-wind collector arrays;
    ion monitor (records the speed, density, temperature and approximate composition of the solar wind ions;
    electron monitor (makes similar measurements of electrons in the solar wind);
    ion concentrator (separates and focuses elements like oxygen and nitrogen into special collector tile).

  68. High Energy Solar Spectroscopic Imager spacecraft (HESSI) - USA 05 February 2002
    Mission will observe thousands of flares. delayed due to damage during testing and unrelated Pegasus failure. L = 2-3 yrs. Prime instrument: hard X-ray/gamma ray imaging spectrometer w/highest resolution to date: 2 arcsec @ 40 keV energies & 36 arcsec @ 1 MeV.

This category is much fuzzier than the others, which are grouped according to destination. Here that sorting method breaks down, as the object of study, Sol, can be observed from almost anywhere, near or far. Thus, placement in this group may seem arbitrary. Space physics experiments of broad applicability (e.g. radiation measurement, magnetic mapping) are not included here. Earth science e.g. geophysics is specifically excluded - it is covered in another page. However, because the interaction between the Sun and the Earth is of obvious importance to the beings sending the missions, those missions are listed on both pages with anchors to link them. Multiple visits to the same body by the same spacecraft (e.g. GEM) do not count as multiple missions (even if they do require multiple visits to Capitol Hill for funding). Multiple visits to different primaries do. A mere gravity assist maneuver without science return doesn't really count as a mission, either - a "flyby" requires at least one instrument to be pointed in the general direction of the celestial body. This was not an accounting issue until a few Big Science missions (e.g. Galileo, Project Vega) flew some very complex trajectories with multiple gravity assists. However, if you don't agree, by all means email me robot@ultimax.com and I might change my policy.

The dearth of Soviet/Russian missions may be due to payloads and purposes of Interkosmos, Prognoz, and especially the generic Kosmos missions not being well documented. Any further information concerning the scientific objectives of the following Kosmos missions, which have been reported to be for astronomical research, would be appreciated: Kosmos-8, -208, -230, -251, -262, -264, -307, and -461.
According to Jonathan's Space Report #458, dated 08Aug2001:

‘Koronas-F, an AUOS-SM type solar-pointing satellite built by Yuzhnoe in Dnepropetrovsk, Ukraine, carries a set of solar physics instruments.
‘There were 11 launches of earth-oriented AUOS-Z satellites between 1976 and 1991, followed by development of the two solar-pointing AUOS-SM satellites AUOS-SM-KI (Koronas-I) and AUOS-SM-KF (Koronas-F), whose names reflect the two research insitutes who were the original principal investigators for the experiment payloads. The I satellite, for the IZMIRAN geophysics institute, was launched in 1994 and reentered earlier this year. The new F satellite carries that designation because the original lead organization was the Lebedev institute known as FIAN in Russian, although it also carries experiments from IZMIRAN and other research centers. ’

Because so many Soviet astronomy payloads piggybacked on military satellites, I have decided to included early US missions such as the Solrad series which also had covert Cold War roles.

Also the success rate of this class can be misleading compared to other destinations. Most missions for studying the Sun take place from low Earth orbit, no farther. In addition, these missions tend to be much smaller in mass, less complex, closer to their controllers, and therefore less risky.
NOAA's GOES-M weather satellite carries a SXI (soft X-ray imager) equivalent to the Japanese Yohkoh instrument.

Credit goes out to TRW Space Log 1957-1996, The Planetary Report published by The Planetary Society, Proton Mission Planner's Manual, and Jonathan's Space Report; to Chris Jones clj@world.std.com and Marc Rayman mrayman@jpl.nasa.gov. A tip o' the leaded visor to David Portree DSFPortree@aol.com for his sharp eyes.

Future Missions to the Sun

  • planned but never designed or built Jupiter/Sun probe - USSR circa 1995-96 on Proton
    According to Anatoliy Zak's RussianSpaceWeb, a 2000 kg-class mission was planned in 1986-87 for launch on a Proton in 1995-96. It would slingshot 'round Jupiter, followed by close approach to the Sun (5-7 radii). During flyby, 500 kg dropsonde would be released into Jovian atmosphere. Another version would continue on to Saturn and the outer system after Jovian slingshot maneuver.

  • Doublestar - ESA/China March 2003
    Cluster style mission to study the Sun.

  • STEREO - USA June 2004.
    Solar-TErrestrial RElations Observatories - dual spacecraft leading & trailing L1 will triangulate and study coronal mass ejections.

  • Solar-B - Japan August 2004.
    Optical, extreme UV, and X-ray instruments will study interaction between sun's magnetic field and atmosphere.

  • Storms - ESA Solar/geomagnetic observatory in 50,000 km circular equatorial earth orbit.

  • Solar Orbiter - ESA Solar observatory in highly eccentric solar orbit, perisol = 30M km (solar synchronous altitude). Successor mission to SOHO and Ulysses.

    More missions are planned. Let us know if we've missed any.

What's Coming to this Page:

Comprehensive list of individual instruments and capabilities (wavelength, aperture, energy, etc.) aboard each observatory. A few more Soviet missions may be added to this list when their objectives clear up. Your comments are welcome: robot@ultimax.com
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