The upcoming solar maximum should be the most exciting one ever for scientists studying the Sun, the Earth, and the space in between. For the first time, many satellites are in place, ready to make detailed observations about the changes that will occur over the next few years and to note the varied activity of the Sun. Possibly, all of this information will lead to groundbreaking discoveries about our star.

Some observations have been available during solar maximum for tens of years, especially from ground-based observatories. The Wilcox Solar Observatory, for example, has made magnetograms of the Sun since 1975. Two solar maxima ago, Skylab took pictures of the Sun (until atmospheric drag caused by increased solar activity caused it to fall to Earth) and the Solar Maximum Mission was launched. During the last solar maximum (around 1989), the Solar Maximum Mission satellite was up (until atmospheric drag caused by increased solar activity caused it to fall to Earth).

Those observations, though extremely helpful to scientists, cannot compare in magnitude to those that will be made during the upcoming solar maximum period. In conjunction with the International Solar-Terrestrial Physics (ISTP) program, many satellites have been launched to study the Sun-Earth connection. SOHO (Solar and Heliospheric Observatory), Yohkoh, Ulysses, and TRACE (Transition Region and Coronal Explorer) view the Sun. Wind and ACE (Advanced Composition Explorer) study the solar wind. Polar watches the aurora. Geotail studies changes deep within the Earth's magnetotail. Other satellites and ground-based observatories constantly receive data about some aspect of the Sun-Earth system.

With this extensive constellation of satellites dedicated to studying the space from the Sun to the Earth, scientists will have access to sophisticated instrumentation and complex data through the upcoming solar maximum and beyond. Some of the satellites and observatories have made it their special mission to study the Sun at the height of the solar maximum; the following sites deal with these specialized instrument centers, their characteristics, and how they will help researchers learn about the solar maximum.

• The Solar and Heliospheric Observatory (SOHO)
  The SOHO satellite, launched in 1995, studies the Sun 24 hours a day from its position 1.5 million kilometers out in space. As the solar maximum approaches, its instruments that image the Sun and detect changes will be particularly useful to scientists.
• Geotail
  Launched on 24 July 1992 by Japan's Institute of Space and Astronautical Science (ISAS) and NASA, the satellite has roamed millions of miles in the tail of the magnetosphere to see how the solar wind and Earth interact downstream.
• Wind
  Launched on 1 November 1994 by NASA, the satellite spends most of its time flying into the solar wind (on the sunny side of Earth) in order to decipher its physical and chemical properties.
• Polar
  Launched on 24 February 1996 by NASA, the satellite makes daily passes over Earth's north and south poles in order to study the energy and particles flowing into and out of the magnetosphere and producing the aurora.
• ACE (Advanced Composition Explorer)
  ACE was launched on August 25, 1997. The primary purpose of ACE is to determine and compare the isotopic and elemental composition of several distinct samples of matter, including the solar corona, the interplanetary medium, the local interstellar medium, and Galactic matter.
• Cluster II
  The first two satellites of the Cluster II quartet were launched July 16, 2000, with the second two to follow soon after. Once in orbit, the four Cluster II spacecraft will spend two years passing in and out of our planet's magnetic field. By making simultaneous measurements, they will be able to make the first detailed, three-dimensional study of the changes and processes taking place in near-Earth space.
• IMAGE (Imager for Magnetopause-to-Aurora Global Exploration)
  IMAGE, just launched in early 2000, will use neutral atom, ultraviolet, and radio imaging techniques to learn about the magnetosphere during substorms and magnetic storms during this upcoming solar maximum.
• Yohkoh
  Yohkoh, a Japanese satellite launched in 1992, uses a soft x-ray telescope to take dramatic pictures of the Sun. It just missed the last solar maximum, so the images it will give of the upcoming maximum should be exciting.
• Transition Region and Coronal Explorer (TRACE)
  TRACE, new to the fleet of Sun-studying satellites (launched in April 1998), will give scientists valuable information on magnetic field conditions in the photosphere, the transition region, and the corona during the upcoming solar maximum.
• Ulysses
  Only one satellite flies in an orbit over the poles of the Sun: Ulysses. The satellite completed its first orbit around the Sun in 1994 and 1995; it is now preparing for a second orbit that will allow to study high-altitude solar wind during solar maximum.
• The Wilcox Solar Observatory
  Located just west of Stanford University in California, the Wilcox Solar Observatory has studied the Sun since 1975, looking for connections between changes in the solar magnetic field and the space weather that affects Earth. Researchers there have a special focus on the solar cycle.
• Solar Maximum Mission
  Though the Solar Maximum Mission satellite has been out of service for ten years, it remains a pioneering mission in the field of solar science. It was launched in 1980 to study solar activity during the solar maximum and collected images and data for nine years.
  
  • An overview of the mission from Views of the Solar System
  • A "QuickLook" from the Jet Propulsion Laboratory
  • An archive of research papers published about the mission
  • Information on SMM's instrumentation, with links to data
  • Links to SMM instrument data archives

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Last Modified: 8/3/00