www.nasa.gov home



Large amounts of plasma (consisting of mostly electrons and protons) ejected from the sun.
Gamma-Ray Bursts
Short bursts of gamma-rays (very high frequency electromagentic radiation) with very energetic explosions. These bursts can last from a few milliseconds to a few about an hour.
Geomagnetic Storms
A disturbance in the Earth's magnetosphere caused by changes in space weather such as solar erutptions.
The region around the sun that is filled with the Sun's gases, solar winds, and magentic fields.
The magnetic field produced by the Sun that is carried through by solar winds.
The uppermost part of the atmosphere. It also forms the inner surface of the magnetosphere and is reponsible for radio communication between distant places on Earth.
Lagrangian Point
Equilibrium points in space where the gravitational pull by a massive body is equal to that of another body.
Forms when a stream of charged particles, such as a solar wind, interacts with the magnetic field of a planet.
The surface of the sun that you see.
Solar Eruptions
These are sudden intense bursts of energy in the sun. They may develop in a few minutes and last for several hours.
Solar Wind
A constant stream pf charged particles, such as electrons and protons, that are continuously ejected from the upper atmosphere of the Sun.
Suprathermal Ions
Ions, charged particles, that have more energy than similar particles of the same type.

Can’t find the word here? Check out our full glossary

ACE Mission

The Earth is constantly bombarded with a stream of accelerated particles arriving not only from the Sun, but also from interstellar and galactic sources. Study of these energetic particles, or cosmic rays, contributes to our understanding of the formation and evolution of the solar system, as well as the astrophysical processes involved. 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.

From a vantage point approximately 1/100 of the distance from the Earth to the Sun, ACE performs measurements over a wide range of energy and nuclear mass, under all solar wind flow conditions and during both large and small particle events including solar flares. ACE provides near-real-time solar wind information over short time periods. When reporting space weather, ACE can provide an advance warning (about one hour) of geomagnetic storms that can overload power grids, disrupt communications on Earth, and present a hazard to astronauts.

ACE launched on a McDonnell-Douglas Delta II 7920 launch vehicle on August 25, 1997 from the Kennedy Space Center in Florida. Ace provides near-real-time 24/7 continuous coverage of solar wind parameters and solar energetic particle intensities (space weather). When reporting space weather ACE provides an advance warning (about one hour) of geomagnetic storms that can overload power grids, disrupt communications on Earth, and present a hazard to astronauts.

ACE orbits the L1 libration point which is a point of Earth-Sun gravitational equilibrium, about 1.5 million km from Earth and 148.5 million km from the Sun. The elliptical orbit affords ACE a prime view of the Sun and the galactic regions beyond. The spacecraft has enough propellant on board to maintain an orbit at L1 until ~2024.

Last updated 01/25/2010 © UC Regents