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Heliophysics Explorers

To complement its strategic mission programs, Heliophysics makes effective use of the Explorer program for competitive PI-led missions.  This program is managed by the Heliophysics Division and solicits missions for both Heliophysics and Astrophysics.

The most recently launched Heliophysics Explorers are AIM, THEMIS, and IBEX.

AIM, the Aeronomy of Ice in the Mesosphere mission, is providing major advances in understanding polar mesospheric clouds (PMCs), the highest clouds in the Earth’s atmosphere. In addition, AIM has made the first global measurements of meteoric smoke particles in Earth’s upper atmosphere.

THEMIS, the Time History of Events and Macroscale Interactions during Substorms mission, has been investigating the ‘double layer’ mechanism that accelerates particles in the Earth’s magnetotail. This same mechanism accounts for the strong, long-lived particle acceleration in the Earth’s aurora.

The latest Heliophysics Explorer mission to launch is IBEX, the Interstellar Boundary Explorer, which observes the heliospheric boundary from high Earth orbit. The most recently selected Heliophysics Explorer is IRIS, the Interface Region Imaging Spectrograph, which will explore the flow of energy and plasma at the foundation of the Sun’s atmosphere. IRIS will launch in 2012.

*Sort missions by clicking the column headers.

DivisionNameLaunch DatePhase
Heliophysics ACE
Advanced Composition Explorer (ACE) observes particles of solar, interplanetary, interstellar, and galactic origins, spanning the energy range from solar wind ions to galactic cosmic ray nuclei. This mission is part of SMD's Explorers Program. This mission is part of SMD's ...
19970825 August 25, 1997 3Operating
Heliophysics AIM
Aeronomy of Ice in the Mesosphere (AIM) is a mission to determine the causes of the highest altitude clouds in the Earth's atmosphere. The number of clouds in the middle atmosphere (mesosphere) over the Earth's poles has been increasing over ...
20070425 April 25, 2007 3Operating
Heliophysics CINDI/CNOFS
The Coupled Ion-Neutral Dynamics Investigations (CINDI) is a mission to understand the dynamics of the Earth's ionosphere. CINDI will provide two instruments for the Communication/Navigation Outage Forecast System (C/NOFS) satellite, a project of the United States Air Force. This mission ...
20080416 April 16, 2008 3Operating
Heliophysics FAST
Fast Auroral Snapshot Explorer (FAST) studies the detailed plasma physics of the Earth's auroral regions. Ground support campaigns coordinate satellite measurements with ground observations of the Aurora Borealis, commonly referred to as the Northern Lights. The science instruments on board ...
19960821 August 21, 1996 4Past
Heliophysics IRIS
The primary goal of the Interface Region Imaging Spectrograph (IRIS) explorer is to understand how the solar atmosphere is energized. The IRIS investigation combines advanced numerical modeling with a high resolution UV imaging spectrograph.
20130401 April 2013 2Development
Heliophysics RHESSI
Reuven Ramaty High Energy Solar Spectroscope Imager (RHESSI) studies solar flares in X-rays and gamma-rays. It explores the basic physics of particle acceleration and explosive energy release in these energetic events in the Sun's atmosphere. This is accomplished by imaging ...
20020205 February 05, 2002 3Operating
Heliophysics THEMIS
Time History of Events and Macroscale Interactions during Substorms (THEMIS) is a study of the onset of magnetic storms within the tail of the Earth's magnetosphere. THEMIS will fly five microsatellite probes through different regions of the magnetosphere and observe ...
20070217 February 17, 2007 3Operating
Heliophysics TRACE
Transition Region and Coronal Explorer (TRACE) observed the effects of the emergence of magnetic flux from deep inside the Sun to the outer corona with high spatial and temporal resolution. This mission was part of SMD's Heliophysics Explorers program. This ...
19980401 April 01, 1998 4Past
Heliophysics TWINS A & B
TWINS will provide stereo imaging of the Earth's magnetosphere, the region surrounding the planet controlled by its magnetic field and containing the Van Allen radiation belts and other energetic charged particles. This mission is part of SMD's Explorers Program. This ...
20080313 March 13, 2008 3Operating