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Solar Terrestrial Probes

The Solar Terrestrial Probes (STP) Program is part of NASA’s Science Mission Directorate Heliophysics Division. The Program addresses fundamental science questions about the physics of space plasmas and the flow of mass and energy through the solar system. The goal is to understand the processes that determine the mass, momentum, and energy flow in the solar system from the Sun to planetary bodies, including Earth, to the interstellar boundary.

STP program objectives are to:

  • Understand the fundamental physical processes of the space environment from the Sun to Earth, to other planets, and beyond to the interstellar medium.
  • Understand how human society, technological systems, and the habitability of planets are affected by solar variability and planetary magnetic fields.
  • Develop the capability to predict the extreme and dynamic conditions in space in order to maximize the safety and productivity of human and robotic explorers.

These objectives support the Agency’s strategic goal to understand the Sun and its effects on Earth and the solar system. The Earth and Sun are linked together to form the system that has given origin and sustenance to our lives. STP missions will study the Earth and Sun system for insights into questions concerning how the system evolved so as to produce and sustain life, what will happen to this unique environment through the course of time, and how it will affect us.

STP missions focus on specific scientific areas required to advance our fundamental understanding of the Sun – Solar System connection. Successive missions target the “weakest links” in the chain of understanding. The missions use a creative blend of in situ and remote sensing observations, often from multiple platforms, to understand the causes and effects of solar variability over the vast spatial scales involved in planetary and heliospheric responses.

*Sort missions by clicking the column headers.

DivisionNameLaunch DatePhase
Heliophysics Hinode (Solar-B)
Hinode (formerly known as Solar-B) is a Japanese ISAS mission proposed as a follow-on to the highly successful Japan/US/UK Yohkoh (Solar-A) collaboration. The mission consists of a coordinated set of optical, EUV and X-ray instruments that are studying the interaction ...
20060923 September 23, 2006 3Operating
Heliophysics MMS
The Magnetospheric Multiscale mission will determine the small-scale basic plasma processes which transport, accelerate and energize plasmas in thin boundary and current layers – and which control the structure and dynamics of the Earth's magnetosphere. MMS will for the first ...
20150312 March 2015 3Operating
Heliophysics STEREO
The goal of STEREO is to understand the origin the Sun's coronal mass ejections (CMEs) and their consequences for Earth. The mission consists of two spacecraft, one leading and the other lagging Earth in its orbit. The spacecraft carries instrumentation ...
20061025 October 25, 2006 3Operating
Heliophysics TIMED
Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) explores the energy transfer into and out of the Mesosphere and Lower Thermosphere/Ionosphere (MLTI) region of the Earth's atmosphere. This mission is part of SMD's Solar Terrestrial Probes Program.
20011207 December 07, 2001 3Operating